Electrochemical degradation of diclofenac using three-dimensional electrode reactor with multi-walled carbon nanotubes

Peroxydisulfate activation by synergized modified AgCuFe2O4@GO nanoparticle electrode with anchored MnO2 in cefixime three-dimensional electrochemical degradation: Optimization and mechanisms

Cefixime (CFX) is a potent antibiotic against gram-positive and gram-negative bacteria that resists degradation and typical removal procedures. This research aimed to synthesize a modified AgCuFe2O4@GO nanoparticle electrode with anchored MnO2 for removing CFX by three-dimensional electrochemical oxidation. The physical and chemical characteristics of the nanocomposite were evaluated using various techniques, including FESEM, XRD, EDS-mapping, FTIR, BET, VSM, and TGA. The analysis found that the AgCuFe2O4@GO with anchored MnO2 nanoparticle electrode has a large specific surface area, acceptable crystal structure, good magnetic characteristics, and a quasi-spherical form. At pH 5, 40 mg/L of CFX concentration, 0.4 g/L of the nanocomposite, 3 cm of electrode interval, 0.12 mM of persulfate electrolyte, and 12.5 mA/cm2 of current density for 40 min, the process reached removal effectiveness of 97.1% for the synthetic sample and 90.7% removal efficiency for the actual sample, while had rate mineralization of 61.8% and 241.1 kWh/g energy consumption. Pseudo-first-order (R2 = 0.997) and Langmuir-Hinshelwood (R2 = 0.769) kinetic experiments provided values of KC = 7.788 mg/L.min and KL-H = 0.011 L/mg, respectively, confirming conformity to these models. The adsorption isotherms demonstrated that the CFX antibiotic complies with the Temkin model with an R2 of 0.959. The particle electrode eliminated 86.1% of the contaminant over five cycles of regeneration and recovery, showcasing outstanding chemical stability. Throughout this process, persulfate functioned as both an oxidizing agent and an electrolyte, so amplifying the production of active radicals that degrade the pollutant and improve removal efficiency. Due to its magnetic properties, chemical stability, reusability, and high efficiency, modified AgCuFe2O4@GO with anchored MnO2 is suggested for purifying industrial and medicinal wastewater.

Advances in three-dimensional electrochemical degradation: A comprehensive review on pharmaceutical pollutants removal from aqueous solution

Water pollution, stemming from various contaminants including organic and pharmaceutical pollutants, poses a significant global challenge. Amidst the array of methods available for pollutant mitigation, the three-dimensional electrochemical approach emerges as a standout solution due to its environmental compatibility, cost-effectiveness, and rapid efficiency. This study delves into the efficacy of three-dimensional electrochemical processes in purging organic and pharmaceutical pollutants from aqueous media. Existing research indicates that the three-dimensional electrochemical process, particularly when employing particle electrodes, exhibits notable success in degrading organic and pharmaceutical pollutants. This achievement is largely attributed to the ample specific surface area of particle electrodes and the shortened mass transfer distance, which collectively enhance efficiency in comparison to traditional two-dimensional electrochemical methods. Moreover, this approach is lauded for its environmental friendliness and cost-effectiveness. However, it is imperative to note that the efficacy of the process is subject to various factors including temperature, pH levels, and current intensity. While the addition of oxidants can augment process efficiency, it also carries the risk of generating intermediate compounds that impede the reaction. In conclusion, the three-dimensional electrochemical method proves to be a viable and practical approach, provided that process conditions are meticulously considered and adhered to. Offering advantages from both environmental and economic perspectives, this method presents a promising alternative to conventional water and wastewater treatment techniques.

Recent progress of particle electrode materials in three-dimensional electrode reactor: synthesis strategy and electrocatalytic applications

With the complete promotion of a green, low-carbon, safe, and efficient economic system as well as energy system, the promotion of clean governance technology in the field of environmental governance becomes increasingly vital. Because of its low energy consumption, great efficiency, and lack of secondary pollutants, three-dimensional (3D) electrode technology is acknowledged as an environmentally beneficial and sustainable way to managing clean surroundings. The particle electrode is an essential feature of the 3D electrode reactor. This study provides an in-depth examination of the most current advancements in 3D electrode technology. The significance of 3D electrode technology is emphasized, with an emphasis on its use in a variety of sectors. Furthermore, the particle electrode synthesis approach and mechanism are summarized, providing vital insights into the actual implementation of this technology. Furthermore, by a metrological examination of the research literature in this sector, the paper expounds on the potential and obstacles in the development and popularization of future technology.

