Organic Degradation Research Articles

Yeast-enhanced activated sludge for improved nitrogen removal in wastewater treatment: Focus on dissolved organic nitrogen degradation

Dissolved organic nitrogen (DON) in effluent of wastewater treatment plants (WWTP), particularly hydrophilic DON, is usually more effective than dissolved inorganic nitrogen (DIN) in stimulating phytoplankton growth and increases the risk of eutrophication in receiving waterbodies. Proteins, amino acids, and nucleic acids, which are the main sources of DON in the effluent, are produced during the hydrolysis of extracellular polymeric substances (EPS) in activated sludge. Herein, a yeast strain Candida tropicalis O2, which was highly efficient in degrading DON in EPS was screened. Within 48-hour batch experiments, the DON removal rates of the extracted hydrophilic and hydrophobic EPS reached 68.26% and 59.27%, respectively. During the continuous 35-day operation of sequencing batch bioreactor (SBR) fed with synthetic wastewater, the yeast-enhanced activated sludge (AS-Y) reactor demonstrated a marked improvement in removing various pollutants compared to the traditional activated sludge (AS) reactor. Specifically, DON removal increased by 1.53 mg/L (24.75%), hydrophilic DON by 1.24 mg/L (27.13%), hydrophobic DON by 0.28 mg/L (12.08%), and COD removal by 4.04 mg/L (6.48%). Although the DIN removal decreased by 0.38 mg/L (3.86%), it did not attenuate the overall TN removal from the system, and an additional TN reduction of 1.15 mg/L (7.13%) was achieved. Metagenomic analysis showed that adding strain O2 slightly inhibited the DIN metabolism, and the relative abundances of napB, nirK/S, norB/C, and nosZ involved in denitrification somewhat decreased. Kyoto Encyclopedia of Genes and Genomes and Carbohydrate-Active Enzymes annotations revealed that adding strain O2 promoted amino acid and carbohydrate metabolism. The increased relative abundance of Candida indicated that strain O2 was able to colonize the sludge in AS-Y reactor, which was conducive to synergistic interactions with other microorganisms. This study provided a novel method for in situ improving nitrogen removal in WWTP and reducing the eutrophication risk of the effluent to receiving waterbodies.

New insight in the biotreatment of produced water: pre-oxidation paves a rapid pathway for substrate selection in microbial community

The deep treatment of produced water (PW) had emerged as a formidable challenge due to the coexistence of hydrocarbons, surfactants, ammonium nitrogen, and other refractory organics. On the basis of the pre-oxidation coupled heterotrophic ammonia assimilation (PHAA) system constructed in previous research, this work refined the catalyst selection and reduced the hydraulic retention time. The stable running PHAA system removed 96.2% of total organic carbon (TOC). The study simulated the effects of organic loading fluctuations on the system and dissected the mechanism of pre-oxidation process and its contribution to microbial community. Pre-oxidation significantly improved the ability of microbial community to handle loading shocks and improved organic degradation efficiency in PW during long-term reactor operation. The PHAA process effectively removed medium to long chain alkanes above C24 in PW and proposed potential degradation pathways and direction. The determination of hydrocarbon enzymes activity showed that pre-oxidation changed the substrate selection, making more aldehydes available as auxiliary carbon sources for microorganisms. Pre-oxidation also enriched and preserved microbial diversity, facilitating the accumulation of functional microorganisms in the PHAA process.

Eco-friendly TiO2/CQDs nanocomposites from banana peel waste: innovations in visible light induced organic pollutant degradation and X-ray shielding applications

Eco-friendly TiO2/CQDs nanocomposites from banana peel waste: innovations in visible light induced organic pollutant degradation and X-ray shielding applications

Performance of co-composting Pholiota nameko spent mushroom substrate and pig manure at different proportions: Chemical properties and humification process.

