Persulfate Treatment Research Articles

Aging of microplastics and its photo-catalytic degradation of coexisting tetracycline

Photodegradation processes play a crucial role in the transforming of antibiotics in aqueous environments, while photochemical aging influences the properties of microplastics (MPs). In this study, the efficacy of ultraviolet (UV) irradiation in eliminating tetracycline (TC) was examined. Especially, TC degradation was mediated by polyethylene microplastics (PE-MPs) was subjected to aging through UV exposure and a combination of UV and thermal-activated persulfate treatments. The effects of MPs concentration, salinity, and pH on TC degradation were investigated. The characteristics of aging PE-MPs and the corresponding active free radicals were analyzed to understand the mechanism of TC degradation. The results showed that the existence of PE-MPs significantly influenced TC degradation under photosensitized conditions. However, as the concentration of PE-MPs increased, the degradation rate initially increased and subsequently declined. TC degradation increased from approximately 35 % to 85 % when pH increased from 3 to 11 mediated by aged PE-MPs. Moreover, the TC degradation ability increased with increasing salinity, and a higher aging degree facilitated the photodegradation of TC, achieving a removal rate of 62 %. At the same time, free radical quenching confirmed that the singlet oxygen (1O2), hydroxyl radical (OH), and superoxide radical (O2·−) produced all involved in the photolysis process of TC mediated by PE-MPs, especially 1O2. The analysis of the degradation products of TC and prediction of its toxicity revealed that the ecological risk associated with the degradation solution diminished compared with that of the TC mother solution.

Enhanced removal of antibiotic-resistant genes by sodium persulfate catalyzed by nanoscale zero-valent iron modified by Ginkgo biloba L. leaf

ABSTRACT In this study, nanoscale zero-valent iron (nZVI) modified by Ginkgo biloba L. leaf (G-nZVI), as an effective catalyst, exhibited excellent activation of sodium persulfate (PS), which could achieve higher removal efficiency of antibiotic-resistant genes (ARGs) in the Fen River than PS + nZVI system. This study utilizes forestry waste to address the limitations of using Fe2+/nZVI as an activator for the removal of ARGs. This approach adheres to the principle of employing waste to treat waste. The technology converts G. biloba L. leaf into plant extracts that are rich in a variety of bioactive components, rather than purifying natural biomolecules, which decreases operational complexity. In addition, the G-nZVI + PS system demonstrates superior removal performance to single components in the system. Consequently, the mechanism underlying the G-nZVI + PS treatment is attributed to peroxidation induced by radicals. In this context, the results of ARG removal by G-nZVI + PS with different G. biloba L. leaf /FeSO4·7H2O volume ratios indicated that the G. biloba L. leaf enhanced the conversion of Fe3+ to Fe2+, thereby generating more radicals through electron transfer between the biomass and G-nZVI. This research underscores the advantages of modifying G. biloba L. leaf for improved catalytic efficiency and the role of the components within the system.

Influence of Tectonically Deformed Coal-Based Activated Carbon and Its Surface Modification on Methane Adsorption.

A series of coal-based activated carbons (CACs) were synthesized from mylonitized fat coal, a type of tectonically deformed coal (TDC) and symbiotic primary structural coal (PSC), followed by oxidative modification. The pore structure, surface oxygen-containing functional groups, and their influence on methane adsorption by CAC as the simplified coal model were investigated by using low-temperature nitrogen adsorption, Fourier transform infrared spectroscopy, Boehm titration, and X-ray photoelectron spectroscopy. The results showed that tectonic deformation fostered smaller pores, particularly ultramicropores in TDC, dominating methane adsorption. Acid-modified TDC-based activated carbons (ACs) showed higher pore parameters and oxygen-containing functional groups than those of PSC-based ACs. Nitric acid introduced abundant carboxyl groups concurrently increasing the pore volume and specific surface area (SSA), while sulfuric acid-ammonium persulfate treatment resulted in increased lactone groups and a partial collapse/blockage of nanopores. Methane adsorption experiments confirmed the importance of micropores and revealed a significant decrease in capacity owing to increased oxygen-containing functional groups as the primary role, with pore wall corrosion playing a secondary role. Thus, the study highlights the surface effects of TDC on methane adsorption and the potential for producing high-performance methane storage materials from China's tectonic coal resources.