Enhanced reduction of nitrate by TDER packed with surface-modified plastic particles electrodes

Based on Iron cathodes, nitrate could be selectively decomposed into other lower-valence nitrogen compounds, including ammonia, nitrogen gas, nitrite and nitric oxide, but the removal efficiencies of nitrate and total nitrogen (TN), are affected significantly by the synergistic effects of anodes, chloride electrolyte and conductive plastic particles electrodes. In this work, the base material Titanium (Ti) metal plates and plastic particles which surfaces were mainly coated with Ru-Sn oxidizing compounds, were applied as plates anodes and conductive particles electrodes in Three Dimensional Electrode Reactors (TDER). The Ti/RuSn plate anodes showed excellent performance on degrading nitrate, more nitrogen gas (83.84%) and less ammonia (15.51%) was produced, less TN and Iron ion (0.02 mg/L) was left in the wastewater, and less amount of chemical sludge (0.20 g/L) was produced. Furthermore, the removal efficiencies of nitrate and TN were further increased by the surface-modified plastic particles, which were cheap, reusable, corrosion-resistance, easy to obtain as manufactured materials and light to be suspended in waters. The degradation of nitrate and its intermediates was enhanced possibly by the continuous synergistic reactions initiated by hydrogen radicals, which was generated on the countless surficial active Ru-Sn sites of Ti/RuSn metal plate anodes and plastic particles electrodes, among residual nitrogen intermediates, most of ammonia was selectively converted to gaseous nitrogen by hypochlorite from chloride ion reaction.

Study on the performance efficiency, mechanism, power consumption and biochemical properties of E/Ce(IV)/PMS on the enhanced removal of RB19

In this study, an advanced oxidation process with E/Ce(IV) synergistic PMS (E/Ce(IV)/PMS) was established for the efficient removal of Reactive Blue 19 (RB19). The catalytic oxidation performance of different coupling systems was examined and the synergistic effect of E/Ce(IV) with PMS in the system was substantiated. The oxidative removal of RB19 in E/Ce(IV)/PMS was excellent, achieving a removal efficiency of 94.47% and a reasonable power consumption (EE/O value was 3.27 kWh·m^-3). The effect of pH, current density, Ce(IV) concentration, PMS concentration, initial RB19 concentration and water matrix on the removal efficiency of RB19 were explored. Additionally, quenching and EPR experiments showed that the solution contains different radicals such as SO₄^·-, HO∙ and ¹O₂, where ¹O₂ and SO₄^·- played key roles, but HO∙ just acted a weaker role. Ce ion trapping experiment confirmed that Ce(IV) was involved in the reaction process and played a major role (29.91%). RB19 was subject to three possible degradation pathways, and the intermediate products displayed well biochemical properties. To conclude, the degradation mechanism of RB19 was explored and discussed. In the presence of current, E/Ce(IV)/PMS performed a rapid Ce(IV)/Ce(III) cycle, continuously generating strong catalytic oxidation Ce(IV), The reactive radicals derived from the decomposition of PMS, in conjunction with Ce(IV) and direct electro-oxidation, efficiently destroyed the molecular structure of RB19 and showed an efficient removal rate.

Nonsteroidal anti-inflammatory drug diclofenac accelerates the emergence of antibiotic resistance via mutagenesis

Overuse of antimicrobial agents are generally considered to be a key factor in the occurrence of antibiotic resistance bacteria (ARB). Nevertheless, it is unclear whether ARB can be induced by non-antibiotic chemicals such as nonsteroidal anti-inflammatory drug (NSAID). Thus, the objective of this study is to investigate whether NSAID diclofenac (DCF) promote the emergence of antibiotic resistance in Escherichia coli K12 MG1655. Our results suggested that DCF induced the occurrence of ARB which showed hereditary stability of resistance. Meanwhile, gene variation was identified on chromosome of the ARB, and DCF can cause bacterial oxidative stress and SOS response. Subsequently, transcriptional levels of antioxidant (soxS, sodA, sodC, gor, katG, ahpF) and SOS (recA, lexA, uvrA, uvrB, ruvA, ruvB, dinB, umuC, polB) system-related genes were enhanced. However, the expression of related genes cannot be increased in high-dosage treatment compared with low-dosage samples because of cytotoxicity and cellular damage. Simultaneously, high-dosage DCF decreased the mutation frequency but enhanced the resistance of mutants. Our findings expand our knowledge of the promoting effect on the emergence of ARB caused by DCF. More attention and regulations should be given to these potential ecological and health risks for widespread DCF.

