Journal of Environmental Chemical Engineering最新文献

Caproic acid (CA) production is a promising way to valorize food waste (FW), but the low CA yield seriously restricts its application. Inoculum source as a key factor can affect the microbial communities and CA fermentation processes, but was not fully explored. In the present study, three common inoculum sources namely anaerobic digestion sludge (AD), pit mud (PM) and raw FW (RFW) were selected as inocula to initiate CA production from FW. The organics conversion properties, microbial community succession processes and bacterial metabolism pathways were investigated. Results showed that carbohydrates were effectively degraded into lactic acid and then to CA based on lactate-based chain elongation. The CA yield (0.37 g-COD/g-VS) using AD was higher than that inoculated with PM (0.26 g-COD/g-VS) and RFW (0.32 g-COD/g-VS). Although microbial communities in inocula were totally different, they exhibited similar succession with Firmicutes and Bacteroidetes as the dominant functional phyla. Logically, lactic acid-producing bacteria (e.g. Lactobacillus, Limosilactobacillus and Sporolactobacillus) were enriched at the early stage to prepare electron donor (lactate), and then were replaced by chain elongation bacteria for CA production. However, unclassified_Ruminococcaceae was dominant in reactor with AD, unclassified_Ruminococcaceae, Bifidobacterium, Clostridium_sensu_stricto and unclassified_Prevotellaceae were largely detected in reactors inoculated with PM and RFW, which resulted in different CA yield. This study provides useful information for caproate production from FW, and widens the knowledge of cleaner production from wastes.

Due to the high biological toxicity and the propensity to induce antibiotic resistance, the treatment of antibiotic wastewater has consistently posed a formidable challenge. The semiconductor photocatalysts can efficiently and completely remove antibiotics from the wastewater to repair the water environment. Therefore, a novel ZnIn₂S₄/Tb-g-C₃N₄ (ZIS/TCN) photocatalyst was successfully synthesized in this paper and its ability to efficiently degrade antibiotics has been verified. The optimized 150ZIS/TCN photocatalyst showed excellent photocatalytic performance and stablility toward the degradation of tetracycline (TC) and tylosin (TYL) under sunlight simulated with a xenon lamp. Compared with pristine g-C₃N₄ and ZnIn₂S₄, the 150ZIS/TCN exhibited superior degradation performance for TC (TYL)，about 3.2 (2.1) and 1.8 (1.5) times higher than them. Based on density functional theory (DFT) calculations and experimental characterization test results, it was confirmed that the Tb doping effectively regulates the intrinsic electric field and visible light absorption capacity. This study unveils the degradation mechanism of ZIS/TCN photocatalysis and provides an effective pathway for enhancing photocatalytic degradation through rare earth doping.

The generation of high-quality syngas combined with high-purity hydrogen is an essential challenge in the chemical looping steam methane reforming (CL-SMR) process, in which the design of oxygen carriers (OCs) is crucial. In this study, La₂FeBO₆ (BCr, Ni，Co) and La₂Fe_2-xCo_xO₆ (x = 0.2, 0.4, 0.6, 0.8, 1.0) double perovskites have been investigated as OCs in the CL-SMR process. Various analytical techniques (BET, XPS, XRD, H₂-TPR, Raman.) have been deployed to characterize the OCs' specific surface area, crystal structure, and surface oxygen species. The fixed-bed experiments revealed that the Cr-modified perovskite had the lowest reactivity, which was attributed to the creation of LaCrO₃ limiting the oxygen release rate of the OC. Meanwhile, Ni doping exhibited the maximum methane conversion (99.15 %), but it resulted in more carbon deposition due to methane cracking, and its carbon deposition was four times than that of Co doping. Whereas, the Co doped double perovskite OCs showed excellent overall performance, in which La₂Fe_1.8Co_0.2O₆ (L₂F_1.8Co_0.2) exhibited the optimum CO selectivity (90.72 %), H₂ selectivity (96.91 %), and H₂ purity (96.84 %), as well as the lowest carbon deposition. Moreover, the L₂F_1.8Co_0.2 also exhibited outstanding stability in 10 cycles, and it could be a prospective material for CL-SMR, enabling the simultaneous generation of high-quality syngas and high-purity hydrogen.

This study investigates the effectiveness of modified micrometer graphite (MMG) in enhancing the biodegradation of perchlorate in sludge. Different MMG types, specifically GO205, GO003, ATGO205, and ATGO003, were evaluated for their impact on perchlorate degradation rates. The results showed a significant acceleration in perchlorate reduction, particularly with the MMG variant GO205, which achieved complete degradation within 48 hours, marking a six-fold increase compared to controls. This rapid degradation also correlated with enhanced microbial activity, as indicated by increased cytochrome C concentrations and electron transport system activity, suggesting a boost in overall microbial metabolic functions. Additionally, shifts in the microbial community composition were observed, with a notable increase in perchlorate-reducing bacteria populations. The study highlights MMG's potential to improve perchlorate remediation processes efficiently and offers promising insights into its application in treating perchlorate-contaminated environments.

C₃N₄/Ag₂S p-n semiconductor heterojunction coupled with Ag-induced SPR effect on carbon fiber cloth with large macroscopic area, recyclability and excellent photocatalytic performance was prepared by thermal condensation-chemical precipitation. CF/C₃N₄/Ag/Ag₂S cloth showed strong Vis-NIR light absorption and outstanding separation efficiency of photo-generated electron and hole pairs. CF/C₃N₄/Ag/Ag₂S cloth displayed a markedly enhanced catalytic activity (94 % of TC, 85 % of Cr(VI)) compared with CF/C₃N₄ cloth (52 % of TC, 50 % of Cr(VI)) or CF/Ag/Ag₂S cloth (34 % of TC, 19 % of Cr(VI)), attributing to the establishment of p-n junction along with Ag SPR effect. Moreover, degradation pathways for TC were proposed utilizing HPLC-MS and Fukui index analysis, and photocatalytic mechanism was confirmed by active species experiments and DFT computations. This facile strategy provides novel approach to the synthesis of material with large macroscopic areas, recyclability, and excellent photocatalytic property for degrading contaminants from wastewater.