Fabrication and performance of PET mesh enhanced cellulose acetate membranes for forward osmosis

Polyethylene terephthalate mesh(PET) enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis(FO) mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2 μm. The performance of the optimal FO membrane was tested using 0.2 mol/L Na Cl as the feed solution and 1.5 mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47 L/(m2·hr) and salt rejection of95.48% in FO mode. While in pressure retarded osmosis(PRO) mode, the water flux was4.74 L/(m2·hr) and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.     

Evaluation of the readsorption of plutonium and americium in dynamic fractionations of environmental solid samples

A dynamic extraction system exploiting sequential injection (SI) for sequential extractions incorporating a specially designed extraction column is developed to fractionate radionuclides in environmental solid samples such as soils and sediments. The extraction column can contain up to 5 g of a soil sample, and under optimal operational conditions it does not give rise to creation of back pressure. Attention has been placed on studies of the readsorption problems during sequential extraction using a modified Standards, Measurements and Testing (SM&T) scheme with four-step sequential extractions. The degree of readsorption in dynamic and conventional batch extraction systems is compared and evaluated by using a double-spiking technique. A high degree of readsorption of plutonium and americium (>75%) was observed in both systems, and they also exhibited similar distribution patterns of the two radionuclides. However, the dynamic system is fully automated, eliminates manual separations, significantly reduces the operational time required, and offers detailed kinetic information.     

石油污染土壤的植物修复研究进展

石油的开采、加工、输送及使用过程中,对大气、土壤、水体带来了严重污染,对土壤环境的危害尤为严重。植物修复以其处理成本低、吸收污染物的生物量大等优点已成为人们普遍能接受的去除污染物的首选技术。植物主要通过三种途径去除土壤中有机污染物,即植物直接吸收有机污染物;释放分泌物和酶,刺激根区微生物活性和生物转化作用;增强根区的矿化作用。植物修复石油烃污染土壤的影响因素有:环境条件、污染物的浓度和滞留时间、营养元素、表面活性剂、根系分布等。通过植物-微生物联合修复、机械-微生物-植物多技术联用等措施,可提高石油烃的降解率。     

Preparation of high concentration polyaluminum chloride by chemical synthesis-membrane distillation method with self-made hollow fiber membrane

A method of direct contact membrane distillation (DCMD) with a self-made hollow polyvinylidene fluoride membrane was applied to prepare high concentration polyaluminum chloride (PACl) with high Al_b content based on chemical synthesis. The permeate flux and Al species distribution were investigated. The experimental results showed that the permeate flux decreased from 14 to 6 kg/(m²·hr) at the end of the DCMD process, which can be mainly attributed to the formation of NaCl deposits on the membrane surface. The Al_b content decreased slightly, only from 86.3% to 84.4%, when the DCMD experiment finished, correspondingly the Al_c content increased slightly from 7.2% to 8.5%, and the Al_a content remained at 7% during the whole DCMD process. A PACl with Al_b content of 84% at total aluminum concentration 2.2 mol/L was successfully prepared by the chemical synthesis-DCMD method.     

某联合站轻烃回收装置职业病危害控制效果评价

目的:评估职业病防护设施防护效果,促进现场职业病防护,保护职工身体健康。方法:运用职业卫生检测法、现场调查法等方法对某建设项目进行职业病危害控制效果卫生学评价。结果:有毒物质检测均符合相关标准要求,天然气压缩机处噪声达94.3dB(A),超过职业接触限值。结论:改进噪声防护设施,达到相关标准要求。     

Fast determination of sulfonamides and their acetylated metabolites from environmental water based on magnetic molecularly imprinted polymers

Group-selective magnetic molecularly imprinted polymers (MMIPs) that can extract four widely used sulfonamide antibiotics and their acetylated metabolites from environmental water were synthesized in this study. The MMIPs with saturation magnetization value of 16.7 emu g^-1 could be separated from the environmental water samples easily by the application of an adscititious magnetic field, reducing the time consumption of pretreatment. The extraction conditions were evaluated, and optimal extraction conditions were as follows: extraction time, 25 min; amount of polymers, 90 mg; washing solvent, 30 % methanol aqueous solution; and elution solvent, methanol–acetic acid (95:5, v/v). The target analytes were detected by liquid chromatography–tandem mass spectrometry, and the detection limits of the method are in the range of 0.38–1.32 ng L^-1. The relative standard deviations of intra- and inter-day are in the range of 1.3–6.8 % and 1.7–9.1 %, respectively. The proposed method is suitable for the analysis of environmental water samples.     

Response to environmental flows in the Lower Tarim River, Xinjiang, China: an ecological interpretation of water-table dynamics

Increased water-dependent development and utilization have led to significant environmental and hydrological degradation of the Tarim River in western China and its dependent ecosystems. Between the 1950s and 1970s, 350 km of the lower reaches were drained and between 1960 and 1980 the water-table fell from between −2 and −3 m to between −8 and −10 m. Subsequently, riparian ecosystems were seriously degraded. In 2000, the Chinese government launched a program to restore the lower reaches of the river. Four environmental flows of 1034×10⁶ m³ were released from 2000 to 2002. This paper interprets and discusses the ecological significance of changes following the releases and identifies the relationship between water-table dynamics and vegetation responses. Short-term objectives for river restoration are proposed with possible monitoring parameters suggested.     

水电工程抗震设防概率水准和地震作用概率模型

本文基于我国已有的二十余个重大水利水电工程场地地震危险性分析的结果,运用概率分析方法探讨了水电工程抗震设防的概率水准和地震作用的概率模型,以便为正在修订中的《水工建筑物抗震设计规范》提供依据。     

依靠政府职能、科技进步、公众参与三者紧密结合,搞好大中城市地震应急工作

总结了在南黄海６．１级地震应急中的成功经验：本省及有关城市充分发挥防震减灾工作的政府职能，各级领导决策及时，指挥果断、地震专业科技人员尽心尽职，迅速判断震情，安抚民心以及新闻部门反应快，报道勤，收效好。并由此提出南黄海６．１级地震应急的３点体会和进一步做好大中城市地震应急工作的３点建议     

水合氧化钛对Cr(Ⅵ)吸附的试验研究

研究了水合氧化钛对水中Cr （Ⅵ）离子的吸附作用。结果表明，吸附过程符合Freundlich经验公式，最佳吸附PH值范围为2≤PH≤4，温度对吸附作用影响较小，采用NaOH溶液可使水合氧化钛的吸附能力得到较好再生。