Can Cu2ZnSnS4 nanoparticles be used as heterogeneous catalysts for sulfadiazine degradation?

Dissecting the ecological risks of sulfadiazine degradation intermediates under different advanced oxidation systems: From toxicity to the fate of antibiotic resistance genes

The incomplete degradation of antibiotics in water can produce intermediates that carry environmental risks and thus warrant concerns. In this study, the degradation of high concentrations of antibiotic sulfadiazine (SDZ) by advanced oxidation processes that leverage different reactive oxide species was systematically evaluated in terms of the influence of different degradation intermediates on the propagation of antibiotic resistance genes (ARGs). The ozone, persulfate, and photocatalytic oxidation systems for SDZ degradation are dominated by ozone, direct electron transfer, and singlet oxygen, hole, and superoxide radicals, respectively. These processes produce 15 intermediates via six degradation pathways. Notably, it was determined that three specific intermediates produced by the ozone and persulfate systems were more toxic than SDZ. In contrast, the photocatalytic system did not produce any intermediates with toxicity exceeding that of SDZ. Microcosm experiments combined with metagenomics confirmed significant changes in microbiota community structure after treatment with SDZ and its intermediates, including significant changes in the abundance of Flavobacterium, Dungenella, Archangium, and Comamonas. This treatment also led to the emergence of sulfonamide ARGs. The total abundance of sulfonamide ARGs was found to be positively correlated with residual SDZ concentration, with the lowest total abundance observed in the photocatalytic system. Additionally, the correlation analysis unveiled microbiota carrying sulfonamide ARGs.

In situ N-doping engineered biochar catalysts for oxidation degradation of sulfadiazine via nonradical pathways: Singlet oxygen and electron transfer

Understanding the structure of non-metallic heteroatom-doped carbon catalysts and the subsequent degradation of new pollutants is crucial for designing more efficient carbon catalysts. Environmentally friendly in situ N-doped biochar catalysts were prepared for peroxymonosulfate (PMS) activation and sulfadiazine (SDZ) degradation. The acid washing process and calcination temperature of catalyst increased π-π* shake up, graphitic N percentage, specific surface area and defects, promoting the transformation of pollutant degradation mechanism from radical pathway to non-radical pathway. 100 % of the SDZ with the initial concentration of 10 mg/L was quickly degraded within 60 min using 0.2 g/L catalysts and 0.5 mM PMS. Excellent catalytic performance was attributed to singlet oxygen and electron transfer-dominated non-radical pathways. The four potential degradation pathways of SDZ were proposed, and toxicity predication indicated that overall biotoxicity of the intermediates during SDZ degradation was decreased. This research deepens our understanding of the mechanisms of non-radical pathways and guides the synthesis of carbon-based catalysts.

A CuCo Bimetal Confined Hollow SiC Hybrid Photothermal Nanoreactor for the Integration of Pollutant Mineralization and Solar-Powered Water Evaporation

Growing attention has been paid to the rational treatment of antibiotics-bearing medical wastewater. However, the complexity of polluted wastewater makes the later comprehensive treatment difficult only by the Advanced Oxidation Process technique. Therefore, the coupled water treatment techniques including contaminant mineralization and regeneration of cleanwater become very attractive. A bimetallic functional hollow nanoreactor defined as (Co@SiO2/Cu-X) was successfully constructed by coating a Cu-doped silica layer on the metal-organic framework (ZIF-67) followed by programmed calcination in nitrogen. The nanoreactor was endowed with a hollow configuration composed of mesoporous N-doping C-Silica hybrid shell encapsulated ultrafine Cu and Co metallic species. Such a configuration allows for the efficient diffusion and open reaction space of big contaminant molecules. The catalytic synergy of exposed Co-Cu bimetals and the easy accessibility of electron-rich contaminants by polar N doping sites triggered surface affinity make the optimal Co@SiO2/Cu-6 afford an excellent catalytic norfloxacin mineralization activity (7 min, kabs=0.744 min-1) compared to Cu-free Co@SiO2-6 (kabs=0.493 min-1) and Co-6 (kabs=0.378 min-1) Benefiting from the above unique advantages, Co@SiO2/Cu-6 show excellent removal performance in degrading different pollutants (carbamazepine, oxytetracycline, tetracycline, and bisphenol A) and persistent recycled stability in removing NFX. In addition, by virtue of the excellent photothermal properties, interfacial solar water evaporation application by Co@SiO2/Cu-6 was further explored to reach the regeneration of cleanwater (1.595 kg m-2 h-1, 97.51 %). The integration of pollutant mineralization and solar water evaporation by creating the monolith evaporation by anchoring the Co@SiO2/Cu-6 onto the tailored melamine sponge allows the regeneration of cleanwater (1.6 kg⋅m-2⋅h-1) and synchronous pollutant removal (NFX, 95 %, 60 min), which provides potential possibility the treatment of complicated wastewater.