Research status of volatile organic compound (VOC) removal technology and prospect of new strategies: a review

As an important component of air pollution, the efficient removal of volatile organic compounds (VOCs) is one of the most important challenges in the world. VOCs are harmful to the environment and human health. This review systematically introduced the main VOC control technologies and research hotspots in recent years, and expanded the description of electrocatalytic oxidation technology and bimetallic catalytic removal technology. Based on a three-dimensional electrode reactor, the theoretical design of a VOC removal control technology using bimetallic three-dimensional particle electrode electrocatalytic oxidation was proposed for the first time. The future research focus of this method was analyzed, and the importance of in-depth exploration of the catalytic performance of particle electrodes and the system reaction mechanism was emphasized. This review provides a new idea for using clean and efficient methods to remove VOCs.

A non-steroidal drug "diclofenac" is a substrate for electrochemical degradation process using graphite anode

In the electrochemical degradation process, the elimination of organic pollutants could be enhanced using supporting electrolyte and applied voltage. After degradation of the target organic compound, some by-products are formed. Chlorinated by-products are the main products formed in the presence of sodium chloride. In the present study, an electrochemical oxidation process has been applied to diclofenac (DCF) using graphite as an anode and sodium chloride (NaCl) as a supporting electrolyte. Monitoring the removal of the by-products and elucidating them were provided using HPLC and LC-TOF/MS, respectively. A high removal% of 94% DCF was observed under the conditions: 0.5 g NaCl, 5 V, and 80 min of electrolysis, while the removal% of chemical oxygen demand (COD) was 88% under the same conditions, but 360 min of electrolysis was required. The pseudo-first-order rate constant values were quite varied based on the selected experimental conditions; the rate constants were between 0.0062 and 0.054 min^-1, between 0.0024 and 0.0326 min^-1 under the influence of applied voltage and sodium chloride, respectively. The maximum values of energy consumption were 0.93 and 0.55 Wh/mg using 0.1 g NaCl and 7 V, respectively. Some chlorinated by-products, C₁₃H₁₈Cl₂NO₅, C₁₁H₁₀Cl₃NO₄, and C₁₃H₁₃Cl₅NO₅, were selected and elucidated using LC-TOF/MS.

A Comprehensive Review for Removal of Non-Steroidal Anti-Inflammatory Drugs Attained from Wastewater Observations Using Carbon-Based Anodic Oxidation Process

Non-steroidal anti-inflammatory drugs (NSAIDs) (concentration <µg/L) are globally acknowledged as hazardous emerging pollutants that pass via various routes in the environment and ultimately enter aquatic food chains. In this context, the article reviews the occurrence, transport, fate, and electrochemical removal of some selected NSAIDs (diclofenac (DIC), ketoprofen (KTP), ibuprofen (IBU), and naproxen (NPX)) using carbon-based anodes in the aquatic environment. However, no specific protocol has been developed to date, and various approaches have been adopted for the sampling and elimination processes of NSAIDs from wastewater samples. The mean concentration of selected NSAIDs from different countries varies considerably, ranging between 3992−27,061 µg/L (influent wastewater) and 1208−7943 µg/L (effluent wastewater). An assessment of NSAIDs removal efficiency across different treatment stages in various wastewater treatment plants (WWTPs) has been performed. Overall, NSAIDs removal efficiency in wastewater treatment plants has been reported to be around 4−89%, 8−100%, 16−100%, and 17−98% for DIC, KTP, NPX, and IBU, respectively. A microbiological reactor (MBR) has been proclaimed to be the most reliable treatment technique for NSAIDs removal (complete removal). Chlorination (81−95%) followed by conventional mechanical biological treatment (CMBT) (94−98%) treatment has been demonstrated to be the most efficient in removing NSAIDs. Further, the present review explains that the electrochemical oxidation process is an alternative process for the treatment of NSAIDs using a carbon-based anode. Different carbon-based carbon anodes have been searched for electrochemical removal of selected NSAIDs. However, boron-doped diamond and graphite have presented reliable applications for the complete removal of NSAIDs from wastewater samples or their aqueous solution.

