Chemical and toxicological evaluation of an emerging pollutant (enrofloxacin) by catalytic wet air oxidation and ozonation in aqueous solution

Efficiency of phytoremediation and identification of biotransformation pathways of fluoroquinolones in the aquatic environment

Phytoremediation is a low-cost and sustainable green technology that uses plants to remove organic and inorganic pollutants from aquatic environments. The aim of this study was to investigate the phytoextraction, phytoaccumulation, and phytotransformation of three fluoroquinolones (FQs) (ciprofloxacin [CIP], enrofloxacin [ENF], and levofloxacin [LVF]) by Japanese radish (Raphanus sativus var. longipinnatus) and duckweed (Lemma minor). Determination of FQs and identification of their transformation products (TPs) were performed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Inter-tissue translocation of FQs in Japanese radish tissues depended on their initial concentration in the medium. CIP (IT = 14.4) and ENF (IT = 17.0) accumulated mainly in radish roots, while LVF in leaves (IT = 230.8) at an initial concentration of 10 µg g-1. CIP (2,104 ng g-1) was detected in the highest concentration, followed by ENF (426.3 ng g-1) and LVF (273.3 ng g-1) in the tissues of both plants. FQs' bioaccumulation factors were significantly higher for duckweed (1.490-18.240) than Japanese radish (0.027-0.103). The removal of FQs from water using duckweed was mainly due to their photolysis and hydrolysis than plant sorption. In the screening, analysis detected 29 FQ TPs. The biotransformation pathways of FQs are described in detail, and the factors that influence their formation are indicated.

Preparation of multilayer strontium-doped TiO2/CDs with enhanced photocatalytic efficiency for enrofloxacin removal

Multilayer strontium-doped TiO₂/carbon dots (CDs) materials (TC) were produced via sol-gel-layered carbonization method. A thorough analysis of the fabricated composites via XRD, SEM, and XPS revealed that strontium ions, TiO₂ and CDs, were combined with each other to form layered structures. According to the UV-Vis diffuse reflectance spectrograms and (αhv)^1/2 vs. hv plots, the electron-donor property of strontium ions caused a more positive TC conduction band position than that in the pure TiO₂, thereby increasing the visible-light absorption range of TC. Based on the photocatalytic degradation data, the degradation rate of enrofloxacin was 84.7% at the dosage of 0.05 g·L^-1 and the concentration of 10 mg·L^-1. The capture experiments and ESR results showed that ·O₂^- and e^- played a major role in the degradation process of TC. The possible degradation mechanism of enrofloxacin was explained in terms of decarboxylation and defluorination, as was detected via ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis.

Detection and removal technologies for ammonium and antibiotics in agricultural wastewater: Recent advances and prospective

With the extensive development of industrial livestock and poultry production, a considerable part of agricultural wastewater containing tremendous ammonium and antibiotics have been indiscriminately released into the aquatic systems, causing serious harms to ecosystem and human health. In this review, ammonium detection technologies, including spectroscopy and fluorescence methods, and sensors were systematically summarized. Antibiotics analysis methodologies were critically reviewed, including chromatographic methods coupled with mass spectrometry, electrochemical sensors, fluorescence sensors, and biosensors. Current progress in remediation methods for ammonium removal were discussed and analyzed, including chemical precipitation, breakpoint chlorination, air stripping, reverse osmosis, adsorption, advanced oxidation processes (AOPs), and biological methods. Antibiotics removal approaches were comprehensively reviewed, including physical, AOPs, and biological processes. Furthermore, the simultaneous removal strategies for ammonium and antibiotics were reviewed and discussed, including physical adsorption processes, AOPs, biological processes. Finally, research gaps and the future perspectives were discussed. Through conducting comprehensive review, future research priorities include: (1) to improve the stabilities and adaptabilities of detection and analysis techniques for ammonium and antibiotics, (2) to develop innovative, efficient, and low cost approaches for simultaneous removal of ammonium and antibiotics, and (3) to explore the underlying mechanisms that governs the simultaneous removal of ammonium and antibiotics. This review could facilitate the evolution of innovative and efficient technologies for ammonium and antibiotics treatment in agricultural wastewater.

