Removal of tetracycline by ultraviolet/sodium percarbonate (UV/SPC)advanced oxidation process in water.

Tetracycline (TC) was widely used and frequently detected in various water bodies, where the presence of TC posed a significant threat to the health of aquatic organisms. Furthermore, antibiotics were hardly degraded by biological treatment. Thus, in order to enhance the removal of TC, we proposed the use of a novel ultraviolet/sodium percarbonate (UV/SPC) advanced oxidation process and initiated an in-depth study. The study investigated the influence of oxidant dosage, initial pH, UV intensity, and TC concentration on the removal of TC. The results demonstrated that the UV/SPC system efficiently removed TC, with removal efficiency increasing as the SPC concentration increased. Within the pH range of 3-11, TC degradation exhibited minimal variation, indicating the UV/SPC system's strong adaptability to pH variations. The research on the impact of the water matrix on TC removal revealed that HCO3- had an inhibitory effect on TC degradation, while NO3- promoted TC degradation. Additionally, the presence of free radical species (·OH, ·CO3-, ·O2-) were detected and rate constants for the secondary reactions (k·OH,TC = 6.3 × 109 L mol-1·s-1, k·CO3-,TC = 3.4 × 108 L mol-1·s-1) were calculated, indicating that ·OH exhibited a stronger oxidative performance compared to ·CO3-. This study did not only present a novel strategy via UV/SPC to remove TC but also uncovered the unique role of ·CO3- for contaminant removal.

Enhancing microfiltration membrane performance by sodium percarbonate-based oxidation for hydraulic fracturing wastewater treatment.

Low pressure membrane takes a great role in hydraulic fracturing wastewater (HFW), while membrane fouling is a critical issue for the stable operation of microfiltration (MF). This study focused on fouling mitigation by sodium percarbonate (SPC) oxidation, activated by ultraviolet (UV) and ferrous ion (Fe(II)). The higher the concentration of oxidizer, the better the anti-fouling performance of MF membrane. Unlike severe MF fouling without oxidation (17.26 L/(m2·h)), UV/SPC and Fe(II)/SPC under optimized dosage improved the final flux to 740 and 1553 L/(m2·h), respectively, and the latter generated Fe(III) which acted as a coagulant. Fe(II)/SPC oxidation enabled a shift in fouling mechanism from complete blocking to cake filtration, while UV/SPC oxidation changed it to standard blockage. UV/SPC oxidation was stronger than Fe(II)/SPC oxidation in removing UV254 and fluorescent organics for higher oxidizing capacity, but the opposite was noted for DOC removal. The deposited foulants on membrane surface after oxidation decreased by at least 88% compared to untreated HFW. Correlation analysis showed that UV254, DOC and organic fraction were key parameters responsible for membrane fouling (correlation coefficient＞0.80), oxidizing capacity and turbidity after oxidation were also important parameters. These results provide new insights for fouling control during the HFW treatment.

Activity and recyclability enhancement of pH-dependent Fe0@BC-mediated heterogeneous sodium percarbonate (SPC)-reducing agents (RA) system.

Dyes pose great threats to the aquatic environment and human health. Fe0-based Fenton-like systems have been widely employed for the degradation of organic dyes. However, the regulation of degradability and recyclability was still unclear. In this study, Rhodamine B (RhB) was served as the model pollutant, hydroxylamine hydrochloride was selected as the RA, the natural photocatalysis system demonstrated stable operation. RA, as performance enhancement agent, was firstly reported in micro/nano-Zero-Valent Iron@Biochar (m/nZVI@BC) based SPC-RA system. Carrier size-fractionated m/nZVI@BC was fabricated by one-step carbothermal method. As a result, RA synergistically interacted with SPC, and the reaction time reduced from 15 min to 4 min. In the 0.010 g m/nZVI@BC-mediated SPC-RA system, over 95% of RhB (100 mg·L-1, 1041.667 mg·g-1) was successfully degraded. The maximum degradation ability could still exceed 1g·g-1 via 5 times repeated applications. Meanwhile, the loss of degradability, caused by halving SPC concentration could be compensated by RA dosage measurement. The entire degradation process was predominantly dominated by free radicals (•OH> 1O2> •O2-> •CO3-). Reactive oxidizing species (ROSs) were primarily excited by α-Fe0, Fe3C and N sites of biochar (BC). Light and BC carrier dedicated slight influence. These discoveries shed a light on the activity and recyclability regulation of catalytic material, aligning with the principles of green chemistry and cleaner production. This study demonstrates a novel approach to efficient management of solid waste disposal, reuse of waste biomass, advanced treatment of dye-containing wastewater, pollution control in aquatic environments.