Carbon nanostructures: a comprehensive review of potential applications and toxic effects

There is no doubt that nanotechnology has revolutionized our life since the 1970s when it was first introduced. Nanomaterials have helped us to improve the current products and services we use. Among the different types of nanomaterials, the application of carbon-based nanomaterials in every aspect of our lives has rapidly grown over recent decades. This review discusses recent advances of those applications in distinct categories, including medical, industrial, and environmental applications. The first main section introduces nanomaterials, especially carbon-based nanomaterials. In the first section, we discussed medical applications, including medical biosensors, drug and gene delivery, cell and tissue labeling and imaging, tissue engineering, and the fight against bacterial and fungal infections. The next section discusses industrial applications, including agriculture, plastic, electronic, energy, and food industries. In addition, the environmental applications, including detection of air and water pollutions and removal of environmental pollutants, were vastly reviewed in the last section. In the conclusion section, we discussed challenges and future perspectives.

High efficiency three-dimensional electrochemical treatment of amoxicillin wastewater using Mn-Co/GAC particle electrodes and optimization of operating condition

In this work, Mn-Co/GAC particle electrode was prepared by loading Mn and Co as catalysts on granular activated carbon (GAC) and used in a three-dimensional (3D) electrochemical system for mineralization of amoxicillin wastewater. Observation results by SEM, EDS and XRD confirmed that Mn and Co catalysts were successfully loaded onto GAC. The electrochemical properties were measured using an electrochemical workstation. Mn-Co/GAC had a much higher oxygen evolution potential (1.46V) than GAC (1.1V), which demonstrated that it could effectively reduce the oxygen evolution side reaction. In addition, Mn-Co/GAC had an electrochemically active surface area 1.34 times that of GAC and a much smaller mass transfer resistance than GAC, which could provide favorable conditions for the degradation of pollutants. The investigation of the influences of single operating parameters on total organic carbon (TOC) removal rate and electrical energy consumption (EEC) indicated that current density and treatment time had the greatest effect. In order to maximize TOC removal rate and minimize EEC, optimization of operating parameters was also carried out using response surface method in combination with central composite design. The optimal operating parameters were determined as current density of 5.68 mA/cm², electrolyte concentration of 0.127M, particle electrode dosage of 31.14g and treatment time of 120min. Under this optimum operating condition, TOC removal rate of 85.24% and amoxicillin removal rate of 100% could be achieved with a low EEC of 0.073 kWh/g TOC. In addition, TOC removal rate and EEC were significantly improved compared to the use of bare GAC as particle electrode under the same operating conditions, demonstrating the excellent electrocatalytic ability of the new particle electrode Mn-Co/GAC. A possible mechanism of enhanced amoxicillin and TOC removal was also recommended. In summary, the 3D electrochemical method using Mn-Co/GAC particle electrodes is a suitable choice for amoxicillin wastewater treatment.

Adsorption of Sodium Diclofenac in Functionalized Palygoskite Clays

The effects of acid and organo-functionalizations on the surface of Brazilian palygorskite clay was investigated, evaluating its potential in the adsorptive capacity of the drug sodium diclofenac present in wastewaters. The modifications on the clay structure were investigated by X-ray diffraction, X-ray fluorescence, thermogravimetric, differential thermal analysis, Fourier transform infrared spectroscopy, surface area by N₂ adsorption (77.5 K) and Zeta potential. The experimental design was carried out to find the best conditions for the adsorption tests, in which concentration, mass and pH were significant. In the kinetic study, the pseudo-second-order model better described the adsorption process for acid and organo-functionalized samples. Such results indicate that the adsorption behavior probably occurs due to the phenomenon of chemisorption. Regarding the adsorption isotherms, the Langmuir model was the one that best adjusted both the experimental data of acid and the organo-functionalized samples, whose maximum adsorption capacity were 179.88 and 253.34 mg/g, respectively. This model also indicates that the sodium diclofenac is adsorbed to monolayers homogeneously through chemisorption. In general, the studied clays proved to be suitable adsorbents for the removal of sodium diclofenac.

