Degradation Rate Of Pollutants Research Articles

Nanobubbles improve peroxymonosulfate-based advanced oxidation: High efficiency, low toxicity/cost, and novel collaborative mechanism

Cl- activated peroxymonosulfate (PMS) oxidation technology can effectively degrade pollutants, but the generation of chlorinated disinfection byproducts (DBPs) limits the application of this technology in water treatment. In this study, a method of nanobubbles (NBs) synergistic Cl-/PMS system was designed to try to improve this technology. The results showed the synergistic effects of NBs/Cl-/PMS were significant and universal while its upgrade rate was from 12.89% to 34.97%. Moreover, the synergistic effects can be further improved by increasing the concentration and Zeta potential of NBs. The main synergistic effects of NBs/Cl-/PMS system were due to the electrostatic attraction of negatively charged NBs to Na+ from NaCl, K+ from PMS, and H+ from phenol, which acted as a "bridge" between Cl- and HSO5- as well as phenol and Cl-/HSO5-, increasing active substance concentration. In addition, the addition of NBs completely changed the oxidation system of Cl-/PMS from one that increases environmental toxicity to one that reduces it. The reason was that the electrostatic attraction of NBs changed the active sites and degradation pathway of phenol, greatly reducing the production of highly toxic DBPs. This study developed a novel environmentally friendly oxidation technology, which provides an effective strategy to reduce the generation of DBPs in the Cl-/PMS system. Environmental ImplicationCl- activated peroxymonosulfate (PMS) oxidation technology results in the formation of chlorinated disinfection byproducts (DBPs), limiting its application in water treatment. In this study, the nanobubbles (NBs) synergistic Cl-/PMS system was designed to enhance the degradation and mineralization rates of ionizable pollutants. Based on luminescent bacterial toxicity tests, the inhibition rate of the NBs/Cl-/PMS system was (9.35%) much lower than that of the control (only phenol, 30.96%) or Cl-/PMS system (100%). This study developed a novel environmentally friendly oxidation technology, which provides an effective strategy to reduce the generation of DBPs in the Cl-/PMS system.

Selective degradation of organic pollutants by highly dispersed Fe, Ni anchored on nitrogen carbon activating persulfate system: Electron transfer promotion, the impact of pollutant redox and adsorption properties

The advanced oxidation processes using persulfate (PS-AOPs) as oxidant is an effective way to remove refractory organic pollutants from environment. Designing activators with higher activation efficiency and stability plays an important role in degradation of organic pollutants via PS-AOPs. Furthermore, redox and adsorption properties of pollutants also affect the selective degradation efficiency. In this study, we synthesized FeNi@CN derived from ZIF-8 in which highly dispersed Fe and Ni were anchored on nitrogen (N) doped carbon (C). The activator exhibited high activation potential and stability for paracetamol (PCT) degradation by activated peroxymonosulfate (PMS). The FeNi@CN/PMS system degraded PCT through electron transfer pathway, and the coordination of Fe-N and Ni-N improved the efficiency of catalyst mediated electron transfer. The abundant pyridinic N provided a large number of sites for PMS complexation. The bimetallic synergistic effect and N doping endowed the excellent comprehensive performance of FeNi@CN. The significant impact of pollutant redox and adsorption properties on degradation efficiency were also studied. It was observed that high half-wave potential (E1/2) and excessive adsorption were not conducive to electron transfer. Multi-parameter linear fitting was performed on the degradation rates of different pollutants using half-wave potential and pseudo first order adsorption rate constants, which showed the good correlation among them. This work not only provided insights into the mechanism and the influence of activator structure on electron transfer in PMS activation, but also proposed a new model to describe the effects of redox and adsorption properties on selective degradation of various category pollutants.

Innovatively-synthesized α-Fe2O3/Ti3C2Tx MXene nanocomposite by dry-impregnation method: Photocatalyst characterization and influence of operational parameters on highly efficient tetracycline degradation