Co-composting is the controlled aerobic degradation of organics, using more than one feedstock. By combining the spent mushroom substrate of Pholiota nameko (SMS) and pig manure (PM), the benefits of each could be used to optimize the composting process and the final product. This study introduced a comprehensive evaluation strategy aimed at identifying the optimal co-composting ratio for these two substrates. A 120-day composting trial was conducted, blending SMS and PM in various ratios to evaluate the benefits of co-composting SMS-PM. The results indicated that dissolved organic matter (DOM) in SMS-derived compost primarily originated from plants, whereas PM-derived compost predominantly consisted of microbial metabolic products, and co-composting combined both sources. An increase in aromaticity and humification degree of DOM occurred during the composting process itself rather than being derived from autochthonous origin. Carbohydrates like phenols and alcohols broke down during composting, and microbes utilized polysaccharides as an energy source for humus formation. As co-composting progressed, the treatments with varying mass ratios of SMS to PM, including 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 were observed to result in a decline in aliphatic hydroxylated chains alongside an enhancement in aromaticity within the compost. Additionally, there was a conversion from organic carbon (C) to carboxyl C within humic acid (HA) due to oxidation and dehydrogenation processes that facilitated the formation of stable nitrogen-containing compounds characterized by condensed aromatic structures. Following thorough evaluation, it was determined that optimal composting efficacy occurred at a mass ratio of SMS to PM equal to 6:4. Post-compost analysis revealed increases in nutrient content; specifically, germination index (GI) value reached 132.7%, while organic matter content attained 45.3%. Conversely, electrical conductivity (EC), C contents of water-soluble substances and humin (Cwss and CHu) decreased by approximately 11.8%, 73.4%, and 29.8% respectively; meanwhile, C contents of humic-extracted acid and HA (CHE and CHA), along with degree of polymerization (DP), increased by 17.3%, 20.3% and 9.9% respectively. The proposed co-compost formula not only facilitated simultaneous recycling of both SMS and PM waste but also transformed them into high-quality organic fertilizers suitable for soil enrichment-effectively addressing challenges faced by both edible fungi cultivation and livestock industries while augmenting organic fertilizer sources for Black land protection.

Multi-Omics Analysis Uncovers the Mechanism for Enhanced Organic Acid Accumulation in Peach (Prunus persica L.) Fruit from High-Altitude Areas

The early-ripening peach industry has undergone rapid development in the Panxi region of the Sichuan Basin in recent years. However, after the introduction of some new peach varieties to the high-altitude peach-producing areas in Panxi, the titratable acid content in peach fruit has significantly increased. This study compared the fruit quality indicators of early-ripening peach varieties cultivated in Xide County (a high-altitude peach-producing area) and Longquanyi District (a low-altitude peach-producing area) in Sichuan Province and analyzed the differences in organic acid metabolism by combining primary metabolomic and transcriptomic approaches. The results showed that the ‘Zhongtaohongyu’ fruit from the high-altitude peach-producing area had a much higher accumulation of malic acid and, accordingly, a significantly higher organic acid content than the other samples. The lower annual average temperature and stronger ultraviolet radiation in high-altitude peach-producing areas may lead to the increased expression of genes (PpNAD-ME1, PpNADP-ME3, and PpPEPC1) in the organic acid synthesis pathway and the decreased expression of genes (PpACO2, PpNAD-MDH2/3/4/5, and PpPEPCK2) in the organic acid degradation pathway in peach fruit, ultimately resulting in the accumulation of more organic acids. Among them, the downregulation of the key genes PpNAD-MDH3/4/5 involved in malic acid metabolism may be the main reason for the higher malic acid accumulation in peach fruit from high-altitude peach-producing areas. Overall, this study elucidates the mechanism by which environmental factors enhance the accumulation of organic acids in peach fruit from high-altitude peach-producing areas from a multi-omics perspective, as well as providing a theoretical basis for screening key genes involved in organic acid metabolism in peach fruit.

