复合胶体作用于Sr在花岗岩裂隙填充物中吸附行为研究

Composite colloid action in Sr sorption by granite fracture filling materials

放射性废物地质处置过程中,核素在固液界面的吸附行为对核废物安全处置具有重要影响.本文以高放废物处置场花岗岩裂隙填充物为研究对象,通过批实验和微观表征技术研究了复合胶体作用下Sr在花岗岩裂隙填充物中的吸附规律.结果表明:腐殖酸胶体与针铁矿胶体结合成为有机–无机复合胶体的方式,主要依靠针铁矿胶体中所含羟基与腐殖酸胶体中所含羧基发生配位体交换反应,复合胶体以针铁矿胶体为主导,腐殖酸附着在针铁矿胶体表面;pH和固液比对复合胶体体系对Sr的吸附行为影响较大;通过改变溶液中Sr离子初始浓度进行等温吸附方程的拟合表明,该吸附体系的吸附为单层吸附且反应更快.结果可为放射性废物处理场中Sr的吸附行为提供科学规律认识.

During geological disposal of radioactive waste,sorption of nuclide at solid-liquid interface is important for the safe disposal of nuclear waste.Granite fracture filling materials at high-level waste disposal site were examined for Sr sorption in batch experiments and by microscopic characterization.The way by which humic acid colloid and goethite colloid combine to form organic-inorganic composite colloid was found to mainly depend on ligand exchange reaction between hydroxyl group in goethite colloid and carboxyl group in humic acid colloid.The composite colloid was found to be dominated by goethite colloid,with humic acid attached to its surface.Effect of pH and solid-liquid ratio on Sr sorption from composite colloid was examined.Fitting isothermal sorption equation with initial Sr concentrations revealed that sorption was monolayer and reaction was fast.This work provides some understanding of Sr sorption in the treatment of radioactive wastes.