Photocatalytic degradation of amoxicillin from aqueous solutions by titanium dioxide nanoparticles loaded on graphene oxide

The photocatalytic degradation of amoxicillin (AMX) by titanium dioxide nanoparticles loaded on graphene oxide (GO/TiO₂) was evaluated under UV light. Experimental results showed that key parameters such as initial pH, GO/TiO₂ dosage, UV intensity, and initial AMX concentration had a significant effect on AMX degradation. Compared to the photolysis and adsorption processes, the AMX degradation efficiency was obtained to be more than 99% at conditions including pH of 6, the GO/TiO₂ dosage of 0.4 g/L, the AMX concentration of 50 mg/L, and the intensity of 36 W. Trapping tests showed that all three hydroxyl radical (OH^•), superoxide radical (O₂^•-), and hole (h⁺) were produced in the photocatalytic process; however, h⁺ plays a major role in AMX degradation. Under UV irradiation, GO/TiO₂ showed excellent stability and recyclability for 4 consecutive reaction cycles. The analysis of total organic carbon (TOC) suggested that AMX could be well degraded into CO₂ and H₂O. The formation of NH₄⁺, NO₃^-, and SO₄^2- as a result of AMX degradation confirmed the good mineralization of AMX in the GO/TiO₂/UV process. The toxicity of the inlet and outlet samples of the process has been investigated by cultivation of Escherichia coli and Streptococcus faecalis, and the results showed that the condition is suitable for the growth of organisms. The photocatalytic degradation mechanism was proposed based on trapping and comparative tests. Based on the results, the GO/TiO₂/UV process can be considered as a promising technique for AMX degradation due to photocatalyst stability, high mineralization efficiency, and effluent low toxicity.

Progress in research and development of particle electrodes for three-dimensional electrochemical treatment of wastewater: a review

A three-dimensional (3D) electrochemical technology is regarded as a very effective industrial wastewater treatment method as it has high treatment efficiency, high current efficiency, and low energy consumption, and especially can completely mineralize nonbiodegradable organic pollutants. The core of the 3D electrochemical technology is a particle electrode, and the particle electrode plays several important roles for removing pollutants during the electrochemical reaction process. Many types of particle electrodes have been developed and used for different types of wastewater treatment. In this paper, a comprehensive review on the research and development of particle electrodes of the 3D electrochemical reactors for wastewater treatment is conducted. Specifically, the role that the particle electrode plays during the 3D electrochemical treatment of wastewater is thoroughly investigated and systematized. In addition, the different types of particle electrodes used in the 3D electrochemical wastewater treatment are classified into several types according to the presence or absence of a catalyst and the main components of the particle electrode or carrier. Also, focusing on the recent research results, the structural characteristics, performance, advantages and defects, and the role of catalyst components of each particle electrodes are evaluated. Finally, the direction and prospect of future research on the particle electrode is presented.

Diclofenac photodegradation with the Perovskites BaFeyTi1-yO3 as catalysts

Perovskite oxides BaFe_yTi_1-yO₃, with y = 0, 0.6, 0.8 and 1, were prepared by ceramic (CM) and complex polymerization methods (CPM) and utilized in UV-LED (365 nm) photocatalytic degradation assays of 25 mg L^-1 diclofenac (DIC) model solutions. BaTiO₃-CM was also used in the photocatalytic degradation test of a real mineral water for human consumption spiked with 2 mg L^-1 DIC. The XRD patterns of the synthesized perovskites showed cubic structure for those prepared by CPM, with distortions of the cubic lattice to hexagonal or tetragonal when prepared by CM, except for BaTiO₃. All the perovskites showed good catalytic activity, higher than photolysis, except BaFeO₃-CM that presented similar results. BaTiO₃-CM and CPM and BaFeO₃-CPM were also utilized in UV-LED photocatalytic DIC degradation assays with peroxydisulfate addition. BaFeO₃-CPM and BaTiO₃-CPM showed better ability to persulfate activation, but the highest mineralization degree was obtained with BaTiO₃-CM. This last perovskite was also able to perform DIC degradation in a real matrix. The studied oxides show potentiality for photocatalytic degradation of organic compounds, with or without persulfate addition. A degradation mechanism is proposed.