Herein, a facile and cost-effective dry-impregnation method was employed to impregnate α-Fe2O3 onto Ti3C2Tx MXene (Ti3C2). The synthesized α-Fe2O3/Ti3C2Tx MXene (FeTM) photocatalyst with a narrow band gap (2.1 eV) was characterized using XRD, EDS, SEM, UV–Vis, TEM, and BET techniques. The photocatalyst was applied for the optimization degradation condition of tetracycline (TC) under visible light irradiation by measuring the absorbance at a wavelength of 357 nm via Response Surface Methodology (RSM)-Central Composite Design (CCD) method. Maximum degradation rate of pollutant (99.13 %) was achieved under optimized condition (Catalyst dosage: 0.606 g/L, tetracycline concentration: 21.67 mg/L, irradiation time: 93 min, and pH: 3.4). The correlation coefficients, F-value, and p-value are determined to be 99.35, 163.35, and < 0.0001, respectively, confirming the validity of the proposed model. Moreover, the reusability test demonstrates the favorable nanocomposite’s stability in the degradation of tetracycline from wastewater. After four cycles, a degradation efficiency of up to 81.4 % is maintained. The photodegradation kinetics was investigated and the result showed R2 = 0.9887 and K value equal to 0.0183 min−1, which represents a reaction with a quick kinetic. The α-Fe2O3/Ti3C2Tx MXene nanocomposite demonstrates remarkable degradation efficiency and high stability, positioning it as a highly promising candidate for wastewater treatment process.

Data-Based Modeling, Multi-Objective Optimization and Multi-Criteria Decision Making of a Catalytic Ozonation Process for Degradation of a Colored Effluent

In the catalytic ozonation process (COP), the reactions are complex, and it is very difficult to determine the effect of different operating parameters on the degradation rate of pollutants. Data-based modeling tools, such as the multilayer perceptron (MLP) neural network, can be useful in establishing the complex relationship of degradation efficiency with the operating variables. In this work, the COP of acid red 88 (AR88) with Fe3O4 nano catalyst was investigated in a semi-batch reactor and a MLP model was developed to predict the degradation efficiency (%DE) of AR88 in the range of 25 to 96%. The MLP model was trained using 78 experimental data having five input variables, namely, AR88 initial concentration, catalyst concentration, pH, inlet air flow rate and batch time (in the ranges of 150–400 mg L−1, 0.04–0.4 g L−1, 4.5–8.5, 0.5–1.90 mg min−1 and 5–30 min, respectively). Its optimal topology was obtained by changing the number of neurons in the hidden layer, the momentum and the learning rates to 7, 0.075 and 0.025, respectively. A high correlation coefficient (R2 &gt; 0.98) was found between the experimental and predicted values by the MLP model. Simultaneous maximization of %DE and minimization of Fe3O4 concentration was carried out by multi-objective particle swarm optimization (MOPSO) and the Pareto-optimal solutions were successfully obtained. The trade-off was analyzed through multi-criteria decision making, and one Pareto-optimal solution was selected. The developed model and optimal points are useful for treatment of AR88 wastewater.

Photocatalytic activity of ZnMn2O4/TiO2 heterostructure under solar light irradiation: Experimental and theoretical study

This study focuses on the application of the hetero-junction ZnMn2O4/TiO2 as an efficient photocatalyst for the degradation of Rhodamine B (RhB), a cationic dye. ZnMn2O4 was synthesized by sol-gel auto-combustion, employing citric acid as fuel. The photocatalysts underwent characterization by X-ray diffraction, Fourier Transform infrared spectroscopy, Scanning Electronic Microscopy with integrated EDX and UV–Vis Diffuse Reflectance. Creating a p-n heterojunction could significantly boost photocatalytic efficiency. In this work, we use TiO2 as a n-type co-catalyst to enhance electron transfer efficiency. The ZnMn2O4 spinel exhibits direct optical transition at 1.97 eV, while TiO2 displays an indirectly allowed transition at 3.24 eV. Mott-Schottky plots revealed flat band potentials of -0.121 and +0.3 V/SCE for ZnMn2O4 and TiO2, respectively. Kinetic data of RhB adsorption were fitted using the pseudo-second order model. The heterojunction p-ZnMn2O4/n-TiO2 demonstrates a significant pollutant degradation rate, with 95% removal within 180 min under sunlight irradiation, surpassing the effectiveness of ZnMn2O4. To validate the experimental results, a theoretical investigation was conducted using density functional theory (DFT) and molecular dynamics (MD) simulations. Geometry optimization of the Rhodamine B molecule was studied in both gas and liquid phases, and various quantum chemical parameters were computed. Molecular dynamics simulations were additionally employed to examine the dynamic behavior of Rhodamine B adsorption on ZnMn2O4 (211) and TiO2 (101) surfaces in an aqueous environment.

