Study On Modification And Application Of Attapulgite

Attapulgite is the local characteristic natural mineral resources in Anhui and Jiangsu Provinces. Based on the analysis of the application and development of attapulgite, Attapulgite were first treated with the hydrochloric acid to get acid modified attapulgite (HATP), then the preparation of silane coupling agent modified acid attapulgite (OHATP) was studied. And the purpose of the paper was to enhance the adsorption capacities of the attapulgite and to development the high-performance of the attapulgite. The adsorption property of chromium ion from aqueous solution onto OHATP was studied.Attapulgite was treated by different concentrations of hydrochloric acid, The products were characterized by FTIR, BET and XRD. The results showed that the surface area of the attapulgite treated with 0.1M HCl improved obviously, and crystal structure did not change。O1HATP,O2HATP adsorbents were synthesized by grafting silane coupling agent (KH-550,KH-792) onto the hydrochloric acidt modified ATP (HATP). The as-prepared products were characterized by FTIR, BET, XRD, TGA and DSC. The results showed that KH-550 and KH-792 was successfully grafted onto the HATP surface. The organic silane modfied products of O1HATP and O2HATP give a maximum hexavalent chromium ion adsorption capacity of up to 4.55mg-g-1 and 5.01mg-g-1, which prepared under reaction conditions:silane coupling agent mass ratio of 1%(relative to HATP), reaction time 4h-6 h, reaction temperature 50℃。The adsorption capacity of hexavalent chromium ion onto the OHATP was investigated through the static adsorption. The higher adsorption capacity of OHATP compared with ATP may be attributed to the ability of chromium ion to form chemical bonds with the amino groups. The kinetics of chromium ion adsorption onto OHATP was based on the assumption of a pseudo-second-order mechanism, which is an important process in chemisorption.70% and 74.9%chromium ion was adsorbed within 20 min and equilibrium was achieved at around 40 min. The equilibrium data fitted the Langmuir and Redlich-Peterson sorption isotherms well, and the maximum adsorption capacity of hexavalent chromium ion onto the O1HATP and the O2HATP was found to be 5.53 mg·g-1 and 5.13 mg·g-1 respectively. Hexavalent chromium ion adsorbed onto OHATP could be effectively desorbed in hot acetic acid solution, and the adsorption capacity of the regenerated adsorbents could still be maintained at 90% by the fourth cycle.