热处理凹凸棒土去除水体中单宁酸的研究

Removal of tannic acid from aqueous solution by heat-treated attapulgite

对凹凸棒土进行热处理,并以其作为吸附剂去除水中单宁酸.考察了焙烧温度、投加量、pH值等因素对单宁酸吸附的影响.结果表明,随着焙烧温度的增加,单宁酸的去除率呈现先增大后减少的趋势,在400℃条件下焙烧的凹凸棒土对单宁酸具有最佳吸附效果;随着吸附剂投加量的增加,单宁酸的去除率逐渐增大至平缓,当投加量为30 mg(0.75g/L)时效果最佳;随着溶液pH的增加,单宁酸的去除率呈现增大的趋势,在碱性条件下具有良好的吸附效果,其最佳pH为8.热处理凹凸棒土对单宁酸的等温吸附曲线可以更好地用Langmuir方程拟合,最大吸附量为54.64mg/g,吸附在700min时达到平衡,吸附动力学符合拟二级动力学方程.

Attapulgite was treated by calcinations and used to remove tannic acid from aqueous solution.The effects of calcinations temperature,pH and adsorbent dosage were studied.The results indicated that the removal rate of tannic acid increased initially and then decreased with the increase of calcination temperature,and the optimum calcinations temperature was400 ℃.The removal rate of tannic acid increased gently with the increase of the adsorbent dosage,and the optimum adsorbent dosage was 30mg（0.75g/L）.The removal rate of tannic acid increased with the increase of pH and favored under alkaline condition,and the optimum solution pH was at 8.The adsorption of tannic acid onto attapulgite was better fitted by Langmuir isotherm model,and the maximum adsorption amount was 54.64 mg/g.The adsorption equilibrium reached at 700 min and the adsorption kinetics could be well described with pseudo-second-order kinetic model.