Sodium Persulfate Research Articles

Preparation of Nickel-Based Bimetallic Catalyst and Its Activation of Persulfate for Degradation of Methyl Orange

In this research, a new catalyst for activating persulfate was developed by loading iron and nickel ions onto powdered activated carbon (PAC) for treating methyl orange, and the preparation process was optimized and characterized. The efficacy of the treatment was evaluated using the Chemical Oxygen Demand (COD) removal rate, which reflects the impact of various process parameters, including catalyst dosage, sodium persulfate dosage, and reaction pH. Finally, the recovery and reuse performance of the catalyst were studied. The optimal conditions for preparing the activated sodium persulfate catalyst were determined to be as follows: a molar ratio of Fe3+ and Fe2+ to Ni of 4:1, a mass ratio of Fe3O4 to PAC of 1:4, a calcination temperature of 700 °C, and a calcination time of 4 h. This preparation led to an increase in surface porosity and the formation of a hollow structure within the catalyst. The active material on the surface was identified as nickel ferrite, comprising the elements C, O, Fe, and Ni. The magnetic property is beneficial to recycling. With the increase in catalyst and sodium persulfate dosage, the COD removal efficiency of the oxidation system increased first, and then, decreased. The catalyst showed good catalytic performance when the pH value was in the range of 3~11. Furthermore, Gas Chromatography–Mass Spectrometry (GC-MS) analysis indicated the complete oxidation of methyl orange dye molecules in the system. This result highlights the important role of the newly developed catalyst in activating persulfate.

Sustainable cotton dyeing with reactive dyes in the recycled dyeing wastewater

Purpose This paper aims to find a suitable solution to degrade the C.I. Reactive Red 24 (RR24) dyeing wastewater by using sodium persulphate to recycle water and inorganic salts. Design/methodology/approach The effects of temperature, the concentration of inorganic salts and Na2CO3 and the initial pH value on the degradation of RR24 were studied. Furthermore, the relationship between free radicals and RR24 degradation effect was investigated. Microscopic routes and mechanisms of dye degradation were further confirmed by testing the degradation karyoplasmic ratio of the product. The feasibility of the one-bath cyclic dyeing in the recycled dyeing wastewater was confirmed through the properties of dye utilization and color parameters. Findings The appropriate conditions were 0.3 g/L of sodium persulphate and treatment at 95°C for 30 min, which resulted in a decolorization rate of 98.4% for the dyeing wastewater. Acidic conditions are conducive to rapid degradation of dyes, while ·OH or SO4−· have a destructive effect on dyes under alkaline conditions. In the early stage of degradation, ·OH played a major role in the degradation of dyes. For sustainable cyclic dyeing of RR24, inorganic salts were reused in this dyeing process and dye uptake increased with the times of cycles. After the fixation, some Na2CO3 may be converted to other salts, thereby increasing the dye uptake in subsequent cyclic staining. However, it has little impact on the dye exhaustion rate and color parameters of dyed fabrics. Originality/value The recommended technology not only reduces the quantity of dyeing wastewater but also enables the recycling of inorganic salts and water, which meets the requirements of sustainable development and clean production.

Dual Growth Factor Delivery Using Photo-Cross-Linkable Gelatin Hydrogels for Effectively Reinforced Regeneration of the Rotator Cuff Tendon.