Photodegradation performance and mechanism of sulfadiazine in Fe(III)-EDDS-activated persulfate system

In order to overcome the shortcomings in the traditional Fenton process, Fe(III)-EDDS-activated persulfate advanced oxidation process under irradiation is carried out as a promising technology. The photodegradation of sulfadiazine (SD) in Fe(III)-EDDS-activated persulfate system was investigated in this paper. The results showed that SD could be effectively degraded in Fe(III)-EDDS/S 2 O 8 2 - /hv system. The effects of Fe(III):EDDS molar ratio, the concentration of Fe(III)-EDDS, and the concentration of S 2 O 8 2 - on SD degradation were explored. At neutral pH, when Fe(III):EDDS = 1:1, Fe(III)-EDDS = 0.1 mM, S 2 O 8 2 -  = 1.5 mM, the best SD degradation was achieved. The experiment of external influence factors showed that the degradation of SD could be obviously inhibited by the presence of C O 3 2 - , S O 4 2 - , whereas the degradation of SD was almost unaffected by the addition ofCl-. The degradation of SD could be slightly inhibited by the presence of humic acid and NO3-. The effect of pH on SD degradation was investigated, and SD could be degraded effectively in the pH range of 3-9. ESR proved that 1O2, ·OH, S O 4 - , and O2- were produced in the process. S O 4 - and ·OH were identified as the main radicals while O2·- also played non-ignorable role. Eleven intermediate products of SD were analysed. The C = N, S-N, and S-C bonds of SD were attacked by radicals firstly, leading to a series of reactions that eventually resulted in the destruction of SD molecules and the formation of small organic molecules.

H2O2 activation and contaminants removal in heterogeneous Fenton-like systems

Emerging contaminants can be removed effectively in heterogeneous Fenton-like systems. Currently, catalyst activity and contaminant removal mechanisms have been studied extensively in Fenton-like systems. However, a systematic summary was lacking. This review summarized: 1) The effects of various heterogeneous catalysts on emerging contaminants degradation by activating H₂O₂; 2) The role of active sites in different catalysts during the activation of H₂O₂ and their contribution to the generation of active species; 3) The modulation of degradation pathways of emerging contaminants. This paper will help scholars to advance the controlled construction of active sites in heterogeneous Fenton-like systems. Suitable heterogeneous Fenton catalysts can be selected in practical water treatment processes.

Sulfadiazine degradation by combination of hydrodynamic cavitation and Fenton-persulfate: parametric optimization and deduction of chemical mechanism

This paper reports the degradation of the sulfadiazine (SDZ) drug with a hybrid advanced oxidation process (AOP) of heterogeneous α-Fe₂O₃/persulfate coupled with hydrodynamic cavitation. The major objectives of the study are parametric optimization of the process and elucidation of the chemical mechanism of degradation. The optimum conditions for maximum SDZ degradation of 93.07 ± 1.67% were as follows: initial SDZ concentration = 20 ppm, pH = 4, α-Fe₂O₃ = 181.82 mg/L, Na₂S₂O₈ = 348.49 mg/L, H₂O₂ = 0.95 mL/L, inlet pressure = 0.81 MPa (8 atm), orifice plate configuration: hole dia. = 2 mm and number of holes = 4. Density functional theory (DFT) calculations revealed that the atoms of SDZ with a high Fukui index (f ⁰) were potentially active sites for the attack of ^•OH and [Formula: see text] radicals. Fukui index calculation revealed that atom 11 N has a higher value of f ⁰ (0.1026) for oxidation at the α-amine group of the sulfadiazine molecule. Degradation intermediates detected through LC-MS/MS analysis corroborated the results of DFT simulations. Using these results, a chemical pathway has been proposed for SDZ degradation.

