Degradation Rate Of Pollutants Research Articles

Synchronicity Between the Rates of Reaeration and Pollutants Degradation During Self-Purification in a Large River.

The pollutants after were discharged into the water can gradually degrade through the self-purification. The oxygen consumption and pollutant degradation rates characterize the self-purification of small and medium-sized streams, while the dynamics of the two characteristics for large rivers has not been reported yet. The in-situ investigation for 297 sites in the 1700km stream of the Yangtze River was conducted. The oxygen consumption rate was 0.003d- 1, and the degradation rate of organic pollutants was greater than that of inorganics. The degradation of anion surfactant was the fastest, while the degradation of TN was the slowest, with rates of 0.043 and 0.001 d- 1, respectively. The oxygen consumption rate was negatively correlated with the degradation rate of COD, anion surfactant, and TP, indicating the synchronicity between reaeration and degradation during the self-purification. This study highlighted the role of synchronicity in modelling of water quality and estimation of environmental capacity for large rivers.

Ultrafast Water Purification by Template-Free Nanoconfined Catalysts Derived from Municipal Sludge.

Nanoconfinement at the interface of heterogeneous Fenton-like catalysts offers promising avenues for advancing oxidation processes in water purification. Herein, we introduce a template-free strategy for synthesizing nanoconfined catalysts from municipal sludge (S-NCCs),specifically engineered to optimize reactive oxygen species (ROS) generation and utilization for rapid pollutant degradation. Using selective hydrofluoric acid corrosion, we create an architecture that confines atomically dispersed Fe centers within a micro-mesoporous carbon matrix in situ. This method maximizes the utilization of silicon and aluminum content from sludge, prevents metal agglomeration, andprecisely regulates the chemical environment of Fe active sites.As a result,the S-NCCs promote a transition from nonradical to hybrid radical/nonradical reaction mechanisms, significantly enhancing ROS efficiency, stability, and pollutant degradation rates. These catalysts demonstrate exceptional pollutant removal performance, achieving a 261-fold increase in degradation efficiency for compounds such as phenol and sulfamethoxazole compared to unconfined analogs, outperforming most state-of-the-art Fenton-like systems. Our findings highlight the transformative potential of nanoconfined catalysis in environmental applications, providing an effective and scalable solution for sustainable water purification.

Enhancing Organic Pollutant Degradation Efficiency through a Photocatalysis-Electro-Fenton System via MoS2 Crystal Morphology Regulation.

A photocatalysis-electro-Fenton (PEF) system was constructed via molybdenum disulfide (MoS2) to remove tetracycline (TC) without an external oxidant supply and solution pH adjustment. In the system, original graphite felt (GF) was used as a cathode, from which H2O2 was in situ generated continuously under power. MoS2 was motivated by visible light to facilitate the cycle of Fe2+/Fe3+, enhancing the Fenton process to produce •OH. The experimental results showed that the system can increase the degradation rate of pollutants by more than 5 times. Moreover, the quenching and electron paramagnetic resonance (EPR) tests demonstrated that •OH was the dominant active species. X-ray photoelectron spectroscopy (XPS) characterization, Mo concentration, and cycle experiments proved the excellent catalytic activity and chemical stability of MoS2. It is worth mentioning that the photocatalytic performances of different morphologies of MoS2 (flower, flake, and radar) were compared. As a result, flower-like MoS2 exhibited a much superior photoresponse than flake and radar, which could accelerate the Fe2+/Fe3+ cycle further effectively. These findings highlight the morphology-performance relationship of MoS2 under a PEF system and the mechanisms of contaminant degradation, which is of great significance for developing photoelectric Fenton technology.