Secondary bond interface assembly of polyethyleneimine on zein microparticles for rapid adsorption of Reactive Black 5

Textile dye wastewater has the characteristics of high concentration, complex composition and changeable color degree and pH, which is difficult to be effectively and completely treated, and easy to cause environmental pollution. Here, a strategy of secondary bond interface assembly of polyethyleneimine on zein microparticles (PEI) (PEI@zein) was constructed to achieve rapid and efficient removal of Reactive Black 5 (RB5), which is one of the most widely used reactive dyes in the textile industry. Structural analysis indicated that the as-prepared PEI layer immobilized on zein microparticles was constructed based on the interface assembly dominated by hydrophobic interactions and electrostatic attraction between PEI molecules and zein chains. The novel interface showed excellent absorption performance for RB5 with an absorption capacity of 631.0 mg·g^-1, rapid adsorption in 2 min, wide pH range of 4-10. Mechanism analysis suggested the effective adsorption of RB5 by PEI@zein microparticles was mainly attributed to secondary bond interface such as electrostatic interaction and hydrogen bond between RB5 and PEI immobilized on the surface of zein microparticles. Moreover, due to the presence of secondary bond interface, RB5 adsorbed on microparticles can be easily desorbed by using 0.01 M NaOH. Therefore, the strategy of secondary bond interface assembly with polyethyleneimine on zein microparticles has high potential for practical application in the treatment of dye-containing wastewater.

Determination of antimicrobial agents and their transformation products in an agricultural water-soil system modified with manure

Manure fertilization is the primary source of veterinary antimicrobials in the water-soil system. The research gap is the fate of antimicrobials after their release into the environment. This study aimed to provide a detailed and multi-faceted examination of fertilized cultivated fields using two types of manure (poultry and bovine) enriched with selected antimicrobials. The research focused on assessing the mobility and stability of antimicrobials in the water-soil system. Additionally, transformation products of antimicrobials in the environment were identified. The extraction (solid-phase extraction and/or solid-liquid extraction) and LC-MS/MS analysis procedures were developed to determine 14 antimicrobials in the soil and pore water samples. Ten out of fourteen antimicrobials were detected in manure-amended soil and pore water samples. The highest concentration in the soil was 109.1 ng g^-1 (doxycycline), while in pore water, it was 186.6 ng L^-1 (ciprofloxacin). Sixteen transformation products of antimicrobials were identified in the soil and soil-related pore water. The same transformation products were detected in both soil and soil pore water extracts, with significantly higher signal intensities observed in soil extracts than in water. Transformation products were formed in oxidation, carbonylation, and ring-opening reactions.

Robust strategies to eliminate endocrine disruptive estrogens in water resources

The widespread occurrence and ubiquitous distribution of estrogens, i.e., estrone (E1), estradiol (E2), and estriol (E3) in our water matrices, is an issue of global concern. Public and regulatory authorities are concerned and placing joint efforts to eliminate estrogens and related environmentally hazardous compounds, due to their toxic influences on the environmental matrices, ecology, and human health, even at low concentrations. However, most of the available literature is focused on the occurrence of estrogens in different water environments with limited treatment options. Thus, a detailed review to fully cover the several treatment processes is needed. This review comprehensively and comparatively discusses many physical, chemical, and biological-based treatments to eliminate natural estrogens, i.e., estrone (E1), estradiol (E2), and estriol (E3) and related synthetic estrogens, e.g., 17α-ethinylestradiol (EE2) and other related hazardous compounds. The covered techniques include adsorption, nanofiltration, ultrafiltration, ultrasonication, photocatalysis of estrogenic compounds, Fenton, Fenton-like and photo-Fenton degradation of estrogenic compounds, electro-Fenton degradation of estrogenic compounds, ozonation, and biological methods for the removal of estrogenic compounds are thoroughly discussed with suitable examples. The studies revealed that treatment plants based on chemical and biological approaches are cost-friendly for removing estrogenic pollutants. Further, there is a need to properly monitor and disposal of the usage of estrogenic drugs in humans and animals. Additional studies are required to explore a robust and more advanced oxidation treatment strategy that can contribute effectively to industrial-scale applications. This review may assist future investigations, monitoring, and removing estrogenic compounds from various environmental matrices. In concluding remarks, a way forward and future perspectives focusing on bridging knowledge gaps in estrogenic compounds removal are also proposed.

Activation of persulfate by a water falling film DBD process for the enhancement of enrofloxacin degradation

A synergetic system of water falling film dielectric barrier discharge (DBD) plasma and persulfate (PS) was established and applied to enhance the enrofloxacin (EFA) degradation in this study. The simultaneous existence of electrons, reactive species, heat and UV-visible light in the DBD plasma system were utilized together to activate the PS to form SO₄^-· and other reactive oxygen species (ROS), and then worked in synergy with the DBD plasma to oxidize the EFA. The obtained results verified that there was a significant increase in the degradation percentages of EFA (20 mg L^-1) in the DBD/PS system, and the trend was more obvious under the condition of larger discharge power input. When 0.8 mM PS was added into the DBD system with 0.8 kW discharge power, the degradation percentage of EFA could reach 99.35% after 60 min treatment, the corresponding synergetic factor (SF) was 7.94. Analysis of the O₃ and the H₂O₂ concentrations in the DBD plasma system before and after the PS addition explained the activation of the PS by the HO·. The quenching experiments on reactive species suggested that SO4^-·, HO·, and ¹O₂ were all important reactive species for EFA degradation. The intermediates formed by the EFA degradation were detected and the degradation pathways were speculated. Results of toxicity analysis illustrated that the toxicity of the initial EFA solution decreased after degradation in the synergetic system of DBD/PS.

