In-situ electro-generation and activation of hydrogen peroxide using a CuFeNLDH-CNTs modified graphite cathode for degradation of cefazolin

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

Deciphering the removal of antibiotics and the antibiotic resistome from typical hospital wastewater treatment systems

Hospital wastewater treatment systems (HWTSs) are a significant source and reservoir of antibiotic resistance genes (ARGs) and a crucial hub for transmitting ARGs from clinical to natural environments. However, there is a lack of research on the antibiotic resistome of clinical wastewater in HWTSs. In this study, we used metagenomics to analyze the prevalence and abundance of ARGs in five typical HWTSs. A total of 17 antibiotics from six categories were detected in the five HWTSs; β-lactam antibiotics were found at the highest concentrations, with up to 4074.08 ng·L-1. We further found a total of 21 ARG types and 1106 subtypes of ARGs with the highest percentage of multi-drug resistance genes (evgS, msbA, arlS, and baeS). The most abundant last-resort ARGs were mcr, which were detected in 100 % of the samples. HWTSs effluent is a major pathway for the transmission of last-resort ARGs into urban wastewater networks. The removal of antibiotics, antibiotic-resistant bacteria, and ARGs from HWTSs was mainly achieved by tertiary treatment, i.e., chlorine disinfection, but antibiotics and ARGs were still present in the HWTSs effluent or even increased after treatment. Moreover, antibiotics and heavy metals (especially mercury) in hospital effluents can exert selective pressure for antibiotic resistance, even at low concentrations. Qualitative analyses based on metagenome-assembled genome analysis revealed that the putative hosts of the identified ARGs are widely distributed among Pseudomonas, Acidovorax, Flavobacterium, Polaromonas, and Arcobacter. Moreover, we further assessed the clinical availability of ARGs and found that multidrug ARGs had the highest clinical relevance values. This study provides new impulses for monitoring and removing antibiotics and ARGs in the hospital sewage treatment process.

An enzyme-free sensor based on La-doped CoFe-layered double hydroxide decorated on reduced graphene oxide for sensitive electrochemical detection of urea

The successful synthesis of La-doped CoFe LDH@rGO nanocomposite is reported combining the advantages of LDH and rGO and shows promising performances in electrochemical sensors. The structure of the obtained nanocomposite was investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction pattern (XRD), and field emission scanning electron microscope images (FE-SEM). Then, it was directly utilized to construct a carbon paste electrode (CPE) for urea detection. The electrochemical performance of the sensor was evaluated by various electrochemical methods. The La-CoFe LDH@rGO electrode exhibited excellent electrocatalytic properties, including a wide linear working range of 0.001-23.5 mM, very high sensitivity of 1.07 ± 0.023 µA µM-1 cm-2, a low detection limit of 0.33 ± 0.11 µM, and rapid response time of 5 s towards urea detection at the working potential of 0.4 V. Furthermore, the sensor displayed a high selectivity in different matrices, appropriate reproducibility, and long shelf life without activity loss during 3 months of storage under ambient conditions. Further tests were performed on serum and milk samples to confirm the capability of the proposed sensor for practical applications, demonstrating a reasonable recovery of 94.8 to 102% with an RSD value below 3%. Consequently, the synergistic effect of each component led to the good electrocatalytic activity of the modified electrode towards urea.

Photocarrier transfer induced by Nδ- → Wδ+ in tungsten trioxide/carbon nitride for dual-path production of hydrogen peroxide towards ciprofloxacin degradation

Photo self-Fenton catalyst is a promising candidate for solar energy conversion and environmental remediation. Here we reported a Tungsten trioxide/carbon nitride (WO3/CN) in which the surficial amino groups on CN are inserted into the WO3 matrix, forming coordinate covalently Nδ- → Wδ+ in construction of an intimate S-scheme heterojunction. The intimantance promotes the transfer of photocarriers under light irradiation. The nanohybrids produced hydrogen peroxide (H2O2) in a rate about 20 times of pristine CN. A dual-path architecture in which H2O2 are produced via hole-water oxidation and electron-oxygen reduction was poposed. It is founded that ciprofloxacin also involved in production of H2O2 by their deprotonation to superoxide anions, and holes and hydroxyl radicals effectively attack the weak sites in skeleton of ciprofloxacin. This work suggests a great significance of strategy in self-producing of H2O2 in utilizing solar energy and molecular oxygen for water, particularly the surface water decontamination.

Soil aggregate-driven changes in nutrient redistribution and microbial communities after 10-year organic fertilization

Research studies on nutrient content and microbial communities after the application of organic manure have been reported, while available information about multi-interaction mechanisms of nutrient stoichiometry and microbial succession in soil aggregates remains limited. This work conducted a 10-year field experiment amended with cow manure (1.5 t/ha), during which the application of organic manure stimulated the fragmentation of soil macro-aggregates (>5 mm) and the agglomeration of soil micro-aggregates (<0.25 mm). Hence, the proportion of medium-size aggregates (0.25-5 mm) was increased in bulk soil, and there was an insignificant difference in the stability of soil aggregates. Meanwhile, the application of organic manure increased soil organic carbon (SOC), total nitrogen (TN) and phosphorus (TP) in all soil aggregate fractions. SOC, TN and TP were higher in micro-aggregates (<0.25 mm) after the application of organic manure, thus the dominating phylum of bacteria and fungi was more abundance in micro-aggregates due to the increase in nutrient level. During the organic fertilization process, fungal communities significantly changed because the variation of carbon-to-nitrogen ratio (C:N) in soil aggregates. Cultivated farmland in Northeast China showed a considerable capacity to sequestrate SOC during the organic fertilization process, but nitrogen may be a primary macro-element limiting soil productivity. Theoretically, organic manure amended with nitrogen fertilizer could be an effective measure to maintain microbial diversity and crop productivity in agro-ecosystems in Northeast China.

Efficient degradation of 2,4-dichlorophenol by heterogeneous electro-Fenton using bulk carbon aerogels modified in situ with FeCo-LDH as cathodes: Operational parameters and mechanism exploration

In this study, an in situ grown FeCo-Layered double hydroxide anchored to the surface of a bulk carbon aerogel (FeCo-LDH/CA) for contaminant degradation during the heterogeneous electro-Fenton (EF) process. The results exhibited that the FeCo-LDH/CA cathode achieved 100% of 2,4-dichlorophenol (2,4-DCP = 20 mg/L) degradation within 120 min at pH = 3, application current 20 mA, and Na2SO4 concentration 0.05 M. Moreover, the degradation efficiency was impressive in the range of pH = 2-9. The coexistence of the Fe (III)/Fe (II) and Co (III)/Co (II) as active sites on the cathode surface promoted the in-situ decomposition of H2O2 to form reactive oxygen species (ROS). •OH and O2- were confirmed to be the major degradation pollutants of ROS. Furthermore, density functional theory (DFT) was used to predict the reaction sites of 2,4-DCP, and its possible degradation pathways were proposed. The toxicity of intermediate products was evaluated and decreased after degradation. In addition, the eight cycle experiments and the degradation of other typical contaminants demonstrated the satisfactory stability and applicability of the synthetic cathode. This study presents the preparation of an efficient and stable EF cathode, further promoting the application of iron-based composites in wastewater treatment.

