MCM-41介孔分子筛的合成及其对铜离子的吸附性能简

以微硅粉为硅源,CTAB和PEG-6000为模板剂,合成MCM-41介孔分子筛。采用XRD、N₂吸附-脱附曲线、FTIR以及TEM表征了其结构、比表面积、孔径分布及晶体形貌,并且以该样品为吸附剂,对含Cu²⁺的溶液进行了静态吸附实验。结果表明,以微硅粉为硅源成功合成了具有典型六方排列孔道结构的MCM-41,其比表面积为869.5 m²/g,孔容为0.97 cm³/g,平均孔径为3.3 nm;溶液pH为5~6时,MCM-41对Cu²⁺的去除效果最好;MCM-41对Cu²⁺的最大吸附吸附容量36.3 mg/g;MCM-41对Cu²⁺的吸附性能符合Langmuir吸附方程的特征。动力学研究表明,该过程符合准二级动力学模型。     

Toxicity of sediment cores from Yangtze River estuary to zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) embryos

Toxicity evaluation is an important segment in sediment quality monitoring in order to protect aquatic organisms and human health. The purpose of this study is to assess the toxicity of sediments from three sediment cores in Yangtze River Estuary, China, using the zebrafish (Danio rerio) embryo tests. Fertilized zebrafish eggs were exposed to both whole sediments and sediment organic extracts prepared from collected sediments, in order to provide a comprehensive and realistic insight into the bioavailable toxicity potential of the sediments. As end points, development parameters (mortality, hatching rate, and abnormality) in the developing embryos were recorded during the 96-h exposure. The results showed that some samples increased mortality, inhibited the hatching of embryos, and induced morphological abnormalities. The embryonic toxicities presented serrated changes and irregular distribution with depth, which may be related to hydrodynamic effect and unstable environmental input. However, lethal and sub-lethal effects were more significant at the sub-surface sediments (10～40 cm), which indicated that the pollution is more serious in recent decades.     

The influences of pH and ionic strength on the sorption of tylosin on goethite

As one of the widely used antibiotics in the world, the environmental risks of tylosin (TYL) received more and more attention. In order to assess its environmental fate and ecological effects accurately, it is necessary to understand the sorption properties of TYL on the soils/sediments. The sorption of TYL on goethite at different pH and ionic strength conditions were measured through a series of batch experiments and the sorption data of TYL were fitted by Freundlich and dual-mode sorption models. It was obvious that sorption was strongly dependent on pH and ionic strength. Sorption capacity of TYL increased as the pH increased and ionic strength decreased. The pH and ionic strength-dependent trends might be related with complexation between cationic/neutral TYL species and goethite. The sorption affinity of TYL on goethite decreased as ionic strength increased, which only occurred at higher TYL concentrations, suggested that inner complex might have dominated process at low concentrations and outer complex might occur at higher concentrations of TYL. Spectroscopic evidence indicated that tricarbonylamide and hydroxyl functional groups of TYL might be accounted for the sorption on mineral surfaces. The experimental data of TYL sorption could be fitted by surface complexation model (FITEQL), indicating that ≡FeOH with TYL interaction could be reasonably represented as a complex formation of a monoacid with discrete sites on goethite. The sorption mechanism of TYL might be related with surface complexation, electrostatic repulsion, and H-bounding on goethite. It should be noticed that the heterogeneous of sorption affinity of TYL on goethite at various environment to assess its environment risk.     

Influence of soil and hydrocarbon properties on the solvent extraction of high-concentration weathered petroleum from contaminated soils

Petroleum ether was used to extract petroleum hydrocarbons from soils collected from six oil fields with different history of exploratory and contamination. It was capable of fast removing 76–94 % of the total petroleum hydrocarbons including 25 alkanes (C₁₁–C₃₅) and 16 US EPA priority polycyclic aromatic hydrocarbons from soils at room temperature. The partial least squares analysis indicated that the solvent extraction efficiencies were positively correlated with soil organic matter, cation exchange capacity, moisture, pH, and sand content of soils, while negative effects were observed in the properties reflecting the molecular size (e.g., molecular weight and number of carbon atoms) and hydrophobicity (e.g., water solubility, octanol–water partition coefficient, soil organic carbon partition coefficient) of hydrocarbons. The high concentration of weathered crude oil at the order of 10⁵ mg kg^?1 in this study was demonstrated adverse for solvent extraction by providing an obvious nonaqueous phase liquid phase for hydrocarbon sinking and increasing the sequestration of soluble hydrocarbons in the insoluble oil fractions during weathering. A full picture of the mass distribution and transport mechanism of petroleum contaminants in soils will ultimately require a variety of studies to gain insights into the dynamic interactions between environmental indicator hydrocarbons and their host oil matrix.     

The adsorption process during inorganic phosphorus removal by cultured periphyton

To explain the detailed process involved in phosphorus removal by periphyton, the periphyton dominated by photoautotrophic microorganisms was employed in this study to remove inorganic phosphorus (P _i ) from wastewater, and the removal kinetics and isotherms were then evaluated for the P _i removal process. Results showed that the periphyton was capable of effectively removing P _i that could completely remove the P _i in 24 h at an initial P _i concentration of 13 mg P L^?1. Furthermore, the P _i removal process by the periphyton was dominated by adsorption at initial stage (~24 h), which involved physical mechanistic process. However, this P _i adsorption process was significantly influenced by environmental conditions. This work provides an insight into the understanding of phosphorus adsorption by periphyton or similar microbial aggregates.

甲苯对UASB反应器中溶解性微生物产物的影响

以乙酸钠为外加碳源,考察了UASB反应器内甲苯对可溶性微生物产物（SMP）的影响。实验结果表明：低质量浓度（20~70 mg/L）的甲苯对微生物有刺激作用,使得污泥增殖速率变小,SMP的质量浓度也逐渐减少,经过一段时间的驯化后,系统COD和TOC的去除率分别达到93%和94%以上,下降趋势较小;较高质量浓度（70~200 mg/L）的甲苯对微生物有抑制作用,污泥活性下降,反应器运行状况开始恶化,SMP的质量浓度也逐渐增大,经过一段时间的驯化后,系统COD和TOC的去除率分别维持在81%和83%以上;当甲苯质量浓度超过200 mg/L时,表现为污泥活性严重下降,对COD的去除效果极差。     

有机改性成都粘土预处理垃圾渗滤液

以成都粘土为原料,十六烷基三甲基溴化铵(HDTMA)为改性剂制备有机改性土,并将其应用于垃圾渗滤液的预处理。采用单因素静态吸附实验,以粘土对垃圾渗滤液COD和氨氮的去除率作为考查指标,初步探究有机改性土预处理垃圾渗滤液的适宜条件;并对有机改性粘土及原土进行性能表征,初步分析其吸附机理。研究结果表明,有机土的处理效果明显优于原土,处理效果上比原土提高了1.6~2.3倍;有机土预处理垃圾渗滤液适宜条件为:投加量120 g/L、搅拌速度200 r/min、搅拌时间50 min、pH=7、静置时间为6 h。