Small Scale Wastewater Treatment Method for Rainwater Garden Based on Photovoltaic Photocatalysis Technology

Conventional small-scale sewage treatment mostly adopts the principle of biological contact oxidation process, which has limited scope of application, low degradation rate of pollutants in sewage, and poor sewage treatment effect. Based on this, a new small-scale sewage treatment method was proposed by introducing photovoltaic photocatalysis technology and taking S sponge community in Ningnan County, Liangshan Prefecture as an example. First, hydrothermal method is used to prepare photocatalyst to provide basic guarantee for sewage treatment. Secondly, the rainwater garden model is simulated and designed to obtain the composition and content of small-scale sewage. On this basis, a rainwater garden photovoltaic photocatalytic water purification system is designed, which establishes an A/O integrated process by connecting the anoxic zone (A section) and aerobic zone (O section) in series to fully achieve the goal of sewage treatment. Experimental analysis shows that the new method can significantly improve the degradation rate of organic pollutants in rainwater garden wastewater, with a degradation rate of over 99% and a maximum degradation time of 10.97 seconds, indicating that the application effect of this method is good.

Coagulation/co-catalytic membrane integrated system for fouling-resistant and efficient water purification

Low-pressure catalytic membranes allow efficient rejection of particulates and simultaneously removing organics pollutant in water, but the accumulation of dissolved organic matters (DOM) on membrane surface, which cover the catalytic sites and cause membrane fouling, challenges their stable operation in practical wastewater treatment. Here we propose a ferric salt-based coagulation/co-catalytic membrane integrated system that can effectively mitigate the detrimental effects of DOM. Ferric salt (Fe3+) serving both as a DOM coagulant to lower the membrane fouling and as a co-catalyst with the membrane-embedded MoS2 nanosheets to drive perxymonosulfate (PMS) activation and pollutant degradation. The membrane functionalized with 2H-phased MoS2 nanosheets showed improved hydrophilicity and fouling resistance relative to the blank polysulfone membrane. Attributed to the DOM coagulation and co-catalytic generation of surface-bound radicals for decontamination at membrane surface, the catalytic membrane/PMS/ Fe3+ system showed much less membrane fouling and 2.6 times higher pollutant degradation rate in wastewater treatment than the catalytic membrane alone. Our work imply a great potential of coagulation/co-catalytic membrane integrated system for water purification application.

The various effects of hydrogen phosphate and bicarbonate in the degradation of some pollutants in the UV/chlorine and the UV/H2O2 processes

In this study, the degradation kinetics of three target pollutants (i.e., levofloxacin (LEV), P-nitrosodimethylaniline (RNO), and basic fuchsin (BF) in four UV-based Advanced Oxidation Processes (UV/AOPs) (i.e., UV/NaOCl/HPO42−, UV/NaOCl/HCO3−, UV/H2O2/HPO42−, and UV/H2O2/HCO3−) were comprehensively investigated. The results showed that LEV and RNO were resistant to UV irradiation, chlorination, and H2O2 when applied separately, but significantly degraded in UV/AOPs. The chlorination process and alkaline conditions were beneficial to the degradation of BF. In UV/AOPs, the degradation rates of the pollutants were enhanced remarkably with different rate constants which were dependent on the dosage of oxidants, and the presence of HPO42− and HCO3−. This enhancement is due to the generation of reactive species (i.e., •OH, RCS, and secondary reactive radicals like PO42•-, and CO3•-). The study also investigated the role and contribution of the reactive species to the degradation of the pollutants in UV/AOPs. The study demonstrated the difference in the degradation kinetics of the pollutants in UV/H2O2/(HPO42− or HCO3−) and UV/NaOCl/(HPO42− or HCO3−) in which the contribution of each oxidizing factor was determined. Acidic conditions were beneficial to the degradation rate of the pollutants in all UV/AOPs, except BF in UV/NaOCl. Seawater and river water were demonstrated to significantly promote the degradation rate of pollutants in UV/NaOCl/(HPO42− or HCO3−) but depressed it in UV/H2O2/(HPO42− or HCO3−). In addition, a typical PPCP (pharmaceutical and personal care product) (here LEV) was selected for further LC-MS analysis to determine its degradation pathway. The results provide a novel alternative strategy in the use of HPO42− and HCO3− in UV/NaOCl and UV/H2O2 to increase the removal efficiency of organic pollutants.

