Boosting the Production of Hydrogen from an Overall Urea Splitting Reaction Using a Tri-Functional Scandium-Cobalt Electrocatalyst.

The creation of highly efficient and economical electrocatalysts is essential to the massive electrolysis of water to produce clean energy. The ability to use urea reaction of oxidation (UOR) in place of the oxygen/hydrogen evolution process (OER/HER) during water splitting is a significant step toward the production of high-purity hydrogen with less energy usage. Empirical evidence suggests that the UOR process consists of two stages. First, the metal sites undergo an electrochemical pre-oxidation reaction, and then the urea molecules on the high-valence metal sites are chemically oxidized. Here, the use of scandium-doped CoTe supported on carbon nanotubes called Sc@CoTe/CNT is reported and CoTe/CNT as a composite to efficiently promote hydrogen generation from highly durable and active electrocatalysts for the OER/UOR/HER in urea and alkali solutions. Electrochemical impedance spectroscopy indicates that the UOR facilitates charge transfer across the interface. Furthermore, the Sc@CoTe/CNT nanocatalyst has high performance in KOH and KOH-containing urea solutions as demonstrated by the HER, OER, and UOR (215 mV, 1.59, and 1.31 V, respectively, at 10 mA cm-2 in 1 m KOH) and CoTe/CNT shows 195 mV, 1.61 and 1.3 V, respectively. Consequently, the total urea splitting system achieves 1.29 V, whereas the overall water splitting device obtaines 1.49 V of Sc@CoTe/CNT and CoTe/CNT shows 1.54, 1.48 V, respectively. This work presents a viable method of combining HER with UOR for maximally effective hydrogen production.

Untargeted LC-HRMS applied to microcystin-producing cyanobacterial cultures for the evaluation of the efficiency of chlorine-based treatments commonly used for water potabilization.

Cyanobacteria in water supplies are considered an emerging threat, as some species produce toxic metabolites, cyanotoxins, of which the most widespread and well-studied are microcystins. Consumption of contaminated water is a common exposure route to cyanotoxins, making the study of cyanobacteria in drinking waters a priority to protect public health. In drinking water treatment plants, pre-oxidation with chlorinated compounds is widely employed to inhibit cyanobacterial growth, although concerns on its efficacy in reducing cyanotoxin content exists. Additionally, the effects of chlorination on abundant but less-studied cyanometabolites (e.g. cyanopeptolins whose toxicity is still unclear) remain poorly investigated. Here, two chlorinated oxidants, sodium hypochlorite (NaClO) and chlorine dioxide (ClO2), were tested on the toxic cyanobacterium Microcystis aeruginosa, evaluating their effect on cell viability, toxin profile and content. Intra- and extracellular microcystins and other cyanometabolites, including their degradation products, were identified using an untargeted LC-HRMS approach. Both oxidants were able to inactivate M. aeruginosa cells at a low dose (0.5 mg L-1), and greatly reduced intracellular toxins content (>90%), regardless of the treatment time (1-3 h). Conversely, a two-fold increase of extracellular toxins after NaClO treatment emerged, suggesting a cellular damage. A novel metabolite named cyanopeptolin-type peptide-1029, was identified based on LC-HRMSn (n = 2, 3) evidence, and it was differently affected by the two oxidants. NaClO led to increase its extracellular concentration from 2 to 80-100 µg L-1, and ClO2 induced the formation of its oxidized derivative, cyanopeptolin-type peptide-1045. In conclusion, pre-oxidation treatments of raw water contaminated by toxic cyanobacteria may lead to increased cyanotoxin concentrations in drinking water and, depending on the chemical agent, its dose and treatment duration, also of oxidized metabolites. Since the effects of such metabolites on human health remain unknown, this issue should be handled with extreme caution by water security agencies involved in drinking water management.

Regulating Pseudo-Graphitic Domain and Closed Pores to Facilitate Plateau Sodium Storage Capacity and Kinetics for Hard Carbon.

