电白槽液中磷酸氢二钠和碳酸纳的分析

Analysis of Na_2HPO_4 and Na_2CO_3 in the White Copper-tin Alloy Plating Bath

介绍了电白槽液中磷酸氢二钠和碳酸钠的分析方法。用磷钼蓝光度法测定电白槽液中磷酸氢二纳的质量浓度,用过硫酸铵破坏氰化物,消除其对测定的干扰。在硫酸介质中,以抗坏血酸作还原剂,硝酸铋作催化剂,使磷酸与钼酸钠生成杂多酸蓝色络合物,以显色剂作参比液,在波长660nm处测定吸光度。试验表明,镀液中的铜离子和其它组份对测定无影响,本法相对平均偏差为1.3%,回收率为97.3%-103%。用硝酸银掩蔽氰化钠,以酚酞作指示剂,用盐酸滴定法直接测定电白槽液中碳酸钠的质量浓度。试验表明,镀液中的Na2[Sn(CN)4]、Na2[Cu(CN)2]和磷酸氢二钠对测定无干扰,本法相对平均偏差为0.54%,回收率为101%。而用传统的铜锡合金镀液分析方法,电白槽中的磷酸氢二钠严重影响碳酸钠的测定。

This paper has introduced the analysis methods of Na2HPO4 and Na2CO3 in the white copper-tin alloy plating bath.The concentration of Na2HPO4 in a white copper-tin alloy bath is determined with a spectrophotometric method.Cyanide is oxidized by ammonium persulfate to eliminate its influence on the determination.Phosphoric acid reacts with sodium molybdate to form blue heteropolyacide complex with cevitamic acid as reducing agent and bismuth nitrate as catalyst.The absorbancy is determined using color develop...