Novel Z-scheme Nb2O5/C3N5 photocatalyst for boosted degradation of tetracycline antibiotics by visible light-assisted activation of persulfate system

Photocatalytic-assisted activation of persulfate (PDS) is regarded as a promising method for the rapid and efficient degradation of refractory pollutants in the water environment. In this study, a novel Nb2O5/C3N5 (NOCN) p-n heterojunctions composite was created by loading n-type Nb2O5 onto p-type C3N5 via an in-situ facile one-step calcination method. The NOCN/PDS system exhibited excellent performance in degrading tetracycline (TC) antibiotics under visible light and had great cyclic stability. The degradation efficiency of the coupled system reached 95 %, surpassing the pure C3N5 and PDS systems by 3.5 times and 2.4 times, respectively. The degradation rate of target pollutants was improved by the coupled system with the photocatalytic activation of PDS. The photogenerated electrons (e-) in NOCN were able to activate PDS effectively, which facilitated the creation of more reactive species. The Photoluminescence (PL) and other photoelectrochemical data demonstrated that the interfacial charge separation and photoresponsivity were remarkably enhanced in the coupled system. According to Mott-Schooky and electron spin resonance (ESR) characterization, it was confirmed that the reaction mechanism was the Z-scheme charge transfer mechanism based on p-n heterojunctions in the NOCN/PDS system. In addition, LC-MS analyses, TOC monitoring and biotoxicity analyses detected that the target pollutants were degraded to weakly bio-toxic micromolecules. In conclusion, this work provides valuable insights into the application of visible light-activated PDS technology in the degradation of organic pollutants, highlighting its potential for practical implementation.

Generation of helical multi-functional microfiber motors based on modified microfluidic spinning method

Due to unique asymmetric shapes and easily realized directional movements, helical micromotors are widely used in applications such as drug delivery, cell manipulation, and wastewater purification. However, most of the hydrogel helical microfiber motors were water-based and had a homogeneous polymer network structure, which limited their practical applications like drug release. In this study, an emulsion-based microfluidic spinning method was used to prepare heterogenous helical hydrogel microfiber motors. Fine oil-in-water (O/W) emulsions were used as the inner phase of the microfluidic spinning process. When dichloromethane was used, micromotors with porous structure were formed after solidification and volatilization, improving the catalytic degradation rate of pollutants in water treatment application. When soybean oil was used, fat-soluble drugs were encapsulated successfully and gradually released as the micromotor degraded. Besides, the diameter and pitch size of the prepared fibers could be easily adjusted, and mass manufacturing (>100 m) was achieved.

Efficient degradation of parathion as a pollutant and diazinon as a nerve agent by reaction mechanism with rGO-Co3O4/ZnO nanocomposite photocatalyst

Chemical warfare agents and agricultural pesticides are two of the deadliest and most nefarious pollutants that have devastating impacts on both people and the environment. In this work, the Zinc oxide-decorated cobalt oxide/reduced graphene oxide nanocomposites (rGO-Co3O4/ZnO NCs) was prepared using a two-step hydrothermal method to employed as photocatalyst for degrade parathion (PA) as a pollutant and diazinon (DZ) as a nerve agent simulant in solution. The synthesized NCs was fully characterized using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS) and elemental mapping, thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller/Barrett-Joyner-Halenda (BET/BJH), dynamic light scattering (DLS), UV–vis differential reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). The structural features confirmed that the NCs was effectively synthesized, and the optical properties demonstrated that the NCs can be activated by visible light irradiation. The photocatalyst degradation rates of DZ and PA pollutants were respectively 99.6% and 99.8% in 140 min. Response surface methodology was also used to consider the effect of pertinent factors so that some parameters affecting the photocatalytic reaction, such as pH, pesticide concentration, photocatalyst amount, time, and light intensity, were optimized by an experimental design. The results show that adding ZnO nanoparticles (NPs) to the rGO-Co3O4 composition reduced the NCs band gap, which in turn reduced the rate at which photo-generated charges recombined.