Facile synthesis of CoOOH@MXene to activate peroxymonosulfate for efficient degradation of sulfamethoxazole: performance and mechanism investigation

Using MXene as substrate, CoOOH@MXene with different mass content of CoOOH were prepared and used to active peroxymonosulfate (PMS) for the sulfamethoxazole (SMX) degradation. The sample characterizations demonstrated the successful preparation of CoOOH@MXene. CoOOH@MXene possessed much higher BET surface area (183.82 m2/g) than CoOOH (85.36 m2/g) and MXene (6.89 m2/g) due to the good dispersibility of CoOOH particles on MXene. Due to its large surface area, 1.3CoOOH@MXene displayed the best catalytic performance for the degradation of SMX. With 0.2 g/L of 1.3CoOOH@MXene and 0.5 mM of PMS, 20 μM of SMX was completely eliminated in 10 min. The degradation followed pseudo-first-order kinetic model well, with rate constants of 0.33 min-1 for 1.3CoOOH@MXene and 0.054 min-1 for CoOOH. Influencing factors of initial pH, catalyst dosage, PMS concentration, SMX concentration, and co-existing anions on SMX degradation were assessed systematically. Recycling tests verified the excellent reusability and stability of the catalyst. Quenching experiments and electron paramagnetic resonance analysis substantiated that 1O2 played a leading role. Moreover, the intermediates were identified, and degradation pathways and activation mechanism of CoOOH@MXene for PMS were proposed. This work may highlight the application of MXene with transition metals in PMS activation.

Degradation of Tetracycline Hydrochloride by Cu-Doped MIL-101(Fe) Loaded Diatomite Heterogeneous Fenton Catalyst

In this work, the combination of high surface area diatomite with Fe and Cu bimetallic MOF material catalysts (Fe_0.25Cu_0.75(BDC)@DE) were synthesized by traditional solvothermal method, and exhibited efficient degradation performance to tetracycline hydrochloride (TC). The degradation results showed: Within 120 min, about 93% of TC was degraded under the optimal conditions. From the physical–chemical characterization, it can be seen that Fe and Cu play crucial roles in the reduction of Fe³⁺ because of their synergistic effect. The synergistic effect can not only increase the generation of hydroxyl radicals (•OH), but also improve the degradation efficiency of TC. The Lewis acid property of Cu achieved the pH range of reaction system has been expanded, and it made the material degrade well under both neutral and acidic conditions. Loading into diatomite can reduce agglomeration and metal ion leaching, thus the novel catalysts exhibited low metal ion leaching. This catalyst has good structural stability, and less loss of performance after five reaction cycles, and the degradation efficiency of the material still reached 81.8%. High performance liquid chromatography–mass spectrometry was used to analyze the degradation intermediates of TC, it provided a deep insight of the mechanism and degradation pathway of TC by bimetallic MOFs. This allows us to gain a deeper understanding of the catalytic mechanism and degradation pathway of TC degradation by bimetallic MOFS catalysts. This work has not only achieved important progress in developing high-performance catalysts for TC degradation, but has also provided useful information for the development of MOF-based catalysts for rapid environmental remediation.

Fabrication of magnetic nickel incorporated carbon nanofibers for superfast adsorption of sulfadiazine: Performance and mechanisms exploration

Herein, novel magnetic nickel incorporated carbon nanofibers (Ni@CNF) were successfully synthesized via electrostatic spinning method for sulfadiazine (SDZ) adsorption. We combined computational and experimental tools to clarify the distinct nature of SDZ on Ni@CNF. Extensive computations and characterizations of SDZ-Ni adsorption complexes evidenced that Ni atoms were indispensable for SDZ adsorption and increasing the number of Ni atoms in Ni@CNF significantly improved SDZ adsorption due to the lower adsorption energy (E_ad). As we surmised, the adsorption capacity of Ni@CNF enhanced gradually with increasing the mass ratio of Ni in the composite. The as-prepared 9%Ni@CNF achieved removal efficiency of 98.9% for SDZ (2.5 mg/L) in 25 min, while the pure CNF hardly removed any SDZ under the identical conditions. The experimental data was better fitted by the Langmuir model with the maximum monolayer adsorption capacity of 103.21 mg/g at 318 K. Besides, the 9%Ni@CNF exhibited great applicability to various organic contaminants, and excellent stability and reusability over five consecutive cycles. Overall, for the first time, we provide the evidence that Ni atoms in the Ni@CNF plays a crucial role in SDZ adsorption, which can guide us for constructing nickle incorporated adsorbents with impressive adsorption capacity in environmental remediation.

