title: Study of the adsorption of Cr(VI) by tannic acid immobilised powdered activated carbon from micro-polluted water in the presence of dissolved humic acid.
abstract: The adsorption of Cr(VI) (0.500 mg/L) onto food-grade tannic-acid immobilised powdered activated carbon (TA-PAC) in the presence of dissolved humic acid (DHA) was investigated at 280 K as a function of pH, along with the adsorption capacities and the adsorption isotherms for chromium ions. The results showed that the presence of DHA improved the adsorption capacities of Cr(VI) and its reduction product (Cr(III)) over a wide pH range (4.0-8.0). The main mechanism for metal-DHA complexation in the Cr(VI) system was the reduction of Cr(VI) followed by complexation between Cr(III) and DHA. The Freundlich isotherms yielded the best fits to all data (R(2)=0.9951, qm=5.639 mg/g) in the presence of DHA. The adsorption mechanisms of Cr(VI) onto TA-PAC in the presence of DHA were summarized into three categories: (i) binding by anion adsorption, (ii) Cr(VI) reduction followed by Cr(III) adsorption, and (iii) adsorption of Cr(III)-DHA complexes.
authors: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors: Xujin
authors: X
authors: Gong
authors: Weiguang
authors: W
authors: Li
authors: Ke
authors: K
authors: Wang
authors: Jinhua
authors: J
authors: Hu
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D002857:Chromium / Q000032:analysis / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis*; D013634:Tannins / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D006812:Humic Substances; D013634:Tannins; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D002244:Carbon