Uptake of Pharmaceutical Pollutants and Their Metabolites from Soil Fertilized with Manure to Parsley Tissues

Manure is a major source of soil and plant contamination with veterinary drugs residues. The aim of this study was to evaluate the uptake of 14 veterinary pharmaceuticals by parsley from soil fertilized with manure. Pharmaceutical content was determined in roots and leaves. Liquid chromatography coupled with tandem mass spectrometry was used for targeted analysis. Screening analysis was performed to identify transformation products in the parsley tissues. A solid-liquid extraction procedure was developed combined with solid-phase extraction, providing recoveries of 61.9–97.1% for leaves and 51.7–95.6% for roots. Four analytes were detected in parsley: enrofloxacin, tylosin, sulfamethoxazole, and doxycycline. Enrofloxacin was detected at the highest concentrations (13.4–26.3 ng g⁻¹). Doxycycline accumulated mainly in the roots, tylosin in the leaves, and sulfamethoxazole was found in both tissues. 14 transformation products were identified and their distribution were determined. This study provides important data on the uptake and transformation of pharmaceuticals in plant tissues.

Suspect screening of antimicrobial agents transformation products in environmental samples development of LC-QTrap method running in pseudo MRM transitions

The aim of the work was to develop a new HPLC-MS/MS method that allows for the simultaneous detection of antimicrobials agents (targeted analysis) and their transformation products (non-targeted analysis), which enabled the elucidation of their transformation pathways in the environment. Targeted analysis was performed for 16 selected antimicrobials agents (AMs) in wastewater collected at different stages of the treatment process and river water from sections before and after wastewater discharge. The samples were collected in the Łyna sewage treatment plant (Olsztyn, Poland) in three measuring periods at different seasons. Analytes were selected from tetracyclines, fluoroquinolones, β-lactams, macrolides, glycopeptides, lincosamides and synthetic antibiotics. As a part of the targeted analysis, 13 AMs were detected in wastewater samples, and 7 of them in river water samples. However, their presence and concentrations were closely related to the type of the sample and the season in which the sample was taken. The highest concentrations of AMs were detected in samples collected in September (max. 1643.7 ng L^-1 TRI), while the lowest AMs concentrations were found in samples collected in June (max. 136.1 ng L^-1 CLR). The total content of AMs in untreated wastewater was in the range of 1.42-1644 ng L^-1, while in the river water was for upstream 1.22-48.73 ng L^-1 and for downstream 2.24-149 ng L^-1. In the non-target analysis, 33 degradation products of the selected AMs were identified, and the transformation pathways of their degradation were speculated. In the course of the research, it was found that as a result of the processes taking place in wastewater treatment plant, the parent substances are transformed into a number of stable transformation products. Transformation products resulted from hydroxylation, ring opening, oxidation, methylation or demethylation, carboxylation, or cleavage of the CN bond of the parent AMs.

Bioelectrochemical systems for environmental remediation of estrogens: A review and way forward

Globally estrogenic pollutants are a cause of concern in wastewaters and water bodies because of their high endocrine disrupting activity leading to extremely negative impacts on humans and other organisms even at very low environmental concentrations. Bioremediation of estrogens has been studied extensively and one technology that has emerged with its promising capabilities is Bioelectrochemical Systems (BESs). Several studies in the past have investigated BESs applications for treatment of wastewaters containing toxic recalcitrant pollutants with a primary focus on improvement of performance of these systems for their deployment in real field applications. But the information is scattered and further the improvements are difficult to achieve for standalone BESs. This review critically examines the various existing treatment technologies for the effective estrogen degradation. The major focus of this paper is on the technological advancements for scaling up of these BESs for the real field applications along with their integration with the existing and conventional wastewater treatment systems. A detailed discussion on few selected microbial species having the unusual properties of heterotrophic nitrification and extraordinary stress response ability to toxic compounds and their degradation has been highlighted. Based on the in-depth study and analysis of BESs, microbes and possible benefits of various treatment methods for estrogen removal, we have proposed a sustainable Hybrid BES-centered treatment system for this purpose as a choice for wastewater treatment. We have also identified three pipeline tasks that reflect the vital parts of the life cycle of drugs and integrated treatment unit, as a way forward to foster bioeconomy along with an approach for sustainable wastewater treatment.