Evaluation of in vitro coculture of keratinocytes derived from foreskin and adipose-derived mesenchymal stem cells (AMSCs) on a multilayer oxygen-releasing electrospun scaffold based on PU/PCL.Sodium percarbonate (SPC)-gelatine/PU.

Despite significant advancements in tissue engineering and regenerative medicine during the last two decades, the fabrication of proper scaffolds with appropriate cells can still be considered a critical achievement in this field. Hypoxia is a major stumbling block to chronic wound healing, which restrains tissue engineering plans because a lack of oxygen may cause cell death. This study evaluated the cocultured human keratinocytes and human adipose-derived mesenchymal stem cells (AMSCs) on a multilayer oxygen-releasing electrospun scaffold based on PU/PCL.Sodium percarbonate (SPC)-gelatin/PU. The scaffold was characterized using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) methods. Flow cytometry confirmed mesenchymal stem cells, and then the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay and DAPI staining were used to assess the in vitro biocompatibility of the scaffold. The experimental results showed that the multilayer electrospun scaffold containing 2.5% SPC could efficiently produce oxygen. Furthermore, according to cell viability results, this structure makes a suitable substrate for the coculture of keratinocytes and AMSCs. Gene expression analysis of various markers such as Involucrin, Cytokeratin 10, and Cytokeratin 14 after 14 days confirmed that keratinocytes and AMSCs coculture on PU/PCL.SPC-gelatin/PU electrospun scaffold promotes dermal differentiation and epithelial proliferation compared to keratinocytes single-cell culture. Therefore, our study supports using oxygen-releasing scaffolds as a potential strategy to hasten skin tissue regeneration. Based on the results, this structure is suggested as a promising candidate for cell-based skin tissue engineering. Given that the developed oxygen-generating polymeric electrospun scaffolds could be used as part of a future strategy for skin tissue engineering, the PU/PCL.SPC-gelatin/PU hybrid electrospun multilayer scaffold in combination with keratinocyte/AMSC coculture is proposed as an effective substrate for skin tissue engineering and regenerative medicine platforms.

Comparison of UV and UV-LED activated sodium percarbonate for the degradation of O-desmethylvenlafaxine.

As an active metabolite of venlafaxine and emerging antidepressant, O-desmethylvenlafaxine (ODVEN) was widely detected in different water bodies, which caused potential harm to human health and environmental safety. In this study, the comparative work on the ODVEN degradation by UV (254 nm) and UV-LED (275 nm) activated sodium percarbonate (SPC) systems was systematically performed. The higher removal rate of ODVEN can be achieved under UV-LED direct photolysis (14.99%) than UV direct photolysis (4.57%) due to the higher values of photolysis coefficient at the wavelength 275 nm. Significant synergistic effects were observed in the UV/SPC (80.38%) and UV-LED/SPC (53.57%) systems and the former exhibited better performance for the elimination of ODVEN. The degradation of ODVEN all followed the pseudo-first-order kinetics well in these processes, and the pseudo-first-order rate constant (kobs) increased with increasing SPC concentration. Radicals quenching experiments demonstrated that both ·OH and CO3·- were involved in the degradation of ODVEN and the second-order rate constant of ODVEN with CO3·- (1.58 × 108 (mol/L)-1 sec-1) was reported for the first time based on competitive kinetic method. The introduction of HA, Cl-, NO3- and HCO3- inhibited the ODVEN degradation to varying degrees in the both processes. According to quantum chemical calculation, radical addition at the ortho-position of the phenolic hydroxyl group was confirmed to be the main reaction pathways for the oxidation of ODVEN by ·OH. In addition, the oxidation of ODVEN may involve the demethylation, H-abstraction, OH-addition and C-N bond cleavage. Eventually, the UV-LED/SPC process was considered to be more cost-effective compared to the UV/SPC process, although the UV/SPC process possessed a higher removal rate of ODVEN.

