Degradation Of Carbamazepine Research Articles

Activation of peracetic acid by a magnetic biochar-ferrospinel AFe2O4 (A = Cu, Co, or Mn) nanocomposite for the degradation of carbamazepine − A comparative and mechanistic study

Peracetic acid (PAA)-based advanced oxidation processes (AOPs) are promising technologies for the efficient treatment of persistent contaminants in wastewater. In this study, three different magnetic biochar (BC)-ferrospinel AFe2O4 (A = Cu, Co, or Mn) nanocomposites were synthesized through a combined sol–gel/pyrolysis process for the activation of PAA to degrade carbamazepine (CBZ). The following order of efficiency was observed for CBZ degradation in the presence of PAA: BC-CoFe2O4 (100 %) > BC-MnFe2O4 (7 %) ≈ BC-CuFe2O4 (7 %). In addition, 0.8 mM PAA, 0.3 g/L catalyst, nearly neutral pH, and 333 K were identified as the optimal operating parameters for the degradation of 1 mg/L CBZ in the BC-CoFe2O4/PAA system. Mechanistic studies revealed that CH3C(O)OO radicals are the dominant active species for the degradation of CBZ in the BC-CoFe2O4/PAA system, and the continuous conversion of Co(II) to Co(III) in this system is responsible for the generation of these radicals. In addition, the water matrices (e.g., humic acid (20 mg/L), NaCl (0.05 M), and NaNO3 (0.01 M)) played negligible roles in the degradation of CBZ in the BC-CoFe2O4/PAA system. This system exhibited highly selective and reactive degradation of organic pollutants with electron-rich groups (e.g., CBZ (0.36 min−1), sulfamethoxazole (0.12 min−1), and diclofenac (0.28 min−1)). Furthermore, the degradation products of CBZ were identified, and possible degradation pathways and toxicity of these transformation products were proposed. The BC-CoFe2O4/PAA system demonstrated outstanding degradation performance in dynamic systems and real wastewater treatment applications. This study describes the performance of an efficient and easy-to-separate catalyst for the activation of PAA. This study facilitates the development and application of PAA-based AOPs for wastewater treatment.

Protecting against micropollutants in water storage tanks using in-situ TiO2 coated quartz optical fibers

Photocatalyst-coated optical fibers (P-OFs) using UV-A LEDs offer a highly promising solution for the degradation of micropollutants within municipal, reuse, industrial or home distribution systems, by integrating P-OFs into water storage tanks. P-OFs have photocatalysts attached to bundles of optical fibers, enabling their direct deployment within tanks. This eliminates the necessity for photocatalyst slurries, which would require additional membrane or separation systems. However, a current limitation of P-OFs is light management, specifically light oversaturation of the coated photocatalysts and short light transmission distances along fibers. This study overcomes this limitation and reveals strategies to improve the light dissipation uniformity along P-OFs, and demonstrates the performance of P-OFs on degrading a model micropollutant, carbamazepine (CBZ). Key tunable variables of fibers and light emission conditions, including photocatalyst coating patchiness (p), minimum light incident angles (θm), radiant flux launched to fibers (Φi), and fiber diameters (D), were modeled to establish their relationships with the light dissipation uniformity in TiO2-coated quartz optical fibers (TiO2-QOFs). We then validated modeling insights by conducting experiments to examine how these variables influence the generation of evanescent waves which are localized energy on fiber surfaces, leading to either photocatalyst activation or the recapture of unused light back into fibers. We observed substantial enhancements in evanescent waves generation by decreasing p and increasing θm, resulting in uniform light dissipation which reduces light oversaturation and improves light transmission distances. Moreover, these optimizations led to a remarkable three-fold improvement in CBZ degradation rates and a 65% reduction in energy consumption. Such improvement substantially reduces the capital and operational cost and enhances practicality of energy-efficient photocatalysis without additional chemical oxidants for micropollutant degradation in water storage tanks.