Rotator cuff tears are currently treated with drugs (steroids and nonsteroidal anti-inflammatory drugs) and surgery. However, the damaged rotator cuff requires a considerable amount of time to regenerate, and the regenerated tissue cannot restore the same level of function as that before the damage. Although growth factors can accelerate regeneration, they are difficult to be used alone because of the risk of degradation and the difficulties in ensuring their sustained release. Thus, hydrogels such as gelatin are used, together with growth factors. Gelatin is a biocompatible and biodegradable hydrogel derived from collagen; therefore, it closely resembles the components of native tissues and can retain water and release drugs continuously, while also showing easily tunable mechanical properties by simple modifications. Moreover, gelatin is a natural biopolymer that possesses the ability to form hydrogels of varying compositions, thereby facilitating effective cross-linking. Therefore, gelatin can be considered to be suitable for rotator-to-tendon healing. In this study, we designed photo-cross-linkable gelatin hydrogels to enhance spacing and adhesive effects for rotator cuff repair. We mixed a ruthenium complex (Ru(II)bpy32+) and sodium persulfate into gelatin-based hydrogels and exposed them to blue light to induce gelation. Basic fibroblast growth factor and bone morphogenetic protein-12 were encapsulated in the gelatin hydrogel for localized and sustained release into the wound, thereby enhancing the cell proliferation. The effects of these dual growth factor-loaded hydrogels on cell cytotoxicity and tendon regeneration in rotator cuff tear models were evaluated using mechanical and histological assessments. The findings confirmed that the gelatin hydrogel was biocompatible and that treatment with the dual growth factor-loaded hydrogels in in vivo rotator cuff tear models promoted regeneration and functional restoration in comparison with the findings in the nontreated group. Therefore, growth factor-loaded gelatin-based hydrogels may be suitable for the treatment of rotator cuff tears.

Acesulfame degradation by thermally activated persulfate: Kinetics, transformation products and estimated toxicity

The existence of the artificial sweetener acesulfame (ACE) in quantities of significance can negatively impact water quality, and its consumption has been associated with deleterious health effects. The present investigation explores the efficacy of heat-activated sodium persulfate (SPS) for eliminating ACE. The complete degradation of 0.50 mg L−1 of ACE was achieved within 45 min under a reaction temperature of 50 °C and 100 mg L−1 of SPS. The impact of thermal decomposition on ACE at a temperature of 60 °C was negligible. This study considers several factors, such as the SPS and ACE loading, the reaction temperature, the initial pH, and the water matrix of the reactor. The results indicate that the method's efficiency is positively correlated with higher initial concentrations of SPS, whereas it is inversely associated with the initial concentration of ACE. Furthermore, higher reaction temperatures and acidic initial pH levels promote the degradation of acesulfame. At the same time, certain constituents of the water matrix, such as humic acid, chlorides, and bicarbonates, can hinder the degradation process. Additionally, the data from LC-QToF-MS analysis of the samples were used to investigate transformation through suspect and non-target screening approaches. Overall, ACE's eight transformation products (TPs) were detected, and a potential ACE decomposition pathway was proposed. The concentration of TPs followed a volcano curve, decreasing in long treatment times. The ecotoxicity of ACE and its identified TPs was predicted using the ECOSAR software. The majority of TPs exhibited not harmful values.

Unraveling the mechanisms behind sodium persulphate-induced changes in petroleum-contaminated aquifers’ biogeochemical parameters and microbial communities

Sodium persulphate (PS) is a highly effective oxidising agent widely used in groundwater remediation and wastewater treatment. Although numerous studies have examined the impact of PS with respect to the removal efficiency of organic pollutants, the residual effects of PS exposure on the biogeochemical parameters and microbial ecosystems of contaminated aquifers are not well understood. This study investigates the effects of exposure to different concentrations of PS on the biogeochemical parameters of petroleum-contaminated aquifers using microcosm batch experiments. The results demonstrate that PS exposure increases the oxidation-reduction potential (ORP) and electrical conductivity (EC), while decreasing total organic carbon (TOC), dehydrogenase (DE), and polyphenol oxidase (PO) in the aquifer. Three-dimensional excitation-emission matrix (3D-EEM) analysis indicates PS is effective at reducing fulvic acid-like and humic acid-like substances and promoting microbial metabolic activity. In addition, PS exposure reduces the abundance of bacterial community species and the diversity index of evolutionary distance, with a more pronounced effect at high PS concentrations (31.25 mmol/L). Long-term (90 d) PS exposure results in an increase in the abundance of microorganisms with environmental resistance, organic matter degradation, and the ability to promote functional genes related to biological processes such as basal metabolism, transmission of genetic information, and cell motility of microorganisms. Structural equation modeling (SEM) further confirms that ORP and TOC are important drivers of change in the abundance of dominant phyla and functional genes. These results suggest exposure to different concentrations of PS has both direct and indirect effects on the dominant phyla and functional genes by influencing the geochemical parameters and enzymatic activity of the aquifer. This study provides a valuable reference for the application of PS in ecological engineering.