A comparative study among catalytic wet air oxidation, Fenton, and Photo-Fenton technologies for the on-site treatment of hospital wastewater

The feasibility of catalytic wet air oxidation, intensified homogeneous Fenton and heterogeneous Photo-Fenton systems for the treatment of real hospital wastewater has been investigated. Wastewater samples were collected from a hospital sewer, during a weekly monitoring program, and fully characterized. Up to seventy-nine pharmaceuticals, including mostly parent compounds and some of their transformation products, were analyzed. Catalytic wet air oxidation allowed the complete removal of several pharmaceutical groups, but it did not allow to eliminate analgesics/anti-inflammatories and antibiotics, whose average removal was around 85%. Intensified Fenton oxidation was the most efficient process for all the drugs removal with an almost complete reduction of the initial pharmaceutical load (99.8%). The heterogeneous Photo-Fenton system reached a 94.5% reduction of the initial pharmaceutical load. The environmental risk of the treated samples by the hazard quotient (HQ) method was also evaluated. Fenton oxidation was the most effective system with a final ∑HQ of 5.4. Catalytic wet air oxidation and Photo-Fenton systems achieved total ∑HQ values of 895 and 88, respectively. This fact was related to the presence of refractory antibiotics in the treated catalytic wet air oxidation samples. On the opposite, the Photo-Fenton system provided the elimination of most pharmaceutical pollutants that pose a high environmental risk such as antibiotics. Simplified cost estimation was finally performed as a preliminary approach of the economy of the three oxidation processes for the hospital wastewater treatment.

Titanium dioxide decorated natural cellulosic Juncus effusus fiber for highly efficient photodegradation towards dyes

The removal of dyes via photocatalytic degradation has been identified as an eco-friendly method for producing clean and purified water. Natural cellulosic fibers are significant renewable resource and important in a wide range of applications. Herein, we report a natural cellulosic Juncus effusus (JE) fiber with 3D network structure as a framework to provide controllable space for the growth of TiO₂ particles. The TiO₂-JE showed remarkable activity in the removal of C.I. Reactive Red 120 (RR120), C.I. Direct Yellow 12 (DY12), and methylene blue (MB) with a photodegradation efficiency of 99.9 % under simulated sunlight irradiation. Additionally, an orientate fabric was fabricated using the prepared TiO₂-JE fibers for the photocatalytic degradation of dye-contaminated water in the sun, further confirming its practical application. The TiO₂ decorated natural cellulosic JE fiber can be a promising material for photocatalysis and sustainable chemistry.

Ozone-assisted catalytic oxidation of aqueous nitrite ions on HZSM-5 zeolites

Simultaneous removal of NO_x and SO₂ during the wet absorption process has made it possible for nitrogen resource utilization. However, nitrites formation at high ratio in absorption solution would limit its application. In this study, the catalytic oxidation behaviors of aqueous nitrite ions assisted by ozone on HZSM-5 zeolites with different SiO₂/Al₂O₃ ratios have been investigated. The experimental results revealed that the oxidation and disproportionation reactions of nitrite ions took place competitively, both of which were accelerated under acidic condition. Moreover, the introduction of HZSM-5 zeolites and ozone would significantly improve the nitrite oxidation rate, where the zeolites with high SiO₂/Al₂O₃ ratios were found to be more effective owing to the enhanced adsorption of nitrite ions and ozone. Based on the results under different operating conditions (such as O₃ concentration, HZSM-5 dosage, pH values and presence of radical scavengers etc.), the reaction mechanism was then proposed. The disproportionation reaction of nitrite ions mainly occurred in the bulk solution. And the catalytic oxidation of nitrite ions over zeolites proceeded via a non-radical surface reaction between the adsorbed nitrite ions and ozone/oxygen molecular.