Insight into the generation of toxic by-products during UV/H2O2 degradation of carbamazepine: Mechanisms, N-transformation and toxicity

Carbamazepine (CBZ) is a widely used anticonvulsant drug that has been detected in aquatic environments. This study investigated the toxicity of its by-products (CBZ-BPs), which may surpass CBZ. Unlike the previous studies, this study offered a more systematic approach to identifying toxic BPs and inferring degradation pathways. Furthermore, quadrupole time-of-flight (QTOF) and density functional theory (DFT) calculations were employed to analyze CBZ-BP structures and degradation pathways. Evaluation of total organic carbon (TOC) and total nitrogen (TN) mineralization rates, revealed carbon (C) greater susceptibility to mineralization compared with nitrogen (N). Furthermore, three rules were established for CBZ decarbonization and N removal during degradation, observing the transformation of aromatic compounds into aliphatic hydrocarbons and stable N-containing organic matter over time. Five potentially highly toxic BPs were screened from 14 identified BPs, with toxicity predictions guiding the selection of commercial standards for quantification and true toxicity testing. Additionally, BP207 emerged as the most toxic, supported by the predictive toxicity accumulation model (PTAM). Notably, highly toxic BPs feature an acridine structure, indicating its significant contribution to toxicity. These findings offered valuable insights into the degradation mechanisms of emerging contaminants and the biosafety of aquatic environments during deep oxidation.

Fenton-like catalysis by MnO2 membrane reactor with oxygen vacancies for carbamazepine degradation

Pathway design for singlet oxygen (1O2) with in-situ regulation has shown great interest for peroxymonosulfate (PMS) activation toward advanced oxidation in water treatment. Herein, we propose a facile method to design MnO2 catalysts with tunable surface oxygen vacancies (OVs) concentration to achieve radical-to-nonradical pathway transition. The surface of the OVs-rich NFM-140 provides an optimal site for PMS adsorption and allows •OH to break through the energy demand limitation and preferentially convert to 1O2 for electrophilic attack to pollutants. This OVs-regulated oxidation system can selectively switch to the 1O2-dominated nonradical pathway in response to pollutant recalcitrance, perfectly eliminating the pollutants and transforming them into the harmless products. Our research presents a novel perspective on the selective generation of reactive oxygen species (ROS) for the degradation of organic pollutants in PMS by utilizing the mediation of OVs.

Kinetic model-based optimization in electro-activated sulfite system for carbamazepine degradation: Aeration and multiple dosages of sulfite

Electro-activated sulfite system (E-SO32−) was an emerging advanced oxidation technology, but its kinetics and process optimization have been overlooked. This study developed a first-principle kinetic model to investigate carbamazepine (CBZ) degradation and optimized this process by aeration and multiple dosages of SO32−. A low aeration rate (140 mL/min) remarkably accelerated sulfate radical (SO4•−) generation because of the enhanced rate of sulfite radical (SO3•−) reacting with oxygen. Thus, the degradation efficiency of CBZ improved from 71 % to 84 % and the electrical energy per order (EE/O) decreased from 4.55 to 2.32 kWh/m3/order at current density of 103 A/m2 and initial dosage of SO32− of 4 mM. However, further increasing the aeration rate diminished the enhancement of SO4•− generation rate due to the limited SO3•− generation, and excessive aeration resulted in decreased degradation efficiency and increased cost of aeration due to the direct oxidation of SO32− by oxygen. Consequently, matching of SO32− concentration, current density and aeration rate was crucial to maximize the generation rate of SO4•−. The most optimal strategy was at current density of 75 A/m2, aeration rate of 100 mL/min and SO32− concentration of 1.1 mM with multiple dosages. 95 % of CBZ was removed in 20 min, 18 % higher than that in single dosage. Finally, the optimal strategy for CBZ degradation was successfully applied in different water matrixes and real wastewater and well predicted by the kinetic model. Furthermore, degradation pathways of CBZ, including hydroxylation and deamidation, were elucidated from density functional theory and LC-MS detection. The toxicity of most intermediates decreased, while some intermediates possessed higher toxicity than CBZ. Overall, the firstly proposed combined strategy of aeration and multiple dosages of SO32− significantly facilitated the application of E-SO32− system in contaminants degradation.

