火焰原子吸收光谱法测定汽车破碎残渣中重金属含量

Determination of Heavy Metals in Automobile Shredder Residues by Flame Atomic Absorption Spectrometry

采用低温酸溶、脱氯结合高温干法灰化的方法消解汽车破碎残渣（AutomotiveShredderResidues，ASR），讨论了样品消解过程中灰化时间、处理温度、酸的类型等条件对重金属的溶解及挥发损失的影响，获得了ASR样品的最佳消解条件，并利用火焰原子吸收光谱法测定了消解液中重金属Cu、Cd、Pb、Zn、Ni和Cr的含量，考察了各元素的干扰情况以及方法的检出限、准确度和精密度。研究结果表明，先加硝酸，再加硫酸，然后在350℃热解除去氯化氢，再高温（550℃）灰化，最后加浓硝酸和氢氟酸溶解灰化残渣，能够有效避免样品消解过程中重金属的损失。方法的检出限分别为0．0040mg／L（Cu）、0．0019mg／L（Cd）、0．0490mg／L（Pb）、0．0032mg／L（Zn）、0．0180mg／L（Ni）、0．0067mg／L（Cr），加标回收率为98．OO％～106．67％，相对标准偏差（RSD）为1．03％～2．84％。

The automobile shredder residues （ASR） samples were digested by high-temperature dry ashing method combined with pretreatment using acid to dissolve and dehydrochiorinate at low temperature. The influence of the time for ashing, processing temperature, the type of the acid used in the digestion process and other conditions on the dissolution and volatile loss of the heavy metals were discussed. The best digestion process of ASR samples was obtained, and six heavy metals including Cu, Cd, Pb, Zn, Ni and Cr in the digestion solution were determined by flame atomic absorption spectrometry with air-acetylene flame. The interference of the elements as well as the detection limit, accuracy and precision of the flame atomic absorption spectrometry（FAAS） were investigated. The results show that the following procedure can effectively avoid the loss of the heavy metals in the sample digestion process： add nitric acid at first and then add sulfuric acid,and then dehydrochlorinate at 350 ~C and dry ashing in high-temperature（550 ~C ）, finally, add concentrated nitric acid and hydrofluoric acid to dissolve the ash. The detection limits of this method were 0. 0040 mg/L for Cu,0. 0019 mg/L for Cd,0. 0490 rag/ L for Pb,0.0032 mg/L for Zn,0. 0180 mg/L for Ni and 0. 0067 mg/L for Cr. The recoveries were in the range of 98.00%-106.67% ,and the relative standard deviations were between 1.03% and 2.84%.