Hard carbon anode demonstrates exceptional potential in sodium-ion batteries due to their cost-effectivenss and superior plateau capacity. However, the proximity of the plateau capacity to the cut-off voltage of battery operation and the premature cut-off voltage response caused by polarization at high rates greatly limit the exploitation of plateau capacities, raising big concerns about inferior rate performance of high-plateau-capacity hard carbon. In this work, a facile pre-oxidation strategy is proposed for fabricating lignin-derived hard carbon. Both high-plateau capacity and sodiation kinetics are significantly enhanced due to the introduction of expanded pseudo-graphitic domains and high-speed closed pores. Impressively, the optimized hard carbon exhibits an increased reversible capacity from 252.1 to 302.0 mAh g-1, alongside superior rate performance (174.7 mAh g-1 at 5 C) and stable cyclability over 500 cycles. This study paves a low-cost and effective pathway to modulate the microstructure of biomass-derived hard carbon materials for facilitating plateau sodium storage kinetics.

The Influence of Al and Nb on the Low Oxygen Pressure Pre-Oxidation Behavior of Fe-35Ni-20Cr-xAl-yNb Alloys at 1000 °C.

To investigate the impact of Al and Nb elements on the formation of a protective oxide layer on the surface of Fe-35Ni-20Cr-xAl-yNb (x = 0, 2, 4, 6 wt.%; y = 0, 1, 2 wt.%) alloys, their oxidation behavior was examined at 1000 °C, 10-17 atm. and 10-25 atm. oxygen pressure, and the oxidation mechanism was analyzed by Factsage and Pandat calculations. Enhancing the Al content at 10-17 atm. inhibited the generation of FeCr2O4 on the alloy surface and increased the Al content in the M2O3 layer. When the Al content exceeded 6 wt.%, the oxide film partially peeled off. It was found that the addition of Nb increased the activity of Cr and Al and decreased the activity of Ni and Fe and promoted the formation of Al2O3, and the appearance of Nb2O5 in the subsurface layer increased the density of the oxide film. In addition, under an oxygen pressure of 10-25 atm., the only protective layer on the surface of the alloy comprised of Al2O3. The experimental results demonstrated that the Fe-35Ni-20Cr-4Al-2Nb alloy generated a continuous and dense Al2O3 protective film, and the reduction in oxygen pressure and the addition of Nb elements were favorable for selective external oxidation of Al2O3.

Effects of Different Oxidation Methods on the Wetting and Diffusion Characteristics of a High-Alumina Glass Sealant on 304 Stainless Steel.

Glass-to-metal seals are a very important element in the construction of vacuum tubes, electric discharge tubes, pressure-tight glass windows in metal cases, and metal or ceramic packages of electronic components. This paper presents the influence of different pretreatment methods on the high-temperature wettability of 304 stainless steel by high-alumina glass sealing. The pretreatment of the steel included laser surface melting and pre-oxidizing. The bonding characteristics of glass and stainless steel directly depend on the wettability in terms of the measured wetting angle, the type of oxide formed at the stainless steel surface, and the microstructural changes during the manufacturing process. The oxide film thickness on the stainless steel surface was evaluated to determine the optimal parameters. The film was wetted with high-alumina glass powder at different temperatures. The results showed that pre-oxidation decreased the wetting angle from 56.2° to 33.6°, while for the laser-melted surface, the wetting angle decreased from 49.8° to 31.5°. Scanning electron microscopy (SEM) revealed that the oxide film on the laser-melted surface was thicker and denser than that formed on the pre-oxidized surface. The present work shows that laser surface melting has a greater beneficial influence on the wetting and diffusion characteristics of 304 stainless steel sealed by high-alumina glass.

Advances and challenges in the technologies for cyanobacterial cells removal in drinking water treatment.

Harmful cyanobacteria in reservoirs pose a serious threat to drinking water safety due to the intracellular metabolites, such as toxins and unpleasant tastes & odours. Effective removal of harmful cyanobacteria with little to no cell damage is very important to ensure the safety of drinking water. This review first introduced development history of cyanobacterial removal technologies in drinking water treatment. Then, impacts of oxidation, coagulation and pre-oxidation enhanced coagulation processes on cyanobacterial removal and integrity of the cells were comprehensively evaluated and discussed. Oxidation can remove cyanobacteria, but high doses of oxidants can result in significant cell lysis and release of intracellular metabolites, especially when using chlorine or ozone. Although there is practically no cell damage during coagulation, the removal efficiency is low in many cases. Pre-oxidation may improve cyanobacterial removal by the subsequent solid-liquid separation processes, and moderate pre-oxidation with little to no cell lysis is very important. Mechanisms of interface interaction between pre-oxidants and cyanobacteria should be defined in future to ensure moderate pre-oxidation of algal cells. Fate of cyanobacterial cells in sludge is also reviewed because more and more waterworks return sludge supernatant to the inlet of plant. Damage to cyanobacterial cells in sludge depends mainly upon coagulant type and dosage, algal species, and cyanobacteria-containing sludge should be treated before cell lysis. Efficient techniques for harmless disposal of cyanobacteria-containing sludge should be developed in future. This paper will help to better understand the cyanobacterial removal processes and provide improved perspectives for future research in this field.