Control of hydrogen concentrations by microbial sulfate reduction in two contrasting anoxic coastal sediments

IntroductionMolecular hydrogen is produced by the fermentation of organic matter and consumed by organisms including hydrogenotrophic methanogens and sulfate reducers in anoxic marine sediment. The thermodynamic feasibility of these metabolisms depends strongly on organic matter reactivity and hydrogen concentrations; low organic matter reactivity and high hydrogen concentrations can inhibit fermentation so when organic matter is poor, fermenters might form syntrophies with methanogens and/or sulfate reducers who alleviate thermodynamic stress by keeping hydrogen concentrations low and tightly controlled. However, it is unclear how these metabolisms effect porewater hydrogen concentrations in natural marine sediments of different organic matter reactivities.MethodsWe measured aqueous concentrations of hydrogen, sulfate, methane, dissolved inorganic carbon, and sulfide with high-depth-resolution and 16S rRNA gene assays in sediment cores with low carbon reactivity in White Oak River (WOR) estuary, North Carolina, and those with high carbon reactivity in Cape Lookout Bight (CLB), North Carolina. We calculated the Gibbs energies of sulfate reduction and hydrogenotrophic methanogenesis.ResultsHydrogen concentrations were significantly higher in the sulfate reduction zone at CLB than WOR (mean: 0.716 vs. 0.437 nM H2) with highly contrasting hydrogen profiles. At WOR, hydrogen was extremely low and invariant (range: 0.41–0.52 nM H2) in the upper 15 cm. Deeper than 15 cm, hydrogen became more variable (range: 0.312–2.56 nM H2) and increased until methane production began at ~30 cm. At CLB, hydrogen was highly variable in the upper 15 cm (range: 0.08–2.18 nM H2). Ratios of inorganic carbon production to sulfate consumption show AOM drives sulfate reduction in WOR while degradation of organics drive sulfate reduction in CLB.DiscussionWe conclude more reactive organic matter increases hydrogen concentrations and their variability in anoxic marine sediments. In our AOM-dominated site, WOR, sulfate reducers have tight control on hydrogen via consortia with fermenters which leads to the lower observed variance due to interspecies hydrogen transfer. After sulfate depletion, hydrogen accumulates and becomes variable, supporting methanogenesis. This suggests that CLB’s more reactive organic matter allows fermentation to occur without tight metabolic coupling of fermenters to sulfate reducers, resulting in high and variable porewater hydrogen concentrations that prevent AOM from occurring through reverse hydrogenotrophic methanogenesis.

FeOOH Quantum Dots Assembled MXene-Decorated 3D Photothermal Evaporator for Synergy Application in Solar Evaporation and Fenton Degradation.

Solar-driven water evaporation is considered as the sustainable approach to alleviate freshwater resource crisis through direct use of solar energy. However, it is still challenging to achieve the multifunctional solar evaporators equipped with both high evaporation and purification performance to handle practical complex wastewater. Here, a simple and cost-effective multifunctional 3D solar evaporator is prepared by alternately decorating the commercial sponge with FeOOH quantum dots (FQDs) supported MXene sheets composites and chitosan hydrogel coatings for enabling the solar water evaporation and organic wastewater photodegradation simultaneously. MXene composites allow the solar evaporator with excellent photothermal conversion performance, the hydrophilic chitosan hydrogel coated interconnecting skeleton structures of sponge serve as the mass transfer and water transport channels. The Fenton-catalytic FQDs anchored on the MXene sheets surface accept the photo-generated electrons of MXene sheets to induce the organic pollutant photo-Fenton degradation reaction under sunlight irradiation. The resulting evaporator possesses both excellent water evaporation rate of 2.54kg m-2h-1 and high degradation efficiency (99.24% for methylene blue), coupled with durable salt-resisting performance during long-term seawater desalination (20 wt.% NaCl). This work provides a simple and feasible strategy for designing multifunctional solar evaporators to meet the potential application scenarios in practice.

