Efficient Degradation Of Organic Pollutants Research Articles

Enhanced Fenton-like catalysis via interfacial regulation of g-C3N4 for efficient aromatic organic pollutant degradation

For the efficient degradation of organic pollutants with the goal of reducing the water environment pollution, we employed an alkaline hydrothermal treatment on primeval g-C3N4 to synthesize a hydroxyl-grafted g-C3N4 (CN-0.5) material, from which we engineered a novel Fenton-like catalyst, known as Cu–CN-0.5. The introduction of numerous hydroxyl functional groups allowed the CN-0.5 substrate to stably fix active copper oxide particles through surface complexation, resulting in a low Cu leaching rate during a Cu–CN-0.5 Fenton-like process. A sequence of characterization techniques and theoretical calculations uncovered that interfacial complexation induced charge redistribution on the Cu–CN-0.5 surface. Specifically, some of the π electrons in the tris-s-triazine units were transferred to the copper oxide particles along the newly formed chemical bonds (C(π)-O-Cu), forming a π-deficient area on the tris-s-triazine plane near the complexation site. In a typical Cu–CN-0.5 Fenton-like process, a stable π-π interaction was established due to the favorable positive-negative match of electrostatic potential between the aromatic pollutants and π-deficient areas, leading to a significant improvement in Cu–CN-0.5's adsorption capacity for aromatic pollutants. Furthermore, pollutants also delivered electrons to the Cu–CN-0.5 Fenton-like system via a “through-space” approach, which suppressed the futile oxidation of H2O2 in reducing the high-valent Cu2+ and significantly improved the generation efficiency of •OH with high oxidative capacity. As expected, Cu–CN-0.5 not only exhibited an efficient Fenton degradation for several typical aromatic organic pollutants, but also demonstrated both a low metal leaching rate (0.12 mg/L) and a H2O2 utilization rate exceeding 80%. The distinctive Fenton degradation mechanism substantiated the potential of the as-prepared material for effective wastewater treatment applications.

MgO-loaded tubular ceramic membrane with spatial nanoconfinement for enhanced catalytic ozonation in refractory wastewater treatment

Heterogeneous catalytic ozonation (HCO) enables the destruction of organic pollutants in wastewater via oxidation by powerful hydroxyl radicals (·OH). However, the availability of short‐lived ·OH in aqueous bulk is low in practical treatment scenarios due to mass transfer limitations and quenching of water constituents. Herein, we overcome these challenges by loading MgO catalysts inside the pores of a tubular ceramic membrane (denoted as CCM) to confine ·OH within the nanopores and achieve efficient pollutant removal. When the pore size of the membrane was reduced from 1000 to 50 nm, the removal of ibuprofen (IBU) by CCM was increased from 49.6 % to 90.2 % due to the enhancement of ·OH enrichment in the nanospace. In addition, the CCM exhibited high catalytic activity in the presence of co-existing ions and over a wide pH range, as well as good self-cleaning ability in treating secondary wastewater. The experimental results revealed that ·OH were the dominant reactive oxygen species (ROS) in pollutant degradation, while surface hydroxyl groups were active sites for the generation of ·OH via ozone decomposition. This work provides a promising strategy to enhance the utilization of ·OH in HCO for the efficient degradation of organic pollutants in wastewater under spatial confinement.

Recent advances of piezo-catalysis and photocatalysis for efficient environmental remediation.

The efficient degradation of organic pollutants in diverse environmental matrices can be achieved through the synergistic application of piezo-catalysis and photocatalysis. The focus of this study is on understanding the fundamental principles and mechanisms that govern the collaborative action of piezoelectric and photocatalytic materials. Piezoelectric nanomaterials, under mechanical stress, generate piezo-potential, which, when coupled with photocatalysts, enhances the generation and separation of charge carriers. The resulting cascade of redox reactions promotes the degradation of a wide spectrum of organic pollutants. The comprehensive investigation involves a variety of experimental techniques, including advanced spectroscopy and microscopy, to elucidate the intricate interplay between mechanical and photoinduced processes. The influence of key parameters, such as material composition, morphology, and external stimuli on the catalytic performance, is systematically explored. This study contributes to the increasing knowledge of environmental remediation and lays the foundation for the development of advanced technologies using piezo and photocatalysis for sustainable pollutant removal.

