凹凸棒土对腐殖酸的低温吸附性能研究

首次研究凹凸棒土对饮用水中腐殖酸的低温吸附性能,考察5℃条件下,吸附时间与腐殖酸初始浓度、吸附剂投加量、pH对凹凸棒土吸附腐殖酸的影响,确定吸附剂的吸附等温线、吸附动力学和热力学等相关理论参数,研究凹凸棒土对腐殖酸的吸附性能与机理。结果表明,江苏盱眙凹凸棒土在温度5℃、pH=4、水中腐殖酸初始浓度为5 mg/L,投加量为15 g/L的条件下,吸附180 min后对腐殖酸的去除率可达97.26%。凹凸棒土对腐殖酸的吸附符合二级吸附动力学方程与Freundlich吸附等温式,吸附过程由孔隙内扩散过程控制,吸附为自发的吸热过程,包括物理吸附与化学吸附。根据Fre-undlich吸附等温式拟合计算,5℃、pH=7时理论最大吸附量为9 mg/g,说明凹凸棒土对于低温饮用水中腐殖酸具有良好的吸附效果。

Adsorption properties of humic acid on attapulgite at low temperatures

Using attapulgite as an adsorbent for adsorption of humic acid from drinking water at low temperatures was studied for the first time.The effects of adsorption time and initial humic acid concentration,adsorbent dosage,pH on the humic acids adsorption onto attapulgite were investigated at 5℃.The related theoretical parameters of adsorption isotherm,kinetics and thermodynamics to research adsorption properties and adsorption mechanisms of attapulgite were determined.The results showed that when temperature is 5℃,pH is 4,the initial concentration of humic acid is 5 mg/L,attapulgite dosage is 15 g/L,contact time is 180 min,humic acid removal rate reaches 97.26%.The humic acid adsorption onto attapulgite accords with Pseudo-second-order model and Freundlich adsorption isotherm,the adsorption process controlled by itraparticle diffusion,is spontaneously endothermic,includes physical adsorption and chemisorption.The maximum theoretical adsorption capacity at 5℃ and pH=7 is 9 mg/g by Freundlich adsorption isotherm fitted curve,which demonstrates that attapulgite has good adsorption effect for treating humic acid-contaminated drinking water at low temperatures.