Integrating UV/persulfate and deficit irrigation of recycled water: Strategy to minimize crop accumulation of trace organic contaminants and enhance crop yield

This study investigated the combination of UV persulfate (UV/PS) treatment of recycled water and deficit irrigation to minimize pharmaceutical and personal care products (PPCPs) accumulation and improve crop quality. Lettuce, carrot, and tomato, commonly consumed raw, were cultivated in a greenhouse using PPCPs spiked recycled water, UV/PS treated recycled water, and tap water control, under irrigation rates at 60 %, 80 % and 100 % of crop evapotranspiration (ETC) rates. UV/PS removed ≥ 99 % of carbamazepine, diclofenac, and fluoxetine from spiked recycled water. Post-treatment, carbamazepine accumulation in harvested lettuce, carrot, and tomato was reduced by 96–99 %, 35–70 % and 72–93 %, respectively. Minimal accumulation of diclofenac and fluoxetine occurred in edible crops due to their existence as dissociated ions. Three edible crops exhibited distinct trends of PPCPs accumulation in response to irrigation rates. Lettuce exhibited a decreasing PPCPs accumulation with a reduced irrigation rate, which was attributed to slower transpiration. In contrast, carrot and tomato exhibited increased PPCP accumulation due to osmotic adjustment. Lettuce and carrot exhibited higher irrigation water utilization efficiency at deficit irrigation, while the opposite was observed for tomato. This study highlights the beneficial integration of UV/PS with deficit irrigation to conserve water, maintain crop yield, and minimize PPCPs accumulation.

Persulfate photolysis and limited irrigation of recycled wastewater for turfgrass growth: Accumulation of pharmaceutical and personal care products and physiological responses

Recycled wastewater effluent irrigation and implementing limited irrigation rates are two promising strategies for water conservation in agriculture. However, one major challenge is the accumulation and translocation of Pharmaceutical and Personal Care Products (PPCPs) from recycled water to crops. This study investigated the effects of UV persulfate (UV/PS) treatment of recycled water and limited irrigation rate on PPCPs accumulation and physiological responses of St. Augustine turfgrass via a 14-week field trial. Carbamazepine (CBZ), sulfamethoxazole (SMX), triclosan (TCS), fluoxetine (FLX) and diclofenac (DCF) were spiked at 0.1–1.5 µg/L into recycled water and two limited irrigation rates corresponding to 60 % and 80 % of reference Evapotranspiration (ETo) were applied. Results showed that UV/PS removed 60 % of CBZ and > 99 % of other PPCPs from recycled water. Irrigation with UV/PS treated recycled water resulted in approximately a 60 % reduction in CBZ accumulation and complete removal of SMX, DCF, FLX and TCS in both turfgrass leaves and roots. A more limited irrigation rate at 60 % ETo resulted in a higher accumulation of CBZ accumulation compared to 80 % ETo. Similarly, the canopy temperature increased under 60 % ETo irrigation rate compared to 80 % ETo, suggesting that turfgrass under 60 % ETo was more prone to water stress. Applying a 60 % ETo irrigation rate was not sufficient to maintain the turfgrass quality in the acceptable range. A negative correlation between the visual quality and cumulative mass of PPCPs in turfgrass leaves at different irrigation rates was observed, yet irrigation rate was the major driver of turfgrass overall quality and health. Insights from this study will help to integrate recycled water with treatment and limited irrigation, thereby enhancing agricultural water reuse practices.

Life Cycle Assessment as a Decision-Making Tool for Photochemical Treatment of Iprodione Fungicide from Wastewater

Water contamination with various micropollutants is a serious environmental concern since this group of chemicals cannot always be removed efficiently with advanced treatment methods. Therefore, alternative chemical- and energy-intensive oxidation processes have been proposed for the removal of refractory and/or toxic chemicals. However, similar treatment performances might result in different environmental impacts. Environmental impacts can be determined by adopting a life cycle assessment methodology. In this context, lab-scale experimental data related to 100% iprodione (a hydantoin fungicide/nematicide selected as the model micropollutant at a concentration of 2 mg/L) removal from simulated tertiary treated urban wastewater (dissolved organic carbon content = 10 mg/L) with UV-C-activated persulfate treatment were studied in terms of environmental impacts generated during photochemical treatment through the application of a life cycle assessment procedure. Standard guidelines were followed in this procedure. Iprodione removal was achieved at varying persulfate concentrations and UV-C doses; however, an “optimum” treatment condition (0.03 mM persulfate, 0.5 W/L UV-C) was experimentally established for kinetically acceptable, 100% iprodione removal in distilled water and adopted to treat iprodione in simulated tertiary treated wastewater (total dissolved organic carbon of iprodione + tertiary wastewater = 11.2 mg/L). The study findings indicated that energy input was the major contributor to all the environmental impact categories, namely global warming, abiotic depletion (fossil and elements), acidification, eutrophication, freshwater aquatic ecotoxicity, human toxicity, ozone depletion, photochemical ozone creation, and terrestrial ecotoxicity potentials. According to the life cycle assessment results, a concentration of 21.42 mg/L persulfate and an electrical energy input of 1.787 kWh/m3 (Wh/L) UV-C light yielded the lowest undesired environmental impacts among the examined photochemical treatment conditions.