Sustainable and effective degradation of aniline by sodium percarbonate activated with UV in aqueous solution: Kinetics, mechanism and identification of reactive species.

In recent decades, sodium percarbonate (SPC) has been widely applied as a solid replacement for H2O2 in advanced oxidation process (AOPs). In this study, ultraviolet (UV) light was utilized for SPC activation to investigate the aniline degradation performance. The effects of SPC dosages and UV irradiation on aniline degradation were elaborated. The removal efficiency was significantly improved by increasing either the SPC dosage or UV irradiation intensity. Moreover, scavenging experiments showed that •OH, CO3•-, and O2•- were the predominant reactive species for aniline degradation. Meanwhile, the variation in the amount of •OH in the UV/SPC system was monitored, which revealed the dominant role of •OH. As a result, the mechanism of aniline degradation by the UV/SPC system was demonstrated based on confirmed free radicals. Furthermore, aniline degradation by the UV/H2O2 and UV/H2O2/Na2CO3 system were compared with the UV/SPC system, and an enhancement by the addition of Fe(II) in the UV/SPC system was verified. Aniline degradation was not significantly affected by the initial pH or the presence of Cl-, SO42- while NO3-, HCO3- and humid acid (HA) suppressed the reaction. In general, the UV/SPC system is a novel, green, and promising technology for aniline removal from aqueous solutions.

Release Kinetics and In Vitro Characterization of Sodium Percarbonate and Calcium Peroxide to Oxygenate Bioprinted Tissue Models.

Oxygen-generating materials have been used in several tissue engineering applications; however, their application as in situ oxygen supply within bioprinted constructs has not been deeply studied. In this study, two oxygen-generating materials, sodium percarbonate (SPO) and calcium peroxide (CPO), were studied for their oxygen release kinetics under a 0.1% O2 condition. In addition, a novel cell-culture-insert setup was used to evaluate the effects of SPO and CPO on the viability of skeletal muscle cells under the same hypoxic condition. Results showed that SPO had a burst oxygen release, while CPO had a more stable oxygen release than SPO. Both SPO and CPO reduced cell viability when used alone. The addition of catalase in SPO and CPO increased the oxygen release rate, as well as improving the viability of skeletal muscle cells; however, CPO still showed cytotoxicity with catalase. Additionally, the utilization of 1 mg/mL SPO and 20 U catalase in a hydrogel for bioprinting significantly enhanced the cell viability under the hypoxic condition. Moreover, bioprinted muscle constructs could further differentiate into elongated myotubes when transferring back to the normoxic condition. This work provides an excellent in vitro model to test oxygen-generating materials and further discover their applications in bioprinting, where they represent promising avenues to overcome the challenge of oxygen shortage in bioprinted constructs before their complete vascularization.

Performance and mechanism of sodium percarbonate (SPC) enhancing short-chain fatty acids production from anaerobic waste activated sludge fermentation.

A novel pretreatment technique (i.e., using Sodium percarbonate, SPC) to improve the short-chain fatty acids (SCFA) production waste activated sludge (WAS) was proposed in this study. Results indicated that the maximum SCFA production of 1605.7 mg COD/L and acetic acid of 52.9% were attained at 0.2 g SPC/g TSS, being 8.4 and 2.8 times of the control (191.3 mg COD/L and 19%), respectively. Meanwhile, the optimal time for SCFA accumulation was decreased from 6d (control) to 4d (0.2 g/g TSS). Mechanism explorations unraveled that SPC largely accelerated WAS solubilization and enhanced the bioavailability of organics released from WAS. It improved enzymatic activities related to hydrolysis and acidogenesis, while suppressed the Coenzyme F420 responsible for SCFA consumption. Illumina MiSeq sequencing analysis showed that SPC substantially enhanced the relative abundances of hydrolytic and/or acid-forming microbes. Furthermore, CO3- and O2- were the key factors to production enhancement in SPC-involved sludge fermentation.

Asymmetric Epoxidation of Olefins with Sodium Percarbonate Catalyzed by Bis-amino-bis-pyridine Manganese Complexes.