Enhanced degradation of carbamazepine in water over Fe3O4@ZIF-8 nanocomposites with persulfate or peroxymonosulfate as activator

In this work, the Fe3O4@ZIF-8 catalyst was prepared by combining Fe3O4 with ZIF-8 for degrading carbamazepine (CBZ) in water, using activated persulfate (PS) and peroxymonosulfate (PMS). We investigated the optimal catalysts and reaction conditions for using PS or PMS as activators by varying the pH, temperature, catalyst dosage, as well as the dosage of PS and PMS, respectively. The results demonstrated that the CBZ removal rate using Fe3O4@ZIF-8 reached 98.1% after 30 min with a mass ratio of Fe3O4 to ZIF-8 = 3:1, temperature = 40°C, catalyst dosage = 0.50 g·L−1, and PS dosage = 0.25 g·L−1, using pH = 3.0. Characterization results show due to the fact that the presence of ZIF-8 facilitates the dispersion of the catalytic active species Fe3O4, prevents the agglomeration of the active species, increases the number of active species, and improves the catalytic performance. Furthermore, radical quenching assay and electron paramagnetic resonance spectra successfully identified the main oxidizing components generated in the system, namely SO4•− and •OH.

Recyclable and dual-functional Ag3PO4/3D graphene aerogel photocatalysts for simultaneous water oxidation and pollutant degradation

Exploiting recyclable and reusable photocatalysts in pollutants elimination and water splitting has drawn extensive research attention for solving the increasing energy and environmental issues. Herein, we designed a high-performance dual functional Ag3PO4/three-dimensional (3D) graphene aerogel (APGA) photocatalyst, in which the 3D GA with extremely lightweight and high mechanical stability served as the support for Ag3PO4 particles, preventing the serious weight loss during the recovery process. Moreover, different from the traditional powder photocatalysts, the application of 3D GA support avoided the secondary contamination caused by the catalyst residue during the reaction. The abundant hydroxyl groups on the surface of porous 3D GA prevented the aggregation of Ag3PO4 particles, forming a close interfacial contact. Profiting from the large number of active sites and high conductivity of 3D GA, the optimized APGA-12 sample showed excellent O2 generation (814.1 μmol·g−1) and synchronous Cr (VI) reduction (87.5 %) efficiency. In addition, the APGA-12 sample also exhibited excellent carbamazepine (CBZ) degradation activity (99 % within 30 min) in the presence of peroxymonosulfate (PMS). Cycling experiments combined with the scaled-up reactions verified the good mechanical and chemical stability of APGA samples. This work provided a promising strategy for solving the problems of catalyst recycling in the field of pollutant degradation and water oxidation.

Microwave assisted plastic waste derived O vacancies enriched cobalt oxide/porous carbon material for highly efficient carbamazepine degradation via peroxymonosulfate activation

In this study, porous carbon catalytic materials prepared by a simple microwave pyrolysis of waste plastic polyethyleneterephthalate (PET) were used to degrade carbamazepine (CBZ) through peroxymonosulfate (PMS) activation. Microwave absorbers cobalt nitrate and initially carbonized α-cellulose were employed to assist the waste plastic PET carbonization. The cobalt oxide formation, cobalt sulfide generation, oxygen vacancies introduction and specific surface area enlargement were all conducive to the improvement of catalytic performance. The optimal catalyst S0.3-Co@P2C could achieve 100.0 % CBZ degradation in 15 min, with the rate constant of 0.7445 min−1. Compared to traditional pyrolysis, the microwave-treated carbon materials were more conducive to the formation and exposure of active sites (CoS and CoO) in the catalytic materials for SO4•- and·OH production via PMS activation. In addition, the introduction of PET was conducive to the formation of C = O in the catalytic materials for the PMS activation to accelerate non-radical CBZ degradation pathway. This study provides new insights into the antibiotic degradation in water with the concept of using waste to deal with waste.

