Preparation and characterization of chitosanipurified attapulgite composite for sharp adsorption of humic acid from aqueous solution at low temperature

In the adsorption treatment of water polluted with humic acid (HA), it is equally important to recover clean water with inexpensive raw materials, mild treatment environments and excellent adsorption capacity. Herein, a composite structured CPA (chitosan-modified purified attapulgite) composed of uniform PA (purified attapulgite) nanorods modified by chitosan was successfully fabricated under acetic acid conditions. Benefiting from the mesoporous structure of the PA nanorods and the carboxyl groups of chitosan, the prepared hybrid CPA exhibited a quick response and excellent adsorption capacity towards HA. The effects of pH, adsorbent dose, adsorption time, initial HA concentration and temperature were systematically studied using PA-90 (PA with purity of 90%) and CPA, respectively. The results show that CPA has a high capture affinity towards HA with a short response time (2 min for 80%) and the maximum adsorption capacity could reach 112.07 mg/g, which is superior to most results that have been reported. We believe CPA could be considered as an efficient and green heterogeneous adsorbent for the adsorption of humic acid, as well as provide a versatile platform for further development of functional hybrid composites for the adsorption of other pollutants. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.