聚合物材料中六价铬萃取方法研究

Extraction Methods for Hexavalent Chromium in Polymers

本研究作为起草国际电工委员会标准IEC62321,Ed.1的第3次国际实验室间比对实验的一部分,考察了用碱溶液对聚合物样品中六价铬进行萃取时样品的基体材料、粒径和萃取时间对萃取效率的影响。研究选取了3种不同粒径(<125μm,125～250μm和250～500μm)的ABS、PVC和EVA/PE样品。用50mL0.5mol/LNaOH-0.28mol/LNa2CO3混合碱性消解液在90～95℃下萃取样品中的六价铬,并在1～6h内逐渐增加萃取时间。测试结果表明:聚合物中六价铬的萃取率明显地受到样品基体材料的影响,PVC材料有很好的萃取效果,ABS中的六价铬也能被有效萃取出;而EVA/PE材料中的六价铬则几乎不能被萃取。对PVC和ABS,3h的萃取时间基本能达到最大萃取率,而样品粒径在减小至<250μm后,萃取率会明显提高。

As a part of international inter-labs study aiming to draft the section of standard IEC62321 regard- ing the measurement of Cr（VI） in polymers, the influences of matrix materials, powder size and extraction duration on extraction efficiency of Cr（VI） in alkaline solution have been investigated. Polymers including acrylonitrile buladiene slyrene （ABS）, polyvinyl chloride （PVC） and elhylene vinyl acetate/polyethylene copolymer （EVA/PE） of three different sizes （ 〈 125 μm, 125 -250 μm, 250 -500 μm） have been selected as samples for this investigation. The samples were digested at 90 -95 ℃ in the alkaline solution of mixture of 0. 28 mol/L Na2CO3 and 0.5 mol/L NaOH, and extraction duration varies from one to six hours. The test results show that the extraction efficiency of Cr（VI） in polymers is dramatically influenced by matrix materials. The extraction efficiency is good for PVC, and tolerable for ABS. But it is almost impossible to extract Cr（VI） from EVA/PE. The maximum extraction efficiency can be achieved within the extraction dura- tion of 3 hours for PVC and ABS. The powder size less than 250 μm will obviously enhance the extraction efficiency.