Strength characteristic and micro-mechanism of organic dredged sludge solidified by cement incorporating sodium persulfate

Cement-based solidification is a widely used sustainable technology for transforming waste dredged sludge (DS) into backfill materials. This study developed a novel solidification/oxidization synergistic (SOS) method, using Portland cement as a binder and sodium persulfate (SP) as an oxidant, for treating the organic DS with different fulvic acid (FA) content. The results demonstrated that adding SP could significantly improve the UCS of the cement-solidified DS doped with FA. When the FA content was 4%, the 28-day UCS of the sample with 25% cement content was only 160.5 kPa. The addition of 6% SP increased the UCS to 2225.5 kPa, which was 15.1 times that of the sample without SP. However, excessive SP hydrolyzed to produce a large amount of sulfuric acid, leading to a low pH value of the pore solution. This in turn hindered further persulfate activation and cement hydration, which was detrimental to the strength of cement-solidified DS.

Remediation of 2,4-dichlorophenol-contaminated soil by electrokinetic delivery of persulfate technology.

2,4-Dichlorophenol (2,4-DCP) is difficult to degrade rapidly in the environment due to its stable chemical properties, so it was easy to lead to serious chlorophenol pollution in soil. Consequently, a remediation method which is efficient, safe, and economical is required. In this study, electrokinetic (EK) remediation was used to transfer sodium persulfate (Na2S2O8) into soil to degrade 2,4-DCP, and the effect of several factors (including the addition location of Na2S2O8, applied voltage, and running time) on the remediation efficiency was explored. The concentration of Na2S2O8, residual efficiency of 2,4-DCP and distribution characteristics of pH, and electrical conductivity were analyzed. The results showed that the cathode was the optimal position to add Na2S2O8. Under this condition, Na2S2O8 was uniformly distributed in the whole soil column through electromigration. The optimal removal efficiency of 2,4-DCP in soil by adding Na2S2O8 was approximately 26% when the voltage gradient was 1.0V/cm and the operating time was 9days, which was mainly due to the degradation of S2O82-.

Revolutionizing wood permeability via microwave-initiated persulfate activation

Poor penetration of modifying reagents in wood due to the influence of extractives and pits in the wood. In this paper, microwave-activated sodium persulfate (MW-PS) solutions were used to remove extractives from fir heartwood and to disrupt pit membranes to improve the permeability of the liquid in wood. The large amount of energy generated by microwave irradiation decomposed S2O82- into SO4·-, while some of the resulting SO4·- combined with H2O to form·OH. The permeability of the liquid in the wood cells and cell wall interstices was increased by oxidative decomposition of the wood extractives by free radicals. The moisture in the wood absorbs the large amount of energy released by the microwaves, vaporizes and expands, destroying the pit membrane and creating new liquid channels. Microwave-activated persulfate-treated fir heartwood not only had a significantly lower extractive content (47.45%), but also an increased average pore size (91.84%). The most important thing is that the penetration of liquid into the fir heartwood was significantly increased (63.45%).

Tuning of food wastes bioavailability as feedstock for bio-conversion processes by acoustic cavitation and SPC, SPS, or H2O2 as external oxidants

The growing amount of food wastes makes them a suitable source for the generation of bioproducts through anaerobic digestion. Appropriate hydrolysis of the feedstock can enhance the efficiency of production of desired products. In this work, acoustic cavitation (AC) was employed as a pretreatment method to enhance hydrolysis stage by the modification of model (potato-based) food waste for increase in soluble chemical oxygen demand (CODs) and dissolved carbohydrate. For the first time high and low frequency AC was compared for this purpose. The application of sole AC at a frequency of 20 kHz for feedstock loading of 3 % has led to 125 % and 124 % increase in CODs and dissolved carbohydrates, respectively. The combination of AC with external oxidants hydrogen peroxide (H2O2), sodium persulfate (SPS), and sodium percarbonate (SPC) was also studied. This part of the studies revealed that SPS has superior properties for increasing CODs by 258 % and dissolved carbohydrates by 240 %. On the other hand, addition of sodium hydroxide (NaOH) as alternative reagent, leads to a 173 % increase in CODs and 155 % increase in dissolved carbohydrates. Making both ways of processing highly effective to increase the bioavailability of food wastes for further biologic processing.