Hydrolysis-induced polyacrylonitrile membranes with high catalytic activity and self-cleaning properties for antibiotic degradation

The immobilization of heterogeneous catalysts on membrane supports can realize highly efficient degradation of organic pollutants to alleviate membrane fouling through in situ catalytic oxidation. In this work, a polyacrylonitrile (PAN)-based catalytic membrane was prepared via a phase inversion method in the presence of core-shell structured perovskite catalysts. Following this, a controlled alkali-induced strategy was employed to simultaneously hydrolyze the –CN groups on the membrane surface and the core-shell structured perovskite catalysts anchored in the membrane matrix. Correspondingly, improved hydrophilicity, permeability, and catalytic efficiency via activating peroxymonosulfate were achieved compared with pristine PAN membrane. Rapid tetracycline (TC) elimination (10 ppm, 500 mL) can be realized (99 % in 30 min) under a flux of 334.5 L/m2h (0.02 MPa). Besides, owing to the intrinsic size sieving of the membrane, favorable TC degradation efficiency can also be accomplished in the presence of humic acid. Furthermore, the accumulation of pollutants on the membrane surface was released owing to the massive generation of sulfate radicals and singlet oxygen, enabling self-cleaning properties. More importantly, the as-prepared catalytic membrane possessed attractive stability with the cobalt leaching below 0.013 mg/L. This work provides a method to synergistically enhance permeability, catalytic activity and anti-fouling performance of the membranes, which shows potential application in wastewater decontamination.

Visible light-driven molecular oxygen activation by lead-zinc smelting slag and tartaric acid for efficient organic pollutant degradation and Cr(VI) reduction

The remediation of heavy metal and organic-contaminated wastewater remains a significant concern in environmental science, necessitating the development of cost-effective and efficient treatment systems. This study focuses on the setup of a highly effective molecular oxygen (O2) activation system using lead–zinc smelting slag (LZSS) and tartaric acid (TA) under visible light. The LZSS-TA complex exhibited rapid photochemical reactions and demonstrated a remarkable capacity for O2 activation, resulting in the in situ generation of hydrogen peroxide (H2O2) and 99 % degradation of para-chloroaniline (p-CA). The formation of H2O2 occurred through a two-step single electron transfer pathway, whereby C-centered radicals (CHOHCHOHCOO−) generated within the system initiated the reduction of O2 to form O2−, as a crucial intermediate. The produced O2− is then reduced by Fe(II) to generate H2O2 via proton-coupled electron transfer (PCET) processes. Light-induced ligand-to-metal charge transfer (LMCT) process is the key to the production of C-centered radicals and Fe(II), which determines the production efficiency of H2O2 and OH. Additionally, this system enabled simultaneous oxidation of p-CA by 98 % and reduction of Cr(VI) by 100 % within 60 min. More importantly, O2 activation by TA-assisted LZSS under natural sunlight/solar irradiation could efficiently degrade p-CA in both ultrapure water (94 %) and reservoir water (92.5 %) within 210 min. This study significantly contributes to the understanding of light-driven O2 activation and lays the foundation for the design of cost-effective and efficient pollution remediation systems.