Establishment of evaluation system for biological remediation on organic pollution in groundwater using slow-release agents

In situ bioremediation through slow-release agents can continuously degrade organic pollutants for a long time and have high application potential in solving problems such as tailing and rebound. However, the existing evaluation system is difficult to reflect the performance of bioremediation through slow-release agents, which is not conducive to the promotion of technology. It is urgent to establish a targeted evaluation system. Therefore, based on the multi-criteria decision-making method (MCDA), a comprehensive evaluation model was established. The evaluation index system was constructed for bioremediation through slow-release agents consisting of 16 indicators including pollutant degradation rate, agent preparation cost, engineering operation and maintenance cost, secondary pollution, long-term degradation stability, slow release time, slow release stability, increase in functional microbial flora, increase in total DNA content, agent particle size, solid agent morphology, liquid agent viscosity, dispersibility in aqueous phase, zeta potential, operability of agent preparation, and engineering operation management difficulty. Then, the weight of the indicators was determined by using the best-worst method (BWM), and evaluation criteria was established based on relevant norms and literature. Both and the indicators aggregation simple additive weighting (SAW) method constitute a quantitative evaluation model. The above content together constitutes a new evaluation system for biological remediation on organic pollution in groundwater using slow-release agents, which was defined as AOBS evaluation system. In order to verify the rationality and scientificity of the evaluation system, a typical bioremediation slow-release agent was evaluated using the established AOBS evaluation system. The results showed that the evaluation system could reasonably and comprehensively evaluate bioremediation through slow-release agents and provide suggestions for agent improvement.

Biomass-derived activated carbon nanocomposites for cleaner production: A review on aspects of photocatalytic pollutant degradation

Nowadays, water contamination resulting from the disposal of industrial and urban waste poses a significant threat to marine life and human. Hence, providing an effective treatment approach to reduce the total cost and duration of the wastewater treatment process is crucial. Although the adsorption and photocatalysis methods show superb potential for removing hazardous pollutants from water, their combination through a suitable synthesis route is one of the most effective ways to overcome their limitations. Activated carbon (AC) significantly accelerates the rate of pollutant degradation for AC-based photocatalysts compared to bare photocatalysts because of its ability to increase the number of attachment sites, strengthen the interaction between pollutants and photocatalysts, and facilitate rapid electron transfer to prevent electron or hole recombination. This study aims to investigate four main objectives: 1) evaluating key parameters to enhance the surface characterization of AC-derived from lignocellulosic sources using physical and chemical techniques; 2) Surveying various approaches for synthesizing AC-based photocatalysts; 3) explaining the mechanism of photocatalytic degradation of pollutants and the operating parameters in the wastewater treatment process; and 4) providing an overview of the opportunities, challenges, suggestions, and potential future outlooks. Future studies should focus on understanding the structural properties of AC to design effective photocatalytic systems for degrading hazardous contaminants. Generally, AC-based nanocomposites reduce both process costs and duration and promote environmental sustainability by effectively eliminating pollutants.

Research on the purification enhancement of ecological ponds: Integrating water cycle optimization and plants layout

The hydrodynamic conditions of ponds are generally poor, which seriously affects the long–term water quality guarantee. In this research, the numerical simulation method was used to establish an integrated model of hydrodynamics and water quality for the simulation of the plant purification effect in ponds. Based on the flushing time using the tracer method, the purification rate of plants was introduced to consider the purification effect of plants on water quality. In–situ monitoring was carried out at the Luxihe pond in Chengdu, and the model parameters such as the purification rate of typical plants were calibrated. The degradation coefficient of NH3–N in the non–vegetated area was 0.014 d−1 in August and 0.010 d−1 in November. In areas with vegetation, the purification rate of NH3–N was 0.10–0.20 g/(m2·d) in August and 0.06–0.12 g/(m2·d) in November. The comparison of the results in August and November showed that due to the higher temperature in August, the plant growth effect was better, and the degradation rate of pollutants and the purification rate of pollutants by plants were higher.The flushing time distribution of the proposed Baihedao pond under the conditions of terrain reconstruction, water replenishment, and plant layout was simulated, and the frequency distribution curve of flushing time was used to evaluate the results. Terrain reconstruction and water replenishment can significantly improve the water exchange capacity of ponds. The reasonable planting of plants can reduce the variability of the water exchange capacity. Based on this combined with the purification effect of plants on NH3–N, the layout plan of Canna, Cattails, and Thalia in ponds was proposed.