Highly flexible, mesoporous structured, and metallic Cu-doped C/SiO2 nanofibrous membranes for efficient catalytic oxidative elimination of antibiotic pollutants

The development of inorganic membranous catalysts with both large mesopores and superb flexibility is extremely favorable for the enhancement of their catalytic oxidation activity for the degradation of antibiotic pollutants in wastewater via sulfate radical-based advanced oxidation processes; however, there still exists a huge challenge for inorganic materials to simultaneously realize these two properties. Herein, metallic copper-doped carbon/silica nanofibrous membranes (Cu@C/SiO2 NFMs) with large mesopores, superb flexibility, and robust mechanical strength were fabricated through a sol-gel electrospinning and subsequent in situ carbonization reduction method. The synthesized Cu nanoparticles were homogeneously distributed throughout the mesoporous C/SiO2 nanofiber matrix, which enabled the resultant Cu@C/SiO2 NFMs to be applied as heterogeneous catalysts, and their catalytic performance was systematically assessed through activating persulfate for the elimination of tetracycline hydrochloride (TCH) in water. The fabricated Cu@C/SiO2 NFMs provided outstanding catalytic performance towards TCH with a high removal efficiency of 95% in 40 min and a rapid removal speed of 0.054 min-1. Moreover, the membranes could be facilely recycled through being directly separated from water without any post-processing. Such a facile strategy for preparing mesoporous and flexible metal-doped inorganic nanofibrous membranes may offer novel insights for designing new types of heterogeneous catalysts for antibiotic-containing wastewater treatment or other potential applications.

Performance of various catalysts on treatment of refractory pollutants in industrial wastewater by catalytic wet air oxidation: A review

The tremendous increase of industrialization and urbanization worldwide causes the depletion of natural resources such as water and air which urges the necessity to follow the environmental sustainability across the globe. This requires eco-friendly and economical technologies for depollution of wastewater and gases or zero emission approach. Therefore, in this context the treatment and reuse of wastewater is an environmental friendly approach due to shortage of fresh water. Catalytic wet air oxidation (CWAO) is a promising technology for the treatment of toxic and non-biodegradable organic pollutants in the wastewater generated from various industries. Various heterogeneous catalysts have been extensively used for treatment of various model pollutants such as phenols, carboxylic acids, nitrogenous compounds and different types of industrial effluents. The present review focuses on the literature published on the performances of various noble and non-noble metal catalysts for the treatment of various pollutants by CWAO. Reports on biodegradability enhancement of industrial wastewater containing toxic contaminants by CWAO are reviewed. Detailed discussion is made on catalyst deactivation and their mitigation study and also on the various factors which affects the CWAO reaction.

Maximization of current efficiency for organic pollutants oxidation at BDD, Ti/SnO2-Sb/PbO2, and Ti/SnO2-Sb anodes

Whereas electrochemical oxidation is noted for its ability to degrade bio-refractory organics, it has also been incorrectly criticized for excessive energy consumption. The present paper rectifies this misunderstanding by demonstrating that the energy actually consumed in the degradation process is much less than that wasted in the side reaction of oxygen evolution. To minimize the side reaction, the possible highest instantaneous current efficiency (PHICE) for electrochemical oxidation of phenol at Boron-doped Diamond (BDD), Ti/SnO₂-Sb/PbO₂ (PbO₂), and Ti/SnO₂-Sb (SnO₂) anodes has been investigated systematically, and found to reach almost 100% at the BDD anode compared with 23% at the PbO₂ anode and 9% at the SnO₂ anode. The significant discrepancy between PHICE values at the various anodes is interpreted in terms of different existing forms of hydroxyl radicals. For each anode system, the PHICEs are maintained experimentally using a computer-controlled exponential decay current mode throughout the electrolysis process. For applications, the minimized energy consumption is predicted by response surface methodology, and demonstrated for the BDD anode system. Consequently, almost 100% current efficiency is achieved (for a relatively meagre energy consumption of 17.2 kWh kgCOD^-1) along with excellent COD degradation efficiency by optimizing the initial current density, flow rate, electrolysis time, and exponential decay constant. Compared with galvanostatic conditions, over 70% of the energy is saved in the present study, thus demonstrating the great potential of electrochemical oxidation for practical applications.

Enhancement of anaerobic digestibility of waste activated sludge using photo-Fenton pretreatment