Phase transformation sequence of pre-oxidized roast-leach ferrovanadium residue.

The depletion of the primary metal sources has prompted the exploration of alternative avenues for metal recovery. In the case of titanium and iron, the ferrovanadium residue produced through roast-leach processing of titanomagnetite presents a viable option for accessing these metals. Titanomagnetite resources, which contain valuable elements, such as iron, vanadium, and titanium, possess significant valuable potential. Titanomagnetite deposits are normally treated via smelting for vanadium or vanadium and iron recovery; titanium is not commercially recoverable. Titanomagnetites have recently been processed through the roast-leach method for vanadium primary production, and iron and titanium are typically part of the waste stream in this process. This study proposes a novel approach to determine the characteristic mineralogy and to study the phase transformation sequence of the roasted-leached ferrovanadium residue during the pre-oxidation process. Leaching was also done to evaluate the extraction potential of Fe, V and Ti on the pre-oxidized residue in comparison to the raw residue The roasted-leached ferrovanadium residue was sampled using the cone and quartering method and then, dried in an oven at temperatures of between 30 and 40 °C, for an hour after which, the remaining moisture content was determined. The bond milling method was employed to reduce the sample size, while the particle size distribution (PSD) was verified by using the standard laboratory Tyler series. Thereafter, the roasted-leached ferrovanadium residue was characterized with XRD, SEM, ICP-OES, and XRF. The samples were pre-oxidized at temperatures ranging from 300 °C to 1000 °C with an aim of improving the grades of iron, vanadium, and titanium-bearing minerals prior leaching. The results revealed the moisture content to be ∼5.07%. The bond work index of typical slags was estimated to be 10.2 kwh/t, with a determined d80 value of 200 µm. According to the XRF analysis, the predominant compounds present are hematite, Fe2O3 (75.55%), titanium dioxide, TiO2 (12.79%), silicon dioxide, SiO2 (3.03%), and alumina, Aℓ2O3 (2.62%), along with minor compounds. XRD patterns exhibited the presence of FeTiO3 and VO2 in the as-received samples, while pre-oxidation induced the evolution of new phases such as hematite, rutile, anatase, and pseudobrookite.

Promotion of levoglucosan production from biomass pyrolysis by hydrogen peroxide pre-oxidation.

Due to the complexity of biomass structures, the conversion of raw biomass into value-added chemicals is challenging and often requires efficient pretreatment of the biomass. In this paper, a simple and green pre-oxidation method, which was conducted under the conditions of 2 wt% H2O2, 80 min, and 150 °C, was reported to significantly increase the production of levoglucosan (LG) from biomass pyrolysis. The result showed that the LG yield significantly increased from 2.3 wt% (without pre-oxidation) to 23.1 wt% when pine wood was employed as a sample for pyrolysis at 400 °C, resulting from the removal of hemicellulose fraction and the in-situ acid catalysis of lignin carboxyl groups formed during the pre-oxidation. When the conditions for pre-oxidation became harsher than the above, the LG yield reduced because the decomposition of cellulose fraction in biomass. The study supplies an effective method for utilization of biomass as chemicals.

Peroxydisulfate activation and versatility of defective Fe3O4@MOF-808 for enhanced carbon and phosphorus recovery from sludge anaerobic fermentation.