Functionalized cements incorporated with nanocomposite photocatalysts for self-cleaning applications

The constantly escalating pollution on the surface of cement-based materials affects architectural aesthetics and residents′ health, necessitating frequent cleaning and maintenance, which contradicts the concept of sustainable development. This study aimed to develop a novel photocatalytic cement material to enhance the self-cleaning capabilities of cement-based materials, thereby extending their service life and reducing maintenance costs. To achieve this, carbon quantum dots (CDs) and g-C3N4 (CN) nanocomposite photocatalysts (CDs@CN) were synthesized and integrated into white cement to prepare photocatalytic cements. The materials were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy. Photocatalytic performance was evaluated by the degradation of Rhodamine B (RhB) under xenon (Xe) lamp, Vis light and UV light. The CDs@CN nanocomposite displayed superior photocatalytic activity, particularly under Xe lamp irradiation, achieving over 95 % degradation of RhB within 1 h. Even under Vis and UV light, the photocatalytic cement retains robust self-cleaning capabilities, achieving pollutant degradation rates of 81 % and 63 %, respectively, within 1 h. This performance exceeded that of pristine CN and control samples, demonstrating effective light absorption and charge separation. The optimal photocatalyst concentration in cement was identified as 0.1∼5.0 wt%, balancing performance and dispersion. The developed CDs@CN-based photocatalytic cement material offers a sustainable solution for self-cleaning and environmental purification. This study provides insights into the design of functional cementitious materials and contributes to the sustainable development of the construction industry.

Scavenger-free solar photocatalytic degradation of Textile Dyes and Antibiotics using magnetically separable bi-junctional photocatalyst

The field of solar photocatalysis has been plagued by photocatalysts with low photon-to-electron conversion efficiency, resulting in poor photocatalytic degradation rates of water pollutants. With a keen idea to improve the existing photocatalysts, we developed a scavenger-free, magnetically separable, bi-junctional solar photocatalyst. The photocatalyst comprises Fe2+ doped zinc ferrite as core, ZnO as shell, and irregular CuO nanoparticles in conjunction with the surface of core-shell nanoparticles prepared using a combination of microwave-assisted solvothermal technique and microwave-assisted reflux method. The photocatalytic degradation properties of the solar photocatalyst were modelled and optimized with the help of Methyl Orange under direct sunlight. This novel composite degrades Methyl Orange roughly four times faster than core-shell nanoparticles. The photocatalyst meets most of the criteria for working of a promising solar photocatalyst, such as 1) excellent absorption of sunlight, 2) two physically distinct heterojunction and absorbing regions for efficient charge carrier generation and separation, 3) scavenger-free degradation of textile dyes and antibiotics, 4) High surface area (39 m2g −1), 5) good stability, 6) excellent reusability, 7) and easy separation of nanoparticles for reuse with the help of a magnet. The prepared photocatalyst efficiently degrades fluoroquinolone antibiotics such as Ciprofloxacin Hydrochloride, Norfloxacin, and Ofloxacin. The photocatalyst demonstrates the capability to efficiently degrade textile dyes such as Methyl Orange, Methylene Blue, Orange G, Fluorescein sodium salt, Rhodamine B, and Crystal Violet. Additionally, the bi-junctional photocatalyst can be coated with a thin layer of silver to achieve twice the degradation rate. This enhancement is attributed to the Localized Surface Plasmon Resonance (LSPR) effect. The current work presents an effective and economical option for removing dyes and antibiotics in wastewater, marking a significant stride towards sustainable industrial practices.

Lignin regulating the active sites and peroxymonosulfate activation capacities of iron incorporated 1D carbon nanofiber for efficient organic pollutant degradation

In this study, 1D iron incorporated carbon nanofiber composite catalysts (PLCF-Fe) were prepared by pyrolyzing iron nitrate embedded polyacrylonitrile/lignin electrospun nanofiber. PLCF-Fe exhibited prominent peroxymonosulfate (PMS) activation capability for organic pollutant degradation, in which 1D structured carbon nanofiber effectively inhibited the aggregation of iron moieties. The introduction of lignin could modulate the oxidation capacities of the prepared PLCF-Fe through regulating both the graphitic degree as well as the oxygen-containing group distributions of the carbon nanofiber, and the crystalline phase composition of the iron compounds in PLCF-Fe. The existence of multiple active sites could concertedly trigger radical and non-radical PMS activation for high-efficient pollutant degradations, during which process negligible iron ions were leached. It was also found that pollutant degradation rate in PLCF-Fe/PMS system was correlated well with their highest occupied molecular orbital positions. Additionally, PLCF-Fe/PMS system could maintain conspicuous catalytic performance in a variety of water matrices with wide pH application range. This study provides an applicable structure and active sites regulating approach to prepare high-efficiency heterogeneous catalyst for PMS based Fenton-like organic decontamination processes.

