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791.
Sorption of tylosin and sulfamethazine on solid humic acid 总被引:3,自引:0,他引:3
Tylosin(TYL) and sulfamethazine(SMT) are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid(HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions(pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H(2.0–7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~+/SMT~+ species and the functional groups of HA.Increasing ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared(FT-IR) and ~13C-nuclear magnetic resonance(NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions. 相似文献
792.
纳米铁由于其反应活性强、来源广泛等优点被广泛应用在去除地下水NO-3-N污染中.利用生物表面活性剂对纳米铁进行改性可以避免采用化学表面活性剂改性对环境造成的二次污染.本研究采用鼠李糖脂、茶皂素、无患子3种生物表面活性剂对纳米铁进行改性后附着在活性炭上构成改性纳米铁/炭复合材料,通过批试验、沉降试验、迁移试验等研究生物表面活性剂对纳米铁/炭复合材料的改性作用.结果表明:鼠李糖脂、茶皂素、无患子对纳米铁/炭改性后去除NO-3-N效果最佳时的投加量分别为0.7%、1.0%、0.7%,此时对比三者改性作用,鼠李糖脂改性纳米铁/炭去除NO-3-N效果最佳,无患子改性纳米铁/炭迁移效果最佳;鼠李糖脂投加量在0.1%到1.3%范围内时,改性纳米铁/炭迁移能力随投加量的增加而增大. 相似文献
793.
采用超声辅助沉淀法—浸渍法制备了WO3/Ag3VO4复合光催化剂,对其进行了表征,考察了其在可见光条件下对罗丹明B的催化降解性能,并对催化机理进行了探讨。表征结果显示:WO3紧密包覆在Ag3VO4颗粒的表面,并未改变Ag3VO4的晶体结构;与Ag3VO4和WO3相比,WO3/Ag3VO4的吸收带边发生了红移。实验结果表明:w(WO3)为3.5%时,WO3/Ag3VO4对罗丹明B的可见光催化降解效果最好;在光催化剂加入量0.8 g/L、初始罗丹明B质量浓度10 mg/L的条件下,于室温下光照180 min时的罗丹明B去除率达95.76%,TOC去除率达96.5%;WO3与Ag3VO4在能带间的耦合作用下形成异质结结构,很好地抑制了光生电子-空穴对的复合。 相似文献
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795.
796.
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798.
Certain organic carbon moieties in drinking source waters of the Sacramento-San Joaquin Delta can react with chlorine during disinfection to form potentially carcinogenic and mutagenic trihalomethanes. The properties of reactive organic carbon in Delta waters, particularly those of soil origin, have been poorly understood. This study attempts to characterize trihalomethane reactivity of soil organic carbon from three representative Delta peat soils. Soil organic carbon was extracted from all three soils with either deionized H2O or 0.1 M NaOH and sequentially separated into humic acids, fulvic acids, and nonhumic substances for quantitation of trihalomethane formation potential. Water-extractable organic carbon represented only 0.4 to 0.7% of total soil organic carbon, whereas NaOH extracted 38 to 51% of total soil organic carbon. The sizes and specific trihalomethane formation potential (STHMFP) of individual organic carbon fractions differed with extractants. Fulvic acids were the largest fraction in H2O-extractable organic carbon, whereas humic acids were the largest fraction in NaOH-extractable organic carbon. Among the fractions derived from H2O-extractable carbon, fulvic acids had the greatest specific ultraviolet absorbance and STHMFP and had the majority of reactive organic carbon. Among the fractions from NaOH-extractable organic carbon, humic acids and fulvic acids had similar STHMFP and, thus, were equally reactive. Humic acids were associated with the majority of trihalomethane reactivity of NaOH-extractable organic carbon. The nonhumic substances were less reactive than either humic acids or fulvic acids regardless of extractants. Specific ultraviolet absorbance was not a good predictor of trihalomethane reactivity of organic carbon fractions separated from the soils. 相似文献
799.
800.
厌氧UASB-混凝沉淀法处理高浓度屠宰废水 总被引:7,自引:1,他引:6
应用UASB混凝沉淀法对高浓度屠宰废水的处理进行了试验研究。用UASB反应器处理屠宰废水,CODCr容积负荷可达6.8g(L·d),CODCr去除率达93%左右,并对UASB出水投加一定量的混凝剂PFS和助凝剂MZ,实验表明:系统出水达到《肉类加工工业水污染物排放标准》(GB1345792)二级标准。 相似文献