Although being viewed as a promising technology for reclamation of carbon and phosphorus from excess sludge, anaerobic fermentation (AF) grapples with issues such as a low yield of volatile fatty acids (VFAs) and high phosphorus recovery costs. In this study, we synthesized Fe3O4@MOF-808 (FeM) with abundant defects and employed it to simultaneously enhance VFAs and phosphorus recovery during sludge anaerobic fermentation. Through pre-oxidization of sludge catalyzed by FeM-induced peroxydisulfate, the soluble organic matter increased by 2.54 times, thus providing ample substrate for VFAs production. Subsequent AF revealed a remarkable 732.73 % increase in VFAs and a 1592.95 % increase in phosphate. Factors contributing to the high VFAs yield include the non-biological catalysis of unsaturated Zr active sites in defective FeM, enhancing protein hydrolysis, and the inhibition of methanogenesis due to electron competition arising from the transformation between Fe(III) and Fe(II) under Zr influence. Remarkably, FeM exhibited an adsorption capacity of up to 92.64 % for dissolved phosphate through ligand exchange and electrostatic attractions. Furthermore, FeM demonstrated magnetic separation capability from the fermentation broth, coupled with excellent stability and reusability in both catalysis and adsorption processes.

Pre-oxidized and composite strategy greatly boosts performance of polyacrylonitrile/LLZO nanofibers for lithium-metal batteries.

The active cyano-group in polyacrylonitrile has severe passivation of lithium anode under larger current density, which restricts the wide application of polyacrylonitrile(PAN) in lithium metal batteries. Herein, in order to address the excessive passivation of lithium metal by PAN, inspired by the pre-oxidation of carbon fibers, PAN was pre-oxidized at 230 °C, which transformed part of the cyano group into a more chemically stable cyclized structure. The electrochemical and mechanical properties of the composite solid electrolyte were effectively improved by introducing the fast ionic conductor Li6.25La3Zr2Al0.25O12 into PAN by electrospinning. The oxidized PAN-based composite solid electrolyte presents high ionic conductivity (3.05 × 10-3 S·cm-1) and high lithium transference number of 0.79 at 25 °C, further contributing to a high electrochemical window (5.3 V). The solid-state batteries assembled by Li||10 wt%-LLZAO@230-oxy-PAN||NCM523 behave superb electrochemical performance, delivering a high initial discharge capacity of 157 mAh g-1 at 0.2 C. After 100 cycles, the capacity retention was 93.3 %, indicating the electrolyte displays great electrochemical stability. This work provides new insights into the structural design of polymer-based high-voltage batteries.

In Situ Study and Improvement of the Temperature Increase and Isothermal Retention Stages in the Polyacrylonitrile (PAN) Fiber Pre-Oxidation Process.

The pre-oxidation process of Polyacrylonitrile (PAN) fibers is a complex procedure involving multiple stages of temperature increase and isothermal temperature retention. However, the impact of the temperature increase stage on PAN fiber has often been overlooked. To address this, samples were collected before and after the temperature increase and isothermal retention stages, treating them as separate influencing factors. Therefore, the pre-oxidation process can be divided into four distinct stages: (1) A temperature increase stage before the cyclization reactions: the PAN fiber's small-size crystals melt, and the crystal orientation changes under fixed tension, leading to shrinkage and increased orientation of the micropore. (2) An isothermal retention stage before the cyclization reactions: The crystal structure maintains well, resulting in minimal micropore evolution. The PAN fiber's crystal orientation and micropore orientation increased under fixed tension. (3) A temperature increase stage after the cyclization reactions: The PAN fiber's crystal melts again, reducing the average chord length and relative volume of the micropore. However, the PAN fiber can recrystallize under fixed tension. (4) An isothermal retention stage after the cyclization reactions: Significant crystal melting of the PAN fiber occurs, but the highly oriented crystals are maintained well. The average chord length and relative volume of the micropore increase. Recommendations for improving the pre-oxidation process are made according to these stages.

Is monochloramine pre-oxidation a viable strategy for enhancing the treatment efficiency of algae-laden water with conventional drinking water treatment process?