Catalytic degradation of mefenamic acid by peroxymonosulfate activated with MWCNTs-CoFe2O4: influencing factors, degradation pathway, and comparison of activation processes

The cobalt ferrite loaded on multi-walled carbon nanotubes (MWCNTs-CoFe₂O₄) was synthesized and used as a novel catalyst for the degradation of mefenamic acid (MFA) in the presence of peroxymonosulfate (PMS). The results showed that MWCNTs-CoFe₂O₄ has higher catalytic performance in the activation of PMS and degradation of MFA compared with MWCNTs, Co²⁺, Fe²⁺, and CoFe₂O₄. The highest kinetic constant rate (0.0198 min^-1) and MFA degradation (97.63%) were obtained at pH = 7, PMS = 4 mM, catalyst = 500 mg/L, MFA = 10 mg/L, and time = 150 min. MFA degradation accelerated with increasing PMS and catalyst dosage but decreased by initial pH. The influence of different anions and water matrix on the catalytic system was investigated, and the results explained a decrease in the MFA rate in the presence of the interfering substances. Scavenging experiments showed that both sulfate radical anion (SO₄^•-) and hydroxyl radical (^•OH) were effective on MFA degradation, but SO₄^•- had a greater effect on the degradation of MFA. In addition, the stability and recyclability of MWCNTs-CoFe₂O₄ were evaluated in the consecutive reaction cycle; the MFA degradation rate reached 89.75% after 4 cycles of reaction. The MFA degradation products were identified by gas chromatography-mass spectrometry (GC-MS) and their degradation pathway was suggested. Finally, a comparison was conducted among the methods used for PMS activation, and the results showed that the cobalt ferrite-based catalyst has high degradation efficiency. However, ultrasound, heat, and ultraviolet (UV) processes can be used to improve the degradation rate of the MWCNTs-CoFe₂O₄/PMS system at different reaction times.

In-situ preparation of biochar-loaded particle electrode and its application in the electrochemical degradation of 4-chlorophenol in wastewater

In order to effectively degrade 4-chlorophenol in wastewater, a biochar-loaded particle electrode was prepared using an in-situ method. The method employed bagasse as the raw material, KOH as the activator, SnCl4·5H2O, MnCl2·4H2O and SbCl3 as the modifiers. Furthermore, X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer were used to characterize the crystal composition, morphology and elemental compositions of the proposed particle electrode. The electrochemical performance of the proposed particle electrode was analyzed using an electrochemical workstation. A three-dimensional packed-bed electrochemical reactor was constructed using the loaded biomass carbon particle electrodes. The effects of different loaded biomass carbon particle electrodes on the electrochemical degradation of 4-chlorophenol were studied, and the mechanism of electrochemical degradation of 4-chlorophenol was discussed. The results showed that the effect of the supported biomass carbon particle electrode on the degradation of 4-chlorophenol was significantly higher than that of the unsupported biomass carbon particle electrode. Additionally, the electrochemical degradation of 4-chlorophenol was greatly influenced by the biomass carbon particle electrode with different loading and concentration. The removal efficiencies of 4-chlorophenol using the electrochemical treatment under the studied experimental conditions were found in the following descending order: Mn/AC > Sn/AC > Sb/AC. Among them, the biomass carbon particle electrode prepared using 150 g L-1 MnCl2·4H2O showed the best treatment effect for 4-chlorophenol. After electrochemical treatment of 500 mg L-1 of 4-chlorophenol-simulated wastewater for 1 h, the removal efficiency of 4-chlorophenol reached 99.93%.

