后处理污溶剂精馏回收工艺优化

乏燃料后处理厂运行过程中会产生大量的污溶剂,对污溶剂进行精馏处理,不仅可减少污溶剂的贮存和处理体积,还可以回收复用其中的有机溶剂,对后处理厂溶剂管理以及实现放射性废物最小化有重要意义。本文结合国内以往的工程工艺流程并对其进行优化设计,优化后的方案提高了系统的安全性和稳定性,并大大降低了能源的损耗,可为后续项目提供设计参考。

草酸甲基肼应用于污溶剂洗涤的研究

在无水乙醇溶液中制得了白色针状草酸甲基肼晶体。经过分析 ,其分子式为 (CH3N2 H4 ) 2 C2 O4 ,10 0g水中的溶解度为 2 4 1g( 2 5℃ )。研究了草酸甲基肼洗涤含少量铀的TBP的性能 ,考察了一些因素对单级洗涤实验的影响。在未经辐照情况下 ,草酸甲基肼对含铀TBP的洗涤效果略差于碳酸钠 ,对含钚TBP的洗涤效果略好于碳酸钠 ;在一定辐照剂量下 ,对钚的洗涤效果明显优于碳酸钠。草酸甲基肼洗涤CMP体系中钚的效果略好于碳酸钠 ;洗涤镅的效果优于碳酸钠。草酸甲基肼四级逆流串级洗涤含铀TBP可获得良好的洗涤效果 ,洗涤后的有机相铀浓度约为 1mg/L。

盲孔及多沟壑类金属零件的镀前清洗技术研究

盲孔及多沟壑类金属零件在机械加工过程中,容易出现顽固污渍和孔底发黑的问题,常规的镀前清洗无法彻底去除。本文提出新的清洗方案,采用新的去污溶剂配方,在不去除零件表面化学元素的情况下,有效去除了干涸油污,并开展了验证。

Distribution and transformation behaviors of heavy metals during liquefaction process of sewage sludge in ethanol-water mixed solvents

Liquefaction of sewage sludge(SS)in ethanol-water cosolvents is a promising process for the preparation of bio-oil/biochar products.Effect of the combined use of ethanol and water on the distribution/transformation behaviors of heavy metals(HMs)contained in raw SS is a key issue on the safety and cleanness of above liquefaction process,which is explored in this study.The results show that pure ethanol facilitates the migration of HMs into biochar products.Pure water yields lower percentages of HMs in mobile/bioavailable speciation.Compared with sole solvent treatment,ethanol-water cosolvent causes a random/average effect on the distribution/transformation behaviors of HMs.After liquefaction of SS in pure water,the contamination degree of HMs is mitigated from high level(25.8(contamination factor))in raw SS to considerable grade(13.4)in biochar and the ecological risk is mitigated from moderate risk(164.5(risk index))to low risk(78.8).Liquefaction of SS in pure ethanol makes no difference to the pollution characteristics of HMs.The combined use of ethanol and water presents similar immobilization effects on HMs to pure water treatment.The contamination factor and risk index of HMs in biochars obtained in ethanol-water cosolvent treatment are 13.1-14.6(considerable grade)and 79.3-101.0(low risk),respectively.In order to further control the pollution of HMs,it is preferentially suggested to improve the liquefaction process of SS in ethanol-water mixed solvents by introducing conventional lignocellulosic/algal biomass,also known as co-liquefaction treatment.

Effect of 3-aminotriazole on the corrosion of copper in polluted and unpolluted media

The inhibition of copper corrosion in unpolluted or polluted 3.5% NaCl solution in the absence and presence of 3-amino-1, 2, 4-triazole （ATA） as a corrosion inhibitor was studied by using different electrochemical techniques. Aminotriazole （ATA） is well known as corrosion inhibitor for corrosion of copper and aluminum in unpolluted salt water. The influence of 3-aminotriazole （ATA） on the corrosion behavior of copper in unpolluted and polluted environment has been studied using potentiodynamie and potentiostatic polarization methods. Surface morphological examinations such as SEM, EDS and XPS have also been carried out to understand the mechanism of inhibition of corrosion. Electrochemical measurements and morphological results are clearly show that the inhibitor is strongly adsorbed on the copper surface and form a protective film on the copper surface.

Magnetite/Reduced Graphene Oxide Nanocomposites： One Step Solvothermal Synthesis and Use as a Novel Platform for Removal of Dye Pollutants

A simple one step solvothermal strategy using non-toxic and cost-effective precursors has been developed to prepare magnetite/reduced graphene oxide （MRGO） nanocomposites for removal of dye pollutants. Taking advantage of the combined benefits of graphene and magnetic nanoparticles, these MRGO nanocomposites exhibit excellent removal efficiency （over 91% for rhodamine B and over 94% for malachite green） and rapid separation from aqueous solution by an external magnetic field. Interestingly, the performance of the MRGO composites is strongly dependent on both the loading of Fe304 and the pH value. In addition, the adsorption behavior of this new adsorbent fits well with the Freundlich isotherm and the pseudo-second-order kinetic model. In further applications, real samples--including industrial waste water and lake water--have been treated using the MRGO composites. All the results demonstrate that the MRGO composites are effective adsorbents for removal of dye pollutants and thus could provide a new platform for dye decontamination.

Use of Organic Solvents to Extract Organochlorine Pesticides (OCPs) from Aged Contaminated Soils

Problems associated with organochlorine pesticide （OCP）-contaminated sites in China have received wide attention. To solve such problems, innovative ex-situ methods of site remediation are urgently needed. We investigated the feasibility of the extraction method with different organic solvents, ethanol, 1-propanol, and three fractions of petroleum ether, using a soil collected from Wujiang （W J）, China, a region with long-term contamination of dichlorodiphenyltrichloroethanes （DDTs）. We evaluated different influential factors, including organic solvent concentration, washing time, mixing speed, solutiomto-soil ratio, and washing temperature, on the removal of DDTs from the WJ soil. A set of relatively better parameters were selected for extraction with 100 mL L-1 petroleum ether （60-90 ℃）： washing time of 180 min, mixing speed of 100 r min-I, solution-to-soil ratio of 10：1, and washing temperature of 50 ℃. These selected parameters were also applied on three other seriously OCP-polluted soils. Results demonstrated their broad-spectrum effectiveness and excellent OCP extraction performance on the contaminated soils with different characteristics.

Combining Solvent Extraction and Bioremediation for Removing Weathered Petroleum from Contaminated Soil

This study aimed to evaluate the efficacy, practicality and sustainability of a combined approach based on solvent extraction and biodegradation to remediate the soils contaminated with high levels of weathered petroleum hydrocarbons. The soils used in this study were obtained from the Shengli Oilfield in China, which had a long history of contamination with high concentrations of petroleum hydrocarbons. The contaminated soils were washed using a composite organic solvent consisting of hexane and pentane （4：1, v/v） and then bioremediated in microcosms which were bioaugmentated with Bacillus subtilis FQ06 strains and/or rhamnolipid. The optimal solvent extraction conditions were determined as extraction for 20 min at 25 ~C with solvent-soil ratio of 6：1 （v/w）. On this basis, total petroleum hydrocarbon was decreased from 140000 to 14000 mg kg-1, which was further reduced to 〈 4000 mg kg-1 by subsequent bioremediatton for 132 d. Sustainability assessment of this integrated technology showed its good performance for both short- and long-term effectiveness. Overall the results encouraged its application for remediating contaminated sites especially with high concentration weathered hydrocarbons.