Photothermal-synergistic peroxymonosulfate activation promoting carbamazepine degradation by Porphyra-derived porous biochar composites: Performance, mechanism, transformation pathway and practical application

Heterogeneous catalysis with peroxymonosulfate (PMS) activation has received increasing attention in recalcitrant contaminants treatment, but multidimensional coupling via engineered biochar materials and photothermal synergy is still rare. Herein, we reported photothermal-synergistic PMS activation by Porphyra-derived porous biochar composites (ZnS/NBC) for carbamazepine (CBZ) degradation. Benefitting from the high specific surface area, highly graphitic structure and strong light-to-heat conversion ability, ZnS/NBC10/PMS/light system showed enhanced degradation performance and nearly complete mineralization of CBZ. Meanwhile, this system maintained high degradation efficiency in real water bodies and natural sunlight condition, respectively. Mechanism analysis confirmed that the predominant role of 1O2 and the auxiliary involvement of SO4−, OH and electron transfer jointly contributed to the CBZ degradation. Finally, the possible degradation pathways of CBZ were elaborated based on the liquid chromatography-mass spectrometry results and Fukui index calculations, and the diminishing ecotoxicity of the accompanying degradation intermediate was evaluated using the toxicity estimation software tool. This study provides a new insight for advancing a comprehensive utilization of photothermal conversion and biochar-based PMS activators to organic wastewater purification.

Insights into the Ligand Effect in β-CD@Fe3O4 Composites to Activate Peroxymonosulfate for Efficient Degradation of Pharmaceutical Contaminants: A Study Employing Density Functional Theory

This study presents a detailed investigation into the use of β-cyclodextrin (β-CD) encapsulated iron oxide nanoparticle (β-CD@Fe3O4) composites, modified with different ligands, to activate peroxymonosulfate (PMS) for the degradation of pharmaceutical contaminants, namely, diclofenac, carbamazepine, and erythromycin. The focus is on understanding the ligand effect, particularly using citric acid (CIT), polyethyleneimine (PEI), and cetyl trimethyl ammonium bromide (CTAB), on the degradation performance of these composites. Employing density functional theory (DFT) calculations, this work examines the electronic structure and charge distributions of β-CD@Fe3O4 composites, providing insights into their interaction with various pollutants. The study reveals that the β-CD@PEI@Fe3O4 composite demonstrates superior degradation efficiency due to optimal electrostatic interactions, regardless of the pollutant’s hydrophobicity. On the other hand, β-CD@CIT@Fe3O4 shows moderate efficiency, and β-CD@CTAB@Fe3O4 exhibits selective efficiency, particularly for hydrophobic compounds. These findings underscore the significant role of surface chemistry in modulating the activation of PMS and the degradation of contaminants, opening avenues for designing tailored β-CD composites for environmental remediation.

Sustained oxidation of Tea-Fe(III)/H2O2 simultaneously achieves sludge reduction and carbamazepine removal: The crucial role of EPS regulation

Establishing an economic and sustained Fenton oxidation system to enhance sludge dewaterability and carbamazepine (CBZ) removal rate is a crucial path to simultaneously achieve sludge reduction and harmless. Leveraging the principles akin to "tea making", we harnessed tea waste to continually release tea polyphenols (TP), thus effectively maintaining high level of oxidation efficiency through the sustained Fenton reaction. The results illustrated that the incorporation of tea waste yielded more favorable outcomes in terms of water content reduction and CBZ removal compared to direct TP addition within the Fe(III)/hydrogen peroxide (H2O2) system. Concomitantly, this process mainly generated hydroxyl radical (•OH) via three oxidation pathways, effectively altering the properties of extracellular polymeric substances (EPS) and promoting the degradation of CBZ from the sludge mixture. The interval addition of Fe(III) and H2O2 heightened extracellular oxidation efficacy, promoting the desorption and removal of CBZ. The degradation of EPS prompted the transformation of bound water to free water, while the formation of larger channels drove the discharge of water. This work achieved the concept of treating waste with waste through using tea waste to treat sludge, meanwhile, can provide ideas for subsequent sludge harmless disposal.

