桉树遗态Fe/C复合材料对水中Cr(Ⅵ)的动态吸附-解吸附特性研究

Characteristics of the column adsorption-desorption of Cr(Ⅵ) by a porous biomorph-genetic Fe_2O_3/Fe_3O_4/C composite with Eucalyptus microstructure

以平衡吸附Cr(Ⅵ)后的桉树遗态Fe/C复合材料(PBGC-Fe/C)为研究对象,选用解吸液类型、浓度、流速和温度为影响因素,重点探讨了PBGC-Fe/C对水中Cr(Ⅵ)的具体解吸附特征、机制及材料的优越性。研究结果表明:5种常见解吸液(HCl、NaCl、NaOH、NaHCO_3和H_2O)均难以在短期内将吸附平衡Cr(Ⅵ)的PBGC-Fe/C进行完全解吸附处理,其中NaCl、H_2O和HCl解吸液对Cr(Ⅵ)的解吸率只有1%左右,表明在中性和酸性条件下已被吸附在材料表面的Cr(Ⅵ)难以被溶出;选用NaOH作为解吸液进行动态解吸研究,在解吸液浓度为1 mol·L^(-1),流速5.14 mL·min^(-1),温度35℃条件下,105 min完成解吸,解吸率高达97.25%;平衡吸附Cr(Ⅵ)后的PBGC-Fe/C表面存在的CrO2-4与OH-的离子交换作用为主要解吸机制,同时伴随着物理作用和静电作用。

Column adsorption-desorption of Cr（Ⅵ）from aqueous solutions by a porous biomorph-genetic Fe2O3/Fe3O4/C composite prepared with a Eucalyptus template（PBGC-Fe/C）was experimentally studied. The effects of the desorption solvent type, solvent concentration, influent rate, and temperature were examined to investigate the desorption mechanism. The results indicated that the adsorbed Cr（Ⅵ）was barely desorbed by the five commonly used desorption solvents, i.e., HCl, NaCl, NaOH, NaHCO3, and H2O solutions, in a short time.The Cr（Ⅵ）desorption capacity was only about 1% for the NaCl, H2O, and HCl solutions, which indicated that it was difficult to desorb the adsorbed Cr（Ⅵ）from the PBGC-Fe/C using neutral and acidic solvents. Under the conditions of 1 mol·L^（-1） NaOH, influent flow rate of 5.14 mL·min^（-1）, operating temperature of 35 ℃, and operating time of 105 min, the Cr（Ⅵ）desorption capacity reached 97.25%. Exchange of OH-ions for CrO2-4 ions on the PBGC-Fe/C surface, which was accompanied by physical desorption and electrostatic interaction, was considered to be the desorption mechanism.