Algal blooms worldwide pose many challenges to drinking water production. Pre-oxidation with NaClO, KMnO4, or ozone is commonly used to enhance algal removal in conventional drinking water treatment processes. However, these currently utilized oxidation methods often result in significant algal cell lysis or impede the operation of the subsequent units. Higher algal removal with pre-chlorination in algal solutions prepared with natural water, compared to those prepared with ultrapure water, has been observed. In the present studies, preliminary findings indicate that ammonium in natural water alters chlorine species to NH2Cl, leading to improved treatment efficiency. NH2Cl with 1.5-3.0 mg∙L-1 as Cl2 with an oxidation time of 3-7 h significantly enhancing algal removal by coagulation. The selective oxidation of surface-absorbed organic matter (S-AOM) by NH2Cl, followed by the subsequent peeling off of this material from the algal surface, leading to an increase in zeta potential from -20.2 mV to -3.8 mV, constitutes the primary mechanism of enhanced algal removal through coagulation. These peeled S-AOM retained their large molecular weight and acted as polymer aids. Compared with NaClO and KMnO4, NH2Cl displays the best performance in improving algal removal, avoiding cell lysis, and decreasing the potential for nitrogenous disinfection byproducts formation under the reaction conditions used in this study. Notably, in major Chinese cities, water purification plants commonly rely on suburban lakes or reservoirs as water sources, necessitating the transportation of raw water over long distances for times up to several hours. These conditions favor the implementation of NH2Cl pre-oxidation. The collective results indicate the potential of NH2Cl oxidation as a viable pretreatment strategy for algal contamination during water treatment processes.

Facile Preparation of Polyacrylonitrile-Based Activated Carbon Fiber Felts for Effective Adsorption of Dipropyl Sulfide.

Activated carbon fibers (ACFs) derived from various polymeric fibers with the characteristics of a high specific surface area, developed pore structure, and good flexibility are promising for the new generation of chemical protection clothing. In this paper, a polyacrylonitrile-based ACF felt was prepared via the process of liquid phase pre-oxidation, along with a one-step carbonization and chemical activation method. The obtained ACF felt exhibited a large specific surface area of 2219.48 m2/g and pore volume of 1.168 cm3/g, as well as abundant polar groups on the surface. Owing to the developed pore structure and elaborated surface chemical property, the ACF felt possessed an intriguing adsorption performance for a chemical warfare agent simulant dipropyl sulfide (DPS), with the highest adsorption capacity being 202.38 mg/g. The effects of the initial concentration of DPS and temperature on the adsorption performance of ACF felt were investigated. Meanwhile, a plausible adsorption mechanism was proposed based on the kinetic analysis and fitting of different adsorption isotherm models. The results demonstrated that the adsorption process of DPS onto ACF felt could be well fitted with a pseudo-second-order equation, indicating a synergistic effect of chemical adsorption and physical adsorption. We anticipate that this work could be helpful to the design and development of advanced ACF felts for the application of breathable chemical protection clothing.

Comparison of four pre-oxidants coupled powdered activated carbon adsorption for odor compounds and algae removal: Kinetics, process optimization, and formation of disinfection byproducts.

Pre-oxidation and powdered activate carbon (PAC) are usually used to remove algae and odorants in drinking waterworks. However, the influence of interaction between oxidants and PAC on the treatment performance are scarcely known. This study systematically investigated the combination schemes of four oxidants (KMnO4, NaClO, ClO2, and O3) and PAC on the inactivation of Microcystis aeruginosa cells and removal of four frequently detected odorants in raw water (diethyl disulfide (DEDS), 2,2'-oxybis(1chloropropane) (DCIP), 2-methylisoborneol (2-MIB) and geosmin (GSM)). O3 showed highest pseudo-first-order removal rate for all four compounds and NaClO exhibited highest inactivation rates for the cell viability and Chlorophyll a (Chl-a). The Freundlich model fitted well for the adsorption of DEDS and DCIP by PAC. When treated by combined oxidation/PAC, the removal ratio of algae cells and odorants were lower (at least 1.6 times) than the sum of removal ratios obtained in oxidation or PAC adsorption alone. Among these four oxidants, the highest synchronous control efficiency of odorants (52 %) and algae (66 %) was achieved by NaClO/PAC. Prolonging the dosage time interval promoted the removal rates. The pre-PAC/post-oxidation processes possessed comparable efficiency for the removal of odorants and algae cells comparing with pre-oxidation/post-PAC process, but significantly inhibited formation of disinfection byproducts (DBPs), especially for the formation of C-DBPs (for NaClO and ClO2), bromate (for O3) and chlorate/chlorite (for ClO2). This study could provide a better understanding of improving in-situ operation of the combined pre-treatments of oxidation and PAC for source water.

Pre-Oxidation Strategy Transforming Waste Foam to Hard Carbon Anodes for Boosting Sodium Storage Performance.