Optimisation of treatment efficiency and effluent toxicity during carbamazepine degradation via electrochemical oxidation

The commercialisation of electrochemical advanced oxidation processes (eAOPs) as a method for removing recalcitrant pollutants from wastewater is currently limited due to the potential for the formation of toxic by-products. In this regard, this research comprised a comprehensive optimisation study aimed at finding a balance between minimising the toxicity effects observed via phytotoxicity assays and maximising the eAOP degradation efficiency under low energy requirements. To this end, carbamazepine (CBZ) was selected as the target pollutant in synthetic wastewater, and the operating conditions considered for optimisation were the nature of the anolyte (i.e., sulfate- or chloride-based), its concentration, and the current density applied. Together with the identification of the CBZ transformation products and their estimated toxicity based on the ECOSAR model, the optimum treatment was found to correspond to the degradation in 500 mg L−1 of a sulfate-based anolyte at a current density of 10 A m−2. These conditions led to the fewest and least toxic transformation products and favoured plant growth indices in phytotoxicity tests. Even if additional process improvements are required to reduce effluent toxicity, continuing such a multi-target optimisation approach can lead to innocuous electrochemical wastewater treatment.

Preparation of Cobalt-Nitrogen Co-Doped Carbon Nanotubes for Activated Peroxymonosulfate Degradation of Carbamazepine.

Cobalt-nitrogen co-doped carbon nanotubes (Co3@NCNT-800) were synthesized via a facile and economical approach to investigate the efficient degradation of organic pollutants in aqueous environments. This material demonstrated high catalytic efficiency in the degradation of carbamazepine (CBZ) in the presence of peroxymonosulfate (PMS). The experimental data revealed that at a neutral pH of 7 and an initial CBZ concentration of 20 mg/L, the application of Co3@NCNT-800 at 0.2 g/L facilitated a degradation rate of 64.7% within 60 min. Mechanistic investigations indicated that the presence of pyridinic nitrogen and cobalt species enhanced the generation of reactive oxygen species. Radical scavenging assays and electron spin resonance spectroscopy confirmed that radical and nonradical pathways contributed to CBZ degradation, with the nonradical mechanism being predominant. This research presents the development of a novel PMS catalyst, synthesized through an efficient and stable method, which provides a cost-effective solution for the remediation of organic contaminants in water.

Facile synthesis of pyrite FeS2 on carbon spheres for high-efficiency Fenton-like reaction

Designing iron-based catalysts for Fenton-like reactions with peroxymonosulfate (PMS) as oxidants have attracted growing attentions. Herein, pyrite FeS2 supported on carbon spheres (FeS2@C) is synthesized by a facile low-temperature method. The FeS2@C/PMS system can degrade carbamazepine (CBZ) effectively in a wide pH range. Sulfate radicals (SO4·-), hydroxyl radicals (·OH), superoxide radical (O2·-), and singlet oxygen (1O2) are the responsible reactive oxygen species (ROSs) for CBZ degradation. Moreover, in the simulated fixed-bed reactor, the FeS2@C/PMS system can maintain a high CBZ removal ratio of >95% for than 8 h, exhibiting its excellent stability. The outstanding performance of FeS2@C/PMS system is attributed to the presence of carbon spheres and lattice S2−, which together promote the Fe(III)/Fe(II) redox cycle. The FeS2@C is a promising catalyst due to its facile synthesis, low cost, high efficiency, and excellent stability to activate PMS for organics degradation.

3D hollow cobalt/carbon fiber-like PMS activator for dynamic carbamazepine degradation: promotional effect and reaction mechanism

Finding effective and practical ways to remove contaminants in the water is a challenging problem, therefore, the construction of recyclable materials has been paid attention to in the practical application of advanced oxidation processes. A three-dimensional hollow tubular surface-loaded cobalt/cotton carbon fiber composite (Co-CCF-600) is successfully prepared by carbonization, which can effectively activate PMS to degrade CBZ. The synthetic Co-CCF-600 degrades 93.47% of CBZ within 60 min. It is worth noting that Co-CCF-600 has good stability and high catalytic activity after 5 cycles, which is attributed to the synergy between Co species (Co0 and CoO) and CCF. In addition, both radical and non-radical processes contribute to the degradation of CBZ, and SO4•− plays a dominant role. After a 118 h wastewater degradation experiment, the Co-CCF-600/PMS system still maintains high degradation efficiency and stability. Overall, this study provides an environmentally friendly, low-cost cobalt/carbon fiber material for the removal of CBZ in wastewater and provides a practical solution for environmental remediation.