Carbon Gels-Green Graphene Composites as Metal-Free Bifunctional Electro-Fenton Catalysts

The Electro-Fenton (EF) process has emerged as a promising technology for pollutant removal. However, the EF process requires the use of two catalysts: one acting as an electrocatalyst for the reduction of oxygen to H2O2 and another Fenton-type catalyst for the generation of ·OH radicals from H2O2. Thus, the search for materials with bifunctionality for both processes is required for a practical and real application of the EF process. Thus, in this work, bifunctional electrocatalysts were obtained via doping carbon microspheres with Eco-graphene, a form of graphene produced using eco-friendly methods. The incorporation of Eco-graphene offers numerous advantages to the catalysts, including enhanced conductivity, leading to more efficient electron transfer during the Electro-Fenton process. Additionally, the synthesis induced structural defects that serve as active sites, promoting the direct production of hydroxyl radicals via a 3-electron pathway. Furthermore, the spherical morphology of carbon xerogels enhances the accessibility of the reagents to the active sites. This combination of factors results in the effective degradation of Tetracycline (TTC) using metal-free catalysts in the Electro-Fenton process, achieving up to an impressive 83% degradation without requiring any other external or additional catalyst.

Highly graphitic Fe-doped carbon xerogels as dual-functional electro-Fenton catalysts for the degradation of tetracycline in wastewater

Fe-doped carbon xerogels with a highly developed graphitic structure were synthesized by a one-step sol-gel polymerization. These highly graphitic Fe-doped carbons are presented as promising dual-functional electro-Fenton catalysts to perform both the electro-reduction of O₂ to H₂O₂ and H₂O₂ catalytic decomposition (Fenton) for wastewater decontamination. The amount of Fe is key to the development of this electrode material, since affects the textural properties; catalyzes the development of graphitic clusters improving the electrode conductivity; and influences the O₂-catalyst interaction controlling the H₂O₂ selectivity but, at the same time is the catalyst for the decomposition of the electrogenerated H₂O₂ to OH^• radicals for the organic pollutants oxidation. All materials achieve the development of ORR via the 2-electron route. The presence of Fe considerably improves the electro-catalytic activity. However, a mechanism change seems to occur at around -0.5 V in highly Fe-doped samples. At potential lower than -0.5 eV, the present of Fe^δ+ species or even Fe-O-C active sites favour the selectivity to 2e-pathway, however at higher potentials, Fe^δ+ species are reduced favoring a O-O strong interaction enhancing the 4e-pathway. The Electro-Fenton degradation of tetracycline was analyzed. The TTC degradation is almost complete (95.13%) after 7 h of reaction without using any external Fenton-catalysts.

A Comprehensive Review on Significance and Advancements of Antimicrobial Agents in Biodegradable Food Packaging

Food waste is key global problem and more than 90% of the leftover waste produced by food packaging factories is dumped in landfills. Foods packaged using eco-friendly materials have a longer shelf life as a result of the increased need for high-quality and secure packaging materials. For packaging purposes, natural foundation materials are required, as well as active substances that can prolong the freshness of the food items. Antimicrobial packaging is one such advancement in the area of active packaging. Biodegradable packaging is a basic form of packaging that will naturally degrade and disintegrate in due course of time. A developing trend in the active and smart food packaging sector is the use of natural antioxidant chemicals and inorganic nanoparticles (NPs). The potential for active food packaging applications has been highlighted by the incorporation of these materials, such as polysaccharides and proteins, in biobased and degradable matrices, because of their stronger antibacterial and antioxidant properties, UV-light obstruction, water vapor permeability, oxygen scavenging, and low environmental impact. The present review highlights the use of antimicrobial agents and nanoparticles in food packaging, which helps to prevent undesirable changes in the food, such as off flavors, colour changes, or the occurrence of any foodborne outcomes. This review attempts to cover the most recent advancements in antimicrobial packaging, whether edible or not, employing both conventional and novel polymers as support, with a focus on natural and biodegradable ingredients.

Degradation of emerging pollutants on bifunctional ZnFeV LDH@graphite felt cathode through prominent catalytic activity in heterogeneous electrocatalytic processes

The heterogeneous Electro-Fenton (EF) process is a promising wastewater treatment technology that can generate onsite H₂O₂, and operate in a wide pH range without generating a metal sludge. However, the heterogeneous EF process needs bifunctional cathode electrodes that can have high activity in 2e^- oxygen reduction reaction and H₂O₂ decomposition. Herein, ZnFeV layered double hydroxide (LDH), as a heterogeneous catalyst, was coated on the graphite felt (ZnFeV LDH@GF) cathode using the electrophoretic deposition method. ZnFeV LDH@GF cathode was able to generate 59.8 ± 5.9 mg L^-1 H₂O₂ in 90 min under a constant supply of O₂. EF process with ZnFeV LDH@GF cathode exhibited 89.8 ± 6.8% removal efficiency for pharmaceutical (ciprofloxacin) at neutral pH. Remarkably, the apparent reaction rate constant (k_app) of the ZnFeV LDH@GF-EF was 2.14 times that of the EF process with pristine GF. ZnFeV LDH coating increased the hydroxyl radical (^•OH) production of the EF process from 1.74 mM to 3.65 mM. The pathway of ^•OH production is thought to be a single electron transfer from redox couples of Fe²⁺/Fe³⁺ and [Formula: see text] to H₂O₂. After 10 reuse cycles, the ZnFeV LDH@GF cathode retained 90.2% of its efficiency. Eight intermediate compounds were identified by GC-MS including cyclic compounds and aliphatic compounds.

An Overview of Photocatalytic Membrane Degradation Development

Environmental pollution has become a worldwide issue. Rapid industrial and agricultural practices have increased organic contaminants in water supplies. Hence, many strategies have been developed to address this concern. In order to supply clean water for various applications, high-performance treatment technology is required to effectively remove organic and inorganic contaminants. Utilizing photocatalytic membrane reactors (PMRs) has shown promise as a viable alternative process in the water and wastewater industry due to its efficiency, low cost, simplicity, and low environmental impact. PMRs are commonly categorized into two main categories: those with the photocatalyst suspended in solution and those with the photocatalyst immobilized in/on a membrane. Herein, the working and fouling mechanisms in PMRs membranes are investigated; the interplay of fouling and photocatalytic activity and the development of fouling prevention strategies are elucidated; and the significance of photocatalysis in membrane fouling mechanisms such as pore plugging and cake layering is thoroughly explored.

