材料期刊网

泡沫塑料富集—硫脲解脱—原子吸收法测定含钨、钼矿石中金的分析结果严重偏低的原因在于样品预处理过程中形成的H2 WO4、H2 MoO4胶状物捕集了部分AuCl4-,导致溶液中AuCl4-与泡沫塑料上活性基团—RNH3+的离子交换程度降低,而与AuCl4-竞争被泡沫塑料同时吸附的WO2-4 、MoO2-4 与泡沫塑料上—RNH3+结合,再次成为捕集硫脲解脱产物Au[SC(NH2)2]2+的类胶状体. 通过控制样品分解溶液的酸度,加入适量Fe(Ⅲ)和NH4 NO3 ,可确保溶液中Au(Ⅲ)的稳定性,将可能的H2 WO4、H2 MoO4胶状物转化为可溶性盐;将硫脲解脱载金泡沫塑料改为无臭灰化载金泡沫塑料,确保了Au的回收率. 该方法操作简便,用于国家标准物质测定,其分析结果的精密度(RSD)小于1.29 %,与标准值的相对误差(RE)小于0.92 %.

Determination of gold in W,Mo ores by foam plastics-thiourea desorption-AAS is significantly lower due to the colloidal H2 WO4 ,H2 MoO4 formed in the sample pretreatment process.The colloids collect part of AuCl4-leading to a lower degree of ion exchange of AuCl4-in solutions and the active group RNH3+in foam plastics,whereas foam plastics-adsorbed WO2-4 ,MoO2-4 competing with AuCl4-in binding RNH3+forms similar colloids to capture thiou-rea desorption product Au[ SC( NH2 ) 2 ] 2+.With proper addition of Fe (Ⅲ) and NH4 NO3 and sample decomposition solution acidity controlled,the stability of Au(Ⅲ) in solutions is guaranteed and colloidal H2 WO4 and H2 MoO4 are transformed to soluble salts;thiourea desorption gold-bearing plastics is transformed to smell-less ashing,ensuring the Au recovery.The method is easily accessible with the result precision(RSD) less than 1.29%when assaying the na-tional standard substance,and the relative error(RE) less than 0.92 %.