Hierarchical ternary titanium dioxide decorated with graphene quantum dot/ZIF-8 nanocomposite for the photocatalytic degradation of doxycycline and dye using visible light

Herein, the ternary nanostructure of titania (TiO2) decorated with graphene quantum dot (GQD)/zeolitic imidazolate framework-8 (ZIF-8) (T/G/Z: TiO2/GQD/ZIF-8) was synthesized by a hierarchical approach, and its photocatalytic activity was investigated for the degradation of the doxycycline (DOX) as a pharmaceutical and dyes under visible light irradiation. Increasing the doping content of the graphene quantum dot from 0.002 g to 0.02 g was accompanied by an increase in photocatalytic activity. A further increase to 0.2 g, the thickening or aggregation of the GQD layer on the TiO2 surface, or the thorough coverage of the TiO2 surface with the GQD occurred and effective light irradiation to TiO2 nanoparticles has not been done well. Thus the reduction of the catalytic activity happened. The photocatalytic degradation rate has increased outstandingly over this period of time for ternary composite in this concentration at intervals of the sampling period. The increase in pollutant concentration was associated with decreased photocatalytic degradation. Increasing the dose of photocatalysts improved the rate of pollutant degradation. The degradation efficiency of doxycycline in the presence of l-ascorbic acid scavenger had a notable decrease, while the presence of formic acid and isopropyl alcohol was less effective in the DOX degradation. It can be explained that the superoxide anion radical has the greatest effect on the degradation process of doxycycline. The DOX degradation kinetics followed the first-order kinetics with high correlation coefficients. This work has provided profound insight based on heterogeneous structures for efficient photocatalysts in the degradation of wastewater pollutants (pharmaceutical and dyes).

Kinetic study on the degradation of organic pollutants in UV/persulfate and in other advanced oxidation processes: Role of radicals and improvement of the degradation rates

Kinetic degradation of five typical pollutants including clothianidin (CLO), levofloxacin (LEV), p-nitrosodimethylaniline (RNO), paracetamol (PCM), and basic fuchsin (BF) by UV/persulfate (UV/PS) and other advanced oxidation processes (AOPs) (i.e., UV/H2O2, Fe2+/H2O2, electrochemical process, UV/PS/heat, UV/PS/Fe2+, UV/PS/Fe2O3, and UV/PS/rGO) were studied. The result showed that all pollutants were effectively degraded by UV/PS with different degradation rates. The oxidizing factors contributing to the pollutant degradation in UV/PS were studied, showing that UV is the predominant contributor to CLO degradation, while its contribution is negligible in the degradation of other compounds. •OH and SO4•- were the main radicals contributing to the degradation of all pollutants in UV/PS, except CLO. The second-order rate constant of •OH and SO4•- towards pollutants was determined according to the competition kinetic model, to be in the range of 109-1010 M−1 s−1. The degradation rate of pollutants in different AOPs were varied, because the oxidizing factors and their role in AOP systems directly affect the degradation efficiency of pollutants. In all AOPs, •OH radical played a major role in their degradation. The presence of water matrices has different influences on the degradation rates of pollutants. For example, 10 mM NO2- inhibited the degradation of pollutants to 99.1%, whereas Br-, SO42-, and F- had a lower inhibitory effect on their degradation. HPO42- can improve the degradation rate of BF, but it also significantly inhibited the degradation of PCM. The results also revealed that UV/PS/Fe2+ and UV/PS/rGO can remarkably increase the degradation efficiency of all pollutants, while using α-Fe2O3 and heat were less efficient. In addition, other parameters including COD removal, energy consumption, and toxicity assessment were also investigated to evaluate the potential application of UV/PS in practice.

Activation of peroxymonosulfate by N, S co-doped magnetic FeCoS for the degradation of ciprofloxacin hydrochloride: Catalytic performance and mechanism

A variety of metal-doped sulfide catalysts with a wide pH application range have a good prospect for activated persulfate removal of pollutants in water. In this article, a microwave-assisted vulcanization method has been utilized to prepare nanoparticles with magnetic properties of FeCoS. It improves the material preparation efficiency and greatly reduces the experimental energy consumption. FeCoS/PMS system has good degradation performance for ciprofloxacin hydrochloride (CIP in the wide pH range of 3–11). The synergistic action of iron and cobalt ions is the main activation mechanism. Compared with single metal-doped sulfide, the recombination of two metals increases the number of electron transfers for enhanced the possibility of breakage of O–O bond in PMS. It makes the catalyst many times more effective in removing pollutants. Stability and recovery experiments show that the FeCoS composite maintains a high catalytic effect under multiple cycles and that the magnetic material can be quickly separated and recovered. And the degradation rate of other typical pollutants can reach more than 90%, showing high degradation performance in the actual waste sample.This study offers a new strategy for the simple development of magnetic and easily recyclable multi-performance catalytic materials and demonstrates their potential application in the degradation of organic pollutants.