Electrochemical degradation of aromatic organophosphate esters: Mechanisms, toxicity changes, and ecological risk assessment

Aromatic organophosphate esters (AOPEs), including triphenyl phosphate (TPHP), tricresyl phosphate (TCP), and 2-ethylhexyl diphenyl phosphate (EHDPP), pose significant health and ecological risks. Electrochemical advanced oxidation process (EAOP) is effective in removing refractory pollutants. In this study, the degradation performance and detoxication ability of AOPEs by EAOP were investigated. Hydroxylation, oxidation, and bond cleavage products were identified as major degradation products (DPs) due to the reaction with ·OH and O₂·-. Toxicity assessments using ecological structure activity relationship (ECOSAR) model and flow cytometry (FCM) revealed the cytotoxicity and aquatic toxicity for DPs were significantly decreased. 16S rRNA gene sequencing of sediment exposure to AOPEs and DPs were applied to assess ecological toxicity, and results showed reduced bacterial richness and diversity with EHDPP and TCP, while TPHP slightly enhanced richness. AOPEs and DPs altered bacterial genera involved in carbon, nitrogen, sulfur cycling and organic compound degradation. Bacterial community assembly suggested elevated stochastic processes and reduced ecotoxicity, confirming AOPEs can be effectively detoxified by 10-min EAOP treatment. Molecular ecological network analysis indicated increased complexity and stability of bacterial communities with DPs. These findings comprehensively revealed the toxicity of AOPEs and their DPs and provided the first evidence of effective degradation and detoxification by EAOP from ecotoxicological perspective.

Oxygen vacancies-enriched spent lithium-ion battery cathode materials loaded catalytic membrane for effective peracetic acid activation and organic pollutants degradation

Advanced oxidation processes combined with membrane filtration technique offer a promising approach for pollution mitigation and catalyst recovery. Herein, a waste ternary lithium-ion battery cathode material of LiNixCoyMnzO2 (LNCM) loaded polytetrafluoroethylene (PTFE) membrane was synthesized for peracetic acid (PAA) activation (LNCM-PTFE/PAA) and 2,4,6-trichlorophenol (TCP) degradation. Such a novel membrane, with a catalyst loading of 10 mg (0.796 mg/cm2) of LNCM achieved 96.4 % removal of TCP (2 mg/L) within 20 min in neutral pH. The redox cycles of surface metals (such as Co3+/Co2+, Ni3+/Ni2+, and Mn4+/Mn3+/Mn2+) in spent LNCM efficiently enhance charge transfer and mediated PAA activation. And intrinsic oxygen vacancies in LNCM facilitated PAA adsorption and its cleavage. The resulting carbon-centered radicals (R-C•, CH3C(O)OO•) and 1O2 are identified as the primary reactive species that collaboratively participate in TCP degradation. Quantitative structure-activity relationship analysis demonstrated a substantial reduction in product toxicity. The successful practical application of the LNCM-PTFE/PAA membrane was exemplified by treating chlorophenol industrial wastewater. This study presents a new LNCM-PTFE/PAA catalytic membrane for high-efficiency water treatment and a novel perspective for green utilization of waste LNCM.

Studying the properties of green synthesized silver oxide nanoparticles in the application of organic dye degradation under visible light.