Asymmetric epoxidation of a series of olefinic substrates with sodium percarbonate oxidant in the presence of homogeneous catalysts based on Mn complexes with bis-amino-bis-pyridine ligands is reported. Sodium percarbonate is a readily available and environmentally benign oxidant that is studied in these reactions for the first time. The epoxidation proceeded with good to high yields (up to 100%) and high enantioselectivities (up to 99% ee) using as low as 0.2 mol. % catalyst loadings. The epoxidation protocol is suitable for various types of substrates, including unfunctionalized alkenes, α,ß-unsaturated ketones, esters (cis- and trans-), and amides (cis- and trans-). The reaction mechanism is discussed.

Efficiency assessment of municipal landfill leachate treatment during advanced oxidation process (AOP) with biochar adsorption (BC).

Leachate generated in landfills are characterized by high toxicity related to, high concentrations of organic and non-organic pollutants, therefore, it is advisable to use highly effective methods of their purification to prevent environmental contamination. The aim of this study was to determine the treatment efficiency of landfill leachate during the application of integrated processes: advanced oxidation (AOP) and biochar adsorption (BC). In the case of the AOP, the chemical process was the Fenton reaction in which the source of hydroxyl radicals was H2O2 (system I) and SPC - sodium percarbonate (system II). Leachate was derived from the regional municipal waste landfill in Silesian Province (Poland) which was characterized by the pH of 8.40, COD value was 3155 mg L-1 and BOD was under 165 mg L-1. The BOD/COD ratio was at a low level (0.053) that indicated low biodegradability. The applied systems allowed of the COD reduction index to the level of 549 mg L-1 (H2O2+BC) and 944 mg L-1 (SPC+BC) where the limit threshold is 125 mg L-1. In the same case of the TOC index, these values were respectively 119 and 186 mg L-1, where the limit value is 30 mg L-1.This study has been aimed to estimate the toxicity of leachate treatment in integrated systems: AOP processes + biochar adsorption. Toxicity of treated and untreated leachate has been analysed by Sinapis alba and Lepidium sativum plants-based tests. It was found that while conducting the Fenton process as system I (H2O2) at all reagent doses, the removal efficiency of COD and TOC was 17% and 12% higher, respectively, compared to system II. The most advantageous dose of regents was 2.5:1 and biochar - 2 g L-1. It was observed that in the SPC+BC system the roots of L. sativum and S. alba were on average 34% and 28% longer compared to the H2O2+BC system. Higher germination index (GI) of both tested plants, indicating lower wastewater toxicity, was recorded for the SPC+BC system.

Application of percarbonate and peroxymonocarbonate in decontamination technologies.

Sodium percarbonate (SPC) and peroxymonocarbonate (PMC) have been widely used in modified Fenton reactions because of their multiple superior features, such as a wide pH range and environmental friendliness. This broad review is intended to provide the fundamental information, status and progress of SPC and PMC based decontamination technologies according to the peer-reviewed papers in the last two decades. Both SPC and PMC can directly decompose various pollutants. The degradation efficiency will be enhanced and the target contaminants will be expanded after the activation of SPC and PMC. The most commonly used catalysts for SPC activation are iron compounds while cobalt compositions are applied to activate PMC in homogenous and heterogeneous catalytical systems. The generation and participation of hydroxyl, superoxide and/or carbonate radicals are involved in the activated SPC and PMC system. The reductive radicals, such as carbon dioxide and hydroxyethyl radicals, can be generated when formic acid or methanol is added in the Fe(II)/SPC system, which can reduce target contaminants. SPC can also be activated by energy, tetraacetylethylenediamine, ozone and buffered alkaline to generate different reactive radicals for pollutant decomposition. The SPC and activated SPC have been assessed for application in-situ chemical oxidation and sludge dewatering treatment. The challenges and prospects of SPC and PMC based decontamination technologies are also addressed in the last section.

Sodium percarbonate as a novel intracoronal bleaching agent: assessment of the associated risk of cervical root resorption.

