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建立了一种利用微晶吸附体系浮选分离-分光光度法测定微量镉的新方法。研究了不同影响因素,如KI、十八烷基三甲基溴化铵(OTMA)的用量、各种盐和酸度等对Cd2+浮选率的影响,探讨了Cd2+的浮选分离机理。在最佳条件下,十八烷基三甲基溴化铵阳离子(OTMA+)与I-反应产生OTMA+.I-微晶物质,由Cd2+和I-,OTMA+形成的不溶于水的三元缔合物(OTMAB)2(CdI4)被定量吸附在OTMA+.I-微晶物质表面而被浮选于盐水相上,而K+,Na+,Ca2+,Mg2+,Zn2+,Mn2+,Ni2+,Co2+,Fe2+,Al3+等离子完全不被浮选,实现了Cd2+与这些离子的定量分离,据此建立了一种测定微量Cd2+的新方法。该方法已于工业废水中微量Cd2+的测定,结果与原子吸收法相符,回收率为94.7%～107.2%。
A new method for the determination of trace cadmium by flotation separation-spectrophotometry was established. The effects of different factors, such as the amount of KI, OTMA, various salts and acidity on the flotation rate of Cd2 + were studied. The mechanism of flotation separation of Cd2 + was also discussed. Under optimal conditions, octadecyltrimethylammonium bromide cation (OTMA +) reacts with I- to produce OTMA + .I-crystallite species, a water-insoluble ternary association of Cd 2+ and I-, OTMA + (OTMAB) 2 (CdI4) was quantitatively adsorbed on the surface of OTMA + .I-crystallites and was floated on the brine phase, while K +, Na +, Ca2 +, Mg2 +, Zn2 +, Mn2 +, Ni2 +, Co2 +, Fe2 +, Al3 + Completely not flotation, to achieve a quantitative separation of Cd2 + and these ions, thus establishing a new method for the determination of trace Cd2 +. The method has been applied to the determination of trace Cd2 + in industrial wastewater. The results are consistent with those obtained by atomic absorption spectrometry. The recoveries ranged from 94.7% to 107.2%.