Na‐Sm Bimetallic Regulation and Band Structure Engineering in CaBi2Nb2O9 to Enhance Piezo‐photo‐catalytic Performance

AbstractThe piezoelectric enhancement of photo‐catalytic activity for water splitting and pollutant degradation is a novel approach to developing renewable energy and environmental protection applications. Herein, a new form of defect engineered Na‐Sm bimetallic‐regulated CaBi2Nb2O9 platelet is synthesized via a molten salt process for water splitting and pollutant degradation applications. An intermediate band structure is introduced by Sm‐doping, and empty orbitals in the conductive band are introduced by Na‐doping. These factors, combined with the increased local charge density around the Sm and Na atoms, result in an increased electrical conductivity, improved electron mobility, and provide additional electrons for enhancing catalytic reactions. As a consequence, the judicious co‐doping of CaBi2Nb2O9 with Sm and Na leads to a unique synergetic piezo‐photo‐electric effect to provide a superior piezo‐photo‐catalytic performance for H2 production (158.53 µmol g−1 h−1) and pollutant degradation (rate constant, k = 0.257 min−1). This new approach provides important insights into the application of defect engineering to exploit the cooperative doping of alkaline earth metals and rare metals to create high‐performance catalysts.

Preparation of Ti/SnO2–Sb/La-βPbO2 electrode and its application in the degradation of some pollutants including prednisolone and 8-Hydroxyquinoline

In this work, a novel La-doped βPbO2 (Ti/SnO2–Sb/La-βPbO2) was prepared using electrodeposition method and applied to the degradation of prednisolone (PRD), 8-Hydroxyquinoline (8-HQ), and other typical organic pollutants. Compared with the conventional electrode Ti/SnO2–Sb/βPbO2, La2O3 doping enhanced oxygen evolution potential (OEP), reactive surface area, stability and repeatability of the electrode. The 10 g L−1 of La2O3 doping exhibited the highest electrochemical oxidation capability of the electrode with [•OH]ss being determined at 5.6 × 10−13 M. The quenching experiments were conducted to confirm the main oxidizing species (here: •OH) in the electrochemical process. The study showed that the pollutants were removed in the electrochemical (EC) process with different degradation rates and indicated that the second-order rate constant of organic pollutants towards •OH (kOP,•OH) has a linear relationship with the degradation rate of organic pollutants (kOP) in the electrochemical process. Another new finding in this work is that a regression line of kOP,•OH and kOP can be used to estimate kOP,•OH of an organic chemical, which cannot be determined using the competition method. kPRD,•OH and k8-HQ,•OH were determined to be 7.4 × 109 M−1 s−1 and (4.6–5.5) × 109 M−1 s−1, respectively. Compared with conventional supporting electrolyte (like SO42−), H2PO4− and HPO42− improved kPRD and k8-HQ by 1.3–1.6-fold, while SO32− and HCO3− inhibited kPRD and k8-HQ significantly, down to 80%. Additionally, the degradation pathway of 8-HQ was proposed based on the detection of intermediates from GC-MS.

CuxO@Cu mesh electrode with {1 1 1} facet for efficient photo-electro-Fenton reaction and low voltage robustness

In this work, CuxO nanoarrays containing Cu2O and CuO with different morphologies were synthesized on the surface of copper mesh by anodic oxidation method, and the prepared CuxO@Cu mesh electrodes were confirmed by X-ray diffraction (XRD), field emission scanning microscope (SEM), and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and photocurrent were used to characterize the composite electrode. The photo-electro-Fenton (PEF) catalytic system constructed with the prepared CuxO@Cu electrode anode has excellent H2O2 utilization efficiency and pollutant degradation rate. Degradation efficiency of methylene blue (MB) by electro-Fenton (EF), photo-Fenton (PF) and photo-electro-Fenton (PEF) processes were investigated, which was in order: PEF > PF > EF. The effects of applied voltage, current density, pH and H2O2 concentration on MB degradation were investigated. MB could be quickly degraded at CuxO@Cu electrode during heterogeneous photo-electro-Fenton process with a first-order kinetic constant of 3.61 h−1 under 300 W simulated sunlight irradiation at 0.6 V, pH 7.0, 4.9 mmol H2O2. The CuxO@Cu electrode anode was stable and could be reused without catalytic reduction, and also had good degradation efficiency on other organic compounds (p-nitrophenol, tetracycline, norfloxacin), having potential application value in wastewater treatment.