A review on the use of persulfate activation in treating antibiotics-contaminated wastewater

With the progress of science and technology and social development, the misuse of antibiotics has led to water pollution that severely impacts the ecological environment and human health, and the effective treatment of antibiotics-contaminated wastewater has become an urgent problem. Recently, advanced oxidation processes based on persulfate have been widely concerned by scholars because of their good effect in degrading antibiotic pollutants. In this paper, the activation mechanism of persulfate degradation of antibiotic pollutants is firstly reviewed, and the two activation mechanisms of radical pathway and non-radical pathway are distinguished. Then, this paper summarizes the common activation techniques for persulfate treatment of wastewater contaminated with antibiotics, analyzes the principles and characteristics of different activation techniques, and focuses on the non-heterogeneous activation of persulfate in transition metal-based materials and carbon-based materials in terms of the generation of responsive species and the surface electron transfer. Finally, in view of the current needs and difficulties, the author puts forward some suggested research directions and challenges faced, intending to provide some theoretical guidance for the efficient treatment and effective control of antibiotics-contaminated wastewater in the future.

Magnetic Fe3O4-C@MoS2 composites coordinated with peroxymonosulfate catalysis for enhanced tetracycline degradation

Tetracycline is an organic compound that poses a significant threat to both the ecological environment and human health during its long-term production and use. Advanced oxidation processes based on sulfate radicals (SR-AOP) have been recognized as effective techniques for treating antibiotic contamination. However, The urgent demand for a green, efficient, and recyclable catalyst to effectively facilitate persulfate treatment of tetracycline pollution is evident. Magnetic Fe3O4-C@MoS2 composite were synthesized using hydrothermal and pyrolysis methods. Degradation experiments, free radical quenching experiments, EPR analysis were carried out to investigate the degradation performance and mechanisms of Fe3O4-C@MoS2 composite. Results showed that the degradation efficiency of 100 mL of 20 mg/L tetracycline solution reached up to 97% within 40 mins with the dosage of 20 mg Fe3O4-C@MoS2 and 30.7 mg peroxmonosulfate. Furthermore, this degradation system exhibited excellent efficiency even over a wide pH range of 3–9. The transformation of Mo (IV) and S2-/Sn2- species valence states facilitated the conversion between Fe(III)/Fe(II). Both free radical (SO4⋅−,⋅OHandO2⋅−) as well as non-free radical species (O21) were found to accelerate the catalytic reaction during the tetracycline degradation. The possible pathways of tetracycline degradation were proposed, and the toxicity of the intermediate products were proved to be lower than that of tetracycline. Finally, magnetic Fe3O4-C@MoS2 composites possessed good reusability and stability after 4 cycles of degradation.

Degrading surface-water-based natural organic matter and mitigating haloacetonitrile formation during chlorination: Comparison of UV/persulfate and UV/hydrogen peroxide pre-treatments