In present study the green synthesis of silver oxide nanoparticles has been effectively achieved using novel plant extract Phragmanthera Macrosolen. This method provides sustainable alternative for nanoparticle synthesis, demonstrating the potential of Phragmanthera Macrosolen as a reducing and stabilizing agent in the production of Ag2O NPs. The synthesized nanoparticles were characterized for their structural, morphological, and optical properties, confirming their successful formation and potential applications in various fields. The effects of different pH values and annealing temperature of the samples on the properties of Ag2O NPs formations, as well as photo-catalytic activities towards Toluidine Blue dye degradations, were studied. Powder XRD reveals that the crystallite natures of Ag2O NPs a long with crystalline size ranges from 25.85 to 35.90nm. FIB-SEM and HR-TEM images displayed that the Ag2O NPs as spherical shapes. UV-vis spectroscopy displayed that Ag2O NPs belong to a direct-band gap of 2.1-2.6eV. FTIR- study shown that the green synthesized Ag2O NPs may be steadied via the interfaces of -OH as well as C = O groups in the carbohydrate, flavonoid, tannin, as well as phenolic acid existing in P. macrosolen L. leaf. The chemical states, electron-hole recombinations and purity of Ag and O in the synthesized Ag2O NPs were confirmed through X-ray Photoelectron Spectroscopy (XPS) and PL analysis respectively. Fascinatingly, the synthesized Ag2O NPs at pH 12 displayed high photo-catalytic degradations for TB dyes. The photo-catalytic degradations of the TB dyes were monitored spectro-photo-metrically in wave-length ranges of 200-900nm, as well as high efficiency (98.50%) with half-life of 9.5798min and kinetic rate constant of 0.07234min-1, was obtained after 45min of reactions. From this study, it can be concluded that Ag2O NPs synthesized from Phragmanthera Macrosolen aqueous extract are promising in the remediation of environmental pollution and water treatment. In this light, the study reports that Phragmanthera Macrosolen green synthesis of Ag2O NPs can effectively address environmental pollution in cost-effective, eco-friendly, and sustainable ways.

Radiolytic support for oxidative metabolism in an ancient subsurface brine system

Abstract Long-isolated subsurface brine environments (Ma-Ga residence times) may be habitable if they sustainably provide substrates, e.g. through water-rock reaction, that support microbial catabolic energy yields exceeding maintenance costs. The relative inaccessibility and low biomass of such systems has led to limited understanding of microbial taxonomic distribution, metabolism, and survival under abiotic stress exposure in these extreme environments. In this study, taxonomic and metabolic annotations of 95 single cell amplified genomes (SAGs) were obtained for one low biomass (103–104 cells/mL), hypersaline (246 g/L), radiolytically enriched brine obtained from 3.1 km depth in South Africa’s Moab Khotsong mine. The majority of SAGs belonged to three halophilic families (Halomondaceae (58%), Microbacteriaceae (24%), and Idiomarinaceae (8%)) and did not overlap with any family-level identifications from service water or a less saline dolomite aquifer sampled in the same mine. Functional annotation revealed complete metabolic modules for aerobic heterotrophy (organic acids and xenobiotics oxidation), fermentation, denitrification and thiosulfate oxidation, suggesting metabolic support in a microoxic environment. SAGs also contained complete modules for degradation of complex organics, amino acid and nucleotide synthesis, and motility. This work highlights a long-isolated subsurface fluid system with microbial metabolism fueled by radiolytically generated substrates, including O2, and suggests subsurface brines with high radionuclide concentrations as putatively habitable and redox-sustainable environments over long (ka-Ga) timescales.

Mathematical model of dissolved microbial products in sewage treatment system

Water is the source of life, but all kinds of water resources in the world are suffering from different degrees of pollution. Water pollution leads to a serious shortage of available fresh water resources, and sewage treatment is the main way to solve water pollution. For the sewage after biological treatment of activated sludge, the organic matter contained in the effluent is mainly the dissolved microbial products (SMPs) produced in the process of microbial metabolism. The composition of SMPs is complex, mainly including macromolecular substances such as protein, polysaccharide, humic acid and DNA and cell fragments. The mathematical model of activated sludge is a quantitative description of the mathematical relationship between substrate degradation parameters and microbial growth. Starting from the Monod equation representing the relationship between substrate consumption and microbial growth, it combines the reactor theory and microbiology theory in the chemical field. Based on the principle of conservation of materials and Monod equation, the mathematical expression of organic degradation model was determined according to the collected data and empirical values of parameters. The general idea of activated sludge model No.1 (ASM1) for activated sludge process simulation was introduced, and the influence of sludge concentration on SBR process water treatment was explored. It was found that the removal rate of COD, ammonia nitrogen, total nitrogen and total phosphorus increases with the increase of sludge concentration. When C/N=8, the removal rate of ammonia nitrogen increased from 62% to 81%, and the removal rate of total nitrogen increased from 64% to 82%, with the most obvious effect.