Biological treatments, such as activated sludge process, are common methods to treat municipal and industrial wastewaters. However, they produce huge amounts of waste activated sludge (WAS). The excess sludge treatment and disposal are a challenge for wastewater treatment plants due to economic, environmental, and regulatory factors. In this study, photo-Fenton pretreatment (oxidation using hydrogen peroxide and iron catalyst aided with UV light) was optimized using response surface methodology (RSM) and central composite design (CCD) to determine the effects of three operating parameters (H₂O₂ dosage, H₂O₂/Fe²⁺ molar ratio, and irradiation time) on disintegration and dewaterability of WAS. MLVSS removal, capillary suction time (CST) reduction, sCOD, and EPS were obtained as 70%, 25%, 12,000 mg/L, and 500 mg/L, respectively, at the optimal conditions, i.e., 725 g H₂O₂/kg TS, H₂O₂/Fe²⁺ molar ratio 80, and irradiation time 40 min. Two batch-fed completely mixed mesophilic anaerobic digesters were then operated at 15-day solid retention time (SRT) and 37 ± 0.5 °C to compare the digestibility of untreated and photo-Fenton pretreated sludge in terms of volatile solids (VS) reduction, COD removal, and biogas production at steady-state operations. Photo-Fenton pretreatment followed by anaerobic digestion of WAS was very effective and yielded 75.7% total VS reduction, 81.5% COD removal, and 0.29-0.31 m³/kg VS_fed·d biogas production rate, compared to 40.7% total VS solid reduction, 54.7% COD removal, and 0.12-0.17 m³/kg VS_fed·d biogas production rate for control. Thus, photo-Fenton can be a useful pretreatment step in sludge management.

Degradation of highly concentrated organic compounds over a supported Ru–Cu bimetallic catalyst

A Ru–Cu/Al–Ti-1 catalyst exhibited efficient performance in the CWAO of organic compounds due to synergistic effects between Ru and Cu.

Oxidation of ciprofloxacin and enrofloxacin by ferrate(VI): Products identification, and toxicity evaluation

Ferrate(VI) (Fe(VI)) has been known to react with emerging organic contaminants containing electron-rich organic moieties, such as phenols, anilines, olefins, reduced sulfur and deprotonated amines. Oxidation of fluoroquinolone antibiotics, ciprofloxacin (CIP) and enrofloxacin (ENR), by Fe(VI) were investigated for their reaction products and toxicity changes as well as biodegradability of these products. Ten products were identified for both CIP and ENR reactions with Fe(VI) using a high-resolution accurate-mass Orbitrap mass analyzer. Structural changes to the CIP and ENR molecule included dealkylation, formation of alcohols and amides in piperazine ring and oxygen transfer to the double bond in quinolone structure. An enamine formation mechanism was tentatively proposed to facilitate the interpretation of CIP and ENR oxidation pathways. Toxicity evaluation using Microbial Assay for toxicity Risk Assessment (MARA) bioassay indicated that Fe(VI) oxidation products of CIP and ENR contributed negligible antibacterial potency and Fe(VI) oxidation treatment can remove the residual toxicity of CIP and ENR impacted source waters. The Fe(VI) oxidation treatment resulted in formation of relatively more biodegradable products (based on in silico assessment) than their corresponding parent compounds. The results showed that Fe(VI) has a good potential to degrade fluoroquinolone antibiotics and their antimicrobial potency in natural waters.

Ce-Fe-reduced graphene oxide nanocomposite as an efficient catalyst for sulfamethazine degradation in aqueous solution

A heterogeneous Fenton catalyst Ce(0)-Fe(0)-reduced graphene oxide (Ce-Fe-RGO) was synthesized with chemical reduction methods and used for degradation of sulfamethazine. The introduction of Ce and graphene increased the dispersibility of iron particles which was confirmed by SEM and TEM. The results of VSM analysis showed good magnetism of Ce-Fe-RGO. The catalyst performance was compared with other kinds of catalysts (Fe(0) and Ce(0)-Fe(0)) for degradation of sulfamethazine. The results showed that Ce(0)-Fe-RGO had good catalytic performance and adsorption. X-ray diffraction showed the change of iron oxide on catalyst surface after use. The total sulfur (TS), total nitrogen (TN), total organic carbon (TOC), and intermediates, such as small organic molecular and anion ions, were analyzed by IC under different pH conditions. Finally, the possible catalytic mechanism was tentatively proposed based on inhibitor experimental results and XPS characterization. The main active species was hydroxyl radical on catalyst surface and the transition between Ce(3+) and Ce(4+) which enhanced the reduction from Fe(3+) to Fe(2+) and formation of ·OH and ·O2 (-).

Use of solar advanced oxidation processes for wastewater treatment: Follow-up on degradation products, acute toxicity, genotoxicity and estrogenicity

Wastewater tertiary treatment by advanced oxidation processes is thought to produce a treated effluent with lower toxicity than the initial influent. Here we performed tertiary treatment of a secondary effluent collected from a Waste Water Treatment Plant via homogeneous (solar/HSO5(-)/Fe(2+)) and heterogeneous (solar/TiO2) solar advanced oxidation aiming at the assessment of their effectiveness in terms of contaminants' and toxicity abatement in a plain solar reactor. A total of 53 organic contaminants were qualitatively identified by liquid chromatography coupled to high-resolution mass spectrometry after solid phase extraction. Solar advanced oxidation totally or partially removed the major part of contaminants detected within 4.5 h. Standard toxicity tests were performed using Vibrio fischeri, Daphnia magna, Pseudokirchneriella subcapitata and Brachionus calyciflorus organisms to evaluate acute and chronic toxicity in the secondary or tertiary effluents, and the EC50% was calculated. Estrogenic and genotoxic tests were carried out in an attempt to obtain an even sharper evaluation of potential hazardous effects due to micropollutants or their degradation by-products in wastewater. Genotoxic effects were not detected in effluent before or after treatment. However, we observed relevant estrogenic activity due to the high sensitivity of the HELN ERα cell line.

