活性炭吸附-X射线荧光光谱法测定电子废弃物中金

电子废弃物中金含量高,传统分析方法操作手续繁杂,分析时间长且对技术要求较高。实验方法采用王水将一定量的含金电子废弃物溶解后定容到100mL容量瓶中,依据金含量高低分取一定体积样品溶液于烧杯中保持介质酸度为5%~30%,加入1.5g活性炭进行静态吸附,然后将活性炭与微晶纤维素按质量比1∶1混合均匀,采用粉末压片-X射线荧光光谱法(XRF)测定其中金的含量。活性炭吸附使电子废弃物大量的基体物质与金分离,从而使分析样片基体主要由活性炭和微晶纤维素组成,由不同分析样品制成的分析样片基体组成基本相同,同时采用金谱线背景作为内标进一步校正基体效应。选择Au-Lα谱线,Ge晶体和适当的PHA范围消除了谱线干扰,方法的检出险为5μg。对3个不同金含量的电子废弃物样品进行精密度考察,结果的相对标准偏差(RSD,n=12)为1.3%~2.0%。对电子废弃物样品的分析结果经与氢醌滴定法对比,基本一致。实验方法避免了化学湿法中高温灰化、滴定等繁杂的手工操作,可以应用于电子废弃物中含量在0.x~xx.xg/kg范围内金的测定。

Determination of gold in electronic wastes by X-ray fluorescence spectrometry with activated carbon adsorption

The content of gold in electronic wastes is high. The operation procedures in traditional analysis methods are complicated and time-consuming. Moreover, these methods usually require high technical skills. In experiments, certain amount of gold-containing electronic wastes was dissolved with aqua regia. The solution was transferred into 100mL volumetric flask and then diluted to the mark. According to the content of gold, certain volume of sample solution was transferred into beaker. The acidity was maintained in range of 5%-30%. And 1.5g of activated carbon was added for static adsorption. Then the activated carbon was mixed uniformly with microcrystalline cellulose in mass ratio of 1∶1. The content of gold was determined by X-ray fluorescence spectrometry (XRF) with pressed powder pellet. The activated carbon adsorption realized the separation of gold from a large amount of matrix materials in electronic wastes. The specimen matrix for analysis was mainly composed of activated carbon and microcrystalline cellulose. In other words, the composition of specimen matrix for analysis prepared from different samples was basically same. The matrix effect was further corrected using spectral background of gold as internal standard. The spectral interference was eliminated by selecting Au-Lα line, Ge crystal and proper PHA range. The detection limit was 5μg. The precision tests were conducted using three electronic waste samples with different gold contents. The relative standard deviations (RSD, n=12) of determination results were between 1.3% and 2.0%. The analysis results of electronic waste samples were basically consistent with those obtained by hydroquinone titration method. The complicated manual operations such as high-temperature ashing and titration in wet chemical method were avoided in experiments. The proposed method was applicable for the determination of gold in electronic wastes with content in range of 0.x-xx.x g/kg.