单晶硅原料中铝的分离和测定

Separation and Determination of Aluminum in Elementary Silicon

单晶硅原料溶于浓氢氟酸中,基体硅以SiF4形式挥发除去。残渣溶于硝酸及盐酸中,再加高氯酸并蒸发至近干,残渣用盐酸(1+1)使其完全溶解。分取部分试液,在pH 4.5的六胺缓冲介质中用吐温-20,PAR及(NH4)2SO4,在总体积为10 mL的溶液中进行萃取。经过萃取可分离除去全部共存的Fe(Ⅲ),Cu(Ⅱ),Cr(Ⅲ)及Ni(Ⅱ),部分钴(Ⅱ)和铅(Ⅱ),而Al(Ⅲ)则与Ca(Ⅱ),Mg(Ⅱ)及Na(Ⅰ)定量地留在下层水相中。用分光光度法在CPC存在下,CAS为显色剂测定下层水相中铅含量,光度测定波长为642 nm,方法的线性范围为0.02~0.50 mg.L-1,检出限为0.01 mg.L-1也试验了方法的回收率及精密度,所测得回收率在96%~101%之间,相对标准偏差(n=5)均小于3.5%。

Sample of elementary silicon was dissolved in conc.HF and the matrix silicon was expelled by volalitalization as SiF4↑. The residue was taken up with HNO3 and HCl and evaporated to near dryness by fuming with HClO4.After dissolving the residue with HCl(1+1),an aliquot of the solution was taken and extracted with Tween-20,PAR and(NH4)2SO4 in a total volume of 10 mL at pH 4.5 buffered with hexamine,to remove all of the co-existing Fe(Ⅲ),Cu(Ⅱ),Cr(Ⅲ) and Ni(Ⅱ),part of Co(Ⅱ) and Pb(Ⅱ),while Al(Ⅲ) remained quanti...