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首页> 外文期刊>Separation and Purification Technology >Solvent extraction of silver from nitric acid solutions by calix[4]arene amide derivatives
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Solvent extraction of silver from nitric acid solutions by calix[4]arene amide derivatives

机译：杯[4]芳烃酰胺衍生物从硝酸溶液中溶剂萃取银

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Solvent extraction experiments were carried out to recover silver from nitric acid solutions using as the extractants calix[4]arene tetramide(LBC)and its thio-analogue(THIO)dissolved in dichloromethane.The stoichiometry of the formation of the silver-calixarene complex differs depending on the used extractant.It was shown that one silver ion reacts with a single molecule of LBC,while two silver ions are extracted with a single THIO molecule.Very high percent extractions(>90% with LBC and>99% with THIO)were achieved with both extractants by just adding surplus extractant(THIO:0.6 mol/mol Ag~+and LBC:1.4-1.5 mol/mol Ag~+).Based on equilibrium data,the extraction isotherm relationship and the extraction constant K_(ex)for each extractant were derived.The extraction results show that THIO is an efficient extractant extracting silver either from acid or from neutral solutions with the same efficiency.Nitric acid,in the concentration range from 0 to 0.1 mol dm~(-3),strongly affects the extraction capability of LBC in less acidic solutions,reducing the percent extraction down to 40%.LBC extracts both silver and sodium collectively and with the same efficiency.The selectivity coefficient has a value close to unity(beta approx=1).THIO has demonstrated extremely high selectivity for silver over sodium in a mixture.Stripping of silver was performed by two-phase electrowinning from the loaded organic phase,thereby achieving a high stripping degree(50-90%)and reasonably high current efficiency(60-90%).The calixarenes did not change their extraction features during the electrowinning process and can be reused for extraction many times.
机译：进行了溶剂萃取实验，从杯硝酸中回收杯中的杯[4]亚芳基四酰亚胺（LBC）及其溶解在二氯甲烷中的硫代类似物（THIO）作为萃取剂。结果表明，一个银离子与单个LBC分子发生反应，而两个银离子则通过单个THIO分子进行提取。极高的提取率（LBC> 90％，THIO> 99％）只需添加过量的萃取剂（THIO：0.6 mol / mol Ag〜+和LBC：1.4-1.5 mol / mol Ag〜+）即可获得两种萃取剂。基于平衡数据，萃取等温线关系和萃取常数K_（ex萃取结果表明，THIO是从酸或中性溶液中以相同的效率萃取银的有效萃取剂。硝酸的浓度范围为0至0.1 mol dm〜（-3），强烈影响额外LBC在弱酸性溶液中的萃取能力降低到40％.LBC能够以相同的效率同时萃取银和钠。选择性系数的值接近于1（β近似= 1）。对银的混合液对钠的选择性极高。通过从负载的有机相中进行两相电解沉积进行银的汽提，从而实现了较高的溶出度（50-90％）和相当高的电流效率（60-90％）杯芳烃在电解沉积过程中没有改变其萃取特性，可以多次重复使用。

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