Haloacetonitriles (HANs) are unregulated disinfection by-products that are more toxic than regulated species. Therefore, efficient decomposition of HAN precursors prior to disinfection is crucial for allaying the potential HAN-induced health risks. This study investigated the key roles of ultraviolet-activated persulfate (UV/PS) treatment in alleviating HAN formation. The effects of UV/PS treatment were evaluated by correlating with the characteristics of organic matter in surface water and comparing with conventional UV/H2O2 treatment. Upon irradiating raw water samples and a Suwannee River humic acid solution spiked with 10 mM PS or H2O2 with 254 nm UV light, UV/PS treatment was found to be more potent than UV/H2O2 in mitigating the HAN production and degrading organic substances; moreover, UV/PS treatment effectively decreased the dissolved organic nitrogen (DON) content. In contrast, UV/H2O2 treatment did not induce any noticeable reduction in DON level. Furthermore, both UV/PS and UV/H2O2 treatments reduced the dichloroacetonitrile (DCAN) formation potential (FP), leading to strong correlations with the degradation of aromatic and humic-acid-like compounds. Notably, UV/PS treatment efficiently decreased the FP of bromochloroacetonitrile (BCAN) and dramatically reduced that of dibromoacetonitrile (DBAN) after a sharp increase; however, UV/H2O2 treatment gradually increased the DBAN-FP. Bromide was activated by sulfate radicals during UV/PS treatment, negatively correlating with the BCAN-FP and DBAN-FP, indicating that the formation of reactive bromine species increased the DBAN-FP; however, excessive oxidation possibly led to the recovery of inorganic bromine for decreasing the BCAN-FP and DBAN-FP. Additionally, UV/PS treatment effectively suppressed toxicity owing to its high reduction rate for brominated HANs; in contrast, UV/H2O2 treatment resulted in less significant BCAN and DBAN reductions, leading to minimal net reduction in toxicity. Overall, UV/PS treatment was remarkably effective at diminishing the toxicity of brominated HANs, underscoring its potential to mitigate drinking-water-related health risks.

Mechanistic insights into removal of bisphenol A from activate peroxymonosulfate by Fe-C coupled biochar with the assistance of electric-field activation

Iron-carbon micro electrolysis activated persulfate (Fe-C/PS) treatment of wastewater is characterized by high oxidation efficiency and no secondary pollution, Limitations such as short reaction lifetime and hardening of Fe-C usually make it insufficient to achieve the desired treatment effect.The research is a new type of electric field in the auxiliary, promote biochar activation peroxymonosulfate (PMS) by micro electrolysis produce active free radicals to degradation of organic pollutants in water. namely IC-BC/PMS-EC，Using biochar as electron shuttle, electric field was introduced in the process of iron-carbon microelectrolysis activation of PMS promoted the electron transfer in the solution， The results showed that the reaction system could achieve 100% removal effect in 20 min. Fe2+/Fe3+ released by Fe-C was below the ambient concentration, which constituted a stable cycle in the electrocatalytic system and efficiently activated PMS. The work found that applied electric field and Fe-C micro-electrolysis activation both improved the efficiency of persulfate advanced oxidation progress. The activated system superimposition strengthened on coupled action and enhanced the performance for the degradation of organic pollutants in water. In summary, IC-BC/PMS-EC system is an economical, efficient and promising new system in the process of activating PMS to degrade pollutants.

Sulfate radical-based advanced oxidation process effects on tire wear particles aging and ecotoxicity

Tire wear particles (TWPs) are widely distributed in natural water and pose as major pollutants in aquatic environments. In this study, heat-activated persulfate (HPT) and ultraviolet-activated persulfate treatments (UPT) were employed to investigate the influence of sulfate radical (SO4−•)-based advanced oxidation process (SAOPs) on TWP physicochemical properties and to clarify their ecotoxic effects in laboratory-level studies. Results showed that the specific surface areas of TWPs increased after UPT but decreased after HPT. In terms of chemical properties, the increase of oxygen-containing functional groups on the surfaces of TWPs was more evident in UPT than that in HPT. The atrazine (ATZ) adsorption capacity of TWPs after HPT and UPT was increased compared with the untreated TWPs. Atrazine adsorbed by TWPs was easily resolved and released in artificial intestinal fluid (1.89–2.08 mg/g) and artificial gastric fluid (1.60–2.04 mg/g) conditions. Acute toxicity experiments of Photobacterium phosphoreum and SEM-EDS detection results suggested that various heavy metals (e.g., Zn2+, Cu2+) in the TWPs would be released into the water system in SAOPs. ATZ released from TWPs that adsorbed ATZ herbicide, rather than TWPs themselves, had a negative effect on aquatic plant growth (e.g., C. vulgaris). The leaching solution of oxidized TWPs (after HPT and UPT) showed a more significant inhibition effect on the zebrafish survival compared with that of untreated TWPs, which was possibly caused by the generation of oxidation byproducts such as N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone.