AIM: To evaluate the extraradicular peroxide release from sodium percarbonate compared to sodium perborate as an intracoronal bleaching agent. METHODOLOGY: Sixty mandibular single-rooted premolars with intact CEJ were selected. After root filling, gutta-percha was removed 4 mm apical to CEJ and 2 mm of GIC was condensed over the root filling. Intracoronal bleaching agents were placed into six groups of teeth (n = 10): sodium perborate with distilled water (SPW); sodium percarbonate with distilled water (SPCW); sodium perborate with 30% hydrogen peroxide (SPHP); sodium percarbonate with 30% hydrogen peroxide (SPCHP); 30% hydrogen peroxide as positive control (HP) and distilled water as negative control (CL). The teeth were then mounted in vials filled with distilled water, kept in an incubator and taken out at 1, 3 and 6 days for spectrophotometric analysis. Extraradicular peroxide release was quantified by the ferrothiocyanate method. Statistical analysis was undertaken with one-way anova and Scheffe post hoc tests. RESULTS: The greatest peroxide release occurred in the HP group, followed by the SPCHP and SPHP groups, and then by the SPCW and SPW groups. Intergroup comparison revealed that there was no significant difference in peroxide release among the groups SPCW and SPW on days 1, 3 and 6 (P > 0.05). Similarly, no significant difference was found between the SPCHP and SPHP treated groups on days 1, 3 and 6 (P > 0.05). CONCLUSION: Extraradicular peroxide release from sodium percarbonate was comparable to that of sodium perborate, as the differences were not significant.

Optimization of sodium percarbonate pretreatment for improving 2,3-butanediol production from corncob.

Sodium percarbonate (SP), a kind of alkaline strong oxidant, was applied to corncob pretreatment. The optimized pretreatment conditions were at 4% (w/v) SP concentration with solid-to-liquid (SLR) ratio of 1:10 treating for 4 hr at 60°C. This pretreatment resulted in 91.06% of cellulose and 84.08% of hemicellulose recoveries with 34.09% of lignin removal in corncob. The reducing sugar yield from SP-pretreated corncob was 0.56 g/g after 72 hr of enzymatic hydrolysis, 1.75-folds higher than that from raw corncob. 2,3-butanediol production by Enterobacer cloacae in simultaneous saccharification fermentation was 29.18 g/L using SP-pretreated corncob as a substrate, which was 11.12 times of that using raw corncob. Scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectra analysis indicated that physical characteristics, crystallinity, and structure of corncob had changed obviously after SP pretreatment. This simple and novel pretreatment method was effective for delignification and carbohydrate retention in microbial production of 2,3-butanediol from lignocellulose biomass.

Enhancement effects of chelating agents on the degradation of tetrachloroethene in Fe(III) catalyzed percarbonate system.

The performance of Fe(III)-based catalyzed sodium percarbonate (SPC) for stimulating the oxidation of tetrachloroethene (PCE) for groundwater remediation applications was investigated. The chelating agents citric acid monohydrate (CIT), oxalic acid (OA), and Glutamic acid (Glu) significantly enhanced the degradation of PCE. Conversely, ethylenediaminetetraacetic acid (EDTA) had a negative impact on PCE degradation, which may due to its strong Fe chelation and HO• scavenging abilities. However, excessive SPC or chelating agent will retard PCE degradation. In addition, investigations using free radical probe compounds and radical scavengers revealed that PCE was primarily degraded by HO• radical oxidation in both the chelated and non-chelated systems, while O2•- also participated in the non-chelated system and the OA and Glu modified systems. According to the electron paramagnetic resonance (EPR) studies, the presence of HO• in the Fe(III)/SPC system was maintained much longer than that in the Fe(II)/SPC system. The results indicated that the addition of CIT, OA or Glu indeed enhanced the generation of HO• in the first 10 min and promoted degradation efficiency by increasing the amount of Fe(III) and maintaining the concentration of HO• radicals in solution. In conclusion, chelated Fe(III)-based catalyzed SPC oxidation is a promising method for the remediation of PCE-contaminated groundwater.

A systematic review on percarbonate-based advanced oxidation processes in wastewater remediation: From theoretical understandings to practical applications.