Efficient degradation of sulfamethazine via activation of percarbonate by chalcopyrite

In this work, the novel application of chalcopyrite (CuFeS₂) for sodium percarbonate (SPC) activation towards sulfamethazine (SMT) degradation was explored. Several key influencing factors like SPC concentration, CuFeS₂ dosage, reaction temperature, pH value, anions, and humic acid (HA) were investigated. Experimental results indicated that SMT could be effectively degraded in the neutral reaction media by CuFeS₂/SPC process (86.4%, 0.054 min^-1 at pH = 7.1). The mechanism of SPC activation by CuFeS₂ was elucidated, which was discovered to be a multiple reactive oxygen species (multi-ROS) process with the coexistence of hydroxyl radical (^•OH), carbonate radical (CO₃^•-), superoxide radical (O₂^•-), and singlet oxygen (¹O₂), as evidenced by quenching experiments and electron spin resonance (ESR) tests. The generated ^•OH via the traditional heterogeneous Fenton-like process would not only react with carbonate ions to yield other ROS but also involve in SMT degradation. The abundant surface-bound Fe(II) was deemed to be the dominant catalytic active sites for SPC activation. Meanwhile, it was verified that the reductive sulfur species, the interaction between Cu(I) and Fe(III) as well as the available O₂^•- derived from the activation of molecular oxygen and the conversion of ^•OH favored the regeneration of Fe(II) on CuFeS₂ surface. Furthermore, the degradation intermediates of SMT and their toxicities were evaluated. This study presents a novel strategy by integrating transition metal sulfides with percarbonate for antibiotic-contaminated water treatment.

Recent advances in waste water treatment through transition metal sulfides-based advanced oxidation processes

With the ever-growing water pollution issues, advanced oxidation processes (AOPs) have received growing attention due to their high efficiency in the removal of refractory organic pollutants. Transition metal sulfides (TMSs), with excellent optical, electrical, and catalytical performance, are of great interest as heterogeneous catalysts. These TMSs-based heterogeneous catalysts have been demonstrated to becapable and adaptable in water purification through advanced oxidation processes. The aim of this review is to conduct an exhaustive analysis and summary of recent progress in the application of TMSs-based AOPs for water decontamination. Firstly, the commonly used tuning strategies for TMSs-based catalysts are concisely introduced, including artificial size and shape control, composition control, doping, and heterostructure manufacturing. Then, a comprehensive overview of the current state-of-the-art progress on TMSs-based AOPs (i.e., Fenton-like oxidation, photocatalytic oxidation, and electro chemical oxidation processes) for wastewater treatment is discussed in detail, with an emphasis on their catalytic performance and involved mechanism. In addition, influencing factors of water chemistry, namely, pH, temperature, dissolved oxygen, inorganic species, and natural organic matter on the catalytic performance of established AOPs are analyzed. Furthermore, the reusability and stability of TMSs-based catalysts in these AOPs are also outlined. Finally, current challenges and future perspectives related to TMSs-based catalysts and their applications for AOPs wastewater treatment are proposed. It is expected that this review would shed some light on the future development of TMSs-based AOPs towards water purification.

Development of oxygen vacancies enriched CoAl hydroxide@hydroxysulfide hollow flowers for peroxymonosulfate activation: A highly efficient singlet oxygen-dominated oxidation process for sulfamethoxazole degradation

In this study, oxygen vacancies enriched cobalt aluminum hydroxide@hydroxysulfide (CoAl-LDH@CoS_x) hollow flowers was synthesized by in-situ etching of CoAl-LDH using sodium sulfide solution. The analysis of SEM, EDS, XRD, and XPS were used to characterize the samples. The as-synthesized 0.2CoAl-LDH@CoS_x displayed higher catalysis performance of sulfamethoxazole (SMX) degradation via the activation of PMS than the pristine CoAl-LDH. 98.5 % of SMX (40 μM) was eliminated with 0.1 g/L 0.2CoAl-LDH@CoS_x and 0.3 mM PMS at pH 6.0 in 4 min. The degradation fitted with the pseudo-first-order reaction kinetics well with rate constant of 0.89 min^-1 for 0.2CoAl-LDH@CoS_x/PMS system and 0.55 min^-1 for CoAl-LDH/PMS system. Singlet oxygen (¹O₂) was verified as dominant reactive oxygen species responsible for SMX degradation via quenching tests. Mechanism investigation suggested that the oxygen vacancies, redox cycles of Co(II)/Co(III) and S₂^2-/(S^2- and sulfate species) on the surface of 0.2CoAl-LDH@CoS_x were crucial for PMS activation. In addition, the plausible degradation pathways of SMX were proposed by analysis of the SMX degradation intermediates. This study not only reveals that 0.2CoAl-LDH@CoS_x is an efficient catalyst to activate PMS for SMX degradation, but also shed a novel insight into development of heterogeneous catalysts with oxygen vacancies.