Elucidating sulfate radical-induced oxidizing mechanisms of solid-phase pharmaceuticals: Comparison with liquid-phase reactions

As a class of organic micropollutants of global concern, pharmaceuticals have prevalent distributions in the aqueous environment (e.g., groundwater and surface water) and solid matrices (e.g., soil, sediments, and dried sludge). Their contamination levels have been further aggravated by the annually increased production of expired drugs as emerging harmful wastes worldwide. Sulfate radicals (SO4•−)-based oxidation has attracted increasing attention for abating pharmaceuticals in the environment, whereas the transformation mechanisms of solid-phase pharmaceuticals remain unknown thus far. This investigation presented for the first time that SO4•−, individually produced by mechanical force-activated and heat-activated persulfate treatments, could effectively oxidize three model pharmaceuticals (i.e., methotrexate, sitagliptin, and salbutamol) in both solid and liquid phases. The high-resolution mass spectrometric analysis suggested their distinct transformation products formed by different phases of SO4•− oxidation. Accordingly, the SO4•−-mediated mechanistic differences between the solid-phase and liquid-phase pharmaceuticals were proposed. It is noteworthy that the products from both systems were predicted with the remaining persistence, bioaccumulation, and multi-endpoint toxicity. Therefore, some post-treatment strategies need to be considered during practical applications of SO4•−-based technologies in remediating different phases of micropollutants. This work has environmental implications for understanding the comparative transformation mechanisms of pharmaceuticals by SO4•− oxidation in remediating the contaminated solid and aqueous matrices.

Alkali-thermal activated persulfate treatment of tetrabromobisphenol A in soil: Parameter optimization, mechanism, degradation pathway and toxicity evaluation

The continued accumulation of halogenated organic pollutants in soil posed a potential threat to ecosystems and human health. In this study, tetrabromobisphenol A (TBBPA) was used as a typical representative of halogenated organic pollutants in soil, for alkali-thermal activated persulfate (PS) treatment. The results of response surface methodology (RSM) showed a optimal debromination efficiency of TBBPA was 88.99 % under the optimum reaction conditions. Quenching experiments and electron paramagnetic resonance (EPR) confirmed that SO4−•, HO•, O2−• and 1O2 existed simultaneously in the oxidation process. SO4−• played a major role in the initial stage of the reaction, and O2−• played a major role in the the last stage. Based on density functional theory (DFT) and intermediate products, two degradation pathways were proposed, including debromination reaction and β bond scission. Moreover, the basic physical and chemical properties of the soil were affected to a certain extent, while the soil surface structure, elements and functional group composition rarely changed. In addition, the T.E.S.T. analysis and biotoxicity tests proved that alkali-thermal activated PS can effectively reduce the toxicity of TBBPA-contaminated soil, which is conducive to the subsequent safe secondary utilization of soil.

Purification of antibacterial attacins induced in Hyalophora cecropia pupae immunized with Enterobacter cloacae C7‐501 using ion‐exchange chromatography, hydrophobic interaction chromatography, and Rotofor® isoelectric focusing

AbstractHyalophora cecropia pupae were infected by Enterobacter cloacae C7‐501 to induce antibacterial attacins for purification. The induction of attacins in immunized pupae was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Ion‐exchange chromatography (IEC), hydrophobic interaction chromatography (HIC), and Rotofor® isoelectric focusing (ISEF) were applied to isolate attacins from the hemolymph. IEC separated attacins from most hemolymph proteins, but the fractions containing attacins also had other proteins of 20 and 64 kDa in length. In IEC, attacin was eluted with ~0.2 M NaCl. The best conditions for IEC were pH 9, flow rate of 2 mL/min, with step elution (0.025, 0.05, 0.075, 0.1, 0.2, 0.4 and 1.0 M NaCl). In HIC, most other proteins were eluted with the ammonium persulfate treatment. HIC isolated attacin proteins under hydrophobic conditions, at ~50% EtOH. However, the fraction with attacins also contained other proteins. The Rotofor® ISEF produced fractions containing attacins at isoelectric points ranging between 5.7 and 8.3. However, non‐specific proteins were detected in the fraction samples, and the recovery of attacins was low. The purification efficiency of ISEF was lower than IEC and HIC. In this study, the expression of attacins was induced in H. cecropia pupae infected with E. cloacae C7‐501, and attacins could be purified by IEC and ISEF. Overall, IEC provided better separation of attacins from the hemolymph of H. cecropia pupae immunized with E. cloacae bacteria than HIC and Rotofor® ISEF.