Percarbonate encompasses sodium percarbonate (SPC) and composite in-situ generated peroxymonocarbonate (PMC). SPC emerges as a promising alternative to hydrogen peroxide (H2O2), hailed for its superior transportation safety, stability, cost-effectiveness, and eco-friendliness, thereby becoming a staple in advanced oxidation processes for mitigating water pollution. Yet, scholarly literature scarcely explores the deployment of percarbonate-AOPs in eradicating organic contaminants from aquatic systems. Consequently, this review endeavors to demystify the formation mechanisms and challenges associated with reactive oxygen species (ROS) in percarbonate-AOPs, alongside highlighting directions for future inquiry and development. The genesis of ROS encompasses the in situ chemical oxidation of activated SPC (including iron-based activation, discharge plasma, ozone activation, photon activation, and metal-free materials activation) and composite in situ chemical oxidation via PMC (namely, H2O2/NaHCO3/Na2CO3, peroxymonosulfate/NaHCO3/Na2CO3 systems). Moreover, the ROS generated by percarbonate-AOPs, such as •OH, O2•-, CO3•-, HO2•-, 1O2, and HCO4-, can work individually or synergistically to disintegrate target pollutants. Concurrently, this review systematically addresses conceivable obstacles posing percarbonate-AOPs in real-world application from the angle of environmental conditions (pH, temperature, coexisting substances), and potential ecological toxicity. Considering the outlined challenges and advantages, we posit future research directions to amplify the applicability and efficacy of percarbonate-AOPs in tangible settings. It is anticipated that the insights provided in this review will catalyze the progression of percarbonate-AOPs in water purification endeavors and bridge the existing knowledge void.

Chitosan-sodium percarbonate-based hydrogels with sustained oxygen release potential stimulated angiogenesis and accelerated wound healing.

The prolonged hypoxic conditions hinder chronic wounds from healing and lead to severe conditions such as delayed re-epithelialization and enhanced risk of infection. Multifunctional wound dressings are highly required to address the challenges of chronic wounds. Herein, we report polyurethane-coated sodium per carbonate-loaded chitosan hydrogel (CSPUO2 ) as a multifunctional dressing. The hydrogels (Control, CSPU, and CSPUO2 ) were prepared by freeze gelation method and the developed hydrogels showed high porosity, good absorption capacity, and adequate biodegradability. The release of oxygen from the CSPUO2 hydrogel was confirmed by the increase in pH and a sustained oxygen release was observed over the period of 21 days, due to polyurethane (CSPU) coating. The CSPUO2 hydrogel exhibited around 2-fold increased angiogenic potential in CAM assay when compared with Control and CSPU dressing. CSPUO2 also showed good level of antibacterial efficacy against E. coli and S. aureus. In a full-thickness rat wound model, CSPUO2 hydrogel considerably accelerated wound healing with exceptional re-epithelialization granulation tissue formation less inflammatory cells and improved skin architecture highlighting the tremendous therapeutic potential of this hydrogel when compared with control and CSPU to treat chronic diabetic and burn wounds.

Modified sono-Fenton process for oxidative degradation of chloramphenicol.

Oxidative degradation of chloramphenicol (CAP) using a hybrid approach (US/HA+/n-Fe2O3/SPC) involving sodium percarbonate (SPC; "solid H2O2" carrier), Fe2O3 nanoparticles (n-Fe2O3; H2O2 decomposition catalyst), hydroxylamine in its protonated form (HA+; Fe (III) to Fe (II) reducer), and ultrasonic cavitation (to increase the generation of hydroxyl radicals) has been studied for the first time. The average size of n-Fe2O3 synthesized by the sonochemical method, as calculated according to the Debye-Scherrer equation, was ~ 18 nm. The maximum degradation degree of CAP (83.1%) and first-order oxidative degradation rate constant of CAP as 1.253 × 10-3 s-1 were achieved using the modified sono-Fenton process under the optimized conditions as the initial concentration of CAP - 50 mg/L, the molar ratio of CAP:HA+:n-Fe2O3:SPC of 1:100:100:100, pH as 3, the temperature as 318 K, the specific ultrasonic power as 53.3 W/L, and the treatment duration of 7200 s. In general, the efficiency and intensity of CAP degradation increased with a decrease in the pH value, an increase in the molar ratio of CAP:HA+:n-Fe2O3:SPC, a decrease in the initial concentration of CAP, an increase in temperature, and showed a minor change with the specific power of US. The synergistic coefficient for the combination of the US and the heterogeneous Fenton process was 17.9. The active participation of hydroxyl radicals in the oxidative degradation of CAP using the modified sono-Fenton process was confirmed by scavenging experiments performed using tert-butyl alcohol. The proposed process can be a promising direction in the remediation of pharmaceutical effluents with significant potential for commercial exploitation.

Improving membrane distillation performance by Fe(II) activated sodium percarbonate oxidation during the treatment of shale gas produced water.