Large reserves, high capacity, and low cost are the core competitiveness of disordered carbon materials as excellent anode materials for sodium-ion batteries (SIBs). And the existence and improper treatment of a large number of organic solid wastes will aggravate the burden on the environment, therefore, it is significant to transform wastes into carbon-based materials for sustainable energy utilization. Herein, a kind of hard carbon materials are reported with waste biomass-foam as the precursor, which can improve the sodium storage performance through pre-oxidation strategy. The introduction of oxygen-containing groups can promote structural cross-linking, and inhibit the melting and rearrangement of carbon structure during high-temperature carbonization that produces a disordered structure with a suitable degree of graphitization. Moreover, the micropore structure are also regulated during the high-temperature carbonization process, which is conducive to the storage of sodium ions in the low-voltage plateau region. The optimized sample as an electrode material exhibits excellent reversible specific capacity (308.0 mAh g-1) and initial Coulombic efficiency (ICE, 90.1%). In addition, a full cell with the waste foam-derived hard carbon anode and a Na3V2(PO4)3 cathode is constructed with high ICE and energy density. This work provides an effective strategy to conversion the waste to high-value hard carbon anode for sodium-ion batteries.

Al and Mn speciation changes during the pre-oxidation with potassium permanganate and coagulation removing natural organic matter and its membrane fouling behavior.

In this study, we systematically explore coagulation behavior, ultrafiltration membrane fouling behavior and the mechanism involved in during the process of pre-oxidation of potassium permanganate and coagulation of aluminum chloride at different condition to treat model pollutants (humic acid, HA) and natural water. The KMnO4 pre-oxidation significantly enhances flocs formation, and for HA artificial water the flocs size increases from 82 to 122 µm at pH 5.5, from 63 to 185 µm at pH 7.0 and from 0 to 75 µm at pH 8.5, respectively, as for natural water it increases from 72 to 139 µm. The enhanced coagulation at pH 5.5 is attributed to the increased polymeric Al speciation after pre-oxidation along with the generated Mn2+ damaging the electric double layer structure. And for pH 8.5 it is mainly caused by the in-situ MnO2 as combination nuclei during pre-oxidation. Besides, for pH 7.0, the combined effect of in-situ MnO2 and the increased polymeric Al speciation both contribute to improvement of the coagulation. What's more, the enhanced Al coagulation by pre-oxidation of KMnO4 also helps alleviate the membrane fouling for both HA artificial water and natural water, and a much rougher surface with larger flocs forms after KMnO4-aided Al coagulation filtration. This study provides an alternative perspective on the mechanism of pre-oxidation coagulation process.

Constructing Abundant Oxygen-Containing Functional Groups in Hard Carbon Derived from Anthracite for High-Performance Sodium-Ion Batteries.

Hard carbon is regarded as one of the greatest potential anode materials for sodium-ion batteries (SIBs) because of its affordable price and large layer spacing. However, its poor initial coulombic efficiency (ICE) and low specific capacity severely restrict its practical commercialization in SIBs. In this work, we successfully constructed abundant oxygen-containing functional groups in hard carbon by using pre-oxidation anthracite as the precursor combined with controlling the carbonization temperature. The oxygen-containing functional groups in hard carbon can increase the reversible Na+ adsorption in the slope region, and the closed micropores can be conducive to Na+ storage in the low-voltage platform region. As a result, the optimal sample exhibits a high initial reversible sodium storage capacity of 304 mAh g-1 at 0.03 A g-1, with an ICE of 67.29% and high capacitance retention of 95.17% after 100 cycles. This synergistic strategy can provide ideas for the design of high-performance SIB anode materials with the intent to regulate the oxygen content in the precursor.

Simultaneous modulation of CHO cell cytotoxicity, turbidity, and DOC by coagulation with or without pre-oxidation in water from the Pearl River Delta region, China.