From Fenton and ORR 2e−-Type Catalysts to Bifunctional Electrodes for Environmental Remediation Using the Electro-Fenton Process

Currently, the presence of emerging contaminants in water sources has raised concerns worldwide due to low rates of mineralization, and in some cases, zero levels of degradation through conventional treatment methods. For these reasons, researchers in the field are focused on the use of advanced oxidation processes (AOPs) as a powerful tool for the degradation of persistent pollutants. These AOPs are based mainly on the in-situ production of hydroxyl radicals (OH•) generated from an oxidizing agent (H2O2 or O2) in the presence of a catalyst. Among the most studied AOPs, the Fenton reaction stands out due to its operational simplicity and good levels of degradation for a wide range of emerging contaminants. However, it has some limitations such as the storage and handling of H2O2. Therefore, the use of the electro-Fenton (EF) process has been proposed in which H2O2 is generated in situ by the action of the oxygen reduction reaction (ORR). However, it is important to mention that the ORR is given by two routes, by two or four electrons, which results in the products of H2O2 and H2O, respectively. For this reason, current efforts seek to increase the selectivity of ORR catalysts toward the 2e− route and thus improve the performance of the EF process. This work reviews catalysts for the Fenton reaction, ORR 2e− catalysts, and presents a short review of some proposed catalysts with bifunctional activity for ORR 2e− and Fenton processes. Finally, the most important factors for electro-Fenton dual catalysts to obtain high catalytic activity in both Fenton and ORR 2e− processes are summarized.

Synthesis of Manganese Zinc Ferrite Nanoparticles in Medical-Grade Silicone for MRI Applications

The aim of this project is to fabricate hydrogen-rich silicone doped with magnetic nanoparticles for use as a temperature change indicator in magnetic resonance imaging-guided (MRIg) thermal ablations. To avoid clustering, the particles of mixed MnZn ferrite were synthesized directly in a medical-grade silicone polymer solution. The particles were characterized by transmission electron microscopy, powder X-ray diffraction, soft X-ray absorption spectroscopy, vibrating sample magnetometry, temperature-dependent nuclear magnetic resonance relaxometry (20 °C to 60 °C, at 3.0 T), and magnetic resonance imaging (at 3.0 T). Synthesized nanoparticles were the size of 4.4 nm ± 2.1 nm and exhibited superparamagnetic behavior. Bulk silicone material showed a good shape stability within the study’s temperature range. Embedded nanoparticles did not influence spin–lattice relaxation, but they shorten the longer component of spin–spin nuclear relaxation times of silicone’s protons. However, these protons exhibited an extremely high r2* relaxivity (above 1200 L s−1 mmol−1) due to the presence of particles, with a moderate decrease in the magnetization with temperature. With an increased temperature decrease of r2*, this ferro–silicone can be potentially used as a temperature indicator in high-temperature MRIg ablations (40 °C to 60 °C).

Critical Review on the Mechanisms of Fe2+ Regeneration in the Electro-Fenton Process: Fundamentals and Boosting Strategies

This review presents an exhaustive overview on the mechanisms of Fe³⁺ cathodic reduction within the context of the electro-Fenton (EF) process. Different strategies developed to improve the reduction rate are discussed, dividing them into two categories that regard the mechanistic feature that is promoted: electron transfer control and mass transport control. Boosting the Fe³⁺ conversion to Fe²⁺ via electron transfer control includes: (i) the formation of a series of active sites in both carbon- and metal-based materials and (ii) the use of other emerging strategies such as single-atom catalysis or confinement effects. Concerning the enhancement of Fe²⁺ regeneration by mass transport control, the main routes involve the application of magnetic fields, pulse electrolysis, interfacial Joule heating effects, and photoirradiation. Finally, challenges are singled out, and future prospects are described. This review aims to clarify the Fe³⁺/Fe²⁺ cycling process in the EF process, eventually providing essential ideas for smart design of highly effective systems for wastewater treatment and valorization at an industrial scale.

Investigation of CuCoFe-LDH as an efficient and stable catalyst for the degradation of acetaminophen in heterogeneous electro-Fenton system: Key operating parameters, mechanisms and pathways

Pharmaceuticals, as anthropogenic pollutants in a wide range of water sources, generally require specific treatment methods for degradation. A trimetallic layered double hydroxide (CuCoFe-LDH) was successfully fabricated by coprecipitation and applied as a novel heterogeneous electro-Fenton (EF) catalyst for the degradation of acetaminophen (ACT) from aqueous environments. The EF experiments showed that the CuCoFe-LDH/EF process achieved 100% of ACT degradation efficiency within 60 min at pH = 5, catalyst dosage of 0.50 g/L, current density of 10 mA/cm² and initial ACT concentration of 20 mg/L. An impressive (>80%) mineralization of ACT was obtained over a wide pH range (pH 3-9) after 180 min. Meanwhile, the role of ·OH and O₂^.- were certified by radical quenching experiments and electron paramagnetic resonance (EPR) analysis. Through mechanism exploration, the coexistence of Cu and Co on Fe-based LDHs can accelerate the interfacial electron transfer and promote the formation of the reactive oxygen species (ROS), thus facilitating the EF process. Furthermore, the degradation by-products and possible degradation pathways of ACT in the CuCoFe-LDH/EF process were proposed. The reusability test and the treatment of various typical organic pollutants experiments indicated that the CuCoFe-LDH/EF process has excellent stability and broad application prospects. This work provides a valuable reference for the treatment of pharmaceuticals by the heterogeneous EF process in a wide range of pH.

Hydrothermal Synthesis of Siderite and Application as Catalyst in the Electro-Fenton Oxidation of p-Benzoquinone

A weak aspect of the electro-Fenton (EF) oxidation of contaminants is the dependence of the Fenton reaction on acidic pH values. Therefore, the rationale of this work was to develop a novel catalyst capable of promoting the EF oxidation process at near-neutral and basic pH values. In this framework, rhombohedral FeCO₃ was synthesized hydrothermally and used as a catalyst in the EF oxidation of p-benzoquinone (BQ). The catalyst was characterized using various surface and spectroscopic methods. Moreover, the effects of applied current (100-500 mA), time (1-9 h), catalyst dosage (0.25-1.00 g L^-1), and initial concentration of BQ (0.50-1.00 mM) on the total organic carbon removal efficiency were determined. The results indicated that a 400 mA current was sufficient for a 95% total organic carbon removal and that the increase in catalyst dosage had a positive effect on the mineralization of BQ. It was determined that at pH 3, FeCO₃ behaved like a homogeneous catalyst by releasing Fe³⁺ ions; whereas, at the pH range of 5-7, it shifted to a homogeneous/heterogeneous catalyst. At pH 9, it worked solely as a heterogeneous catalyst due to the decrease of Fe ions passing into the solution. Finally, the spent catalyst did not undergo structural deformations after the EF treatment at higher pH values and could be regenerated and used several times.