Combined effects of electrical current and nonsteroidal antiinflammatory drugs (NSAIDs) on microbial community in a three-dimensional electrode biological aerated filter (3DE-BAF)

Three-dimensional electrode biological aerated filter (3DE-BAF) with particulate bioelectrode from lithium slag was used to simultaneously remove diclofenac and clofibric acid from the synthetic domestic sewage, and the combined effects of electrical current and nonsteroidal antiinflammatory drugs (NSAIDs) on microbial community was analyzed. The results indicated that (1) the average diclofenac and clofibric acid removal efficiency in the 3DE-BAF firstly increased, attained the peak of 79.40 ± 6.74% and 69.50 ± 6.26% at 0.35 A, and then decreased to 71.82 ± 4.90% and 55.92 ± 5.17% at 0.40 A, respectively; (2) the concentration of the diclofenac and clofibric acid in 3DE-BAF gradually decreased with the increase of reactor height; (3) the current intensity and space position affected the microbial structure at the different level; (4) at the optimum current intensity, Thiothrix, Flavobacteriaceae, Halothiobacillaceae, Hydrogenophaga, and Comamonadaceae accounted for the main bacterial community for removal diclofenac and clofibric acid in the 3DE-BAF.

Current Trends in the Application of Nanomaterials for the Removal of Emerging Micropollutants and Pathogens from Water

Water resources contamination has a worldwide impact and is a cause of global concern. The need for provision of clean water is becoming more and more demanding. Nanotechnology may support effective strategies for the treatment, use and reuse of water and the development of next-generation water supply systems. The excellent properties and effectiveness of nanomaterials make them particularly suitable for water/wastewater treatment. This review provides a comprehensive overview of the main categories of nanomaterials used in catalytic processes (carbon nanotubes/graphitic carbon nitride (CNT/g-C₃N₄) composites/graphene-based composites, metal oxides and composites, metal–organic framework and commercially available nanomaterials). These materials have found application in the removal of different categories of pollutants, including pharmaceutically active compounds, personal care products, organic micropollutants, as well as for the disinfection of bacterial, viral and protozoa microbial targets, in water and wastewater matrices. Apart from reviewing the characteristics and efficacy of the aforementioned nanoengineered materials for the removal of different pollutants, we have also recorded performance limitations issues (e.g., toxicity, operating conditions and reuse) for their practical application in water and wastewater treatment on large scale. Research efforts and continuous production are expected to support the development of eco-friendly, economic and efficient nanomaterials for real life applications in the near future.

Hazardous waste treatment technologies

This is a review of the literature published in 2018 on topics related to hazardous waste management in water, soils, sediments, and air. The review covers treatment technologies applying physical, chemical, and biological principles for contaminated water, soils, sediments, and air. PRACTITIONER POINTS: The management of waters, wastewaters, and soils contaminated by various hazardous chemicals including inorganic (e.g., oxyanions, salts, and heavy metals), organic (e.g., halogenated, pharmaceuticals and personal care products, pesticides, and persistent organic chemicals) was reviewed according to the technology applied, namely, physical, chemical and biological methods. Physical methods for the management of hazardous wastes including adsorption, coagulation (conventional and electrochemical), sand filtration, electrosorption (or CDI), electrodialysis, electrokinetics, membrane (RO, NF, MF), photocatalysis, photoelectrochemical oxidation, sonochemical, non-thermal plasma, supercritical fluid, electrochemical oxidation, and electrochemical reduction processes were reviewed. Chemical methods including ozone-based, hydrogen peroxide-based, persulfate-based, Fenton and Fenton-like, and potassium permanganate processes for the management of hazardous were reviewed. Biological methods such as aerobic, anaerobic, bioreactor, constructed wetlands, soil bioremediation and biofilter processes for the management of hazardous wastes, in mode of consortium and pure culture were reviewed.

Recent progress on carbon nanomaterials for the electrochemical detection and removal of environmental pollutants

Rapid global industrialization and explosive population growth have resulted in an increase in the discharge of harmful and toxic compounds. These toxic inorganic gases, volatile organic compounds, heavy metals, personal care products, endocrine-disrupting chemicals, dyes, and pharmaceuticals are destroying the balance in the Earth and increasing environmental toxicity at an alarming rate. Thus, their detection, adsorption and removal are of great significance. Various carbon nanomaterials including carbon nanotubes, graphene, mesoporous carbon, carbon dots, and boron-doped diamond have been extensively utilized and further proven to be ideal candidates for resolving environmental problems, emerging as adsorbents, electrochemical sensors and electrodes. Herein, we review the recent advances, progress and achievements in the design and properties of carbon nanomaterials and their applications for the electrochemical detection and removal of environmental pollutants.