Coagulation with or without pre-oxidation are important drinking water treatment processes. However, the efficacy of these processes in mitigating water toxicity remains unknown. To further improve drinking water safety, we employed water from the Pearl River Delta region of southern China to investigate a treatment approach consisting of coagulation with or without pre-oxidation to simultaneously modulate health-relevant cytotoxicity to CHO cells, on top of the conventional foci of turbidity and dissolved organic carbon (DOC) during water treatment. Three coagulants (two aluminum-based and one iron-based salts) and three pre-oxidants (ozone, permanganate, and peroxymonosulfate) were studied. For coagulation without pre-oxidation, intermediate coagulant doses and pH reached optimum cytotoxicity to CHO cells, turbidity, and DOC control simultaneously. Introducing oxidants reduced cytotoxicity to CHO cells significantly, enhanced by increasing oxidant concentrations and pre-oxidation duration. The cytotoxicity to CHO cells mitigation capabilities of three pre-oxidants were: ozone > peroxymonosulfate > potassium permanganate. Modulation of water cytotoxicity to CHO cells was mostly attributable to controlling DOC (specifically humic-acid like substances, tyrosine, tryptophan). However, the addition of pre-oxidants led to significant shifts in water cytotoxicity to CHO cells forcing drivers, rendering humic-acid like substances the sole decisive cytotoxicity-inducing fluorophores. For the first time, 'sweet spots' were identified to simultaneously monitor cytotoxicity to CHO cells alongside turbidity and DOC. These methods better modulate water cytotoxicity to CHO cells without sacrificing conventional water treatment goals while shedding light onto the mechanisms behind.

Gravity-driven membrane coupled with oxidation technology to modify the surface properties and biofilm formation: Biofouling mitigation.

Biofilms caused by biological fouling play an essential role in gravity-driven membranes' (GDMs) flux decline and rejection rate. The effects of ozone, permanganate, and ferrate (VI) in-situ pretreatment on membrane properties and biofilm formation were systematically studied. Due to the selective retention and adsorption of algal organic matter by biofilms and oxidative degradation, the rejection efficiency of dissolved organic carbon (DOC) in algae-laden water pretreated with permanganate by GDM was up to 23.63%. Pre-oxidation extraordinarily postponed flux decline and biofilm formation of GDM and reduced membrane fouling. The total membrane resistance decreased by 87.22%-90.30% within 72 h after pre-ozonation. Permanganate was more effective than ozone and ferrate (VI) in alleviating secondary membrane fouling caused by algal cells destroyed by pre-oxidation. Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory revealed that the distribution of electrostatic force (EL), acid-base (AB), and Lifshitz-van der Waals forces (LW) interactions between M. aeruginosa and the released intracellular algogenic organic matter (IOM) and ceramic membrane surface was similar. The membrane and foulants are always attracted to each other by LW interaction at different separation distances. The dominant fouling mechanism of GDM combined with pre-oxidation technology shifts from complete pore blocking to cake layer filtration during operation. After pre-oxidation of algae-laden water by ozone, permanganate, and ferrate (VI), GDM can treat at least 131.8%, 37.0%, and 61.5% more feed solution before forming a complete cake layer. This study provides new insights into the biological fouling control strategies and mechanisms for GDM coupled with oxidation technology, which is expected to alleviate membrane fouling and optimize the feed liquid pretreatment procedure.

Rapid degradation of long-alkanes by mild Fe-SOM pre-oxidation in soils.

In this study, a novel mild pre-oxidation mode was successfully explored by fabricating Fe-SOM prepared by adding 2.5% and 20% fulvic acid (FA). This study explored the mechanism of mild Fe-SOM pre-oxidation to stimulate rapid biological degradation of long-alkanes in oil-contaminated soils. Results showed that under mild Fe-SOM pre-oxidation, the total •OH intensity and bacterial killing degree（D） were low, and hydrocarbon conversion（C）was fast, resulting in rapid degradation of long-alkanes. Additionally, the fast group removed 1.7-fold more than slow group and biodegraded long-alkanes 182 days significantly faster. Furthermore, compared with slow group (8.26 log CFU/g), the fast group (51.48 log CFU/g) characterized much more bacteria. Besides, the fast group had higher C (5.72%-15.95%), thus increasing the degradation rate of long-alkanes (7.61%-18.86%). A shift in the microbial community was found after mild Fe-SOM pre-oxidation, with an average relative abundance of 18.6% for the dominant genus Bacillus. Therefore, the mild pre-oxidation reduced the D, and the high bacterial abundance promoted nutrients consumption and C, which shortened bioremediation period and increased the long-alkanes degradation rate. This study provided a promising novel mild Fenton pre-oxidation mode to rapid remediate heavily multicomponent oil-contaminated soils.