Effect of sulfur source on photocatalytic degradation performance of CdS/MoS2 prepared with one-step hydrothermal synthesis

Cd S/Mo S_2,an extremely efficient photocatalyst,has been extensively used in hydrogen photoproduction and pollutant degradation.Cd S/Mo S_2can be synthesized by a facile one-step hydrothermal process.However,the effect of the sulfur source on the synthesis of Cd S/Mo S_2via one-step hydrothermal methods has seldom been investigated.We report herein a series of one-step hydrothermal preparations of Cd S/Mo S_2using three different sulfur sources:thioacetamide,L-cysteine,and thiourea.The results revealed that the sulfur source strongly affected the crystallization,morphology,elemental composition and ultraviolet(UV)–visible-light-absorption ability of the Cd S/Mo S_2.Among the investigated sulfur sources,thioacetamide provided the highest visible-light absorption ability for Cd S/Mo S_2,with the smallest average particle size and largest surface area,resulting in the highest efficiency in Methylene Blue(MB)degradation.The photocatalytic activity of Cd S/Mo S_2synthesized from the three sulfur sources can be arranged in the following order:thioacetamideL-cysteinethiourea.The reaction rate constants(k)for thioacetamide,L-cysteine,and thiourea were estimated to be 0.0197,0.0140,and 0.0084 min~(-1),respectively.However,thioacetamide may be limited in practical application in terms of its price and toxicity,while L-cysteine is relatively economical,less toxic and exhibited good photocatalytic degradation performance toward MB.     

A novel graphene oxide-carbon nanotubes anchored α-FeOOH hybrid activated persulfate system for enhanced degradation of Orange II

Persulfate activation has been applied as one of the efficient advanced oxidation processes(AOPs) to remediate polluted environments. In this study, a novel α-FeOOH anchored by graphene oxide(GO)-carbon nanotubes(CNTs) aerogel(α-FeOOH@GCA) nanocomposite activated persulfate system(α-FeOOH@GCA + K_2S_2O_8) was applied for decolorization of Orange Ⅱ(OⅡ). The decolorization of OⅡ was remarkably enhanced to a level of ～ 99% in this system compared with that of pristine α-FeOOH(～ 44%) or GO-CNTs(～18%). The enhanced catalytic activity of α-FeOOH@GCA was due to the formation of a heterojunction byα-FeOOH and GO-CNTs as confirmed by the presence of Fe–O–C chemical bonds. The degradation intermediates of OⅡ were comprehensively identified. The proposed degradation pathway of OⅡ begins with the destruction of the conjugated structures of OⅡ by the dominant reactive oxygen species, surface-bound SO_4~(·-). The decolorization efficiency of OⅡ by the α-FeOOH@GCA activated persulfate system decreased from the first to third cycle of recycling. Ultraviolet(UV) irradiation or introduction of a small amount of Fe~(2+) could restore the activation of this system. The results show that the α-FeOOH@GCA persulfate activation system promises to be a highly efficient environmental remediation method for organic pollutants.     

Brominated dioxins and furans in a cement kiln co-processing municipal solid waste

A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).     

呼吸型填埋场覆盖层技术研究Ⅰ：热动力自充氧装置构建

填埋场最终覆盖层（以下简称＂覆盖层＂）中的氧气含量是影响甲烷氧化效果的重要因素.本研究基于空气热力学原理提出了一种呼吸型覆盖层技术,构建了利用垃圾堆体与外界环境的温差而实现覆盖层自充氧的热动力自充氧装置,并优化了其空气/氧气充气效率.结果表明,导气管路内空气流速（v）与温差（ΔT）呈线性关系（v=0.0281ΔT-0....     

同步脱氮除磷复配菌剂对河流水质净化效果研究

通过选择培养基、溴麝香草酚蓝（Bromothymol Blue,BTB）培养基筛选及脱氮除磷性能检测,从城市河道中成功筛选出6株异养硝化-好氧反硝化菌株,分别属于假单胞菌属（Pseudomonas）、产碱杆菌属（Alcaligenes）、无色杆菌属（Achromobacter）和陶厄氏菌属（Thauera）,其中3株菌株兼具硝化、反硝化和聚磷能力,菌株MC-5除磷能力最优.在此基础上,将筛选出的6株单菌株进行复配,考察了复配菌剂在不同COD/TN下的脱氮除磷性能.根据群落结构变化分析,发现复配菌剂中的产碱杆菌属在脱氮除磷中发挥了更为关键的作用.水中碳源耗尽时补加碳源能显著提升复配菌剂的脱氮除磷性能,氨氮和总磷去除率分别由55.87%和50.48%提高到100%和98.89%,而水中COD/TN高于20会对微生物产生抑制作用.探究复配菌剂处理受污染河水最佳投加量的试验结果表明,投加量为1.69 g·m-3时,总磷指标能够从地表水劣Ⅴ类提高至Ⅲ类水质标准,氮类指标能够提升至接近地表水Ⅴ类水质标准.适当提高菌剂投加量能提高氮、磷元素降解速率,缩短河道水质修复时间.这说明本研究中的同步脱氮除磷...     