Efficient recovery of iron from anaerobic roasted cyanide tailings using advanced oxidation technology

Persulfate-mediated advanced oxidation process (AOP) has been used to oxidize iron and sulfur bearing minerals, but the iron leaching process and the activation of persulfate by minerals themselves has been neglected. In this study, AOP was used to leach iron from cyanide tailings, roasted in a nitrogen atmosphere. The oxidation behavior of pyrrhotite and the activation mechanism of persulfate were proposed through process optimization, product analysis, reactive species and degradation area. The iron leaching efficiency from roasted cyanide tailings was 97.1%, with a mass loss ratio of 32.5%. The gold grade in leach residues increased from 1.19 g/t to 2.07 g/t under the leaching conditions: sodium persulfate concentration of 0.3 mol/L, leaching temperature of 60 °C, slurry concentration of 30 g/L, and stirring speed of 300 rpm. The pyrrhotite in roasted cyanide tailings was oxidized by persulfate and the free radicals produced by its activation. Oxidation products were Fe3+, SO42−, and elemental sulfur. The oxidation of pyrrhotite was dominated by the indirect oxidation by the free radicals OH• and SO4−•, and their contributions to the iron leaching efficiency were 66.6% and 24.2%, respectively. The reason for the thermally enhanced iron leaching effect was the activation of persulfate to produce a certain amount of OH•. The Fe2+ produced by the oxidation of pyrrhotite activated persulfate to produce SO4−• and OH•. Besides, S(II) in pyrrhotite mediated the circulation of iron ions, thereby continuously producing Fe2+ to activate persulfate.

Removal of p-nitrophenols by BC@nZVI activated persulfate: A study of key factors and mechanisms

Straw biochar loaded zero-valent iron nanoparticles were prepared by co-precipitation method using agricultural waste straw biochar as a carrier for the removal of p-nitrophenol (PNP) by activated sodium persulfate (PS). The physicochemical properties of BC@nZVI were characterized using SEM, EDS, FTIR, BET, and RAMAN. The effects of PS concentration, catalyst concentration, initial pH, coexisting anions, and different activation systems on the degradation of PNP were investigated. The results showed that the best activation effect was exhibited at pH= 7, BC@nZVI dosage of 2 g/L, and PS concentration of 1 mM, and the removal of 40 mg/L PNP reached 91.7 % in 10 min. The high concentration of PS (4 mM) triggered free radical competition to inhibit the degradation, and the removal rate was only 74.5 % at 1 mM. In addition, bicarbonate ions (0–20 M) had a significant inhibitory effect on this system. Electron spin resonance (ESR) demonstrated that SO4⋅− and·OH were the major radicals, and SO4⋅− was preferentially generated. The intermediate products were identified by LC-MS, XRD and XPS characterization, which showed that adsorption and redox were the main degradation mechanisms, with p-benzoquinone was the oxidized product and substances such as 4-heptanone and propionic acid were the reduced products. This study proves that BC@nZVI activated PS is an efficient and excellent means of removing PNP and a good way to reuse agricultural waste.

Ultrasonication-flotation-advanced oxidation tertiary treatment of oil-based drilling cuttings

The treatment of oil-based drilling cuttings (OBDCs) with high oil content is difficult. In this study, a tertiary treatment of ultrasonication–flotation–advanced oxidation for treating OBDCs with a high oil content of 20.10 wt% was proposed for the first time. All stages of the treatment processes were optimised. The recommended parameters for ultrasonication at room temperature were a mass ratio of OBDCs to the degreaser of 1:8, an ultrasonication power of 600 W and treatment time of 30 min. After the ultrasonication treatment, the oil content of the OBDCs decreased from 20.10 wt% to 5.00 wt%. Flotation was performed at room temperature with a mass ratio of OBDCs to the degreaser of 1:10, a stirring speed of 400 rpm, an aeration head aperture of 3 μm and airflow rate of 400 mL/min under N2 injection for 60 min. After the flotation treatment, the oil content of the OBDCs decreased from 5.00 wt% to 2.01 wt%. Advanced oxidation was performed at room temperature with a mass ratio of OBDCs to water of 1:10, 3.57 wt% sodium persulphate in water, 4.17 wt% ferrous sulphate heptahydrate in water and ultrasonication power of 1000 W for 100 min. Following the advanced oxidation treatment, the oil content of the OBDCs decreased from 2.01 wt% to 0.58 wt%. The results of this study provide a new method and idea for treating OBDCs with high oil content.