Homogenous VUV advanced oxidation process for enhanced degradation and mineralization of antibiotics in contaminated water

This study was aimed to evaluate the degradation and mineralization of amoxicillin(AMX), using VUV advanced process. The effect of pH, AMX initial concentration, presence of water ingredients, the effect of HRT, and mineralization level by VUV process were taken into consideration. In order to make a direct comparison, the test was also performed by UVC radiation. The results show that the degradation of AMX was following the first-order kinetic. It was found that direct photolysis by UVC was able to degrade 50mg/L of AMX in 50min,while it was 3min for VUV process. It was also found that the removal efficiency by VUV process was directly influenced by pH of the solution, and higher removal rates were achieved at high pH values.The results show that 10mg/L of AMX was completely degraded and mineralized within 50s and 100s, respectively, indicating that the AMX was completely destructed into non-hazardous materials. Operating the photoreactor in contentious-flow mode revealed that 10mg/L AMX was completely degraded and mineralized at HRT values of 120s and 300s. it was concluded that the VUV advanced process was an efficient and viable technique for degradation and mineralization of contaminated water by antibiotics.

Evaluation of the oxidation of enrofloxacin by permanganate and the antimicrobial activity of the products

Permanganate [Mn(VII)] oxidation of the fluoroquinolone (FQ) antibiotic enrofloxacin (ENR) was investigated with respect to kinetics and mechanisms, and the products were evaluated for residual antibacterial activity. The degradation of ENR by Mn(VII) obeyed second-order kinetics. A modern liquid chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer (LC-Q-TOF) was used to determine the accurate mass of the measured degradation products. The structures of nine oxidation products were identified at a neutral pH, one of which was an N-oxide product formed from the oxidation of tertiary amines. One proposed plausible reaction pathway was that the oxidation occurred on the piperazine ring; the C-H adjacent to the amine group was attacked by Mn(VII). The identified products from ENR arose through four pathways involving two mechanisms of N-dealkylation, C-hydroxylation and the reactions of amine oxides. The quinolone core remained intact for all of the products. The residual antibacterial activity of the oxidative reaction byproducts against the nonresistant Escherichia coli (G(-)) reference strain DH5ɑ was evaluated by quantifying the bacterial colonies. The oxidation products exhibited reduced antibacterial activity compared with their parent compound.

Ex-Situ Remediation Technologies for Environmental Pollutants: A Critical Perspective

Pollution and the global health impacts from toxic environmental pollutants are presently of great concern. At present, more than 100 million people are at risk from exposure to a plethora of toxic organic and inorganic pollutants. This review is an exploration of the ex-situ technologies for cleaning-up the contaminated soil, groundwater and air emissions, highlighting their principles, advantages, deficiencies and the knowledge gaps. Challenges and strategies for removing different types of contaminants, mainly heavy metals and priority organic pollutants, are also described.

Plasma metabonomics study on Chinese medicine syndrome evolution of heart failure rats caused by LAD ligation

BACKGROUND

Chinese medicine syndromes (Zheng) in many disease models are not clearly characterized or validated, and the concepts of Chinese medicine syndromes are confounding and controversial. Metabonomics has been applied to the evaluation and classification of the Chinese medicine syndromes both in clinical and nonclinical studies. In this study, we aim to investigate the evolution of the Chinese medicine syndrome in myocardial infarction induced heart failure and to confirm the feasibility of the Zheng classification by plasma metabonomics in a syndrome and disease combination animal model.

METHODS

The heart failure (HF) model was induced by ligation of the left anterior descending coronary artery (LAD) in Sprague-Dawley rats. The rats were divided into the following two groups: the HF model group (LAD ligation) and the sham operated group. GC-MS was used with pattern recognition technology and principal component analysis (PCA) to analyze the plasma samples at 4, 21 and 45 day after operation.