Sulfate radical dominated rapid pollutants degradation leaded by selenium vacancies in core-shell N-doped carbon wrapped cobalt diselenide nanospheres

Herein, a new heterogeneous CoSe2-x@NC material with abundant selenium vacancies is synthesized via an in-situ carbonization-selenization process from cobaltic metal organic framework (Co-MOF). The obtained CoSe2-x@NC has a unique electronic structure and rich active sites, which can activate peroxymonosulfate (PMS) to degrade carbamazepine (CBZ) with superior catalytic performance and stability. The quenchingexperiments and EPR test show that SO4•− is the dominant reactive oxidation species (ROSs) for CBZ degradation. Significantly, systemic electrochemical tests and theoretical calculations illustrated that the dominant role of SO4•− is attributed to the existence of abundant selenium vacancies in CoSe2-x@NC, which can adjust the density of electron cloud of the Co atoms in CoSe2-x@NC to improve the PMS adsorption and promoting the conversion of transition metallic redox pairs (Co3+/Co2+). This work provides a facile way to improve the activity and stability of CoSe2 by defect engineering in the PMS based advanced oxidation process (AOPs).

Exploring the roles of ascorbic acid/L-cysteine in boosted carbamazepine degradation by biochar-CuFe2O4/Fe2O3/CuO/peroxymonosulfate: Taguchi optimization and mechanistic studies

The present research aimed to improve the efficiency of a novel walnut shell biochar-CuFe2O4/Fe2O3/CuO (BC-CuFeO) nanocomposite for the activation of peroxymonosulfate (PMS) for the degradation of carbamazepine (CBZ), as a recalcitrant organic pollutant. Ascorbic acid (H2A) and L-cysteine (LC) were utilized to significantly increase CBZ removal efficiency in the BC-CuFeO/PMS system. An L-16 Taguchi design was applied to identify the relative significance of the operating parameters for the degradation of CBZ. In addition, both the BC-CuFeO/PMS/H2A and BC-CuFeO/PMS/LC systems demonstrated outstanding CBZ degradation performance in the presence of humic acid, sodium chloride, and sodium nitrate, respectively. The scavenging experiments indicated that 1O2, ·OH, O2•−, and SO4•− were responsible for CBZ degradation in the BC-CuFeO/PMS/H2A system, while O2•−, 1O2, and ·OH contributed to CBZ degradation in the BC-CuFeO/PMS/LC system. Furthermore, the intermediates and pathways of CBZ degradation were determined via Q-TOF-MS analysis, and the potential toxicity of the products was assessed via Toxicity Estimation Software Tool analysis. The practicality of the nanocomposites was also evaluated through the fabrication of catalytic balls and catalytic membranes, followed by the study of their stability for wastewater treatment. In conclusion, this study provides novel and promising PMS activation methods for the efficient removal of recalcitrant pollutants from wastewater.