Enhanced photocatalytic degradation of organic pollutants by randomly oriented 2D SnS2 nanostructures

Abstract In this study, we present a bottom-up solvothermal technique using tin tetrachloride pentahydrate (SnCl4.5H2O) and thioacetamide as precursors to synthesize SnS2 nanostructures. Different solvents including isopropyl alcohol, ethanol (EN), and ethylene glycol were used in the reaction to enhance the photodegradation efficiency of organic pollutants, Methylene Blue (MB), and Tetracycline (TC) in an aqueous medium under simulated solar light irradiation. The SnS2 nanostructures synthesized with these solvents were characterized using various structural, morphological, and optical techniques, including x-ray diffraction, RAMAN, field emission scanning electron microscope, x-ray photoelectron spectroscopy, UV–Vis, and Brunauer–Emmett–Teller analysis. The choice of solvent was found to significantly affect the structural, morphological, and optical properties of the SnS2 nanostructures. Notably, the sample synthesized with EN as the solvent displayed a unique morphology, enhanced light-harvesting ability, efficient charge carrier separation, and a larger specific surface area, all of which contributed to its superior photocatalytic activity. This sample achieved 99.9% degradation of MB and 95% degradation of TC within 20 and 40 min, respectively. The kinetic analysis revealed maximum rate constant (k) values of 0.15242 min−1 for MB and 0.060 95 min−1 for TC, as determined by the pseudo-first-order kinetic model. We also discuss the plausible mechanism involving visible light-induced electron–hole pairs that generate reactive species, leading to the mineralization of dyes into H2O, CO2, and other gaseous products. The synthesized SnS2 nanostructures demonstrate significant potential for enhanced photocatalytic activity in organic pollutant degradation, underscoring their promise in addressing water pollution challenges.

Catalyst Activation of Peroxymonosulfate for Reactive Species Generation and Organic Pollutant Degradation: A Mini Review

This review focuses on the application and mechanisms of peroxymonosulfate (PMS) in advanced oxidation processes (AOPs). It clarifies the significance of PMS in degrading organic pollutants, highlighting its high efficiency in treating persistent contaminants, such as antibiotics. The review details the roles and mechanisms of various catalysts, including single-atom catalysts, metal oxides, non-metal oxides and their composites, as well as metal-organic frameworks (MOFs), in activating PMS. It emphasizes the influence of catalyst surface active sites on both radical and nonradical activation pathways. Key factors affecting PMS activation efficiency, such as PMS concentration, pH value, coexisting ions, and temperature, are examined to underline the importance of optimizing these parameters for effective reaction conditions. By synthesizing existing research, the review not only illustrates the extensive application potential of PMS in AOPs but also identifies future research challenges and directions. This provides a theoretical foundation and technical support for developing efficient, economical, and sustainable water treatment technologies.

Synergistic uranium extraction, organic degradation, and electricity generation by a self-driven photoelectrochemical system with TNR/Si PVC photoanode and copper foam cathode

Herein, we develop a self-driven photoelectrochemical system (SDPS) featuring a TiO2 nanorod array (TNR)/Si photovoltaic cell (Si PVC) photoanode and a porous copper foam (CF) cathode for efficient uranium recovery. Under simulated sunlight illumination, this SDPS simultaneously achieves ∼ 99.4 % UO22+ recovery and ∼ 99.2 % sulfamethoxazole (SMX) removal, with observed rate constant (kobs) value of 0.121 min−1 and 0.029 min−1, respectively, and a maximum power density (Pmax) of 0.89 mW·cm−2 when treating complex wastewater of SMX (10 mg·L−1)-UO22+ (10 mg·L−1). The TNR photoanode absorbs short-wavelength light (λ < 412 nm), generating electron-hole pairs, while the rear Si PVC absorbs transmission light, creating a self-bias potential that drives electrons transfer towards CF cathode, continuously generating electrical energy in the external circuit. The retained holes and derived •OH oxidize SMX, breaking UO22+-SMX complexation, while electrons on the CF reduce UO22+ to insoluble tetravalent uranium (U(IV)) species. This SDPS demonstrates robust performance across varying UO22+ (5 ∼ 40 mg·L−1) and SMX (0 ∼ 40 mg·L−1) concentrations, pH ranges (4 ∼ 8), coexisting ions, and different types of uranium-containing wastewaters, maintaining stability over 20 cycles. It achieves ∼ 97.5 % UO22+ extraction and ∼ 99.8 % SMX removal in simulated seawater, with a Pmax of 1.27 mW·cm−2. This work presents a promising resource strategy for uranium extraction.