Fabrication and characterization of Ti/polyaniline-Co/PbO2-Co for efficient electrochemical degradation of cephalexin in secondary effluents

The traditional interlayer of PbO₂ electrode possessed many problems, such as short service lifetime and limited specific surface area. Herein, a novel and efficient Ti/polyaniline-Co/PbO₂-Co electrode was conctructed employing cyclic voltammetry to introduce a Co-doped polyaniline interlayer and anodic electrodeposition to synthetize a β-PbO₂-Co active layer. Compared with pristine PbO₂ electrode, Ti/polyaniline-Co/PbO₂-Co exhibited more compact crystalline shape and higher active sites amounts. Pratically, the electrochemical degradation of 5 mg L^-1 cephalexin in real secondary effluents was effectively achieved by the novel anode with 87.42% cephalexin removal and 71.8% COD mineralization after 120 min of 15 mA cm^-2 electrolysis. The hydroxyl radical production and electrochemical stability were increased by 3.16 and 3.27 times respectively. The cephalexin degradation pathway was investigated by combining a density functional theory-based theoretical approach and LC-QTrap-MS/MS. The most likely cleavage point of the β-lactam ring was the O=C-N bond, whose attack would produce small molecular compounds containing the thiazole and 4, 6-thiazine rings. Further oxidation produced inorganic ions; quantitative investigations indicated the amino groups to undergo decomposition to form aqueous NH₄⁺, which was further oxidized to NO₃^-. The accumulation of NO₃^- and SO₄^2-, combined with a decrease in toxicity toward Escherichia coli, demonstrated the efficient mineralization of cephalexin on the Ti/polyaniline-Co/PbO₂-Co electrode.

Facile preparation of visible light-sensitive layered g-C3N4 for photocatalytic removal of organic pollutants

The graphite-phase carbon nitride (g-C₃N₄) photocatalytic materials were prepared by one-step calcination method to degrade methylene blue (MB) and potassium butyl xanthate (PBX) under visible light irradiation. The prepared g-C₃N₄ photocatalytic materials were investigated in detail by various characterizations, and the experiments showed that the graphitic phase carbon nitride photocatalytic materials were successfully prepared by the one-step calcination method. The material possesses excellent optical properties and strong visible light absorption, thus achieving photocatalytic degradation of MB and PBX. The catalyst dosage, pH, the initial concentration of pollutants have important effects on photocatalytic activity of MB and PBX. The photocatalytic degradation efficiency was 98.99% for MB and 96.83% for PBX under the optimal conditions (catalyst dosage, initial pollutant concentration and pH value were 500 mg L^-1, 20 mg L^-1 and 7, respevtively). The photocatalytic mechanisms on MB and PBX were elucidated. ·OH was the key specie for MB, while ·O₂^- was the key specie for PBX. This study advances the development of photocatalytic technology for mineral wastewater.

Removal of antibiotics from wastewaters by membrane technology: Limitations, successes, and future improvements

Antibiotics and related pharmaceuticals are applied to enhance public health and life quality. A major environmental concern is wastewaters from pharmaceutical industries, which contain significant amounts of antibiotics. Pharmaceutical industries apply conventional processes (biological, filtration, coagulation, flocculation, and sedimentation) for wastewater treatment, but these approaches cannot remove antibiotics completely. Moreover, unmetabolized antibiotics released by humans and animals are dangerous for municipal and effluent wastewater. Besides, antibiotic resistance is another challenge in treatment of wastewater for superbugs. This comprehensive study summarizes different techniques for antibiotic removal with an emphasis on membrane technology in individual and hybrid systems such as chemical, physical, biological, and conditional-based strategies. A combination of membrane processes with advanced oxidation processes (AOPs), adsorption, and biological treatments can be the right solution for perfect removal. Furthermore, this review briefly compares different procedures for antibiotic removal, which can be helpful for further studies with their advantages and drawbacks.

Recent trends on electrochemical determination of antibiotic Ciprofloxacin in biological fluids, pharmaceutical formulations, environmental resources and foodstuffs: Direct and indirect approaches

In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminants. These compounds can have both chronic and acute harmful effects on aquatic ecosystems and consequently on human health. Therefore, there is an urgent need for the development of extremely sensitive, portable, and low-cost devices to perform analysis. In the present review article, recent reports on the application of various voltammetric and photo-electrochemical techniques using different electrode materials for the determination of antibiotic Ciprofloxacin (CIPRO) are reported. This review provides an insight into direct and indirect electrochemical approaches as well as the photoelectrochemical methods used for the determination of CIPRO. Emphasis is put on the applications of unmodified and modified carbon-based electrodes considering the modifier, supporting electrolytes, analytical method, concentration range, limit of detection, and real matrices. Carbon-based electrodes are the most used materials attributed to their commercial availability, reduced cost, high chemical stability, and non-toxicity.

An intriguing Z-scheme titania loaded on fibrous silica ceria for accelerated visible-light-driven photocatalytic degradation of ciprofloxacin

A novel Z-scheme titania loaded on fibrous silica ceria (Ti-FSC) was triumphantly fabricated via hydrothermal followed by electrolysis method and evaluated for the visible-light degradation of ciprofloxacin (CIP). Noticeably, Ti-FSC exhibits as an efficient photocatalyst for CIP photodegradation with 95% as followed by titania loaded on fibrous silica (Ti-FS) (68%), Ti-CeO₂ (35%), FSC (47%), FS (22%), and CeO₂ (17%). The combination of the inherent merits of Ti loaded on FSC is able to realize the crucial role of Ce in harnessing the high dispersion of Ti, which could beneficial for improving the performance proven by XRD, FESEM, TEM and FTIR. Consequently, high dispersion of Ti on FSC has worthwhile towards the interaction of the Si-O-Ti, Ce-O-Ti, and Si-O-Ti, which could enhance the CIP photodegradation by providing more surface defects, narrowing the band gap, improving electron-hole separation and suppressing electron-hole recombination that revealed by XPS, UV-vis/DRS, Nyquist plots and PL studies, respectively. The scavenger study revealed that the controlling species in the system was hydroxyl radical and holes. A potential Z-scheme heterojunction mechanism for Ti-FSC was deduced from the band structure analysis. The possible photodegradation pathway was proposed based on GCMS analysis. Besides, the acceptable reusability, which exceeded 90% of degradation indicated the great application potential of Z-scheme Ti-FSC in wastewater treatment and others application.

Impact of Antibiotics as Waste, Physical, Chemical, and Enzymatical Degradation: Use of Laccases

The first traces of Tetracycline (TE) were detected in human skeletons from Sudan and Egypt, finding that it may be related to the diet of the time, the use of some dyes, and the use of soils loaded with microorganisms, such as Streptomyces spp., among other microorganisms capable of producing antibiotics. However, most people only recognise authors dating between 1904 and 1940, such as Ehrlich, Domagk, and Fleming. Antibiotics are the therapeutic option for countless infections treatment; unfortunately, they are the second most common group of drugs in wastewaters worldwide due to failures in industrial waste treatments (pharmaceutics, hospitals, senior residences) and their irrational use in humans and animals. The main antibiotics problem lies in delivered and non-prescribed human use, use in livestock as growth promoters, and crop cultivation as biocides (regulated activities that have not complied in some places). This practice has led to the toxicity of the environment as antibiotics generate eutrophication, water pollution, nutrient imbalance, and press antibiotic resistance. In addition, the removal of antibiotics is not a required process in global wastewater treatment standards. This review aims to raise awareness of the negative impact of antibiotics as residues and physical, chemical, and biological treatments for their degradation. We discuss the high cost of physical and chemical treatments, the risk of using chemicals that worsen the situation, and the fact that each antibiotic class can be transformed differently with each of these treatments and generate new compounds that could be more toxic than the original ones; also, we discuss the use of enzymes for antibiotic degradation, with emphasis on laccases.