Persulfate-based ISCO for field-scale remediation of NAPL-contaminated soil: Column experiments and modeling

An experimental and computational investigation of in situ chemical oxidation (ISCO) of weathered diesel fuel in soil columns was undertaken to validate a reactive-transport model capable of predicting contaminant mass reduction from a residual source zone. Reactivity tests with contaminated groundwater in batch reactors were used to estimate a priori the kinetic parameters of a phenomenological model of the oxidation of petroleum hydrocarbon (PHC) mixture fractions. The transport model, which incorporated groundwater flow, dissolution of main PHC fractions, and homogeneous reaction in the aqueous phase, was subsequently validated against experimental data of ISCO in soil columns using repetitive treatments with unactivated and alkaline-activated persulfate. No significant effect of the initial concentration of persulfate on the remediation performance was observed in the batch system, but alkaline activation significantly improved performance. The alkaline-activated persulfate treatment achieved ∼80% removal of the initial NAPL mass in soil columns. The combination of models and experiments described herein should enable the rational design of field-scale advanced oxidation strategies for the removal of weathered petroleum hydrocarbons. This expectation was supported by a comprehensive demonstration study at a historical site contaminated by weathered diesel fuel present as a residual source within the soil and dissolved within groundwater.

In Situ Synthesis of MXene with Tunable Morphology by Electrochemical Etching of MAX Phase Prepared in Molten Salt

AbstractMXenes, a rapidly growing family of 2D transition metal carbides, carbonitrides, and nitrides, are one of the most promising high‐rate electrode materials for energy storage. Despite the significant progress achieved, the MXene synthesis process is still burdensome, involving several procedures including preparation of MAX, etching of MAX to MXene, and delamination. Here, a one‐pot molten salt electrochemical etching (E) method is proposed to achieve Ti2C MXene directly from elemental substances (Ti, Al, and C), which greatly simplifies the preparation process. In this work, different carbon sources, such as carbon nanotubes (CNT) and reduced graphene oxide (rGO), are reacted with Ti and Al micro‐powders to prepare Ti2AlC MAX with 1D and 2D tuned morphology followed by in situ electrochemical etching from Ti2AlC MAX to Ti2CTx MXene in low‐cost LiCl‐KCl. The introduction of the O surface group via further ammonium persulfate (APS) treatment can act in concert with Cl termination to activate the pseudocapacitive redox reaction of Ti2CClyOz in the non‐aqueous electrolyte, resulting in a Li+ storage capacity of up to 857 C g−1 (240 mAh g−1) with a high rate (86 mAh g−1 at 120 C) capability, which makes it promising for use as an anode material for fast‐charging batteries or hybrid devices in a non‐aqueous energy storage application.

Experimental insight into the dissolution behavior and interaction of key components in shale-persulfate system

Shale-persulfate interaction is ubiquitous in hydraulic fracturing, but the underlying geochemical reaction and its impact on the shale matrix are still not well understood. In this study, key components, including pyrite, calcite, chlorite, and kerogen, were chosen to react with sodium persulfate (Na2S2O8) at reservoir temperature. Results showed the oxidation-dominated reaction in the pyrite-persulfate system turned to acidification in calcite/chlorite-persulfate. In the pyrite-rich kerogen (PRK), however, kerogen competed with pyrite for persulfate consumption. An increased concentration of Na2S2O8 enhanced the dissolution of pyrite, PRK, and chlorite but resulted in the mass increase of solid in the calcite-Na2S2O8 system because of gypsum precipitation. The concentration of dissolved cations significantly correlated with the mass change of the corresponding components during persulfate stimulation, demonstrating the feasibility of water chemistry for evaluating the potential matrix alteration. Reaction in the treatment of persulfate on a multi-component mixture further suggested a complex interaction. The higher amounts of PRK, calcite, and chlorite led to the enhanced dissolution of Fe, Ca, and Mg, respectively. Various chemical reactions also influenced the dissolution behavior of cations. At low pyrite dosage, chlorite was acidly etched and slightly contributed to the dissolution of Fe. The dissolution of calcite and precipitation of gypsum affected the behavior of Ca. Element Mg mainly came from chlorite, but persulfate hydrolysis and PRK oxidation also changed its dissolution. Based on the total mass change of the multi-component mixture after persulfate treatment, a binary model was established to predict the mass change and quantify the potential matrix alteration during shale-persulfate interaction. This model could be used for selecting a potential reservoir during the in situ application of persulfate stimulation for shale permeability enhancement.