Tailored BiPO4/Bi‐MOF heterostructure photocatalysts with diverse morphologies for highly efficient organic pollutant degradation

Three distinct morphologies of Bi‐MOFs were innovatively employed as carriers, facilitating the formation of heterojunctions with BiPO4. Among these, the optimal photocatalytic performance was demonstrated by the type II heterojunction BiPO4/CAU‐17. Bi3+ competitively coordinated to crucially aid CAU‐17's transformation into a heterojunction, enhancing interfacial contact in BiPO4/CAU‐17. These photocatalysts effectively degraded dyes (RhB, MO, MB) and tetracycline (TC) under light exposure. RhB degradation was 3.33 times faster with BiPO4/CAU‐17 than BiPO4, 1.45 times faster than FCAU‐17, 1.36 times faster than FRCAU‐17, and 1.32 times faster than CAU‐17. Analyzing carrier density, Fermi level, and band structure through VB‐XPS, UV–VIS, and Mott–Schottky provided insights into enhanced separation of photoexcited electron–hole pairs. This study presents a novel approach to tackle the aggregation challenge of the wide‐bandgap material BiPO4 by using suitable MOFs as carriers. It offers valuable perspectives for the design and application of photocatalysts in environmental remediation.

All‐In‐One Self‐Floating Wood‐Based Solar‐Thermal Evaporators for Simultaneous Solar Steam Generation and Catalytic Degradation

AbstractSolar‐driven steam generation has emerged as a sustainable technology for addressing freshwater scarcity. However, significant challenges still exist in developing high‐performance, multifunctional evaporators that are adept at both efficiently evaporating water and degrading pollutants, primarily because of the trade‐offs among functional designs. Here, a self‐floating solar evaporator is reported by functionalizing balsa wood with solar‐thermal conversion material carbon nanotubes and catalytic manganese dioxide (MnO2) nanoflowers for simultaneous solar evaporation and pollutant degradation. MnO2 nanoflowers are rich in oxygen vacancies that can effectively activate peroxymonosulfate to generate reactive oxygen species for efficient organic pollutant degradation. A distinctive non‐wetted porous interior structure and a precisely targeted water pathway are spontaneously established in the multifunctional evaporator, ensuring fast water supply, thermal insulation, efficient mass transfer, and high buoyancy. The resulting evaporators successfully combine an impressive evaporation rate of 2.74 kg m−2 h−1, a high pollutant degradation efficiency (98.3% for 100 mg L−1 tetracycline and 97.4% for 200 mg L−1 Methyl orange), and stable self‐floating and self‐standing capabilities that ensure long‐term operation stability even in complex real‐world environments. This work provides an approach to design multifunctional solar evaporators, ensuring strong alignment with practical requirements while expanding their potential application scenarios.

Synergistic Engineering of Energy Band Alignment and Interfacial Electric Field Distribution over Bi-bismuth-Based Hetero-nanofibers for Boosting Visible-Light-Driven Photocatalytic Ammonia Synthesis and Antibiotic Removal.

Synergistic engineering of energy band alignment and interfacial electric field distribution is essential for photocatalyst design but is still challenging because of the limitation on refined regulation in the nanoscale. This study addresses the issue by employing surface modification and thermal-induced phase transformation in Bi2MoO6/BixOyIz hetero-nanofiber frameworks. The energy band alignment switches from a type-II interface to a Z-scheme contact with stronger redox potentials and inhibited electron traps, and the optimized built-in electric field distribution could be reached based on experimental and theoretical investigations. The engineered hetero-nanofibers exhibit outstanding visible-light-driven photocatalytic nitrogen reduction activity (605 μmol/g/h) and tetracycline hydrochloride removal rate (81.5% within 30 min), ranking them among the top-performing bismuth series materials. Furthermore, the photocatalysts show promise in activating advanced oxidants for efficient organic pollutant degradation. Moreover, the Bi2MoO6/Bi5O7I hetero-nanofibers possess good recycling stability owing to their three-dimensional network structure. This research offers valuable insights into heterojunction design for environmental remediation and industrial applications.