Enhanced photocatalytic performance of (Mg, Cu) Dual-Doped ZnS nanosheets for Solar-Driven water treatment and embedded with PVA polymer membrane for reusability

Photocatalysis uses semiconductor materials to solar energy effectively purify to water by eliminating pollutants. Organic Dye degradation serves as a standard to assess the photocatalytic effects of the materials. In this study Mg, Cu dual-doped ZnS nanosheets were synthesized using the coprecipitation method. The impact of the concentration on the structural, morphology, optical, and degradation efficiency was investigated with XRD, XPS, TEM with EDAX, and UV spectroscopy. The pure ZnS and Zn0.98-xCu0.02MgxS (x = 0, 0.01, 0.02) (ZCM1, ZCM2, ZCM3, and ZCM4) nanosheets, exhibited cubic structure with high phase purity. The average crystalline size was calculated as 1.66, 1.60, 1.45, and 1.47 nm for the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets, respectively. TEM analysis revealed the presence of crumpled nanosheets. The bandgap of the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets were 3.99, 3.78, 4.03, and 4.09 eV respectively. This study investigated the photocatalytic activity of crystal violet dye when exposed to natural sunlight irradiation. Notably, ZCM3 nanosheets exhibited a high degradation rate of 99 % over 120 min under sunlight. Furthermore, the proposed dye degradation mechanism, effect of dosage, effect of dye variation, reusability, scavenging activity, and hemolytic activity were comprehensively discussed. The nanosheets embedded with the Polyvinyl alcohol (PVA) polymer membrane for reusability.

Sunflower-disc-inspired vertical growth of 2D ZnIn2S4 on ultra-thin TiO2: Constructing a 3D porous photocatalytic glass film for ultra-efficient organic pollutant degradation

Thin-film catalysts show immense potential for photocatalytic applications due to their versatility and ease of recovery. However, their stability is often compromised by detachment and poor surface utilization. In this study, inspired by the architecture of sunflower discs, we present a novel 3D porous photocatalytic film by vertical growth of 2D ZnIn2S4 on ultra-thin TiO2/glass for ultra-efficient degradation of organic pollutants. Crucially, ZnIn2S4 nanosheets were vertically grown on the stable TiO2/glass substrate to form a 3D porous structure, and the vertical growth mechanism is demonstrated by DFT. In contrast, when directly grown on glass, only aggregated ZnIn2S4 spheres formed. The enhanced surface area of the 3D ZnIn2S4 structure allows for maximum light absorption, while the rapid separation and transfer of photogenerated charges follow a Z-scheme charge transfer mechanism in the ZnIn2S4/TiO2 heterojunction. This synergy significantly improves the photocatalytic performance, surpassing most previously reported semiconducting films.

Straw additive enhances manure compost quality by promoting diverse aerobic bacteria and unitary thermophilic fungi

Shortening the initial activation time and extending the duration of the thermophilic phase are key to improving compost product quality in cold-climate regions. This study set up three treatments that cattle manure (CM), manure with rice straw (MR), and manure with maize straw (MM) in the field with ambient temperature ranging from –6 to 7 ℃. Compared with traditional manure composting, composting with straw performed more effectively, and the effect of the addition of maize straw surpassed that of the addition of rice straw. Straw additives markedly increased the compost pile temperature and extended the thermophilic phase duration. In addition, straw addition improved compost product maturity, as indicated by the humic-like substance content, absorbance ratio, and germination index. To further illustrate this result, the microbial community structure during the composting process was studied. During the thermophilic phase, straw additives, especially maize straw, improved the formation of a diverse aerobic bacterial community and a unitary thermophilic fungal community, and promoted a stronger relationship between the bacterial and fungal communities, as revealed by co-inertia analysis. The abundance of functional genes indicated that straw addition increased the activities of organic carbon degradation and transformation. This study demonstrated the necessity of enhancing the interaction between thermophilic–aerobic bacteria and thermophilic fungi to improve compost product quality.

