聚乙烯醇-Cr^(3+)树胶状物的形成

FORMATION OF RESINOUS SUBSTANCE FROM POLYVINYL ALCOHOL AND Cr(Ⅲ)

在12≤pH≤13的5%PVA中添加0.2g CrCl_3·6H_2O有灰蓝色树胶状物析出。XPS、ESR、IR和电泳等研究表明,PVA的部分羟基发生脱质子反应而提供配位基L^-该配位基能与Cr(Ⅲ)盐和NaOH生成的初生Cr(OH)_3·nH_2O的Cr^(3+)形成配位键,从而发生配位体与Cr^(3+)间的交联反应,生成Cr(Ⅲ)-PVA配位聚合物。该析出物具有顺磁性,溶于盐酸,从而可用以富集和回收Cr(Ⅲ)。

A greyish blue resinous substance was separated by adding Cr^(3+) to a basic aqueous solution of 5% PVA at 12≤pH≤13. The formation of the resinous substance has been studied by XPS,ESR, IR and electrophoretie techniques. It is considered that at the experimental conditions deprotonation of some hydroxyl groups in the PVA may afford a ligand L^- which may form coordinate with Cr^(3+) through partial ionic bond. Thus,it results in a cross-linking between Cr^(3+) and deprotonated hydroxyl groups of PVA. The product is paramagnetic. This phenomena may be applied to treating Cr^(3+) containing waste for chromium recovery by dissolving the complex in hydrochloric acid.