Valorization of olive mill solid waste-derived biochar: An efficient approach for simultaneous adsorption and oxidation of micropollutant in surface water

This study explores the utilization of olive mill solid waste (OMSW) as a source of biochar (BC) for effective removal of micropollutants during surface water treatment. The conversion of OMSW into BC was accomplished via pyrolysis conducted at varying temperatures ranging from 400 to 600 °C. To improve its performance, BC was subjected to activation through either physical-thermal or chemical techniques. BC samples were characterized by SEM microscopy revealing a porous structure, surface area analysis showed an increase in surface area for biochar samples subjected to physical-thermal activation (BC-T) (20 m2/g) and chemical activation using potassium hydroxide (BC-KOH) (70 m2/g) or zinc/iron (BC-Zn/Fe) (456 m2/g). The zero point of charge range from <3 to 4.2 for the different BC samples whereas FTIR measurements showed that physical activation at 900 °C favors a graphitic structure in BC.The catalytic properties of the biochar samples were investigated in the activation of sodium persulfate (PSF) for the oxidation of micropollutants (MPS), including ciprofloxacin (CPX), sulfamethoxazole (SMZ), and paracetamol (PCM), in natural Lake Kinneret water. BC-KOH exhibited the highest removal efficiency, and the removal of MPS increased with higher dosages of BC and PSF. Under optimized conditions ([biochar]: 500 mg/L and [PSF]: 200 mg/L), significant removal efficiencies were achieved for PCM (88.2 % ± 0.7), CPX (80.8 % ± 1.9), and SMZ (64.1 % ± 3.2) after a 5-hour treatment. Finally, MPS adsorbed on BC experienced significant surface oxidation, resulting in removal efficiencies for PCM (97.9 %), CPX (92 %), and SMZ (77.9 %). This oxidation process is expected to enhance the treatment effectiveness prior to regeneration.

Photo-Cross-Linkable, Injectable, and Highly Adhesive GelMA-Glycol Chitosan Hydrogels for Cartilage Repair.

Hydrogels provide a promising platform for cartilage repair and regeneration. Although hydrogels have shown some efficacy, they still have shortcomings including poor mechanical properties and suboptimal integration with surrounding cartilage. Herein, hydrogels that are injectable, cytocompatible, mechanically robust, and highly adhesive to cartilage are developed. This approach uses GelMA-glycol chitosan (GelMA-GC) that is crosslinkable with visible light and photoinitiators (lithium acylphosphinate and tris (2,2'-bipyridyl) dichlororuthenium (II) hexahydrate ([RuII(bpy)3 ]2+ and sodium persulfate (Ru/SPS)). Ru/SPS-cross-linked hydrogels have higher compressive and tensile modulus, and most prominently higher adhesive strength with cartilage, which also depends on inclusion of GC. Tensile and push-out tests of the Ru/SPS-cross-linked GelMA-GC hydrogels demonstrate adhesive strength of ≈100 and 46kPa, respectively. Hydrogel precursor solutions behave in a Newtonian manner and are injectable. After injection in focal bovine cartilage defects and in situ cross-linking, this hydrogel system remains intact and integrated with cartilage following joint manipulation ex vivo. Cells remain viable (>85%) in the hydrogel system and further show tissue regeneration potential after three weeks ofin vitroculture. These preliminary results provide further motivation for future research on bioadhesive hydrogels for cartilage repair and regeneration.