The degradation of 8 PPCPs in UV/chlorine: Effect of chloride and sulfate ions and the role of radicals

The degradation of 8 structurally diverse pharmaceuticals and personal care products (PPCPs) by UV/chlorine and the effects of Cl- and SO42- were systematically investigated. The 8 PPCPs are divided into 2 groups based on their stability under UV light. This is the first time the kinetic degradation of the 8 PPCPs in the presence of Cl- and SO42- have been intensively evaluated. The results showed that the high degradation rate of the PPCPs is attributed to their second-order rate constants towards radicals (i.e., •OH, and reactive chlorine species (RCS)). 0–500 mM Cl- enhanced kPPCPs, while this range of SO42- inhibited most of them (except in the case of ciprofloxacin (CIP)). An overview of the effect of 0–200 mM Cl-/SO42- on the degradation of micropollutants by different UV-based advanced oxidation processes (UV-AOPs) in previous studies indicates that Cl-/SO42- can cause varying effects on the degradation rate of pollutants (i.e., “increase”, “decrease”, or “no effect”), depending on the type of pollutant and the process. Cl-/SO42- did not change the trend of pH influence on the PPCPs degradation rates by UV/chlorine. Acidic and neutral conditions were favorable to the degradation of the PPCPs in all cases. Under three operating conditions (i.e., the control process, 500 mM Cl- and SO42-), [•OH]ss decreased considerably, but [Cl•]ss or ([Cl•]ss + [SO4•-]ss) slightly fluctuated when the pH was increased from 2.5 to 10.5. The synergistic effect of seawater and Cl-/SO42- significantly improved some kPPCPs, thereby, decreasing energy consumption.

Green biosynthesized N-doped CuO@Zeolite nanocomposite for the efficient photodegradation of toxic organic pollutants from wastewater

Nanotechnology is one of the most advanced methods available for the degradation of toxic pollutants from the environment. Specifically, nanoparticles generated with plant extracts are more stable and biocompatible than those produced using traditional chemical and physical processes. The current study focuses on the green synthesis of N-CuO@Zeolite nanocomposite with Camellia sinensis (green tea) leaf extract. The green synthesized nanocomposite was used for the photocatalytic degradation of hazardous organic pollutants, including Auramine-O (AO) and yellow color textile industrial dye (YD). Under direct sunlight irradiation, synthesized nanomaterials exhibited excellent photocatalytic activity for AO and YD degradation. The best conditions for photocatalytic degradation were found to be pollutant concentrations of 2 mg L−1 for AO and 6 mg L−1 for YD, photocatalyst dosages of 15 mg for both AO and YD, and neutral pH for both pollutants. Within 150 minutes, the synthesized N-CuO@zeolite nanocomposite attained degradation efficiencies of 95 % for AO and 92 % for YD, compared to its parent materials N-CuO (80 % for AO and 76 % for YD) and CuO (68 % for AO and 65 % for YD). The degradation rates of both pollutants were accurately described by first-order kinetics, consistent with the Langmuir adsorption model. Additionally, the ecologically sustainable novel N-CuO@Zeolite nanocomposite illustrated superior reliability and reusability, keeping photocatalytic efficiency even after ten cycles of constant utilization, and its long-term stability was confirmed by PXRD analysis after processing. The material's excellent reusability and stability emphasize the nanocomposite's potential as a long-term solution for industrial wastewater treatment applications.

