Search

Hypophosphite (P(I)) is ubiquitous in some waste streams. It may contribute to the eutrophication of water bodies, yet conventional methods are ineffective in treating P(I)-laden wastewater. Here, we propose a novel CaO2/ultraviolet (UV) system that can simultaneously remove P(I) and recover Ca-phosphate. This system lies in the simultaneous release of OH-, Ca2+, and H2O2, with the last being activated and producing reactive oxygen species (ROS) under UV irradiation. Subsequently, the generated ROS converts P(I) to phosphite and phosphate, forming Ca-phosphate with the released Ca2+ at pH 11.0. Beyond activating H2O2, UV light also promotes the dissolution of CaO2 powders. The system removes 97.0% of 1.0 mM P(I) in 6 h with dosing 2.0 mM CaO2. The presence of 5.0 mM HCO3- drops P(I) removal from 97.0 to 14.1% by competing with P(V) toward Ca2+. Nitrate and humic acid show similar effects by adsorbing UV light or quenching ROS. However, we may overcome the adverse effects with an enhanced CaO2 dose. For example, with 10 mM CaO2, the CaO2/UV system removed more than 78% of non-ortho P from actual electroless rinse water. These results confirmed that CaO2/UV is an exciting all-in-one system for treating P(I)-laden wastewater and recovering valuable P products.

Nanomaterials are preferred for scientific studies due to their spectral properties and perfect surface appearance. This study aims to introduce a novel, environmentally friendly, photocatalytic method for degrading methylene blue (MB) in aqueous solutions. With this purpose in mind, the study synthesizes nanoceria particles and coats them with zahter (Thymbra spicata; zahter-coated nanoceria, ZCNC) following the main outlines of green chemistry as characterized by SEM and FTIR analyses. The study proposes this new nanoparticle (with the aid of H2O2 and UV combinations) as an alternative to iron in Fenton-type reactions for enabling MB degradation. The maximum efficiency was observed through the ternary combination of zahter-coated nanoceria, UV light, and H2O2 at 63% concentration. The degradation of the MB solution was achieved by installing a small amount of ZCNC (0.1g), after which the absorbance values were measured at 664 nm. According to the possible reaction kinetics discussed within the study, the reaction rate was calculated at 1.49 × 10-2 min -1, thus enabling a faster reaction for a better evaluation of the reaction mechanism compared to other degradation processes that have been previously investigated. WOS:000925337200008 2-s2.0-85147663956

Electrochemical degradation performances of three non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen (ACT), aspirin (ASP) and ibuprofen (IBP), were investigated and compared in their alone and mixture conditions using Ti/SnO2-Sb/La-PbO2. The pseudo-first-order degradation kinetics (k) order was kIBP-A (0.110 min−1) ˃ kASP-A (0.092 min−1) ˃ kACT-A (0.066 min−1) in their alone condition, while that was kACT-M (0.088 min−1) ˃ kASP-M (0.063 min−1) ˃ kIBP-M (0.057 min−1) in their mixture condition. The •OH apparent production rate constant of 5.23 mmol L−1 min−1 m−2 and an electrical energy per order (EEO) value of 6.55 Wh/L could ensure the synchronous degradation of the NSAIDs mixture. The mineralization efficiency of NSAIDs mixture was 86.9% at 240 min with a mineralization current efficiency of 1.67%. Acetic acid and oxalic acid were the main products in the mineralization process for the both conditions. In the mixture condition, there were higher k values at lower initial concentrations and higher current density, while the presence of carbonate and humic acid inhibited their degradation. The results indicated electrochemical advanced oxidation process can effectively and synchronously mineralize NSAIDs mixture in wastewater.

Peracetic acid (PAA)-based system is becoming an emerging advanced oxidation process (AOP) for effective removal of organic contaminants from water. Various approaches have been tested to activate PAA, while no previous researches reported the application of metal-organic frameworks (MOFs) materials for PAA activation. In this study, zeolitic imidazole framework (ZIF)-67, a representative MOFs, was facile synthesized via direct-mixing method at room temperature, and tested for PAA activation and sulfachloropyridazine (SCP) degradation. The as-synthesized ZIF-67 exhibited excellent performance of PAA activation and SCP degradation with 100% of SCP degraded within 3 min, owing to the specific MOFs structure and abundant Co2+ sites. The pseudo-first-order kinetic model was applied to fit the kinetic data, with rate constant k1 of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co3O4 activated PAA and direct oxidation by PAA. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis indicated that CH3C(O)OO• played a major role in this PAA activation system. Then, the Fukui index based on density functional theory (DFT) calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH3C(O)OO•. In addition, the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection, which mainly included the S-N bond cleavage and SO2 extrusion and followed by further oxidation, dechlorination, and hydroxylation. Therefore, ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants (EOCs) from water.

The aim of this study was to investigate the influence of UV/H2O2 advanced oxidation process on the natural organic matter content and disinfection by-products formation potential of different water matrices. Three water matrices (two natural waters and a synthetic humic acid solution) with different natural organic matter characteristics and concentrations were analysed. The carbonaceous disinfection by-products: trihalomethanes, haloacetic acids and haloketones, as well as nitrogenous disinfection by-products: haloacetonitriles and chloropicrin were investigated after chlorination. The UV/H2O2 treatment resulted in significant trihalomethane and haloacetic acids precursors removal (up to 53% and 30%, respectively) in humic acid solution in conditions ≥ 1.0 mg H2O2/mg DOC, in combination with a dose of UV irradiation ≥ 3000 mJ/cm2. Under the same reaction conditions, in natural groundwater rich in hydrophobic natural organic matter, the advanced process was less effective in DBP precursors removal. On the other hand, the advanced process was very effective in trihalomethaneprecursors removal (up to 76%) in groundwater with hydrophyilic natural organic matter. Haloketones were formed after treatment in very low concentrations. Nitrogenous disinfection by-products were only formed in the natural water containing hydrophilic organic matter, during the advanced process at 3.0 mg H2O2/mg DOC. The UV/H2O2 process resulted in negligible organic matter mineralization, but increased the brominated disinfection by-products formation in waters with low to medium bromide contents. It was concluded that under the same advanced oxidation process reaction conditions different natural organic matter structures showed different reactivities with chlorine toward the formation of the investigated disinfection by-products.

In the past few years, pharmaceutical compounds have appeared as emerging category of environmental pollutants. These microcontaminants can exhibit adverse acute and chronic effects on natural flora and fauna. The detection of pharmaceutical residues in surface waters (rivers, streams, and lakes), seawater, groundwater, soils, sludges, and wastewater treatment plants has been widely documented. Advanced oxidation processes (AOPs) have garnered extensive attention for abetment of emerging pharmaceutical contaminants and minimize their associated environmental risks. Given a clean and efficient oxidizing agent, hydrogen peroxide (H2O2) has been extensively utilized in AOPs. Integration of H(2)O(2 )with different substrates/catalysts boosts up its oxidizing features. H(2)O(2 )may be combined with ozone, UV, Fe2+/Fe3+ ions (Fenton and photo-Fenton-like processes) and with heterogeneous systems (TiO2). The generation of strong oxidative hydroxyl radical (HO:) in H2O2-assisted AOP by various types of activating methods is likely to play a critical role in micropollutants treatment, reusing, and risk reduction. Advanced oxidation process catalyzed by H(2)O(2)may consists of combination of following catalysts: UV/H2O2, O-3/UV/ H2O2, H2O2/TiO2/UV, Fe2+/H2O2, Fe2+/H2O2/UV, Electro-Fenton, O3/H2O2). In this review, we have discussed current reports on various hydrogen peroxide-based advanced oxidation processes for degradation of pharmaceutical pollutants of emerging concern. The ongoing challenges, conclusive remarks and imperative future directions are also outlined. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

In this study, the electro-Fenton process (with response surface methodology as an experiments design and optimisation technique) was applied to evaluate the effects of five independent variables on the chemical oxygen demand (COD) and colour removal from paper pulp wastewater (PW). The parameters were statistically optimised under response surface methodology. The optimum conditions for 98.2% of COD and 96.8% of colour removal experimentally were at a reaction time of 30 min, current density of 79.9 mA/cm2, pH of 6.9, hydrogen peroxide (H2O2)/PW volume ratio of 1.7 ml/l, hydrogen peroxide (H2O2)/ferrous ions (Fe2+) molar ratio of 1.6, electrode consumption of 0.1 (g/l) and energy consumption of 1.3 (kWh/m3). In the next step, the filtration process was carried out on the treated effluent obtained at the optimal conditions. Then, this was mixed with activated sludge in a ratio of 1 : 10; 99.9% of COD and colour removal was found after 150 and 60 min, respectively.

In this study, a functionalized Co3O4-Bi2O3-Ti catalytic membrane (CBO-Ti-M) was prepared and applied for removing organic pollutants via activating peroxymonosulfate (PMS) in the dead-end filtration mode. Characterizations including scanning electron microcopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the Co3O4-Bi2O3 catalyst was successfully supported on the Ti membrane. The CBO-Ti-M /PMS system could efficiently remove various organic pollutants such as sulfamethoxazole, methyl orange, bisphenol A and methylene blue, achieving removal efficiencies of 98.0%-99.5%. The effects of PMS concentration, flow rate and solution environment on degradation efficiency were investigated in detail. Furthermore, quenching experiments, electron spin resonance (ESR) and in-situ open circuit potential (OCP) tests collectively demonstrated that singlet oxygen as well as the non-radical electron transfer pathway mainly contributed in the reaction mechanism. The synergistic effect of Co and Bi was illustrated according to XPS results, and the possible degradation pathway of MB was proposed based on LC-MS analysis. Reusability test showed that pollutant removal efficiency with the CBO-Ti-M /PMS system remained stable in four runs and limited metal leaching was observed.

Acid mine drainage (AMD) is a multi-factor pollution formed from complex chemical, physical, and biological interactions that takes place under ambient conditions in abandoned and active mines. Over the years, researchers have been investigating ways to mitigate its potential impact on the environment through various treatment technologies. The aim of this review was to critically analyze the broad spectrum of treatment methods that have been engaged in published literature on the remediation of AMDs. Adsorption treatment using zeolites, fly ash, biochar activated carbon, clay-based minerals and biomass-based adsorbents was discussed. Given an appropriate choice of adsorbent, ions in AMD can be reduced between 50% and 99%. Membrane separation processes like nanofiltration, reverse osmosis and hybrid systems were discovered to be more effective than adsorption and can effect over 90% rejection at optimized conditions. Biological processes showed a far wider range of performance amongst all treatment types due to the selectivity in performance of the different micro-organisms used although Advanced Oxidation Process (AOPs) have been shown to achieve>80% ions removal. In all biological processes studied ranging from wetlands to bioreactors, algal bioreactors seemed the most effective in this domain. Most of these treatment technologies are corrective while preventive techniques can be explored to prevent the production of AMD. Despite the positive outcomes of the different types of treatment, they have associated technical issues. It is recommended that more preventive techniques be explored to reduce the production of AMD. The review discussed how AMD treatment would affect environmental protection and water resource management.

Photocatalysis is a promising advanced oxidation process (AOPs). It is often used in the degradation of phenolic derivatives due to their simplicity and easy handling, by converting organic molecules with total mineralisation into nontoxic H2O and CO2. In this study, a combination of microwave-assisted (MW) and facile electrochemical method was applied in the synthesis of catalysts (Fe-MTN and Cu-MZN). The characterisation of catalysts was tested using XRD, UV–Vis DRS and FTIR. It was found that there was no new bonding formed when Fe was introduced onto MTN, while the introduction of Cu onto MZN formed a new Zn-O-Cu. The introduction of Fe and Cu onto MTN and MZN also decreased the bandgap energy from 3.15 to 2.35 eV and 2.92 to 2.63 eV, respectively. The pH of the solution is one of the essential parameters that need to be measured in the photocatalytic process due to the amphoteric properties of semiconductor, which influenced the surface-charged properties of the catalysts. Fe-MTN and Cu-MZN were used in photocatalytic degradation of 2-chlorophenol (2-CP) and 2,4-diclorophenol (2,4-DCP), respectively. After the effect of pH over 2-CP and 2,4-DCP was tested in the range of 3 to 11, the greatest degradation of 2-CP using Fe-MTN was at pH 5 with 99% while 100% degradation of 2,4-DCP at pH 3 for Cu-MZN. These results are probably due to the amphoteric characteristic of catalyst, where it can be tested using point zero charged (pHZPC). The pHZPC value of Fe-MTN and Cu-MZN was 6.1 and 5.5, respectively illustrated that the photoactivity of both catalysts better in acidic condition compared to an alkaline condition.

A novel advanced oxidation process (AOP) system with high adaptability and long-term oxidation ability was firstly constructed for organic pollutant degradation via a non-radical process.

Herein, carbon felt (CF) modified with N and Co (Co–N@CF) was prepared as an anode to effectively activate peroxymonosulfate (PMS) for tetracycline (TC) removal. The influencing factors, kinetic characteristics and the transformation of generated active radicals were further investigated. The results show that N and Co modification of CF via a galvanostatic electrodeposition method results in a significant decrease in the charge transfer resistance (Rct) of the CF. The fabricated Co–N@CF anode exhibits high catalytic performance and stability towards PMS activation, wherein the TC removal efficiency reached 92.2% within 1 h under optimal conditions. Radical quenching tests and electron paramagnetic resonance spectroscopy experiments demonstrated that SO4˙−, OH˙ and O2˙− are the main contributors towards TC removal, while 1O2 generation is inhibited significantly. The PMS decomposition process driven by the activator enhances the generation of OH˙. The electricity energy demand per order (EE/O) in the reaction system (Co–N@CF anode + PMS) is only 0.072 kWh m−3, which makes it an energy-saving approach for pollutant removal. The newly developed fabrication of the Co–N@CF anode for PMS activation could provide insights into the SO4˙−-based electrochemical advanced oxidation process (EAOP) applied in wastewater treatment.

Emerging contaminants in wastewater pose a greater threat to the environment and the organism in water bodies. The emerging contaminant Atenolol (ATL) belongs to a class of drugs known as beta-blockers. Even micro-level of these contaminants may harm the environment adversely. Hence removal of Atenolol and other emerging contaminants is given prime focus. In this study, modelling of Advanced Oxidation Process (AOP) as the treatment techniques for the removal of Atenolol was performed. Based on literature review, the input parameters for this study were chosen and includes Initial concentration of Atenolol (10–30 mg/L), pH range (7–11), TiO2 Catalyst Concentration (500–1000 mg/L) and Reaction Time (40–120 min). Further the two types of radiation (UV and Visible light radiations) were considered and the process modelled using MINITAB, regression equations and Pareto charts were obtained. In this study, the optimum experimental conditions for maximum removal of ATL was obtained for UV/ TiO2 and Visible light/ TiO2.

Metal-free activation of peroxydisulfate (PDS) for degrading organic pollutants in water has received increasing attention because it can prevent secondary pollution. However, most of the catalysts that are efficient are derived from non-renewable fossil resources, are very expensive and have complex preparation processes. Also, the emerging non-radical mechanism is still unclear. Herein, 3D sucrose-derived N-doped carbon xerogels (NCXs) were synthesized by a simple and sustainable hydrothermal process and then employed as novel metal-free PDS activators to degrade organic pollutants. The structure, composition and performance of NCXs were regulated by changing the carbonization temperature. The sample carbonized at 900 °C (NCX900) exhibited the best catalytic performance, completely removing bisphenol A in 60 min. Quenching experiments and linear sweep voltammograms demonstrated that PDS was activated mainly through an electron-transfer non-radical mechanism. It was found that graphitic N played a critical role in activating PDS. With this non-radical mechanism, the NCX900/PDS system could adapt well to the wide pH range (3–11) and high Cl− concentration; it selectively oxidized organic pollutants with low ionization potentials. This work provides a sustainable approach to the low-cost and efficient metal-free catalysts for wastewater treatment.

To evaluate the ultraviolet (UV) advanced oxidation process (AOP) in a potable reuse facility, we characterized organic compounds in upstream reverse osmosis (RO)-treated recycled municipal wastewa...

Carbonaceous materials (CMs), as high-efficiency activators in a persulfate-based advanced oxidation process (PS-AOP), are attracting increasing attention for environmental remediation due to their high efficiency, low toxicity, and environmental friendliness. The correlations between the structural and surface properties of carbonaceous materials and the catalytic reaction efficiency in PS-AOP have been focused on experimentally and theoretically. In this Perspective, we discuss the effect of the microstructure of carbonaceous materials on the catalytic reaction efficiency, which can depend on the reaction pathways, including adsorption, free-radical routines, and non-free-radical pathways. Various features of carbonaceous materials, covering the dimensionality, pristine carbon configuration, crystallinity, defects, porosity, chemically active groups, and heterogeneous doping, can be involved. Those characteristics mainly affect the electronic process and mass transfer during the whole PS-AOP. An important target in the field is how to rationally regulate the intrinsic properties of carbonaceous substances to control both the reaction pathways and catalytic efficiency. Therefore, we conclude with a critical discussion and presentation of future challenges.

The microwave enhanced advanced oxidation process (MW-AOP) has been applied to pre-treat different sludge types and high solids content. Secondary sludge not only had the highest solids and nutrient content but also yielded higher treatment efficiency than primary or mixed sludge. In the case of secondary sludge with 4% total solids (TS), the total suspended solids (TSS) concentration was reduced by 32% while soluble chemical oxygen demand concentration increased from 1% to 40% after treatment at 110°C. A high level of nutrient release was also achieved; about 65% total phosphate (TP) solubilized at 110°C. The degree of secondary sludge disintegration was dictated by temperature and hydrogen peroxide dosage. The optimal operating temperature for the system was 110°C, and sludge containing TS up to 8% was treated effectively. Secondary sludge with 8% TS had a TSS reduction of 41% after treatment at 110°C while COD solubilization was about 45%; about 55% TP was solubilized at 10 min holding time. Treatment of sludge with higher solids content would allow for handling larger amounts of sludge at a given period and reduce heating cost per unit of treated sludge. The inter-relationship between the degree of sludge disintegration and changes in chemical and physical properties was also clearly demonstrated here. The treated sludge would be an ideal substrate for anaerobic digestion or phosphorous recovery processes. High levels of nutrients (phosphorus and nitrogen) and metal release, and solids disintegration from sludge containing high solids content would make subsequent resource recovery processes more effective and economical.

In this study, a rotating microreactor made of Plexiglas was utilized for the removal of methylene blue and methyl oranges from aqueous solutions with these two dyes at different concentrations. To this end, an advanced oxidation process of ultraviolet/hydrogen peroxide/titanium dioxide was performed while setting various conditions for this operation. Box–Behnken experimental design method was implemented to design the experiments. In addition, five variables of initial dye concentration (10, 30, and 50 mg/L), residence time (1, 1.5, and 2 min), hydrogen peroxide concentration (0, 300, and 600 mg/L), titanium dioxide concentration (10, 30, and 50 mg/L), and ultraviolet lamp power (0, 15 and 30 W) were set as the desired variables under the study and a total of 43 tests were performed to remove each dye. Finally, optimal operating conditions for the removal of each of the two items (methylene blue and methyl orange) were obtained. The highest rate of the removal of methylene blue dye (under optimal conditions of initial dye concentration of 36 mg/L, residence time of 2 min, hydrogen peroxide concentration of 235 mg/L, titanium dioxide concentration of 12 mg/L, and ultraviolet lamp power of 30 W) was 99.83% and the highest rate of methyl orange dye removal (under optimal conditions of initial dye concentration of 50 mg/L, residence time of 1.75 min, hydrogen peroxide concentration of 540 mg/L, titanium dioxide concentration of 30 mg/L, and ultraviolet lamp power of 30 W) was 68.69%.

The following work provides a perspective on the degradation of cytostatic pollutants through TiO2 heterogeneous photocatalysis. Cytostatic drugs are emerging pollutants used for cancer treatment found in hospital and domestic wastewater. Small amounts of cytostatic pollutants may pose severe health problems in human beings, animals, and plants after prolonged contact. This research presents a general review of some water treatment methods, such as aerobic activated sludge, enzymatic degradation, nanofiltration and chlorination, that have been used for the degradation or elimination of cytostatic drugs in wastewater. In recent years, photocatalysis has become important to solve this problem; these advanced oxidation process uses pure and modified TiO2 to degrade cytostatic contaminants and convert them into non-harmful substances or to eliminate them completely. This work contains a comprehensive review of the heterogeneous photocatalysis process and mechanism, and its application on the removal of cytostatic pollutants. Even if research on the topic is still scarce, this literature review provides interesting highlights on the scope of the research field, and the path such research could follow.

As an advanced oxidation process, vacuum ultraviolet/ultraviolet (VUV/UV) has been intensively studied for drinking water treatment, but assessment of its feasibility for wastewater treatment has rarely been conducted. This study investigated the treatment of fluorine-containing pharmaceutical wastewater by VUV/UV process and examined the defluorination and therefore the improvement of biodegradability of the wastewater after the process. The results indicated that the degradation of a model fluorine-containing organic compound (namely, 4-fluorophenol) was mainly achieved via the attack of the fluorine atom linking directly to the aromatic ring by the HO• generated from VUV photolysis of water. As the solution pH increased from 4.0 to 10.0, the COD removal efficiency of the real pharmaceutical wastewater decreased slightly from 18.1 to 15.9%, while the release ratio of F− increased from 50.8 to 75.5%. As the dissolved oxygen increased from 0.15 to 12 mg L−1, the removal efficiency of COD and the release ratio of F− increased from 9.2 to 17.1% and from 48.2 to 75.5%, respectively. The biodegradability index (BOD/COD) increased significantly from 0.24 to 0.47 after the VUV/UV irradiation, which confirmed the feasibility of applying the VUV/UV process for improving biodegradability of the pharmaceutical wastewater.

The iron(II)-activated peroxymonosulfate [Fe(II)/PMS] process is effective in degrading organic contaminants with a rapid oxidation stage followed by a slow one. Nevertheless, prior studies have greatly underestimated the degradation rates of organic contaminants in the rapid oxidation stage and ignored the differences in the kinetics and mechanism of organic contaminants degradation in these two oxidation stages. In this work, we investigated the kinetics and mechanisms of organic contaminants in this process under acidic conditions by combining the stopped-flow spectrophotometric method and batch experiments. The organic contaminants were rapidly oxidized with rate constants of 0.18-2.9 s-1 in the rapid oxidation stage. Meanwhile, both Fe(IV) and SO4•- were active oxidants and contributed differently to the degradation of different organic contaminants in this stage. Additionally, the presence of Cl- promoted the degradation of both phenol and estradiol but the effects of Br- and humic acid on phenol degradation differed from those on estradiol degradation in the rapid oxidation stage. In contrast, the degradation of phenol and estradiol was slow and the amounts of Fe(IV) and SO4•- generated were small in the slow oxidation stage. This work updates the fundamental understanding of the degradation of organic contaminants in this process.

In this study, photocatalytic degradability of Floxin antibiotic by UV/ZnO/sulfite (UZS) advanced oxidation process was evaluated. The degradation rate of Floxin antibiotic by UV/ZnO (UZ) and UV alone processes were 30% and 15%, respectively, within 5 min. It was observed sulfite has a synergistic effect on the performance of UZ, as the complete destruction of Floxin was achieved when sulfite was introduced into the photocatalytic medium. The complete degradation of Floxin by UZS was obtained at pH of 12.0, sulfite/ZnO molar ratio of 1:3 after 5 min of reaction. According to kinetic studies, the observed rate of Floxin degradation (robs (mg L-1 min)) by UZS was 63 and 25 times that of UV alone and UZS, respectively. The values of energy consumption and the total cost for UV alone, UZ and UZS processes were estimated to be (50 kWh m-3 and 1.4 $ m-3), (20 kWh m-3 and 0.98 $ m-3) and (0.78 kWh m-3 and 0.82 $ m-3), respectively.

Chlorinated organic pollutants are highly toxic and widespread in the environment, which cause ecological risk and threaten the human health. Chlorinated pollutants are difficult to degrade and mineralize by the conventional advanced oxidation process as the C-Cl bond is resistant to reactive oxygen species oxidation. Herein, we designed a bifunctional Fe/Cu bimetallic single-atom catalyst anchored on N-doped porous carbon (FeCuSA-NPC) for the electro-Fenton process, in which chlorinated pollutants are dechlorinated on single-atom Cu and subsequently oxidized by the ·OH radical produced from O2 conversion on single-atom Fe. Benefitting from the synergistic effect between dechlorination on single-atom Cu and ·OH oxidation on single-atom Fe, the chlorinated organic pollutants can be efficiently degraded and mineralized. The mass activity for chlorinated organic pollutant degradation by FeCuSA-NPC is 545.1-1374 min-1 gmetal-1, excessing the highest value of the reported electrocatalyst. Moreover, FeCuSA-NPC is demonstrated to be pH-universal, long-term stable, and environment friendly. This work provides a new insight into the rational design of a bifunctional electrocatalyst for efficient removal of chlorinated organic pollutants.

Landfill leachate poses significant risks to the environment and human health if not managed properly due to its potential to contaminate soil, ground, and surface waters. Consequently, effluent standards for landfill leachate have been continuously reviewed to manage these risks. A combination of treatment techniques (e.g., physico-chemical and biological) are usually required to treat landfill leachate due to its complexity, variability, and potentially high concentrations of pollutants. This review considers the various types of techniques used to treat landfill leachate/leachate concentrate, including advanced oxidation process (AOP), membrane bioreactor, denitrification, biofilm reactors, and electrocoagulation. The occurrence and treatment of emerging contaminants in landfill leachate, and opportunities for development are also considered. The review covers the basic principles through to the latest developments in research, including the effectiveness of engineering applications, their economic and technical challenges, together with current gaps in the knowledge and the prospects for leachate treatment. A systematic review of the technical characteristics of the engineering applications, used in leachate membrane concentrate treatment, showed that low-energy direct heat transfer evaporation technology had good prospects for future development. Refractory organic compounds, high concentrations of ammonia, high salinity, and concentrated leachate were of high concern. Hence, extensive research has been conducted on the degradation of refractory organic compounds using various AOPs, and the denitrification of ammonia species by novel biological pathways (e.g., anaerobic ammonium oxidation, short-cut denitrification processes). Despite the significant number of promising laboratory scale applications, further research is needed to demonstrate their effectiveness on a commercial/large scale.

The advanced oxidation process (AOPs) has caused great concern in recent years. Among them, biochar has been widely studied as a catalyst for advanced oxidation process because of its low price and low environmental risk. In this study, a novel ball milling assisted KOH activation biochar (MKBC) was prepared and applied in peroxydisulfate (PDS) activation to degrade tetracycline hydrochloride (TC-H). In comparison with the oxidation (3.48%) by PDS alone and adsorption (36.19%) by MKBC alone, the removal rate of TC-H was increased to 84.15% in the MKBC/PDS system, indicating that MKBC can successfully activate PDS. Besides, the catalytic activity of the MKBC to activate PDS for the degradation of TC-H is 58.33% higher than that of pristine biochar (PBC). In addition, MKBC has outstanding stability that after three repeated experiments, the removal rate of TC-H by the MKBC/PDS system still remains 77.35%. Meanwhile, the mechanism was investigated that the singlet oxygen (1O2) seized the principal position in the degradation of TC-H in the PDS/MKBC system. This study explored a novel, solvent-free and economic method to propose this extraordinary biochar, which provided a new strategy for the future research of biochar.

Background Removal of organic contaminants by UV-based advanced oxidation processes (AOPs) has been considered as one of the most effective procedures among environmental remediation methods. Ultraviolet light-emitting diodes (UV-LEDs) have possessed a unique place as an emerging technology in AOPs. Methods In the present research, the impact of pulsed illumination on the overall efficiency of AR14 degradation by UV-LEDs and persulfate (PS) was considered. In comparison with continuous illumination, pulsed irradiation of UV-LEDs gifts the radiation of light in a programmed order to benefit its flexible pulse pattern, high-frequency utilization, and lower energy consumption attitudes. Duty cycles, pulse periods/frequencies, oxidant, and also removal kinetics were considered as operational parameters. Significant findings Outcomes showed the efficacy of UV-LED and PS processes were both quite slow, while the hybrid route, UV-LED/PS showed great ability in degradation of AR14. Results depicted removal efficiency of (~93%) in UV-LED/PS system. Pulsed illumination has shown to be a beneficial technique providing higher output power and improved thermal management. 80% of the Duty cycle and 30 ms of the pulsed period was considered as optimized destruction state. Furthermore, results demonstrated that PS addition to the system significantly enhances the AR14 destruction efficiency by a pseudo-first-order rate constant (k) by 44 times.

Stable and recyclable catalysts are crucial to the peroxymonosulfate (PMS) based advanced oxidation process (AOPs) for wastewater treatment. Herein, nitrogen-rich carbon wrapped Fe3C (Fe3C@CN) on carbon felt (CF) substrate was synthesized by using Prussian blue (PB) loaded CF as the precursors. The obtained Fe3C@CN/CF catalyst was applied for degradation of bisphenol A (BPA) via the heterogeneous catalytic activation of PMS. Results showed that ~91.7%, 95.2%, 98.1% and 99.1% of BPA (20 mg/L) were eliminated in the Fe3C@CN/CF + PMS system within 4, 10, 20 and 30 min, respectively. The fast degradation kinetics is attributed to the production of abundant reactive species ( OH, SO4 − and 1O2) in the Fe3C@CN/CF + PMS system, as demonstrated by the electron paramagnetic resonance spectroscopy and quench experiments. The Fe3C@CN/CF catalyst was stable and can be easily recycled by using an external magnet. The results indicated that the nanoconfined Fe3C endowed Fe3C@CN/CF with high stability and magnetic property and enabled the efficient electron transfer for PMS activation. This study provides a cost-effective approach for the fabrication of stable and recyclable Fe3C@CN/CF catalyst, and shed a new light on the rational design of multifunctional catalyst for advanced water remediation.

We present an electrochemical advanced oxidation process (eAOP) reactor employing expanded graphite, potassium iodide (KI), and electrical current, which demonstrates an exceptionally high rate of ...

Landfilling in many countries is the most embraced method for disposal of municipal, agricultural and industrial waste. However, the main issue imposed for landfilling is the landfill leachate (LL)...

As a H2 O2 generator, a 2e- oxygen reduction reaction active electrocatalyst plays an important role in the advanced oxidation process to degrade organic pollutants in sewage. To enhance the tendency of NiCo2 S4 towards the 2e- reduction reaction, N atoms are doped in its structure and replace S2- . The result implies that this weakens the interaction between NiCo2 S4 and OOH*, suppresses O-O bond breaking and enhances H2 O2 selectivity. This electrocatalyst also shows photothermal effect. Under photothermal heating, H2 O2 produced by the oxidation reduction reaction can decompose and releaseOH, which degrades organic pollutants through the advanced oxidation process. Photothermal effect induced by the advance oxidation process shows obvious advantages over the traditional Fenton reaction, such as wide pH adaptation scope and low secondary pollutant due to its Fe2+ free character. With Zn as anode and the electrocatalyst as cathode material, a Zn-O2 battery is assembled. It achieves electricity generation and photothermal effect induced by the advance oxidation process simultaneously.

The following work provides a perspective on the potential application of solar heterogeneous photocatalysis, which is a nonselective advanced oxidation process considered as a sustainable technology, to assist in arsenic removal from water, which is a global threat to human health. Heterogeneous photocatalysis can oxidize trivalent arsenic to pentavalent arsenic, decreasing its toxicity and easing its removal with other technologies, such as chemical precipitation and adsorption. Several lab-scale arsenic photocatalytic oxidation and diverse solar heterogeneous photocatalytic operations carried out in different reactor designs are analyzed. It was found out that this technology has not been translated to operational pilot plant scale prototypes. General research on reactors is scarce, comprising a small percentage of the photocatalysis related scientific literature. It was possible to elucidate some operational parameters that a reactor must comply to operate efficiently. Reports on small-scale application shed light that in areas where other water purification technologies are economically and/or technically not suitable, and the solar energy is available, shed light on the fact that solar heterogeneous photocatalysis is highly promissory within a water purification process for removal of arsenic from water.

Electrochemical oxidation of water to produce highly reactive hydroxyl radicals ( OH) is the dominant factor that accounts for the organic compounds removal efficiency in water treatment. As an emerging carbon-based material, the investigation of electrocatalytic of water to produce OH on Graphdiyne (GDY) anode is firstly evaluated by using first-principles calculations. The theoretical calculation results demonstrated that the GDY anode owns a large oxygen evolution reaction (OER) overpotential (ηOER = 1.95 V) and a weak sorptive ability towards oxygen evolution intermediates (HO*, not OH). The high Gibbs energy change of HO* (3.18 eV) on GDY anode makes the selective production of OH (ΔG = 2.4 eV) thermodynamically favorable. The investigation comprises the understanding of the relationship between OER to electrochemical advanced oxidation process (EAOP), and give a proof-of-concept of finding the novel and robust environmental EAOP anode at quantum chemistry level.

The efficiency of ozonation depends on the water matrix and the reaction time. Herein, these factors were addressed by assessing the removal of five pharmaceutical and personal care products (PPCPs) by ozonation. The main aims were: (i) to assess the effects of the water matrix on the degradation kinetics of PPCPs, individually and in mixture, following ozonation; and (ii) to assess the ecotoxicological impact of the ozone reaction time on the treatment of a spiked municipal wastewater (MW) added the five PPCPs over several species. The degradation of the PPCPs was faster in ultrapure water, with all PPCPs being removed in 20 min, whereas in the MW, a 30 min ozonation period was required to achieve a removal close to 100%. Increasing the number of PPCPs in the water matrix did not affect the time required for their removal in the MW. Regarding the ecotoxicity assessment, Raphidocelis subcapitata and Daphnia magna were the least sensitive species, whereas Lemna minor was the most sensitive. The temporal variation of the observed effects corroborates the degradation of the added PPCPs and the formation of toxic degradation by-products. The removal of the parent compounds did not guarantee decreased hazardous potential to biological species.