Novel S-scheme WO3/ZnO-modified g-C3N4 heterojunction for optimizing norfloxacin photodegradation condition via DoE: Synthesis, characterization, and mechanism evaluation

Norfloxacin, an antimicrobial agent, has been recurrently observed in municipal wastewater facilities, posing a conjectured threat to human health and environmental integrity. Herein, novel ternary heterojunction of WO3/ZnO-modified g-C3N4 was fabricated utilizing the impregnation technique for the organic pollutant degradation, presenting a significant challenge. XRD, XPS, TEM, HR-TEM, SEM, EDS, BET, EIS, Mott-Schottky, ESR, PL, photocurrent, and DRS techniques were used to explore the structural, morphological, textural, and optical features of the produced materials. In this ternary system, ZnO served as an electron transfer conduit, facilitating the formation of a heterojunction interface between the semiconductor constituents. Establishment of the S-scheme within the charge transfer dynamics of the heterojunction markedly augmented charge separation, enhancing the efficacy of the photocatalytic activity. Under optimized conditions via the DoE software (i.e.; photocatalyst dosage: 0.54 g/L, NOR concentration: 25.87 mg/L, Irradiation time: 41.71 min and pH: 6.9), 97.19 % of NOR elimination was achieved by the optimized 20-WZC photocatalyst with a pseudo-first-order kinetic model (k = 0.05 min−1). ESR data, alongside quenching experiments, corroborated the pivotal involvement of O2−, OH, and h+ in the NOR degradation mechanism. The investigation of NOR's potential decontamination pathways was performed using HRLC-MS. TOC analysis revealed a significant mineralization of 82.45 %, indicating the conversion of NOR into H2O, CO2, and other degradable substances. The optimized photocatalyst also demonstrated notable efficiency in the degradation of Tetracycline: 98.15 %, Ciprofloxacin: 93.27 %, Methylene Blue: 98.89 %, and Enrofloxacin: 91.54 % pollutants. The photocatalytic activity of the 20-WZC catalyst remained consistently high, without significant reduction, over five successive cycles.

Fe3C@Fe decorated carbonized wood Fiber catalyst for organic dyes degradation: Preparation, characterization and mechanism

The extensive use of organic dyes has led to significant water pollution. Using lignocellulosic waste as a precursor for catalysts preparation for sewage remediation presents an effective alternative with numerous advantages in sustainability, cost-effectiveness, and environmental compatibility. In this work, wood fiber waste collected from wood processing plants was decorated with Prussian blue (PB) and then annealed to produce carbonized wood fiber catalyst (Fe3C@Fe-CB). In the presence of peroxymonosulfate (PMS), the prepared catalyst could achieve over 98.69 % efficiency in degrading methylene blue (MB) solutions (20 mg/L) in 60 min across a pH range of 3 to 11. Electrochemical test and electron paramagnetic resonance (EPR) analysis respectively verified that electron transfer pathway and radical pathway were the key factors for the degradation of MB. Cyclic degradation tests demonstrated that the degradation efficiency remained above 93.67 % after five recycling experiments. Moreover, the used magnetic catalyst can be easily recycled by magnet. This study proposed a facile and sustainable carbonized wood fiber catalyst decorated by Fe3C@Fe-CB, which could realize efficient elimination of organic dyes. Moreover, we offered a novel choice for dyes-polluted water treatment and paving a new route for converting low-value lignocellulosic waste to high-value utilizations.