Synergistic degradation levofloxacin through dielectric barrier discharge and sodium persulfate

The release of antibiotics that are difficult to degrade by themselves into the environment have received increasing attention because they have posed great threat to natural ecosystem and human health. Sodium persulfate (PS) is used to treat organic wastewater because of its strong oxidation, but it needs to be activated. Dielectric barrier discharge (DBD) can product stable gas discharge plasma that is suitable for activating PS. The synergistic degradation process of levofloxacin (LFX) by air DBD plasma with PS were investigated. The effects on the degradation ratio and energy efficiency of LFX were studied, including input power, air flow rate, original concentration, discharge spacing, and PS dosage. The degradation kinetics and synergistic factors were calculated under different PS additions. After plasma alone treatment 45 min, the maximum degradation ratio of LFX was 58.74 % and 88.63 % via plasma alone and plasma synergistic with PS under 15 W input power and 50 mg·L−1 LFX original concentration. The energy efficiency, the first-order reaction rate constant and the synergistic factor SI was 0.1532 g·(kW·h)−1, 4.116 × 10−2 min−1 and 1.64, respectively. The change of ozone concentration in the reaction system after adding PS was measured. The effects on the synergistic degradation of LFX of two radical scavengers, methanol (MeOH), and tert-butanol (TBA), were investigated. After calculation, the contribution ratios of ·OH and SO4-· were 48.08 % and 26.97 %, respectively. The intermediate products were analyzed by LC-MS in the decomposition process of LFX, and the probable decomposition pathway of LFX was presented.

Dynamic Release Characteristics and Kinetics of a Persulfate Sustained-Release Material.

Sustained-release materials are increasingly being used in the delivery of oxidants for in situ chemical oxidation (ISCO) for groundwater remediation. Successful implementation of sustained-release materials depends on a clear understanding of the mechanism and kinetics of sustained release. In this research, a columnar sustained-release material (PS@PW) was prepared with paraffin wax and sodium persulfate (PS), and column experiments were performed to investigate the impacts of the PS@PW diameter and PS/PW mass ratio on PS release. The results demonstrated that a reduction in diameter led to an increase in both the rate and proportion of PS release, as well as a diminished lifespan of release. The release process followed the second-order kinetics, and the release rate constant was positively correlated with the PS@PW diameter. A matrix boundary diffusion model was utilized to determine the PS@PW diffusion coefficient of the PS release process, and the release lifespan of a material with a length of 500 mm and a diameter of 80 mm was predicted to be more than 280 days. In general, this research provided a better understanding of the release characteristics and kinetics of persulfate from a sustained-release system and could lead to the development of columnar PS@PW as a practical oxidant for in situ chemical oxidation of contaminated aquifers.

Coupled adsorption and photocatalysis: A green synthesized g‐C3N4@Mn–FeOOH@molecularly imprinted photocatalysis system for targeted removal of various heterocyclic amines

AbstractPhotocatalysis‐based advanced oxidation technologies have been developed as an attractive strategy for degrading pollutants. However, the question of how to increase removal specificity without sacrificing the degradation effect remains a difficult one. In this work, a photocatalytic system for the simultaneous targeted elimination of nine heterocyclic amines (HCAs) is established using a green‐prepared photocatalyst (CN@Mn–FeOOH@MIP) that activates sodium persulfate (PS) under visible light. Mn–FeOOH clusters are in situ covered on laminar g‐C3N4 (CN) carrier to form a heterojunction, along with a molecularly imprinted layer self‐polymerized from dopamine, which is grown on the outer layer, resulting in both the desired photochemical activity and specific sites for recognition. The conditions of composite and photocatalysis are explored and optimized for efficient and selective degradation. Notably, CN@Mn–FeOOH@MIP is synthesized free of any organic reagents, and the biosafety is confirmed by cellular and in vivo toxicity evaluation. The developed CN@Mn–FeOOH@MIP/PS system with visible‐light‐driven is applied to the removal of HCAs in coffee samples with the recoveries over 70% and the reuse rates greater than 85%. It coupled the advantages of specific enrichment and rapid degradation, which furnishes a novel approach for the control of trace thermal processing pollutants.