Emerging dye pollution from textile industrial effluents is becoming more challenging for researchers worldwide. The contamination of water by dye effluents affects the living organisms in an ecosystem. Methylene blue (MB) and malachite green (MG) are soluble dyes with a high colour intensity even at low concentration and are hazardous to living organisms. The adsorption method is used in most wastewater plants for the removal of organic pollutants as it is cost-effective, has a high adsorption capacity, and good mechanical stabilities. In this study, a composite adsorbent was prepared by impregnating iron modified silica (FMS) onto polyurethane (PU) foam to produce an iron modified silica/polyurethane (FMS/PU) composite. The composite adsorbent was utilised in batch adsorption of the cationic dyes MB and MG. The effect of adsorption parameters such as the adsorbent load, pH, initial dye concentration, and contact time were discussed. Adsorption kinetics and isotherm were implemented to understand the adsorption mechanism for both dyes. It was found that the adsorption of MB and MG followed the pseudo-second order model. The Langmuir model showed a better fit than the Freundlich model for the adsorption of MB and MG, indicating that the adsorption occurred via the monolayer adsorption system. The maximum adsorption capacity of the FMS/PU obtained for MB was 31.7 mg/g, while for MG, it was 34.3 mg/g. The thermodynamic study revealed that the adsorption of MB and MG were exothermic and spontaneous at room temperature. In addition, the regeneration of FMS/PU was conducted to investigate the composite efficiency in adsorbing dyes for several cycles. The results showed that the FMS/PU composite could be regenerated up to four times when the regeneration efficiency dropped drastically to less than 20.0%. The impregnation of FMS onto PU foam also minimised the adsorbent loss into the environment.

Coffee consumption over the past four years has continued to increase the amount of used coffee grounds. Usually, the used coffee grounds are simply thrown away. In fact, it can still be used as other materials that are more efficient and environmentally friendly, such as activated carbon. Activated carbon can be utilized as an adsorbent to adsorb compounds that are carcinogenic and potentially last a long time in the environment, such as phenols. Phenol decomposition through chemical can be carried out by Advanced Oxidation Process (AOP) which utilize hydroxyl radicals. This method used a catalyst such as iron(III) oxide under ultraviolet light. Phenol decomposition can also be carried out using ultrasound. This study presents the performance of the combination of activated carbon-catalyst with ultrasound in phenol decomposition. The results showed that the mass of the composite influenced the 0.1 M phenol degradation by the activated carbon–iron(III) oxide assisted with ultraviolet light, ultrasound, and 0.01 M hydrogen peroxide. for 45 minutes. The best degradation of phenol was obtained when 0.5 g adsorbent was applied with the adsorption capacity of phenol was 704.37 mg/g. The concentration of hydrogen peroxide also affects the decomposition of phenol in solution. From the variation of the hydrogen peroxide solution used (0.01; 0.02; and 0.03 M), the optimal concentration in degrading phenol was 0.01 M with the adsorption capacity of phenol was 393.70 mg/g.

This study presents a scientometric analysis on biochar research to investigate the research status and developments as well as future trends in this field in 2020. A total of 3671 publications were retrieved from the Web of Science core collection database in 2020, which were analyzed for categories, countries, authors, and keywords. China and USA played a leading role in the research of biochar. Yong Sik Ok and Daniel C. W. Tsang were the most prolific authors in the application of biochar in agriculture, environment, and energy. Based on the keywords clustering analysis, biochar applications in “bioenergy production”, “global climate change mitigation”, “salinity and drought stress amelioration”, “organic pollutants degradation”, “heavy metals immobilization”, and “bioremediation” were the main hotspots. Biochar for salinity and drought stress amelioration became the focus in biochar area in 2020 as biochar amendment had great potential in alleviating salt- and drought-affected soils. Organic pollutants’ degradation via advanced oxidation process (AOPs) represents a sustainable growing topic. Radical and non-radical pathways were summarized for AOPs. Bioremediation using functional bacteria (e.g., heavy metal-resistant bacteria and organic pollutant-degraders) immobilized on biochar was still a research hotspot. Immobilized cells showed excellent performance in removing various contaminants by combining the advantages of highly efficient physiochemical sorption of biochar and microbial metabolisms. The review improves our understanding on scientific advances and potential future research directions in biochar research.

In this study, an attempt was carried out to degrade ofloxacin (OFX) and metronidazole (MTZ) antibiotics by a new advanced oxidation process. UV/ZnO/sulphite (UZS) was employed for the destruction ...

The combination of Co(II) and peracetic acid (PAA) is an important alternative advanced oxidation process (AOPs), in which R-O• radicals including acetyloxyl radicals (CH3C(O)O•) and acetylperoxyl ...

Ultraviolet (UV)/chlorine draws increasing attention for the abatement of recalcitrant organic pollutants. Herein, it was found that TiO2 would significantly promote the degradation of dimethyl phthalate (DMP) in the UV/chlorine system (from 19 to 84%). Hydroxyl radicals (HO•) and chlorine radicals (Cl•) were the dominant reactive species for DMP degradation in the UV/chlorine/TiO2 system. Chlorine decayed much faster in UV/chlorine/TiO2 compared with UV/chlorine, which is possibly because photogenerated electrons (ecb-) and superoxide radicals (O2•-) have high reactivity with chlorine. As a result, the recombination of photogenerated holes (hvb+) and ecb- was inhibited and the accumulation of HO• and Cl• was facilitated. A kinetic model was established to simulate the reaction process, and it was found that the concentrations of HO• and Cl• were several times to dozens of times higher in UV/chlorine/TiO2 than that in UV/chlorine. The contributions of HO• and Cl• to DMP degradation were 70.3 and 29.7% by model simulation, respectively, and were close to the probe experiment result. In the UV/chlorine/TiO2 system, the degradation of DMP did not follow pseudo-first-order kinetics but the degradation of benzoate fitted well with pseudo-first-order kinetics. This phenomenon was elucidated by the structure of the pollutant and TiO2 and further tested by calculating the adsorption energy (Eads)/binding energy (Eb) with density functional theory. Due to faster decay of chlorine, lower amounts of disinfection byproducts formed in UV/chlorine/TiO2 compared with UV/chlorine. Adding TiO2 into the UV/chlorine system can promote the degradation of recalcitrant organic pollutants in an aqueous environment.

