El-Shahawi M S, El-Sonbati M A
Chemistry and Environmental Science Department, Faculty of Science at Damietta, Mansoura University, Mansoura, Egypt.
Talanta. 2005 Oct 15;67(4):806-15. doi: 10.1016/j.talanta.2005.04.012.
Polyurethane foams (PUFs) loaded with the chromogenic reagent 4,4'-dichlorodithizone (Cl(2)H(2)D(Z)) have been investigated for the quantitative retention, chemical speciation and sequential determination of traces of inorganic selenium(IV) and (VI) from aqueous media containing bromide ions. The retention profile of selenium(IV) onto the reagent loaded foam followed a dual-mode sorption mechanism involving both absorption related to "solvent extraction" and an added component for surface adsorption. The kinetics and thermodynamic characteristics of selenium(IV) uptake onto PUFs have been studied. The kinetics of selenium(IV) sorption onto PUFs was found fast, reached equilibrium in few minutes and followed a first-order rate constant in presence of bromide ions in the extraction media. The thermodynamic parameters, DeltaH, DeltaS and DeltaG, indicated the exothermic and spontaneous nature of the sorption process. The sorption and the recovery percentages of inorganic selenium(IV) from fresh water by the proposed loaded foam columns were achieved quantitatively. The height equivalent to theoretical plate (HETP), the number of layers (N), breakthrough capacity and the critical capacity for selenium(IV) uptake onto Cl(2)H(2)D(Z) loaded foams columns were found to be 1.3, 103, 8.6 and 7.2 mg/g, respectively. The method was successfully applied for the chemical speciation and sequential determination of inorganic selenium(IV) and/or (VI) species spiked to fresh and industrial wastewaters.
负载显色剂4,4'-二氯双硫腙（Cl₂H₂D(Z)）的聚氨酯泡沫（PUF）已被用于从含溴离子的水介质中定量保留、化学形态分析及痕量无机硒（IV）和（VI）的连续测定。硒（IV）在负载试剂的泡沫上的保留情况遵循双模式吸附机制，包括与“溶剂萃取”相关的吸收以及表面吸附的附加成分。研究了硒（IV）在PUF上的吸附动力学和热力学特性。发现硒（IV）在PUF上的吸附动力学很快，在几分钟内达到平衡，并且在萃取介质中存在溴离子的情况下遵循一级速率常数。热力学参数ΔH、ΔS和ΔG表明吸附过程是放热且自发的。通过所提出的负载泡沫柱对淡水中无机硒（IV）的吸附和回收率实现了定量。负载Cl₂H₂D(Z)的泡沫柱上硒（IV）的理论塔板高度（HETP）、层数（N）、穿透容量和临界容量分别为1.3、103、8.6和7.2 mg/g。该方法成功应用于加标到淡水和工业废水中的无机硒（IV）和/或（VI）物种的化学形态分析及连续测定。