In‐situ remediation of TPH‐polluted soil by Na2FeO4 in the Loess Plateau of China

AbstractIn recent years, the oil pollution problem on the Loess Plateau in western China is becoming increasingly serious, therefore, the use of hydroxyl radical (·OH) advanced oxidation process has increased due to its ability to efficiently degrade total petroleum hydrocarbon (TPH) in soil. However, the ability to produce ·OH of different oxidants varies widely, and the removal effect of specific pollutants has fluctuations and differences. The objective of this study is to screen the best oxidant according to the physico‐chemical properties and pollution situation of polluted soil, and to reveal the degradation mechanism of pollutants. In this study, we employed sodium ferrate (Na2FeO4) to produce ·OH for the degradation of TPHs in aged oil‐polluted soil located in the western part of the Loess Plateau in China. The results showed that the removal rates of TPH in the soil samples by hydrogen peroxide (H2O2), sodium persulfate (Na2SO4) and Na2FeO4 could reach 45.5%, 62.4%, and 65.6% respectively. The ·OH produced during the process played a major role in TPH oxidation with a contribution of more than 80%; H2O2 was intermediate substance that generated ·OH, biochar could induce the production of ·OH, the addition of biochar could activate H2O2 to promote the generation of ·OH and the removal rate is significantly increased by 19.2%. In situ remediation of polluted soil on the Loess Plateau using Na2FeO4, with a TPH degradation rate of 87.5%. The results of this study will provide a new method for the efficient degradation of TPH in loessial soil.

Preparation and properties of anatase - rutile mixed crystal Fe-TiO2 with high catalytic activity under visible light

With the development of society, water pollution is becoming more and more serious, especially dyeing wastewater. Fe-doped TiO2 nano-photocatalyst was prepared by hydrothermal method. The crystal structure, morphology, optical properties, band gap width (Eg) and photocatalytic properties of the synthesized nanoparticles were characterized by XRD, SEM, TEM, EDS, XPS, FT-IR and UV–vis. The results show that Fe-TiO2 is a mixed crystal form of rutile type and anatase type, the average crystal diameter of anatase type is 11 nm, and the diameter of rutile type is 10–50 nm. The addition of Fe can effectively reduce the band gap width of TiO2 from 3.22 eV to 2.33 eV, so as to expand the visible light absorption range. Under 350 W xenon lamp irradiation, the degradation rate of Rhodamine B (RhB) reached 95.3% with 2% Fe-TiO2 nanoparticles in the synergistic effect of sodium persulfate (PS) for 40 min, and the nanoparticles had good reusability. Free radical quenching experiments showed that·OH, SO4-·, e-, and h+ pairs favored RhB degradation. The addition of Fe can form additional energy levels in TiO2, so that the smaller energy photons can excite the electrons and holes trapped in the additional energy levels, so that the absorption of TiO2 is redshifted and the visible light absorption range is extended. Meanwhile, PS accelerates the transformation between Fe(Ⅲ) and Fe(Ⅱ), thereby effectively improving the photocatalytic efficiency.

A parametric study on intensified degradation of textile dye water using hydrodynamic cavitation based hybrid technique

In this paper, a detailed investigation of the treatment of model textile dye wastewater (MTDW) by applying a hybrid approach of hydrodynamic cavitation (HC) coupled with UV light and different oxidants is reported. A distinct hybrid strategy of HC combined with inline UV and different oxidants was employed to treat model textile dye wastewater comprising mixed dyes under neutral to alkaline conditions and in the presence of salt and detergent, which form significant components of textile wastewater. The model textile dye wastewater was made of three dyes: Reactive Yellow 84, Reactive Black 8, and Reactive Violet 5 with 100 ppm of total concentration. Effects of various operating conditions, such as feed pressure at the venturi inlet, initial pH, process time, and different oxidizing agents, on percentage COD reduction were investigated. The extent of dye decolourization using HC combined with different oxidizing agents, viz., hydrogen peroxide (H2O2), sodium persulfate (NaPS), and potassium peroxymonosulfate (PPMS), were studied. HC coupled with UV and potassium peroxymonosulfate (PPMS) oxidant produced maximum decolourization of dyes to the extent of 100 % at pH 7. A maximum COD reduction of 87.7 % was obtained at the optimized operation conditions of hydrodynamic cavitation (HC) coupled with UV and PPMS. The treatment of model dye wastewater utilizing a hybrid strategy of HC+UV+PPMS achieved a synergetic index of 1.92, which was significantly better than standalone treatments. The current work contributes significantly to our understanding of the performance of cavitation-based systems for treating complicated textile effluent.