The continuous discharge of organic pollutants into waterbody has seriously threatened the health of humankind and natural life. Hence, it is imperative to find solutions to deal with this issue. Catalytic advanced oxidation process (AOPs) has drawn increasing attention due to its remarkable performance in removing low-concentration stubborn pollutants. Many catalysts were developed with high-efficiency. Particularly, covalent organic frameworks (COFs) have been frequently reported as the catalyst or support due to their unique properties. In this review, the research progress of COF-based materials in different degradation processes are summarized, especially emphasizing on the structure–activity relationship between the composite strategy and the catalytic degradation ability. In addition, the potential application of COF-based materials to industrial wastewater treatment is also discussed.

The residual antibiotics in different environmental media pose a serious threat to human health and the ecosystem. The high-efficient elimination of antibiotics is one of the foremost works. In this study, chloramphenicol (CAP) was eliminated efficiently by electrocatalytic advanced oxidation process with carbon nanotubes/agarose/indium tin oxide (CNTs/AG/ITO) electrode. The influences of different experimental parameters on the degradation efficiency were systematically studied. Under the optimal conditions (4 V potential, 10 wt% CNTs dosage, and pH = 10), the maximum degradation efficiency of CAP (20 mg L− 1) achieved 88% within 180 min. Besides, the electrocatalytic degradation pathway and mechanism for CAP were also investigated, •O2− played a major role in the process of electrocatalytic degradation. Based on the QSAR (quantitative structure-activity relationship) model, the toxicities of CAP and identified intermediates were analyzed. Compared with the parent compound, the maximal chronic toxicity of intermediate ((E)-3-(4-nitrophenyl)prop-1-ene-1,3-diol) for daphnid increased 197-fold. Besides, the hybrid toxicity of the degradation system was further confirmed via disk agar biocidal tests with Escherichia coli ATCC25922, which changed slightly during the degradation process. Based on the above results, it is worth noting that the degradation pathway and toxicity assessment should be paid more attention to the treatment of antibiotic wastewater.

In the present study, the sol–gel method is used to synthesize pure TiO2, TiO2–ZnO and TiO2–ZnO–NiO (TZN) nanoparticles. The study aims at investigating the photocatalytic efficiency of the synthesized nanoparticles used in order to remove methyl orange (MO, as a model water pollutant) dye, as exposed to black light radiation. Moreover, it also addresses the factors that may positively or negatively affect the efficiency of the photocatalytic process. XRD, SEM and DRS analyses were used to determine the nanocatalysts’ properties. The response surface method (RSM) was used to investigate the effect of four operating parameters [including the catalyst loading (TZN), basic dye concentration, pH and H2O2 concentration] and optimize the photocatalytic process of MO dye degradation in 60 min. Maximum dye removal percentage was obtained under the best operating conditions (catalyst loading = 0.3 g/l, dye concentration = 15 mg/l, pH 3 and H2O2 concentration = 15 ml/l). The high correlation coefficient (R2 = 0.9930) showed that there is an acceptable level of consistency between the experimental data and the resulted MO dye degradation predictions using the response surface model. Appropriate modules were used to carry out the two-dimensional steady-state computational fluid dynamic (CFD) simulation of the advanced oxidation process in the photocatalytic reactor. A quasi-first-order kinetic equation derived from the Langmuir–Hinshelwood model (kapp = 0.015 min−1) was used to account for the photocatalytic process of MO dye degradation. The value of R2 = 0.8865 indicated the significant consistency between the simulated CFD concentration values and experimental data.

Ozonation, combined with suitable catalyst represents an interesting option in removing poorly degraded pollutants from stabilized landfill leachate. Therefore, this study aimed to eliminate chemic...

Vacuum ultraviolet (VUV) process has been regarded as a novel advanced oxidation process for its unique way of generating HO• via direct photolysis of water. This study investigates the kinetics of the VUV process for degradation of a typical pesticide, glyphosate (GLY), by using a photoreactor equipped with a precision sampler. The precision sampler enables us to take samples at distances ranging from 0.1 to 1.5 cm to the irradiation source so that GLY degradation by VUV in different parts of the reaction volume can be evaluated. The results of experiments on H2O2 production from VUV photolysis of water confirmed that there existed an extremely uneven distribution of VUV flux and HO• generated in the VUV process. Enhancing mass transfer by agitation could significantly increase GLY degradation efficiency by improving the distribution of HO•. The initial concentrations of water and GLY governed the reaction kinetics of GLY degradation in the VUV process. As the solution pH increased from 5.0 to 9.0, the overall degradation efficiency of GLY decreased from 97.6% to 77.8%. Depending on their molar absorption coefficients, inorganic anions affected adversely on the degradation of GLY by VUV in the order of NO 3 − >HCO 3 − (alkalinity)>Cl−>SO 4 2− . As a strong HO• scavenger, natural organic matter shows a much more adverse impact on GLY degradation than that of inorganic anions. Based on the experimental results, this study has provided insights into the kinetics of VUV process for pollutant degradation.

In this study, removal of P-Nitrophenol (PNP) as a nitro-aromatic contaminant from the aqueous medium have been investigated using the photochemical oxidation process by UV-activated periodate. The...