Boosting peroxymonosulfate activation over partial Zn-substituted Co3O4 for florfenicol degradation: Insights into catalytic performance, degradation mechanism and routes

Florfenicol (FLO) is a broad-spectrum halogenated antibiotic (containing F and Cl atoms), and the discharged FLO in wastewater exhibits potential biotoxicity. Peroxymonosulfate (PMS) activation can generate reactive oxygen species (ROSs) to realize efficient degradation of organic pollutants. Herein, Zn-substituted Co3O4 (ZnxCo) catalysts were prepared and applied in PMS activation for FLO degradation. The physicochemical properties were systematically studied by combining experiments and density functional theory (DFT) calculation. The Zn partial substitution induced electron rearrangement and promoted oxygen vacancy (OV) formation in Co3O4. Zn0.03Co catalyst exhibited superior FLO removal, achieving a higher reaction rate of 0.112 min−1 than Co3O4 (0.053 min−1). The FLO degradation was highly dependent on the factors of PMS/Zn0.03Co/FLO dosage, temperature, initial pH, and coexisting inorganic anions. The Zn0.03Co also displayed outstanding performance in PMS activation for degradation of various typical organic pollutants. Electron paramagnetic resonance (EPR) spectra and quenching experiments indicated that both radical species (·OH, SO4·-, and ·O2-) and nonradical species (1O2) contribute to FLO removal. The redox cycle of Co3+/Co2+ and OVs played an essential role in PMS activation. The electron structure of FLO and parameters of PMS adsorbed on ZnxCo were calculated. The longer length of CoO and OO bonds for the adsorbed PMS could enhance its activation to generate ROSs. The intermediates were detected, and five degradation pathways were proposed. The acute and chronic toxicities of intermediates suggested that the dechlorination process is important for the toxicity attenuation of FLO. This study clarified the performance enhancement mechanism of Zn substitution on FLO degradation by PMS activation using Co3O4 based catalyst, which favors the development of PMS-based advanced oxidation processes for wastewater treatment.

Solar-driven Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 heterojunction for efficient degradation of organic pollutants: Insights into adsorption mechanism, charge transfer and degradation pathway

Actualizing controllable construction of efficient heterojunction nanocomposites remains a challenge in the field of photocatalytic water remediation, which can be got over through exploiting in-situ attachment approaches between different semiconductors. Based on this, we successfully fabricated a unique separable Z-scheme Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 (BON/BW) nanoflowers by an in-situ growth strategy. The profitable photogenerated carriers transfer mediated by Z-scheme heterojunction greatly accelerated the generation of •O2– and •OH. The strong adsorption of 4-nitrophenols (4-NP) with parallel configuration on side Bi2WO6 in BON/BW nanocomposites also provides great convenience for subsequent degradation steps. By optimizing multiple steps in the photocatalytic reaction process, BON/BW showed far superior photodegradation performance compared to single components. The causes and consequences of 4-NP photodegradation were explored through LC-MS tests, theoretical calculations, and toxicity analysis, and a green and safe degradation pathway was proposed. More experiments have confirmed that the synthesized BON/BW composites also have excellent degradation ability against other pollutants under sunlight, demonstrating excellent universality. With any luck, the logical design of heterojunction photocatalysts for effective photocatalytic water remediation should be aided by this study.

Activating peroxymonosulfate by high nitrogen-doped biochar from lotus pollen for efficient degradation of organic pollutants from water: Performance, kinetics and mechanism investigation