Time-dependent metabolomics uncover dynamic metabolic adaptions in MCF-7 cells exposed to bisphenol A

● Metabolomic temporal profiling of cells exposed to xenobiotics. ● Global metabolome dysregulation patterns with time-resolved landscapes. ● Synchronized regulation behavior and specific dysregulation sensitivity. ● Temporal metabolic adaptions indicated cellular emphasis transition. The biochemical consequences induced by xenobiotic stress are featured in dose-response and time-resolved landscapes. Understanding the dynamic process of cellular adaptations is crucial in conducting the risk assessment for chemical exposure. As one of the most phenotype-related omics, metabolome in response to environmental stress can vary from seconds to days. Up to now, very few dynamic metabolomics studies have been conducted to provide time-dependent mechanistic interpretations in understanding xenobiotics-induced cellular adaptations. This study aims to explore the time-resolved metabolite dysregulation manner and dynamically perturbed biological functions in MCF-7 cells exposed to bisphenol A (BPA), a well-known endocrine-disrupting chemical. By sampling at 11 time points from several minutes to hours, thirty seven significantly dysregulated metabolites were identified, ranging from amino acids, fatty acids, carboxylic acids and nucleoside phosphate compounds. The metabolites in different pathways basically showed distinct time-resolved changing patterns, while those within the common class or same pathways showed similar and synchronized dysregulation behaviors. The pathway enrichment analysis suggested that purine metabolism, pyrimidine metabolism, aminoacyl-tRNA biosynthesis as well as glutamine/glutamate (GABA) metabolism pathways were heavily disturbed. As exposure event continued, MCF-7 cells went through multiple sequential metabolic adaptations from cell proliferation to energy metabolism, which indicated an enhancing cellular requirement for elevated energy homeostasis, oxidative stress response and ER-α mediated cell growth. We further focused on the time-dependent metabolite dysregulation behavior in purine and pyrimidine metabolism, and identified the impaired glycolysis and oxidative phosphorylation by redox imbalance. Lastly, we established a restricted cubic spline-based model to fit and predict metabolite’s full range dysregulation cartography, with metabolite’ sensitivity comparisons retrieved and novel biomarkers suggested. Overall, the results indicated that 8 h BPA exposure leaded to global dynamic metabolome adaptions including amino acid, nucleoside and sugar metabolism disorders, and the dysregulated metabolites with interfered pathways at different stages are of significant temporal distinctions.     

反硝化脱硫菌的代谢特征及其环境应用研究进展

反硝化脱硫菌(NR-SOB)是一种具有同步硝酸盐还原和硫氧化能力的功能微生物。探讨了NR-SOB的代谢特征及其影响因素,并对它在废水处理,防腐,天然气、工业废气脱硫方面的应用进行了综述。最后,还指出了今后NR-SOB在环境应用方面的研究方向。     

泄爆夹层内障碍物对泄爆效果影响的数值模拟研究

为研究泄爆夹层内障碍物位置对燃气泄爆效果的影响,以某大型商业综合体暗厨房为研究对象,考虑泄爆夹层中结构梁不同位置的泄爆效果,对暗厨房燃气爆炸的泄爆过程开展数值模拟研究。研究结果表明：在火焰没有到达泄爆窗前的爆炸初始阶段,障碍物对火焰结构和传播速度基本没有影响,当火焰进入泄爆夹层后,障碍物的存在可引发火焰加速现象;当障碍物距离泄爆窗1.7 m时,火焰加速现象较为明显,火焰最大传播速度可达591.5 m/s,此时厨房内压力峰值约2.9 MPa,约为没有结构梁情况下1.42倍;障碍物距离泄爆窗较近时,二者将协同影响火焰传播;厨房内压力峰值随着障碍物与泄爆窗距离的增大遵循增大-突降-增大的规律。研究结果可为商业综合体暗厨房泄爆设计提供一定理论依据。     

荧光法生物气溶胶监测仪标准物质研制及校准方法研究

生物气溶胶监测仪是利用激光或紫外光诱导生物粒子发射荧光,从而实现对空气中的生物气溶胶进行监测的仪器.目前,国内尚无生物气溶胶监测仪校准用标准物质和评价方法.以聚苯乙烯微球为核,通过Friedel-Crafts酰基化反应,研制出能够自身受激发产生荧光的聚苯乙烯(PS-PB)微球.PS-PB微球粒径分布的相对标准偏差为1....     

Abundance and distribution of ammonia-oxidizing archaea in Tibetan and Yunnan plateau agricultural soils of China

As low oxygen and high ultraviolet （UV） exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea （AOA） in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR （q-PCR） and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria （AOB）, and characterize the community structures of AOA in the samples. The number of AOA cells （9.34 × 10^7-2.32× 10^8 g^-1 soil） was 3.86-21.84 times greater than that of AOB cells （6.91 × 10^6-1.24 × 10^8 g^-1 soil） in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall＇s correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance.