Adsorption properties of humic acid on attapulgite at low temperatures
凹凸棒土对腐殖酸的低温吸附性能研究

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.