Determination of Color Removal and Fading Performance of Environmentally Friendly Chemical Alternatives to Hydrosulfite in Reactive Dyed Cotton Knitted Fabrics Depending on Dye Chromophore

ABSTRACT As is known, color stripping can be done with oxidizing or reducing agents. Today, reactive dye stripping is conventionally carried out via reductive method using hydrosulfite. However, from an environmental point of view, the use of more ecological chemicals has gained importance. In this study, it is aimed to determine the performances of reducing and oxidizing chemical alternatives to hydrosulfite, depending on the reactive dye chromophore. On the other hand, it was also aimed to provide a color fading effect on reactive dyed cotton fabrics with a treatment applied after dyeing. For this purpose, color stripping and/or fading effect was investigated on cotton knitted fabrics dyed with four different reactive dyes having anthraquinone (Reactive Blue 19), phthalocyanine (Reactive Blue 21), monoazo (Reactive Red 239) and metal azo (Reactive Red 23) chromophores. Studies were carried out with hydrosulfite, sodium hydroxymethane sulfinate and potassium persulfate at five different concentrations. It can be said that sodium hydroxymethane sulfinate and potassium persulfate can be used as an alternative to hydrosulfite in red dyes and blue dyes, respectively. COD and BOD values of wastewater of potassium persulfate treatment was found to be lower than hydrosulfite, which indicates that it is an ecological alternative over hydrosulphite.

Acid-washed zero-valent aluminum as a highly efficient persulfate activator for degradation of phenacetin.

Phenacetin (PNT) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the water ecosystems, which poses a potential risk to environmental aquatic organisms. Acid-washed zero-valent aluminum (ZVAl) as a highly efficient activator for persulfate (PS) process was investigated to degrade PNT from the aqueous solution. The results indicated that acid-washed pretreatment for ZVAl could efficiently increase the degradation efficiency of PNT in the PS treatment. The degradation efficiency of PNT (50 μM) was up to 90% in 4 hours with the addition of 0.2 g/L acid-washed ZVAl and 8 mM PS at pH 6.8 and 25 °C. The PNT degradation followed pseudo-first order kinetics in the present system. High activator dosage, PS concentration, and reaction temperature could enhance the PNT degradation. The presence of inorganic anions (i.e., NO3-, HCO3-) and humic acid (HA) showed inhibitory effects on the PNT degradation. The reuse results illustrated the acid-washed ZVAl material would have continuous and efficient activation performance for PS to degrade thePNT. Radical scavenger experiments and electron paramagnetic resonance indicated that both SO4•- and •OH were major reactive species during the PNT degradation. The possible degradation pathways of PNT mainly included the break of C-N and C-O bonds and further oxidation.

Degradation of tetracycline by UV/Fe3+/persulfate process: Kinetics, mechanism, DBPs yield, toxicity evaluation and bacterial community analysis

As a widely produced and used antibiotic, tetracycline (TC) has been frequently found in rivers, soil and drinking water. In this study, the degradation of TC was investigated by UV/Fe3+/persulfate (PS) coupled process. The degradation behavior was well fitted with pseudo-first-order model. Hydroxyl radicals (·OH), sulfate radicals (SO4−·) and superoxide radical (O2−·) were identified as the primary reactive oxygen species (ROS) in UV/Fe3+/PS process, the contribution to TC degradation were found to be 41.94%, 33.94% and 17.44% at pH 3.0, respectively. Fe(IV) generated from the system also played a crucial role in TC removal. The effects of process parameters (PS/Fe3+ dosages, pH, humic acid, Cl−, HCO3−, NO3− and CO32−) on degradation were investigated. It was found that the degradation of TC was highly pH-dependent, and the optimal performance was obtained at pH 3.0. Except for Cl−, the presence of HA, HCO3−, NO3− and CO32− inhibited TC degradation. The possible transformation pathway involving the hydroxylation, N-demethylation, hydrogenation and dehydroxylation was proposed. Furthermore, the toxicity and mutagenicity of TC and transformation products (TPs) were estimated using ECOSAR and TEST softwares, demonstrating that the toxicity level of most TPs was lower/equal to their precursors. The evaluation of DBPs showed that UV/Fe3+/PS process could reduce the potential of DBPs formation, especially for TCAA and TCM. Microbial community composition was analyzed by 16 S rDNA sequencing, and the relative abundance of ARG-carrying opportunistic pathogens was significantly declined after UV/Fe3+/PS treatment. In general, this study provides an economical, efficient and safe strategy for TC removal.