A review on synergistic coexisting pollutants for efficient photocatalytic reaction in wastewater remediation

With the tremendous development of the economy and industry, the pollution of water is becoming more serious due to the excessive chemical wastes that need to remove thru reduction or oxidation reactions. Simultaneous removal of dual pollutants via photocatalytic redox reaction has been tremendously explored in the last five years due to effective decontamination of pollutants compared to a single pollutants system. In a photocatalysis mechanism, the holes in the valence band can remarkably promote the oxidation of a pollutant. At the same time, photoexcited electrons are also consumed for the reduction reaction. The synergistic between the reduction and oxidation inhibits the recombination of electron-hole pairs extending their lifetime. In this review, the binary pollutants that selectively removed via photocatalysis reduction or oxidation are classified according to heavy metal-organic pollutant (HM/OP), heavy metal-heavy metal (HM/HM) and organic-organic pollutants (OP/OP). The intrinsic between the pollutants was explained in three different mechanisms including inhibition of electron-hole recombination, ligand to metal charge transfer and electrostatic attraction. Several strategies for the enhancement of this treatment method which are designation of catalysts, pH of mixed pollutants and addition of additive were discussed. This review offers a recent perspective on the development of photocatalysis system for industrial applications.

Surfactant stabilized gold nanomaterials for environmental sensing applications - A review

Surfactant stabilized Gold (Au) nanomaterials (NMs) have been documented extensively in recent years for numerous sensing applications in the academic literature. Despite the crucial role these surfactants play in the sensing applications, the comprehensive reviews that highlights the fundamentals associated with these assemblies and impact of these surfactants on the properties and sensing mechanisms are still quite scare. This review is an attempt in organizing the vast literature associated with this domain by providing critical insights into the fundamentals, preparation methodologies and sensing mechanisms of these surfactant stabilized Au NMs. For the simplification, the surfactants are divided into the typical and advanced surfactants and the Au NMs are classified into Au nanoparticles (NPs) and Au nanoclusters (NCs) depending upon the complexity in structure and size of the NMs respectively. The preparative methodologies are also elaborated for enhancing the understanding of the readers regarding such assemblies. The case studies regarding surfactant stabilized Au NMs were further divided into colorimetric sensors, surface plasmonic resonance (SPR) based sensors, luminescence-based sensors, and electrochemical/electrical sensors depending upon the property utilized by the sensor for the sensing of an analyte. Future perspectives are also discussed in detail for the researchers looking for further progress in that particular research domain.

Constructing a 3D interconnected "trap-zap" β-CDPs/Fe-g-C3N4 catalyst for efficient sulfamethoxazole degradation via peroxymonosulfate activation: Performance, mechanism, intermediates and toxicity

A novel and high-efficiency catalyst Fe doped g-C₃N₄ (Fe-g-C₃N₄) composited with β-cyclodextrin polymers (β-CDPs) was synthesized for activating peroxymonosulfate (PMS). The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that the catalyst was 3D interconnected porous structure. The degradation rate constant of sulfamethoxazole (SMX) in β-CDPs/Fe-g-C₃N₄+PMS system was estimated to be 0.132 min^-1, which was 14.7 times and 2.2 times that of g-C₃N₄+PMS and Fe-g-C₃N₄+PMS system, respectively. In addition, the β-CDPs/Fe-g-C₃N₄ exhibited superior degradation performance in a wide pH range (3.0-9.0) and good selectivity in the presence of other inorganic anions and natural organics. Radical scavenging, electron paramagnetic resonance (EPR) and electrochemical measurements indicated that ¹O₂ and Fe(V)O were the main active species for SMX degradation in β-CDPs/Fe-g-C₃N₄+PMS system. Moreover, β-CDPs accelerated electron transfer between catalyst and PMS and promoted the generation of reactive oxygen species (ROS) during PMS activation. The loading of β-CDPs increased the yields of Fe(V)O and ¹O₂ in the system and limited the leaching of Fe³⁺. In addition, the possible degradation pathways of SMX were described based on the intermediates detected by liquid chromatography-mass spectrometry (LC-MS), and the toxicity of the intermediates was also evaluated. This work investigate the role of β-CDPs in PMS activation for the first time and develop a promising material with potential for water treatment.

A sensitive colori/fluorimetric nanoprobe for detection of polyphenols using peroxidase-mimic plasma-modified MoO3 nanoparticles

Herein, MoO₃ nanoparticles were synthesized and modified using Argon cold plasma treatment (Ar-MoO₃NPs) for the first time. Various characterization studies were performed using various methods, including SEM, XRD, and FTIR techniques. The catalytic activity of MoO₃NPs before and after modification was investigated using fluorometric and colorimetric experiments. The results indicated that the enzyme-mimic activity of MoO₃NPs increased after plasma-surface modification (1.5 fold). Also, a fluorometric method based on the oxidation of a non-fluorescent terephthalic acid by Ar-MoO₃NPs in the presence of H₂O₂ and the production of a compound with a high emission was designed for polyphenols detection. Quercetin was used as a polyphenol standard for the optimization of the proposed system. Under the optimum conditions, the dynamic ranges of the calibration graphs and the detection limits were calculated for different polyphenols (μmol/L): quercetin (2-232, 12.22), resveratrol (2-270, 61.89), curcumin (39-400, 38.89), gallic acid (2-309, 21.5) and ellagic acid (39-309, 16.25). Also, the precision of the method, which was expressed as RSD%, was in the range of 0.286-1.19%. The proposed system could detect individual polyphenols and total polyphenols in three different fruit extracts (apple, orange, and grapes) with high sensitivity. The obtained total concentrations of polyphenols in real samples were comparable to those calculated by the spectrophotometric method. So, a novel and sensitive optical nanosensor for the detection of polyphenols was reported as an alternative to the routine Folin-Ciocalteu spectrophotometric technique.

