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991.
Laurent Goujard Pierre-Jean Roumanet Bruno Barea Yann Raoul Fabio Ziarelli Jean Le Petit Nathalie Jarroux Elisée Ferré Philippe Guégan 《Journal of Polymers and the Environment》2016,24(1):64-71
This work compares the biodegradability of polyesters produced by an esterification reaction between glycerol and oleic di-acid (D 18:1) issued from green chemical pathways, via either classical thermo-chemical methods, or an enzymatic method using the immobilized lipase of Candida antartica B (Novozym 435). An elastomeric polymer synthesized by enzymatic catalysis is more biodegradable than an elastomeric thermo-chemical polyester synthesized by a standard chemical procedure. This difference lies in percentage of the dendritic motifs, in values of the degree of substitution, and certainly in cross-links inducing an hyper-branched structure less accessible to the lipolytic enzymes in a waste treatment plant. However, when the elastomeric polymer synthesized by enzymatic catalysis is processed at high temperature as required for certain industrial applications, it presents an identical rate of biodegradation than the chemical polyester. The advantages of the thermo-chemical methods are greater speed and lower cost. Enzymatic synthesis appears be suited to producing polyesters, devoid of metallic catalysts, which must be used without processing at high temperature to keep a high biodegradability. 相似文献
992.
城市河道生态修复技术研究进展 总被引:5,自引:0,他引:5
随着城市经济和社会的发展,城市河道受到了不同程度的环境污染,严重影响了城市人们的生活质量,并对城市下一步的可持续发展起到了严重的阻碍作用,近年来由于各界的普遍关注,有关城市河道生态修复技术的研究工作也取得了相应的发展.文章首先概述了城市河道的现状,并对城市河道生态修复的内涵进行了阐述,然后介绍了一些国内外有关城市河道生态修复技术研究的现状,并对城市河道生态修复技术中的物理修复、化学修复和生物修复技术进行了系统的分类阐述;在最后展望了未来城市河道生态修复技术的发展方向. 相似文献
993.
994.
耦合光催化与生物处理4-氯酚废水 总被引:11,自引:0,他引:11
采用三相内循环式流化床光反应器和固定床生物反应器耦合处理4-氯酚(4-CP)废水。光反应器中采用粗孔硅胶负载的具有高活性和长寿命的TiO2为催化剂,处理效率高。废水的BOD5/COD及固定床生物反应器处理效果表明,4-CP为难生物降解物,光催化预处理能显著增强废水的可生化性。在单级耦合处理中,光催化预处理4h后进行生物处理,能达到最佳效率,但要完全矿化COD则需要延长预处理时间。光催化预处理为生物处理提供可降解性COD,后者却没有机会作用于前者。在多级耦合处理中,两者之间存在协同作用,使多级耦合处理效率大大提高。 相似文献
995.
Gu Zhiqi Bian Jianmin Wu Juanjuan Ruan Dongmei Yu Yexiang Zhang Han 《Environmental science and pollution research international》2022,29(14):20479-20495
Environmental Science and Pollution Research - The groundwater environment changes under the influence of anthropogenic activities. Because of the construction of the Da’an irrigation area,... 相似文献
996.
Chemical oxidative degradation of methyl tert-butyl ether in aqueous solution by Fenton's reagent 总被引:12,自引:0,他引:12
Degradation of methyl tert-butyl ether (MTBE) in aqueous solution by Fenton's reagent (Fe2+ and H2O2) was investigated. Effects of reaction conditions on the oxidation efficiency of MTBE by Fenton's reagent were examined in batch experiments. Under optimum conditions, 15 mM H2O2, 2 mM Fe2+, pH 2.8 and room temperature, the initial 1 mM MTBE solution was reduced by 99% within 120 min. Results showed that MTBE was decomposed in a two-stage reaction. MTBE was first decomposed swiftly based on a Fe2+/H2O2 reaction and then decomposed somewhat less rapidly based on a Fe3+/H2O2 reaction. The detection of Fe2+ also supported the theory of the two-stage reaction for the oxidation of MTBE by Fenton's reagent. The dissolved oxygen in the solution decreased rapidly in the first stage reaction, but it showed a slow increase in the second stage with a zero-order kinetics. A reaction mechanism involving two different pathways for the decomposition of MTBE by Fenton's reagent was also proposed. Chemicals including tert-butyl formate, tert-butyl alcohol, methyl acetate and acetone were identified to be the primary intermediates and by-products of the degradation processes. 相似文献
997.
间接原子吸收法测定水中氯化物研究 总被引:6,自引:2,他引:6
本工作以Cl^-与过量Ag^+生成AgCl沉淀反应为基础,较详细地探讨了各种强电解质作为絮凝剂对AgCl沉淀的影响,确定了反应的条件,从而提出了一个测定水中Cl^-的是接原子吸收法,Cl^-浓度在0-50μg/10ml范围呈线性,用建立的方法测定自来水中Cl^-,再现性与准确度俱佳,用本法测定废水中Cl^-的结果与经典的比浊法,和离子色谱法的结果相符。 相似文献
998.
Source apportionment of ambient total suspended particulates and coarse particulate matter in urban areas of Jiaozuo, China 总被引:2,自引:0,他引:2
Feng Y Xue Y Chen X Wu J Zhu T Bai Z Fu S Gu C 《Journal of the Air & Waste Management Association (1995)》2007,57(5):561-575
Approximately 750 total suspended particulates (TSPs) and coarse particulate matter (PM10) filter samples from six urban sites and a background site and >210 source samples were collected in Jiaozuo City during January 2002 to April 2003. They were analyzed for mass and abundances of 25 chemical components. Seven contributive sources were identified, and their contributions to ambient TSP/PM10 levels at the seven sites in three seasons (spring, summer, and winter days) and a "whole" year were estimated by a chemical mass balance (CMB) receptor model. The spatial TSP average was high in spring and winter days at a level of approximately 530 microg/m(3) and low in summer days at 456 microg/m(3); however, the spatial PMo0 average exhibited little variation at a level of approximately 325 microg/m(3), and PM10-to-TSP ratios ranged from 0.58 to 0.81, which suggested heavy particulate matter pollution existing in the urban areas. Apportionment results indicated that geological material was the largest contributor to ambient TSP/PM10 concentrations, followed by dust emissions from construction activities, coal combustion, secondary aerosols, vehicle movement, and other industrial sources. In addition, paved road dust and re-entrained dust were also apportioned to the seven source types and found soil, coal combustion, and construction dust to be the major contributors. 相似文献
999.
1000.