Nitrogen-doped biochars are promising metal-free catalysts for peroxymonosulafe (PMS) activation due to their low-cost, high chemical stability and metal-free leaching. However, the nitrogen content in the biochar is usually low with unsatisfactory performance, and the in-depth analysis on the kinetic of pollutant degradation is still insufficient. Herein, high nitrogen doped biochars were prepared by one-step pyrolysis of lotus pollen (LP) and melamine, which were used to trigger PMS for degrading organic pollutants in water. The optimized nitrogen-doped LP biochar (N-LPC-5) possessed ultrahigh nitrogen content (up to 15.75 at%) and abundant oxygen-containing functional groups, which exhibited the optimal performance in activating PMS to degrade reactive black 5, atrazine, ketoprofen and p-nitrophenol. The removal efficiency for all the organic pollutants in the N-LPC-5/PMS system can reach above 90 % in 20 min, and the degradation performance was outstanding in a wide pH range from 2.0 to 10.5. The pollutant degradation followed a two-stage process including a fast stage of initial oxidation and a slow stage. An appropriate mathematic kinetic model was proposed to describe the two-stage reaction. Fitting the experimental data with the proposed kinetic model, the initial removal rate and the maximal oxidation capacity can be obtained accordingly, and the correlation coefficients were very close to 1.0, indicative of the excellent fitness of the proposed model. In addition, the catalytic mechanisms such as the reactive oxygen species, electron-transfer pathway and active sites were also investigated by various techniques. The present study highlights the tremendous potential of N-biochar for wastewater remediation, and helps to understand the dynamic kinetics and catalytic mechanism of metal-free carbon activating PMS.

Chemical inertness conversion of carbon fraction in coal gangue via N-doping for efficient benzo(a)pyrene degradation

Efficient degradation of organic pollutants in complex media via advanced oxidation processes (AOPs) is still critical and challenging. Herein, nitrogen (N)-doped coal gangue (CG) catalysts (N-CG) with economic competitiveness and environmental friendliness were successfully synthesized to activate peroxymonosulfate (PMS), exhibiting ultrafast degradation performance toward benzo(a)pyrene (BaP) with 100.00 % and 93.21 % in contaminated solution and soil under optimized condition, respectively. In addition, 0.4 N-CG possessed excellent reusability toward BaP degradation with over 80.00 % after five cycles. However, BaP removal efficiency was significantly affected by some co-existing anions (HCO3− and SO42−) and humic acid (HA) in solution and soil, as well as inhibited under alkaline conditions, especially pH ≥ 9. According to the characterizations, N-doping could promote the generation of pyridinic N and graphitic N in N-CG via high-temperature calcination, which was conducive to produce hydroxyl radical (•OH), sulfate radical (SO4•−), superoxide radical (•O2−) and single oxygen (1O2). In 0.4 N-CG/PMS system, 1O2 and •O2− were proved to be the predominant reactive oxygen species (ROSs) in BaP degradation, as well as •OH and SO4•− made certain contributions. To sum up, this work provided a promising strategy for synthesis of CG-based catalysts by chemical inertness conversion of carbon fracture via N-doping for PMS activation and opened a novel perspective for environmental remediation of hydrophobic and hydrophilic contaminants pollution.

Superoxide radical-induced rapid valence cycling of Mn(II/III/IV) for efficient degradation of organic pollutants

Transition metal oxides are one of the commonly used catalysts for ozone oxidation, and the slow redox cycling of different valence metal components inside the catalysts currently becomes a key bottleneck limiting their catalytic activity. In this work, the superoxide radicals generated at the N/C sites were used to reduce the neighboring high-valence metal components to low-valence states to construct a new mechanism for the rapid cyclic transition of Mn (II/III/IV) valence states. What's more, N/C sites enhanced the ozone adsorption and conversion ability, synergized with the adjacent MnO2 sites to generate interfacial hydroxyl radicals and superoxide radicals, and effectively inhibited the quenching effect of inorganic salt ions (e.g., Cl-, SO42-) on the free radicals. For the actual printing and dyeing wastewater, the COD (chemical oxygen demand) removal rate was as high as 70 % in 60 min and remained stable in 10 cycles with almost no manganese ions leaching. In addition, characterization such as EPR combined with DFT calculations showed that the dual-site structure significantly increased the oxygen vacancy content and Lewis acidity, and the synergistic interaction between graphite N and MnO2 was the most favorable for ozone conversion with the lowest reaction energy barriers.

Constructing a type-II heterojunction of AgI/CO32−-Bi2O2CO3 for enhanced photocatalytic degradation of organic pollutants

The construction of heterojunctions is a well-established approach for enhancing the photocatalytic efficiency of semiconductor materials. To improve the photocatalytic activity of CO32−-Bi2O2CO3, AgI/CO32−-Bi2O2CO3 type-II heterojunction photocatalysts were synthesized using an electrostatic self-assembly method with varying composite ratios. The performance of AgI/CO32−-Bi2O2CO3 catalyst was investigated by photocatalytic degradation of 2-Hydroxy-1, 4-naphthoquinone and levofloxacin under a 300 W xenon lamp (λ ≥ 420 nm). The results demonstrated that the composite photocatalyst (0.5ACBOC), prepared by incorporating 0.5 mL of AgNO3 and KI, exhibited exceptional photocurrent responsiveness and efficient charge carrier separation. 0.5ACBOC displayed the highest degradation efficiency towards 2-Hydroxy-1,4-naphthoquinone (67.5%) and levofloxacin (78.0%). Free radical capture experiments and electron paramagnetic resonance (EPR) analysis revealed ·O2− as a crucial reactive species in the photodegradation process. Moreover, the photocatalytic degradation of 2-Hydroxy-1,4-naphthoquinone exhibited consistent removal efficiency even after undergoing four cycles, thereby demonstrating the excellent cycle stability of the composite catalyst. These findings highlight that AgI/CO32−-Bi2O2CO3 can be easily synthesized and holds great potential as a photocatalyst for efficient degradation of organic pollutants.

Insight into the activation of peroxymonosulfate by N-doped copper-based carbon for efficient degradation of organic pollutants: Synergy of nonradicals

The contamination of water resources by phenolic compounds (PCs) presents a significant environmental hazard, necessitating the development of novel materials and methodologies for effective mitigation. In this study, a metallic copper-doped zeolitic imidazolate framework was pyrolyzed and designated as Cu-NC-20 for the activation of peroxymonosulfate (PMS) to degrade phenol (PE). Cu-NC-20 could effectively address the issue of metal agglomeration while simultaneously diminishing copper dissolution during the activation of PMS reactions. The Cu-NC-20 catalyst exhibited a rapid degradation rate for PE across a broad pH range (3–9) and demonstrated high tolerance towards coexisting ions. According to scavenger experiments and electron paramagnetic resonance analysis, singlet oxygen (1O2) and high-valent copper-oxo (Cu(III)) were the predominant reactive oxygen species, indicating that the system was nonradical-dominated during the degradation process. The quantitative structure-activity relationship (QSAR) between the oxidation rate constants of various substituted phenols and Hammett constants was established. It indicated that the Cu-NC-20/PMS system had the optimal oxidation rate constant with σ− correlation and exhibited a typical electrophilic reaction pattern. This study provides a comprehensive understanding of the heterogeneous activation process for the selective removal of phenolic compounds.

Development of a novel pH-Responsive PVA/GO-Glu/TiO2 nanocomposite hydrogel for efficient degradation of organic pollutants

Water pollution poses a grave threat to public health and the environment. There is an urgent need for sustainable remediation strategies to remove toxic contaminants from water sources. In this study, we report the development of a novel pH-responsive nanocomposite hydrogel for the effective degradation of organic pollutants. The hydrogel was synthesized using polyvinyl alcohol, graphene oxide, glutamic acid, and titanium dioxide through an in-situ crosslinking method. Characterization using SEM, FTIR and UV–vis spectroscopy confirmed the successful formation of the nanocomposite structure. Batch experiments demonstrated that the hydrogel was able to degrade over 90% of methylene blue dye within 35 min under sunlight irradiation, owing to the synergistic effect of pH-sensitivity and the photocatalytic activity of titanium dioxide. Degradation efficiency increased with rising pH, reaching a maximum at pH 11. This eco-friendly nanohybrid holds tremendous potential for water remediation applications through low-cost, solar-powered degradation of toxic pollutants.

Efficient degradation of organic pollutants with sodium percarbonate by activation with CuFeS2 prepared from precursors of different valence states

Four chalcopyrite (CuFeS2) catalysts were fabricated by a hydrothermal method using different copper and iron precursors at different valence states. The prepared CuFeS2 samples were then evaluated for the oxidative degradation of Congo red (CR) using sodium percarbonate (SPC) as the oxidant. The sample of CuFeS2-1, which was prepared from Cu (I) and Fe (II) precursors, exhibited the highest CR removal efficiency of 96.6% among the four CuFeS2 samples. Using CuFeS2-1 as the optimum catalyst, the effects of operation and environmental factors on the removal efficiency of CR were investigated in detail. Mechanism studies showed that CO3•− was the main reactive oxidative species in the reaction process, while O2•− and low-valent sulfur species together promoted the regeneration of Fe (II) and Cu (I) sites on the catalyst. Furthermore, density functional theory (DFT) calculations were used in combination with liquid chromatography-mass spectrometer (LC-MS) to propose the plausible degradation pathway. Finally, toxicity prediction showed that most of the degradation products showed decreased toxicity compared to the parent CR, and toxicity evaluation with Vigna radiata further revealed the declined toxicity.

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.

Enhanced degradation of tetracycline by TiO2@MXene with peroxydisulfate under visible light irradiation

Photocatalysis and peroxydisulfate (PS) based advanced oxidation techniques are promising technologies in the field of water treatment that can be used to destroy increasingly persistent organic contaminants. The current work used a simple hydrothermal approach to synthesize a catalyst made of composites of TiO2 nanospheres and multi-layer Ti3C2Tx sheets (TiO2@MXene). Tetracycline (TC) was then effectively degraded by the TiO2@MXene material integrated with PS activation (300 mg/L). Under simulated sunlight (AM 1.5G, P = 2.8 W) irradiation, the combination method dramatically increases TC degradation. Following a 30-min treatment with 300 mg/L TiO2@MXene (wt.10 %), the optimal efficiency can reach 100 %. As the reactive functional species, holes (h+), SO4-•, •OH, and •O2− dominate the catalytic process. Furthermore, investigation was conducted into significant factors such as catalyst dosage, PS dosage, common anions, and TiO2 loading dosage. The TiO2@MXene material was demonstrated to be a feasible and sustainable strategy worth taking into consideration in the mitigation of emerging water contaminants due to its ease of recovery, stability of surface properties, and recyclability. Furthermore, the proposed degradation mechanism further demonstrated the viability of TiO2@MXene with PS in TC degradation. This, this study provides insights into the design of effective photocatalyst coupling PS activation for the efficient degradation of organic pollutants.

A Co-doped Ag3PO4 photocatalyst: Efficient degradation of organic pollutants and enhancement mechanism

In this study, an efficient Co-doped Ag3PO4 photocatalyst was prepared by the deposition method. Compared with Ag3PO4, the degradation efficiency of the optimal sample CAP-2 (the mole ratio of Co/Ag was 0.057 %) for MO (20 mgL−1) increased from 53.4 % to 95.0 % within 20 min, and the degradation efficiency for phenol (20 mgL−1) increased from 57.9 % to 91.8 % within 80 min. Moreover, the CAP-2 sample performed excellent mineralization ability and stable recycling capacity. Free radical capture experiments and electron spin resonance (ESR) measurements indicated that holes (h+) and superoxide radicals (⋅O2−) were the main active radicals. Doping Co ions broadened the optical absorption, introduced impurity level to promote the separation of carriers, and generated additional ⋅O2− owing to the mutual conversion of Co3+ and Co2+, thus considerably improving Ag3PO4 photocatalytic performance. This work provides a new reference for doping metal ions modified semiconductor photocatalysts to efficiently degrade organic pollutants.