Interaction of bovine serum albumin with ellagic acid and urolithins A and B: Insights from surface plasmon resonance, fluorescence, and molecular docking techniques

Human serum albumin (HSA) shows the sequence homology and structural similarity with bovine serum albumin (BSA). Therefore, here, the interaction of natural phenolic antioxidants, ellagic acid (ELA), and its derivatives-urolithins A (ULA) and B (ULB)-with BSA was investigated. The results of surface plasmon resonance (SPR) indicated a high affinity of ELA, ULA, and ULB to BSA, with KD value < 1 × 10-6 M. The KD values of binding of the studied compounds to BSA increased with temperature, revealing a reduction in affinity with an increase in temperature. Fluorescence data showed that the quenching of BSA by tested compounds occurred via a static quenching. However, the affinity of ELA for BSA was higher than that of ULA and ULB, which may be because of the presence of a large number of hydroxyl groups in its structure. The assessment of the antioxidant activity of BSA and BSA-ELA/ULA/ULB complexes using the DPPH assay indicated that the DPPH scavenging activity of BSA increased after complex formation with ELA/ULA/ULB in the following order: BSA-ELA > BSA-ULA > BSA-ULB > BSA, which was due to their structural differences. The results of the docking analysis were in agreement with the experimental results.

Graphene-derived antibacterial nanocomposites for water disinfection: Current and future perspectives

Antimicrobial nanomaterials provide numerous opportunities for the synthesis of next-generation sustainable water disinfectants. Using the keywords graphene and water disinfection and graphene antibacterial activity, a detailed search of the Scopus database yielded 198 and 1433 studies on using graphene for water disinfection applications and graphene antibacterial activity in the last ten years, respectively. Graphene family nanomaterials (GFNs) have emerged as effective antibacterial agents. The current innovations in graphene-, graphene oxide (GO)-, reduced graphene oxide (rGO)-, and graphene quantum dot (GQD)-based nanocomposites for water disinfection, including their functionalization with semiconductor photocatalysts and metal and metal oxide nanoparticles, have been thoroughly discussed in this review. Furthermore, their novel application in the fabrication of 3D porous hydrogels, thin films, and membranes has been emphasized. The physicochemical and structural properties affecting their antibacterial efficiency, such as sheet size, layer number, shape, edges, smoothness/roughness, arrangement mode, aggregation, dispersibility, and surface functionalization have been highlighted. The various mechanisms involved in GFN antibacterial action have been reviewed, including the mechanisms of membrane stress, ROS-dependent and -independent oxidative stress, cell wrapping/trapping, charge transfer, and interaction with cellular components. For safe applications, the potential biosafety and biocompatibility of GFNs in aquatic environments are emphasized. Finally, the current limitations and future perspectives are discussed. This review may provide ideas for developing efficient and practical solutions using graphene-, GO-, rGO-, and GQD-based nanocomposites in water disinfection by rationally employing their unique properties.

Heterogeneous Advanced Oxidation Processes: Current Approaches for Wastewater Treatment

Nowadays, water pollution is one of the most dangerous environmental problems in the world. The presence of the so-called emerging pollutants in the different water bodies, impossible to eliminate through conventional biological and physical treatments used in wastewater treatment plants due to their persistent and recalcitrant nature, means that pollution continues growing throughout the world. The presence of these emerging pollutants involves serious risks to human and animal health for aquatic and terrestrial organisms. Therefore, in recent years, advanced oxidation processes (AOPs) have been postulated as a viable, innovative and efficient technology for the elimination of these types of compounds from water bodies. The oxidation/reduction reactions triggered in most of these processes require a suitable catalyst. The most recent research focuses on the use and development of different types of heterogeneous catalysts, which are capable of overcoming some of the operational limitations of homogeneous processes such as the generation of metallic sludge, difficult separation of treated water and narrow working pH. This review details the current advances in the field of heterogeneous AOPs, Fenton processes and photocatalysts for the removal of different types of emerging pollutants.

Comparative degradation of 5-fluorouracil in aqueous solution by using H2O2-modified subcritical water, photocatalytic oxidation and electro-Fenton processes

This study investigated the degradation of the antineoplastic agent 5-fluorouracil (5-FU) widely applied to treat different cancers using different advanced oxidation processes such as electro-Fenton (EF), photocatalysis with TiO_2, and H₂O₂-modified subcritical water oxidation. The treatment with the EF process was the most efficient compared to others. Interestingly, in the EF process, the oxidative degradation of 5-FU behaved differently depending on the anode used. At low currents (20 and 40 mA), Pt and DSA anodes performed better than BDD and Ti₄O₇ anodes. In contrast, at the higher current of 120 mA, the production of heterogeneous hydroxyl radicals (M(^•OH)) became important and contributed significantly to the oxidation of 5-FU in addition to homogeneous ^•OH generated in the bulk solution. These latter have high O₂-evolution overpotential leading to the high amount of physisorbed M(^•OH) compared to Pt and DSA. The oxidative degradation of 5-FU was then performed by titanium dioxide-based photocatalytic oxidation and subcritical water oxidation processes, both of which showed a lower degradation efficiency and failed to achieve complete mineralization. Finally, a comparison was performed in laboratory-scale, taking into account the following performance indicators: the degradation efficiency, the mineralization power, the cost of equipment and reagents, and the energy required for the treatment of 5-FU.

MoS2/N-TiO2/Ti mesh plate for visible-light photocatalytic ozonation of naproxen and industrial wastewater: comparative studies and artificial neural network modeling

This paper presents the results of visible-light assisted photocatalytic ozonation for the degradation of naproxen as a model pharmaceutical pollutant from water using MoS₂/N-TiO₂ immobilized on a titanium mesh plate in addition to treatment of a real industrial wastewater. The batch studies were performed for naproxen degradation by varying the reaction variables such as ozone flow rate, initial pH and pollutant concertation. It was observed that almost 90% degradation was achieved at pH = 4, ozone flow rate = 3 L min^-1 and initial naproxen concentration = 5 mg L^-1. The catalyst exhibited constant activity even after seven successive cycles. Comparative studies among sorption, ozonation, photocatalysis, catalytic ozonation and photocatalytic ozonation revealed that the later process had the highest degradation of pollutant. Moreover, an artificial neural network (ANN) model was developed to simulate the performance of visible-light photocatalytic ozonation in naproxen degradation. The developed ANN model could estimate the visible-light photocatalytic ozonation process under the different experimental conditions. Finally, the applicability of the photocatalytic ozonation was successfully approved for industrial wastewater treatment. The results showed that the COD removal efficiency reached 65% within 150 min. HIGHLIGHTS: • MoS₂/N-TiO₂/Ti was synthesized by the quick electrophoretic deposition method. • The catalyst showed good ability in naproxen degradation via visible-light photocatalytic ozonation. • A three-layer artificial neural network model was developed to predict the naproxen degradation. • Naproxen degradation efficiency through the photocatalytic ozonation was higher than the individual methods. • COD of real wastewater was reduced significantly after the visible-light photocatalytic ozonation process.