Nanoconfinement steers nonradical pathway transition in single atom fenton-like catalysis for improving oxidant utilization

The introduction of single-atom catalysts (SACs) into Fenton-like oxidation promises ultrafast water pollutant elimination, but the limited access to pollutants and oxidant by surface catalytic sites and the intensive oxidant consumption still severely restrict the decontamination performance. While nanoconfinement of SACs allows drastically enhanced decontamination reaction kinetics, the detailed regulatory mechanisms remain elusive. Here, we unveil that, apart from local enrichment of reactants, the catalytic pathway shift is also an important cause for the reactivity enhancement of nanoconfined SACs. The surface electronic structure of cobalt site is altered by confining it within the nanopores of mesostructured silica particles, which triggers a fundamental transition from singlet oxygen to electron transfer pathway for 4-chlorophenol oxidation. The changed pathway and accelerated interfacial mass transfer render the nanoconfined system up to 34.7-fold higher pollutant degradation rate and drastically raised peroxymonosulfate utilization efficiency (from 61.8% to 96.6%) relative to the unconfined control. It also demonstrates superior reactivity for the degradation of other electron-rich phenolic compounds, good environment robustness, and high stability for treating real lake water. Our findings deepen the knowledge of nanoconfined catalysis and may inspire innovations in low-carbon water purification technologies and other heterogeneous catalytic applications.

Silver and Zinc Nanoparticles Biosynthesis Using Laurel Extract and Investigation of the Photocatalytic Properties

Metal nanoparticles that are widely studied in optoelectronics, catalysis, medicine, and sensors offer remarkable optical and electronic properties. To address the cost and environmental concerns associated with their synthesis, this study employs an environmentally friendly method using Laureus nobilis extract to produce silver and zinc nanoparticles, which are prominent in nanotechnology. This study includes investigations of factors such as reaction time, AgNO3/laurel ratio, Zn(Ac)2·H2O/laurel ratio and temperature in nanoparticle biosynthesis to optimize the process. The next stage was set to evaluate the photocatalytic performance of these nanoparticles, specifically against the methylene blue dye under dark and UV light conditions. Parameters such as pollutant decomposition, degradation rate, catalyst stability, and nanoparticle recovery were analysed. Structural characterization of the obtained nanoparticles was performed using UV-Vis, FTIR, SEM, and XRD techniques. The photocatalytic results showed significant degradation percentages for LB-AgNP (silver nanoparticles synthesized with Laureus nobilis extract) (97.5%) and LB-ZnNP (zinc nanoparticles synthesized with Laureus nobilis extract) (90.9%). LB-ZnNP showed superior performance. Therefore, LB-AgNP and LB-ZnNP are promising photocatalysts for water purification and the elimination of toxic organic pollutants.

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.

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.

Enhancing the efficiency of PVDF-based piezoelectric catalysis through water-induced polarization and a micro-nano-composite strategy.

Polyvinylidene fluoride (PVDF)-based piezoelectric catalysts show promise in mechanical force-driven catalysis due to their good biocompatibility, flexibility, and ease of fabrication. However, the catalytic activity of pristine PVDF is limited due to its low piezoelectric phase content (<20%), poor orientation, and low surface carrier concentration. Here, we introduce an efficient PVDF-based composite nano-catalyst (rGO/PVDF) with high piezoelectric catalytic performance. We achieve this by employing a composite strategy that combines nanoscale water-induced polarization with polar functional group-modified graphene (rGO) serving as a nanoelectrode. The nanoscale water polarization effect, together with the two-dimensional planar structure of PVDF and the modified graphene's polar functional groups, effectively induces orientation in the PVDF piezoelectric phase to increase the functional β phase content. As a result, the β phase content and crystallinity of rGO/PVDF reach 95% and 40%, respectively, which are 600% and 170% higher compared to those of pristine PVDF. This enhancement plays a crucial role in endowing the material with strong force-to-electricity conversion characteristics. Additionally, the surface-modified rGO also boosts PVDF's surface carrier concentration and provides active sites for catalysis on the rGO/PVDF composite. Notably, under optimized conditions, our catalyst achieves a ∼99.1% degradation rate of organic pollutants (10 mg L-1) after 12 minutes of sonication at 240 W and maintains a high efficiency of ∼93.7% even at a 10 times higher pollutant concentration (100 mg L-1). Our piezoelectric catalyst also demonstrates efficient H2O2 production at 95.8 mmol grGO-1 h-1, which is ∼9-fold and ∼134-fold higher than those of untreated PVDF and previously reported PVDF-based piezoelectric catalysts, respectively. This work paves the way for the development of highly efficient PVDF-based piezoelectric catalysts, thereby offering valuable insights for the advancement of mechanically driven catalysis in the environmental, energy, and chemical sectors.

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.