RESULTS

It was determined that the period from 7 to 28 days was the stable time window of ischemic heart failure with qi deficiency and blood stasis syndrome (QDBS), and the qi deficiency syndrome occurred at 1 to 4 days and 45 to 60 days after operation. The results exhibited 5 plasma metabolite changes in the same trend at 4 and 21 day after the LAD operation, 7 at 21 and 45 day, and 2 at 4 and 45 day. No metabolite showed the same change at all of the 3 time points. At day 21 (the QDBS syndrome time point) after operation, 4 plasma metabolites showed the same trends with the results of our previous study on patients with the blood stasis syndrome.

CONCLUSIONS

The syndrome diagnosis is reliable in the HF rat model in this study. Plasma metabolites can provide a basis for the evaluation of Chinese medicine syndrome animal models.

Degradation of phenol via wet-air oxidation over CuO/CeO2-ZrO2 nanocatalyst synthesized employing ultrasound energy: physicochemical characterization and catalytic performance

Catalytic wet air oxidation (CWAO) of phenol was carried out under atmospheric pressure of oxygen at 160 degrees C in a stirred batch reactor over copper catalysts supported by CeO2-ZrO2. The copper with different loadings were impregnated over the composite support by a sonication process. The catalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) specific surface area and Fourier-transformed infrared analyses. Characteristic peaks attributed to copper were not found in XRD patterns even at high loadings, but based on EDX results, the existence of copper particles was confirmed. It means that sonochemical synthesis method even at high loadings produced small copper particles with low crystallinity and excellent dispersion over the CeO2-ZrO2 composite. FESEM micrographs indicated just slight enhancement in particle size at high loadings of Cu. Blank CWAO experiments illustrated low conversion of phenol using bare CeO2-ZrO2 support. Although some agglomeration of particles was found at high loadings of copper but owning to the fact that almost all ZrO2 particles incorporated into the CeO2 lattice at high contents of Cu, catalyst activity not only did not decrease but also the phenol conversion reached to the higher values. The optimal catalyst loading for phenol degradation was found to be 9 g/l. Complete conversion of phenol was achieved using CuO/CeO2-ZrO2 in 9 g/l catalyst loading with initial phenol concentration of 1000 ppm after 3 h of reaction.

Activated sludge systems removal efficiency of veterinary pharmaceuticals from slaughterhouse wastewater

The knowledge on the efficiency of wastewater treatment plants (WWTPs) from animal food production industry for the removal of both hormones and antibiotics of veterinary application is still very limited. These compounds have already been reported in different environmental compartments at levels that could have potential impacts on the ecosystems. This work aimed to evaluate the role of activated sludge in the removal of commonly used veterinary drugs, enrofloxacin (ENR), tetracycline (TET), and ceftiofur, from wastewater during a conventional treatment process. For that, a series of laboratory-controlled experiments using activated sludge were carried out in batch reactors. Sludge reactors with 100 μg/L initial drug charge presented removal rates of 68 % for ENR and 77 % for TET from the aqueous phase. Results indicated that sorption to sludge and to the wastewater organic matter was responsible for a significant percentage of drugs removal. Nevertheless, these removal rates still result in considerable concentrations in the aqueous phase that will pass through the WWTP to the receiving environment. Measuring only the dissolved fraction of pharmaceuticals in the WWTP effluents may underestimate the loading and risks to the aquatic environment.

Treatment of refractory nano-filtration reject from a tannery using Pd-catalyzed wet air oxidation

We attempted catalytic wet air oxidation (CWAO) of nanofiltration (NF)-reject using Pd based catalyst viz., Pd/activated charcoal (AC) and PdCl2 with the objective of degradation of refractory organic pollutants. Refractory organic pollutants in NF-reject before and after WAO and CWAO were confirmed by GC-MS analysis. Experiments were conducted to investigate the effects of temperature, catalyst dosage and air partial pressure on the rate of removal of total organic carbon (TOC). The reaction kinetics can be conveniently described by considering two-stage first order kinetics. The use of Pd/AC afforded 85% TOC removal, the corresponding rate constant (k) was 2.90 ± 0.075 × 10(-3)min(-1) (Pd/AC, 100mg/L; T, 473.15K; Pair, 0.69 MPa). On the other hand, 75% TOC was removed with k=2.31 ± 0.075 × 10(-3)min(-1) using Pd(2+) catalyst (Pd(2+), 16.66 mg/L; T, 473.15K; Pair, 0.69 MPa). The observed rate of mineralization under Pd-catalyzed conditions was significantly higher than that of the uncatalyzed oxidation (41%) under the similar experimental conditions. Catalyst stability experiments were performed and TEM, SEM, XRD, Raman and XPS characterization data collected. Despite some morphological transformation of support, Pd catalyst was stable under CWAO conditions.