Layered double hydroxide based materials applied in persulfate based advanced oxidation processes: Property, mechanism, application and perspectives

Recently, persulfate-based advanced oxidation processes (persulfate-AOPs) are booming rapidly due to their promising potential in treating refractory contaminants. As a type of popular two-dimensional material, layered double hydroxides (LDHs) are widely used in energy conversion, medicine, environment remediation and other fields for the advantages of high specific surface area (SSA), good tunability, biocompatibility and facile fabrication. These excellent physicochemical characteristics may enable LDH-based materials to be promising catalysts in persulfate-AOPs. In this work, we make a summary of LDHs and their composites in persulfate-AOPs from different aspects. Firstly, we introduce different structure and important properties of LDH-based materials briefly. Secondly, various LDH-based materials are classified according to the type of foreign materials (metal or carbonaceous materials, mainly). Latterly, we discuss the mechanisms of persulfate activation (including radical pathway and nonradical pathway) by these catalysts in detail, which involve (i) bimetallic synergism for radical generation, (ii) the role of carbonaceous materials in radical generation, (iii) singlet oxygen (¹O₂) production and several special nonradical mechanisms. In addition, the catalytic performance of LDH-based catalysts for contaminants are also summarized. Finally, challenges and future prospects of LDH-based composites in environmental remediation are proposed. We expect this review could bring new insights for the development of LDH-based catalyst and exploration of reaction mechanism.

Occurrence and distribution of antibiotics in groundwater, surface water, and sediment in Xiong'an New Area, China, and their relationship with antibiotic resistance genes

The emergence and pollution of antibiotics in surface water in various regions have drawn widespread concern because of the harm to aquatic ecosystems and human health. In this study, we aim to first investigate contamination and ecological risks of 39 antibiotics in Xiong'an New Area (XANA), China, and then illuminate relative abundances of antibiotic resistance genes (ARGs) and their correlations with antibiotics. The sum of antibiotic concentrations in the water circulation system, including surface water, groundwater, and sediment was 12.71-260.56 ng/L, ND-196.12 ng/L, and 38.03-406.31 ng/g, respectively. In surface water and sediment, cephalosporins and quinolones were the primary antibiotics, accounting for 45% and 16% of the total antibiotic concentrations in surface water and for 62% and 32% of the total antibiotic concentrations in sediment; this suggests a significant interaction between the two media. The antibiotic concentration was the highest in shallow groundwater at depths of <50 m (mean concentration of 79.22 ± 56.46 ng/L), indicating that surface water was a possible source of antibiotic contamination in groundwater. AMX presented the highest risk in both surface and groundwater and should be controlled as a priority. Moreover, the selection pressure of antibiotics on ARGs was discovered in the sediment in XANA, because the enrichment of sulA was significantly correlated with spiramycin and lincomycin and the enrichment of bla_OXA-1 was significantly correlated with roxithromycin, ciprofloxacin, ofloxacin, and sulfapyridine. Thus, our investigation revealed potential antibiotic contamination in multiple environmental media in XANA, which should be addressed to prevent more serious pollution.

Layered double hydroxides for removing and recovering phosphate: Recent advances and future directions

Eutrophication is a widespread environmental challenge caused by excessive phosphate. Thus, wastewater engineers primarily aim to limit the phosphate concentration in water bodies. Layered double hydroxides (LDHs) are lamellar inorganic materials containing tunable brucite-like structures. This review discusses the fundamental aspects and latest developments in phosphate removal using LDH-based materials. Based on the divalent cations, Ca, Mg, and Zn-containing LDHs are largely used along with trivalent cations such as Al and Fe owing to their limited toxicities. However, classical LDHs are affected by the presence of co-existing anions, have a narrow working pH range, and have moderate adsorption capacities. Binary LDHs have been designed to be selective towards phosphate by the addition of a third metal such as Zr⁴⁺. Developing LDH composites with magnetic, polymeric or carbon materials are feasible approaches for increasing adsorption capacity, stability, and reusability of LDHs. Biochar as a carrier material for LDHs achieved remarkable phosphate adsorption performance and improved LDH dispersion, anion exchange capacity, and ease of separation. The use of recovered phosphate as an SRF, which is a type of bioavailable fertilizer, is a promising approach.

One-step preparation of Co2V2O7: synthesis and application as Fenton-like catalyst in gas diffusion electrode

Bimetallic oxides and MOFs have been employed as catalysts for ORR via two-electron and Fenton-based processes. This work reports the development of a new green one-step route for obtaining Co2V2O7....

Determination of Salicylic Acid Using a Highly Sensitive and New Electroanalytical Sensor

Background:

A drug sensor (salicylic acid, in this case) was designed and made up of this research. The senor was made by modification of paste electrode (MPE) with CuO-SWCNTs and 1-hexyl-3-methylimidazolium chloride (HMICl). The MPE/CuO-SWCNTs/HMICl showed catalytic activity for the oxidation signal of salicylic acid in phosphate buffer solution.

Methods:

Electrochemical methods were used as a powerful strategy for the determination of salicylic acid in pharmaceutical samples. Aiming at this goal, carbon paste electrode was amplified with conductive materials and used as a working electrode.

Results:

The MPE/CuO-SWCNTs/HMICl was used for the determination of salicylic acid in the concentration range of 1.0 nM – 230 µM using differential pulse voltammetric (DPV) method. At pH=7.0, as optimum condition, the MPE/CuOSWCNTs/HMICl displayed a high-quality ability for the determination of salicylic acid in urine, pharmaceutical serum, and water samples.

Conclusion:

The MPE/CuO-SWCNTs/HMICl was successfully used as a new and high performance working electrode for the determination of salicylic acid at a nanomolar level and in real samples.

High-performance carbon black electrode for oxygen reduction reaction and oxidation of atrazine by electro-Fenton process

The aim of this study is to produce an electrode that can be used in H₂O₂ production and Electro-Fenton (EF) process by an effective, cheap, and easy method. For this reason, a superhydrophobic electrode with a higher PTFE ratio and high thickness was produced with a simple press. The produced electrode was used in the production of H₂O₂ and mineralization of Atrazine. First, the effect of pH, cathode voltage, and operation time on H₂O₂ production was evaluated. The maximum H₂O₂ concentration (409 mg/L), the highest current efficiency (99.80%), and the lowest electrical energy consumption (3.16 kWh/kg) were obtained at 0.8 V, 7.0 of pH, and 120 min, and the stability of the electrode was evaluated up to 720 min. Then, the effects of the operational conditions (pH, cathode voltage, operating time, and catalyst concentration) in electro-Fenton were evaluated. The fastest degradation of Atrazine (>99%) was obtained at 2.0 V, 3.0 of pH, and 0.3 mM of Fe²⁺ in 15 min. In the final part of the study, the degradation intermediates were identified, and the characterization of the electrode was evaluated by SEM, XRD, FT-IR, tensiometer, potentiostat, and elemental analyzer.

Recent Advantages of Mediator Based Chemically Modified Electrodes; Powerful Approach in Electroanalytical Chemistry

Background:

Modified electrodes have advanced from the initial studies aimed at understanding electron transfer in films to applications in areas such as energy production and analytical chemistry. This review emphasizes the major classes of modified electrodes with mediators that are being explored for improving analytical methodology. Chemically modified electrodes (CMEs) have been widely used to counter the problems of poor sensitivity and selectivity faced in bare electrodes. We have briefly reviewed the organometallic and organic mediators that have been extensively employed to engineer adapted electrode surfaces for the detection of different compounds. Also, the characteristics of the materials that improve the electrocatalytic activity of the modified surfaces are discussed.

