摘要
自虾、蟹壳等水产加工废料中提取的甲壳质,经脱乙酰基反应,可得氨基葡聚糖,单体结构可表示为左图。该碱性多糖无毒,不溶于水及碱性溶液,在pH～4.5的稀酸中会溶涨,酸性更强时可溶解并成盐。若要求该聚合物以稳定的固态存在于水中,介质的酸性只允许在很小的范围内变化。聚糖中的氨基与过渡金属离子有良好的螯合作用,可作为固体吸附剂吸附水中微量的有害重金属离子。据文献报导,这类吸附大多呈Langmuir型,但Pb(Ⅱ)与Cr(Ⅲ)是例外,它们的吸附等温线表现出单层吸附饱和后,又呈现多层吸附的特征。扫描电镜的照片表明聚糖吸附Pb(Ⅱ)、Cr(Ⅲ)后,表面有瘤状小结节生成。
The uptake of Cu(Ⅱ) on chitosan is corresponding to the monolayer adsorption model at 30.0℃ and the equilibrium concentration of Cu(Ⅱ) is less than 61.1mg dm^(-3). When the pH values are 6.00 and 4.88 respectively, the saturated specific adsorption amounts are kept constant, 26.5mg·g^(-1), but the adsorption constants are dropped down from 0.202 to 0.0491 dm^3·mg^(-1). It means that an acidized solution may cause the desorption of Cu(Ⅱ) from chitosan uptaken the ions before. Chitosan is very stable at pH～2 by using a 2.5 mol·dm^(-3) acidized NaCl solution because the ionic strength of solution is high enough to prevent the swelling of chitosan. The effect of pH of 2.5 mol·dm^(-3) acidized NaCl solutions on the desorption percentage of Cu(Ⅱ) from samples used is determined, and the desorption percentage is found to be 81.5% when pH is 3.87.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1989年第5期600-603,共4页
Acta Physico-Chimica Sinica
