Journal of Environmental Engineering Technology•2026•DOI: 10.13205/j.hjgc.202604007
Low C/N ratios in wastewater treatment plant effluent necessitate external carbon sources for denitrification, but conventional liquid carbon sources are costly and unstable. This study prepared nine composite solid-phase carbon sources by combining PHBV with natural cellulose materials (straw, sawdust, corncob) at different mass ratios. Dynamic release experiments, DOC analysis, UV-Vis spectroscopy, and EEM fluorescence were employed to characterize carbon release. Results showed that increasing cellulose proportion in corncob-based sources led to release patterns opposite to those of straw- and sawdust-based sources. For straw and sawdust, higher cellulose ratios accelerated release rates, increased total release and duration, reduced aromaticity and molecular weight of released DOM, and promoted protein-like components (tryptophan, tyrosine), indicating enhanced bioavailability. Under identical ratios, corncob-based sources exhibited moderate total release, release durations exceeding 134 h, lower DOM aromaticity and molecular weight, and lower humic substance proportion, indicating superior bioavailability and engineering potential. Among the nine sources, JG5, MX5, and CC4 (PHBV:cellulose mass ratios of 4:5, 4:5, and 1:1, respectively) showed optimal comprehensive performance with low theoretical maximum release, long release periods, and high mass transfer coefficients. EEM-PARAFAC identified three DOM components (protein-like C1, C2; humic-like C3), with protein-like components dominating. This study validates the relationship between cellulose proportion and release kinetics and reveals synergistic regulation of DOM components, offering guidance for designing effective solid-phase carbon sources.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.3724/2097-213X.2026.JFCT.0003
Phosphorus and transition metal-modified ZSM-5 zeolites were prepared via incipient wetness impregnation and characterized by XRD, N2 adsorption-desorption, and pyridine-IR spectroscopy. The effects of modified zeolites on catalytic pyrolysis of n-heptane, 3-methylhexane, and methylcyclohexane were systematically investigated, revealing the structure-activity relationship between acid properties and catalytic performance. Results indicate that phosphorus and transition metal modification can regulate the L/B acid ratio of ZSM-5, which significantly influences product distribution. An excessively high L/B acid ratio promotes hydrogen and coke formation, leading to pore blockage and reduced conversion, whereas an appropriate L/B acid ratio facilitates mild dehydrogenation, enhancing ethylene and propylene yields. Reactant conversion followed the order: n-heptane > 3-methylhexane > methylcyclohexane. Efficient conversion of 3-methylhexane and methylcyclohexane requires catalysts with high L acid amount, strong Brønsted acid amount, optimized L/B acid ratio, as well as high specific surface area and micropore specific surface area. This study provides critical insights for designing high-efficiency alkane pyrolysis catalysts.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025041502
Microplastics (MPs), defined as plastic particles smaller than 5 mm, are ubiquitous environmental contaminants with documented presence in urban, rural, marine, remote, and polar atmospheres. The atmosphere serves as a primary medium for their long-range transport, raising concerns regarding climate interactions and human health. This review synthesizes recent advances in atmospheric MPs research, encompassing sampling strategies, pretreatment protocols, analytical techniques, occurrence characteristics, and ecological ramifications. Passive and active sampling methods are delineated, with active samplers enabling quantitative flux measurements. Pretreatment typically involves sequential steps of sieving, density separation, digestion, staining, and filtration to isolate MPs from complex matrices. Identification relies on visual inspection, micro-Fourier transform infrared spectroscopy (μ-FTIR), micro-Raman spectroscopy, laser direct infrared imaging (LDIR), and mass spectrometry. Reported atmospheric MPs predominantly exhibit dimensions below 700 μm, with fibrous morphologies being most prevalent. Color distribution is dominated by black, followed by white and transparent particles. Over 20 polymer types have been identified, with textiles, tire wear, and dust identified as principal sources. Atmospheric MPs can influence solar radiation balance, cloud formation processes, and pose risks to flora, fauna, and human health. However, research remains nascent; standardization of sampling and analytical protocols, along with comprehensive toxicological assessments, are critical knowledge gaps requiring urgent attention.
Journal of Fuel Chemistry and Technology•2026•DOI: 10.1016/S1872-5813(26)60667-6
The introduction of an appropriate amount of Cu effectively enhances the catalytic performance of ZnO-ZrO2 solid solution catalysts in CO2 hydrogenation to methanol. However, systematic studies on the effect of Cu content in ZnO-ZrO2 solid solution catalysts remain limited. In this work, a ZnO-ZrO2 solid solution and a series of Cu/ZnO/ZrO2-x catalysts (x = 0.3, 0.7 and 0.9, denoting the molar ratio of Cu/(Cu+Zn+Zr)) were prepared by co-precipitation method. Among these catalysts, the Cu/ZnO/ZrO2-0.7 catalyst exhibited the optimal catalytic performance, with a space-time yield of methanol (162.7 g/(kg·h)) that was 6.6 times higher than that of the ZnO-ZrO2 solid solution catalyst (24.8 g/(kg·h)) at 250 °C. Structural characterizations reveal that the introduction of an appropriate amount of Cu led to the coexistence of a solid solution and individual metal oxides, and promoted the formation of medium-strength basic sites. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results further confirm that Cu introduction facilitated the conversion of key reaction intermediates. This work provides a systematic investigation of the influence of Cu content on the methanol synthesis performance of ZnO-ZrO2 solid solution catalysts and elucidates the promotional mechanism induced by Cu incorporation.