Objective:

Improvement and promotion of pragmatic CMEs have generated a diversity of novel and probable strong detection prospects for electroanalysis. While the capability of handling the chemical nature of the electrode/solution interface accurately and creatively increases , it is predictable that different mediators-based CMEs could be developed with electrocatalytic activity and completely new applications be advanced.

Zn0.94Mn0.06O for adsorption and photo-degradation of methyl orange dye under visible irradiation: Kinetics and isotherms study

Three photocatalyst-adsorbents consist of Zn_0.97Mn_0.03O, Zn_0.94Mn_0.06O, and Zn_0.92Mn_0.08O were synthesized by hydrothermal method and calcined at 800 °C. The structural and optical properties of the sample Zn_0.94Mn_0.06O were characterized by using XRD; TEM; SEM; EDS; DLS; and DRS. The surface of the sample Zn_0.94Mn_0.06O consists of nano-particles (<100 nm) and nano-holes (18.4 nm), also the band-gap of it was obtained 2.89 eV. Adsorption and photo-degradation of methyl orange (MO) dye was investigated in darkness and under visible light irradiation (200 W tungsten). The sample Zn_0.94Mn_0.06O showed the most decolorization efficiency in the shortest time, so that 0.15 g of it adsorbed and destroyed the MO dye molecules (99 ± 1 %) in 40 s under irradiation. The most adsorption capacity of Zn_0.94Mn_0.06O was obtained 30.06 mg/g and the mechanism of the dye adsorption was investigated by using BET analysis and zeta potential. Also the adsorption isotherm and kinetics were calculated for describing the adsorption of MO onto the Zn_0.94Mn_0.06O.

Properties and Recent Advantages of N,N’-dialkylimidazolium-ion Liquids Application in Electrochemistry

:

N,Nʹ-dialkylimidazolium-ion liquids is one of the important ionic liquids with a wide range of application as conductive electrolyte and in electrochemistry. The modified electrodes create a new view in fabrication of electroanalytical sensors. Many modifiers have beeen suggested for modification of electroanalytical sensor since many years ago. Over these years, ionic liquids and especially room temperature ionic liquids have attracted more attention due to their wide range of electrochemical windows and high electrical conductivity. N,Nʹ-dialkylimidazolium-ion liquids are one of the main important ionic liquids suggested for modification of bare electrodes and especially carbon paste electrodes. Although many review articles have reported onthe use of ionic liquids in electrochemical sensors, no review article has been specifically introduced so far on the review of the advantages of N,Nʹ-dialkylimidazolium ionic liquid. Therefore, in this review paper we focused on the introduction of recent advantages of N,Nʹ-dialkyl imidazolium ionic liquid in electrochemistry.

Photodeposition of CoOx nanoparticles on BiFeO3 nanodisk for efficiently piezocatalytic degradation of rhodamine B by utilizing ultrasonic vibration energy

Piezoelectric materials have received much attention due to their great potential in environmental remediation by utilizing vibrational energy. In this paper, a novel piezoelectric catalyst, CoOx nanoparticles anchored BiFeO3 nanodisk composite, was intentionally synthesized via a photodeposition method and applied in piezocatalytic degradation of rhodamine B (RhB) under ultrasonic vibration. The as-synthesized CoOx/BiFeO3 composite presents high piezocatalytic efficiency and stability. The RhB degradation rate is determined to be 1.29 h-1, which is 2.38 folds higher than that of pure BiFeO3. Via optimizing the reaction conditions, the piezocatalytic degradation rate of the CoOx/BiFeO3 can be further increased to 3.20 h-1. A thorough characterization was implemented to investigate the structure, piezoelectric property, and charge separation efficiency of the CoOx/BiFeO3 to reveal the nature behind the high piezocatalytic activity. It is found that the CoOx nanoparticles are tightly adhered and uniformly dispersed on the surface of the BiFeO3 nanodisks. Strong interaction between CoOx and BiFeO3 triggers the formation of a heterojunction structure, which further induces the migration of the piezoinduced holes on the BiFeO3 to CoOx nanoparticles. The recombination of electron-hole pairs is retarded, thereby increasing the piezocatalytic performance greatly. This work may offer a new paradigm for the design of high-efficiency piezoelectric catalysts.

Recent advances in degradation of pharmaceuticals using Bi2WO6 mediated photocatalysis - A comprehensive review

The pollution of water bodies by residual pharmaceuticals is a major problem globally. Bismuth tungstate mediated photocatalysis has been effective in the removal of these organics from water. Bismuth tungstate (Bi₂WO₆) has proven to be an excellent visible light active photocatalyst because of its non-toxicity, low band gap energy and ease of preparation. It has been widely applied for the removal of a wide array of organic pollutants, particularly dyes, from wastewater. However, recently, much attention has been channelled to its application for the degradation of pharmaceuticals. In this present review, the recent trends in the applications of Bi₂WO₆ based photocatalysts for the removal of pharmaceuticals in wastewater are comprehensively discussed. The fabrication of Bi₂WO₆ based photocatalysts with enhanced photocatalytic performances through morphology control, doping and formation of heterojunctions are highlighted. Much discussion centres on the mechanisms and possible degradation pathways of antibiotic pharmaceuticals in wastewater. Finally, areas needing more attention and investigation on the use of Bi₂WO₆ based photocatalysts for removal of pharmaceuticals from wastewater especially towards real-life applications are presented for future research directions.

Core-shell structured nanocomposites formed by silicon coated carbon nanotubes with anti-oxidation and electromagnetic wave absorption

The silicon coated Carbon nanotubes (CNTs) nanocomposite (CNTs@Si) with a shell structure was successfully synthesized by a simple chemical vapor deposition (CVD) method. In this work, the CNTs@Si is not only introduced as a structural material providing oxidation performance, but also as an extremely effective electromagnetic wave (EMW) absorption nanocomposite. Dielectric characteristics EMW absorption properties within the frequency range of 2-18 GHz of CNTs@Si were studied, and the oxidation resistance of CNTs@Si was characterized. Due to the dense space conductive network formed by CNTs, the EMW absorbing properties of CNTs@Si nanocomposite features excellent electromagnetic wave absorption capacity at a filling amount of 1%. The maximum reflection loss (RL) reaches -61.57 dB at the thickness of 1.8 mm, and a wide effective absorption bandwidth (EAB, RL < -10 dB) of 2.88 GHz is achieved. The obtained CNTs@Si core-shell nanocomposites exhibit excellent antioxidant performance and absorbing performance due to silicon bridging. Efficient electromagnetic wave absorption and excellent oxidation resistance of CNTs@Si can be regarded as a brand-new competitive candidate for EMW absorption materials in harsh environment.