Degradation of Carbamazepine in Water by UV-activated Sulfite Process

In this study, the degradation efficiency and mechanism of carbamazepine (CBZ), a typical emerging contaminant in water, in the UV/sulfite process were investigated. The effects of different concentrations of dissolved oxygen [ρ(DO)] on the degradation of CBZ by UV-activated sulfite were investigated. Additionally, under a simulated natural water environment-controlled initial ρ(DO) of (8.0 ±0.2) mg·L-1, the effects of different process parameters (sulfite dosages and reaction pH) and water environmental factors (the presence of HCO3-, Cl-, and humic acids) on the degradation of CBZ were comprehensively analyzed. The results showed that the UV/sulfite process efficiently degraded CBZ with a degradation rate of 85.3% during the 30 min reaction time and followed the pseudo-first order kinetic model with the constant of 0.055 7 min-1. Using the electron spin resonance detection, reactive species quenching tests, and the competition kinetics, the sulfate radicals (SO4-·) and hydroxyl radicals (·OH) in the UV/sulfite process were determined to be the main reactive species and were responsible for the degradation of CBZ with contribution rates of 43.9% and 56.1%, respectively. In addition, the degradation efficiency of CBZ decreased with the increasing concentration of HCO3-, and the presence of Cl- had little effect on the degradation of CBZ, whereas the presence of humic acids significantly inhibited the degradation of CBZ. Moreover, the accumulation of sulfate during the reaction was significantly lower than the limit of the Standard for Drinking Water (GB5749-2022). Additionally, the sulfite consumption rate constant was 0.004 4 min-1, which was significantly lower than the degradation rate constant of CBZ, indicating that sulfite could be activated efficiently by UV light to degrade CBZ in water.

Monodispersed ZIF-67 in situ nucleated on CoAl-LDH nanosheets for efficient carbamazepine degradation via activation of peroxymonosulfate

Abundant exposed ligand-unsaturated sites of Co have been found to enhance the catalytic oxidation property of ZIF-67 material for peroxymonosulfate (PMS) catalysis. Nevertheless, serious stacking of ZIF-67 still poses a challenge to its application. Herein, we employed a specific in situ growth strategy to establish an LDHNS@ZIF-67 composite based on morphology modulation and performance optimization for carbamazepine (CBZ) degradation. ZIF-67 crystals were successfully grown in situ via nucleating on the CoAl-LDH nanosheets (LDHNSs) substrate surface, which facilitated the crystals’ dispersion. LDHNS@ZIF-67 (0.1 M) was optimized to display outstanding PMS catalytic activity for CBZ degradation, with almost 100% degradation in 5 min (PMS dose, 0.2 mM, catalyst dose, 25 mg/L, and CBZ concentration, 5 ppm). Quenching and electron paramagnetic resonance (EPR) tests confirmed that both radical substances (SO4•-) and nonradical substances (1O2) dominated the reaction system. As the active site, Co(II) ions on the LDHNS@ZIF-67 (0.1 M) surface effectively promoted active substance formation. The intermediate degradation products and pathways for CBZ were investigated. Toxicity assessment for CBZ and its intermediates was conducted. This work will broaden the application of ZIF-67 materials in advanced oxidation process design based on persulfate.

Enhanced hydrogen peroxide production and organic substrates degradation using atomically dispersed antimony P-doped carbon nitride photocatalysts

In this work atomically dispersed antimony P-doped carbon nitride was prepared with the aim of producing hydrogen peroxide under visible light irradiation and of obtaining organic contaminants degradation. The conjugation of the P-doping can induce significant increase in visible light harvesting, narrowing of band gap energy and shift of the upper edge of the VB to less positive value and the introduction of Sb can efficiently trap oxygen molecules in the Sb-OO end-on structure and at the same time accumulate electrons which act as the photoreduction sites for O2 via a 2e− ORR pathway. Pristine C3N4 and P-doped C3N4 were prepared as references using melamine and ammonium dihydrogen phosphate as precursors and different amount of Sb were added (x = 0.5, 1, 3, 5 mmol) to synthetize Sbx P-doped C3N4. All materials were characterized with multiple techniques, tested for the hydrogen peroxide production and for the degradation of carbamazepine. The pristine C3N4 led to a H2O2 poor production but with the introduced modifications the yield increased and an upward trend during the time was observed. The optimum amount of Sb was found to be 1 mmol and it led to the production of more than 7 times the amount produced by pristine carbon nitride. The degradation of carbamazepine using only visible radiation required prolonged timescales but when we expand the light spectrum to include near-UV, the abatement of the pollutant is achieved in a few hours. The efficiency of the synthesized materials in hydrogen peroxide production suggests possible future developments that take advantage of the excellent peroxide production of atomically dispersed antimony P-doped carbon nitride photocatalysts in Fenton-like processes or involve the use of peroxidase enzymes to achieve enhanced degradative performances.