Accelerated Rhodamine B removal by enlarged anode electric biological (EAEB) with electro-biological particle electrode (EPE) made from steel converter slag (SCS)

Electro-biological particle electrode (EPE) made from steel converter slag (SCS) was used as a particle electrode in an enlarged anode electric biological (EAEB) reactor for Rhodamine B (RhB) wastewater treatment, and its purification performance and microbial community were examined. The results revealed that (1) the EAEB reactor showed much higher average removal rates of RhB, COD and NH₄⁺-N, i.e. 91.68%, 87.63%, and 90.54%, which meant an increase by 59.86%, 20.48%, and 14.22%, respectively, compared with BAF; (2) The optimum current intensity (CI) for simultaneously removing RhB, COD and NH₄⁺-N in the EAEB reactor was at 1.00 A; and (3)Methylophilus, Aeromonas, Pseudomonas, Pelomonas and Zoogloea accounted for the main bacterial community in EAEB. Therefore, the EAEB reactor with EPE produced from steel converter slag (SCS) was suitable to simultaneously remove RhB, COD and NH₄⁺-N.

Removal of diclofenac by three-dimensional electro-Fenton-persulfate (3D electro-Fenton-PS)

Diclofenac (DIC) is a new type of contaminant that has been widely detected in the water environment, posing threats to the ecological environment and human health. However, the conventional wastewater treatment process has a very limited ability to reduce DIC. In this research, persulfate is added to electro-Fenton with the three-dimensional particle electrode (TDE) process whose particle electrodes were formed from manganese slag with loaded active substance (Cu: Fe = 1:1) to construct a three-dimensional electro-Fenton-persulfate (3D electro-Fenton-PS) process to investigate the removal rate of DIC under the optimum working conditions. The effects of different persulfate addition, activator addition and different activators on the removal rate of DIC were researched, respectively. The removal rate of DIC reached 96.3% when the persulfate and the Fe⁰ addition were 1.50 mM and 3.00 mM, respectively. The results showed that and OH existed simultaneously in the reaction system, and the removal of DIC was the result of the two free radicals. Moreover, degradation pathways and mechanism of DIC were also discussed. The study may provide a new theoretical basis and technical support for the treatment of DIC in municipal wastewater.

Catalytic degradation of diclofenac from aqueous solutions using peroxymonosulfate activated by magnetic MWCNTs-CoFe3O4 nanoparticles

CoFe₃O₄ nanoparticles supported on multi-walled carbon nanotubes (MWCNTs-CoFe₃O₄) were synthesized by the co-precipitation method as a novel catalyst for degradation of diclofenac (DCF). The comparative experiments indicated that MWCNTs-CoFe₃O₄ has a better catalytic activity in degradation of DCF and activation of peroxymonosulfate (PMS) compared to other catalytic systems. This can be attributed to the interaction of MWCNTs with CoFe₃O₄ in accelerating the absorption process and activating the PMS (E_a = 22.93 kJ mol⁻¹). The removal efficiencies of DCF and total organic carbon (TOC) were 99.04% and 50.11%, under optimum conditions, e.g., pH of 7, PMS dosage of 4 mM, DCF concentration of 30 mg L⁻¹, catalyst dosage of 500 mg L⁻¹, and reaction time of 120 min. The oxidation of DCF was fitted by the pseudo-first-order kinetic model and the constant rate was increased by increasing the pH, temperature, dosage of PMS and catalyst. The production of reactive species was studied using scavengers such as TBA and ethanol and the results showed that sulfate radical is the reactive species responsible for the degradation of DCF. The MWCNTs-CoFe₃O₄ catalyst showed high stability and reusability based on five successful repeated reactions, X-ray diffraction and energy dispersive X-ray spectroscopy analysis. Based on the intermediates detected by gas chromatography-mass spectrometry (GC-MS), the possible pathways for DCF catalytic oxidation were proposed. The results explained that the PMS/MWCNTs-CoFe₃O₄ system is a promising method for treating DCF solution due to high efficiency, good reusability of catalyst and greater PMS activation.

The MWCNTs-CoFe₃O₄ as a novel catalyst showed high catalytic activity in activation of proxymonosulfate for degradation of diclofenac.