Membrane distillation (MD) offers promise for recycling shale gas produced water (SGPW), while membrane fouling is still a major obstacle in standalone MD. Herein, sodium percarbonate (SPC) oxidation was proposed as MD pretreatment, and the performance of the single MD, SPC-MD hybrid process and Fe(II)/SPC-MD hybrid process for SGPW treatment were systematically evaluated. Results showed that compared to raw SGPW, the application of SPC and Fe(II)/SPC led to the decrease of the fluorescent organics by 28.54 % and 54.52 %, respectively. The hydrophobic fraction decreased from 52.75 % in raw SGPW to 37.70 % and 27.20 % for SPC and Fe(II)/SPC, respectively, and the MD normalized flux increased from 0.19 in treating raw SGPW to 0.65 and 0.81, respectively. The superiority of SPC oxidation in reducing the deposited membrane foulants and restoring membrane properties was further confirmed through scanning electron microscopy observation, attenuated total reflection fourier transform infrared, water contact angle and surface tension analyses of fouled membranes. Correlation analysis revealed that hydrophobic/hydrophilic matters and fluorescent organics in SGPW took a crucial role in MD fouling. The mechanism of MD fouling mitigation by Fe(II)/SPC oxidation was attributed to the decrease in concentrations and hydrophobicity of organic by synergistic oxidation, coagulation and adsorption.

Molecular mechanisms underlying sodium percarbonate treatment suppress the recovery and growth of Pseudanabaena sp. in early spring.

Increasing frequency and intensity of cyanobacterial blooms in water sources is a growing global issue. Algicides are usually implemented in summer or autumn when blooms break out, however, the blooms will form again when algicide's concentration declines to a certain extent. Preventing the recovery and growth of cyanobacteria in early spring may be conducive to abatement of the blooms in summer or autumn. In this study solid sodium percarbonate (SPC) was used as an algicide to suppress recovery and growth of Pseudanabaena sp., a common odour-producing cyanobacterium, in early spring (12 °C). Results showed that 3.0 and 6.0 mg/L SPC were able to kill most of the algal cells after 12 h treatment at 12 °C, and the residual cells gradually died during the re-cultivation period at 25 °C. As a control, although SPC also caused most of algal cells to lyse at 25 °C, regrowth of cells was found during the period of re-cultivation at 25 °C. Transcriptomic analysis revealed that the dysregulated genes were strongly associated with translation and photosynthesis after SPC treatment. All differentially expressed unigenes related to translation and photosynthesis were down-regulated after SPC oxidation at 12 °C, whereas key genes associated with translation and photosynthesis were upregulated after SPC treatment at 25 °C.

In-situ generation of iron activated percarbonate for sustainable sludge dewatering.

Effective dewatering of sewage sludge could potentially address the issues of high energy consumption and large carbon footprint inherent in the sludge treatment process, advancing toward carbon neutrality in environmental remediation. Yet, the surface hydrophilic characteristics and water-holding interfacial affinity in sludge led to dwindled sludge-water separation performance. Here, the integration of in-situ generation of iron from zero-valent scrap iron (ZVSI) and sodium percarbonate (SPC) was attempted to attenuate the water-retaining interfacial affinity within sludge, thus achieving superior sludge dewatering performance. Results showed that under the optimal conditions, the ZVSI + SPC system led to a remarkable decline of 76.09 % in the specific resistance to filtration of the sludge, accompanied by a notable decline of 34.96 % in the water content. Moreover, the utilization of ZVSI + SPC system could be a viable alternative to the traditional strategies in terms of enhanced sludge dewaterability, offering application potential with stable operating performance, economic feasibility, and reduced carbon emissions. Investigation into dewatering mechanism revealed that ZVSI could maintain the Fe3+/Fe2+ in a stable dynamic cycle and continuously in-situ generate Fe2+, thereby efficaciously fostering the SPC activation for the ceaseless yield of reactive oxygen species. The predominant •OH and 1O2 efficiently decomposed the hydrophilic biopolymers, therefore minimizing the hydrophilic protein secondary structures, along with the hydrogen and disulfide bonds within proteins. Subsequently, the water-holding interfacial affinity was profoundly diminished, leading to intensified hydrophobicity, self-flocculation, and dewaterability. These findings have important implications for the advancement of efficacious ZVSI + SPC conditioning techniques toward sustainable energy and low-carbon prospects.