National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Pakistan.
Colloids Surf B Biointerfaces. 2010 Jan 1;75(1):149-55. doi: 10.1016/j.colsurfb.2009.08.025. Epub 2009 Aug 21.
Biosorption of divalent metal ions, i.e. Pb(II), Cd(II), Zn(II) and Cu(II) onto rice husk activated (RHA) is investigated over pH range (1-10) via batch adsorption technique. The chemical and thermal activation of rice husk with 0.1M HNO(3) and 1M K(2)CO(3) at 473 K enhanced the removal efficiency of RHA (35+/-2.1-99+/-0.5%, 33+/-1.2-97+/-0.6%, 32+/-1.3-96+/-0.8% and 28+/-1.8-95+/-0.9% before and after treatment, respectively). The surface area analysis of RHA by BET (Brunauer, Emmett and Teller) nitrogen adsorption method provided pore area and average pore diameter to be 542+/-2.3m(2)g(-1) and 1076+/-5.6 nm respectively. SEM and FTIR analyses of RHA were carried out to determine the surface morphology and functional groups involved in metal binding mechanism, respectively. The adsorption equilibrium was well described by Freundlich, Langmuir and Dubinin-Radushkevish (D-R) isotherm models by employing (4.8-48, 8.9-89, 15.3-153 and 15.7-157)x10(-5)M solution concentrations of sorbates, respectively, at equilibrium time of 20 min at pH 6 and onto 0.2g of sorbent. The kinetics of mass transfer and intra-particle diffusion for metal ions sorption onto RHA were studied with Lagergren and Morris-Weber kinetic models. The numerical values of thermodynamic parameters indicated the exothermic nature, spontaneity and feasibility of the sorption process. The desorption study of metal components from RHA surface was carried out with 0.1M HCl. The sorption mechanism developed illustrates the strong interactions of sorbates with the active sites of the sorbent coupled with efficient and environmentally clean exploitation of rice waste product.
采用静态吸附法，研究了在 pH 值（1-10）范围内，稻壳经 0.1M HNO(3)和 1M K(2)CO(3)化学和热激活后（在 473K 下）对稻壳吸附剂（RHA）吸附二价金属离子（如 Pb(II)、Cd(II)、Zn(II)和 Cu(II)）的影响。处理前后，RHA 的去除效率分别提高了 35+/-2.1-99+/-0.5%、33+/-1.2-97+/-0.6%、32+/-1.3-96+/-0.8%和 28+/-1.8-95+/-0.9%。通过 BET（Brunauer、Emmett 和 Teller）氮吸附法对 RHA 的表面积分析，提供了孔面积和平均孔径分别为 542+/-2.3m(2)g(-1)和 1076+/-5.6nm。对 RHA 进行 SEM 和 FTIR 分析，分别确定了表面形态和参与金属结合机制的官能团。采用 Freundlich、Langmuir 和 Dubinin-Radushkevish（D-R）等温模型，通过采用 4.8-48、8.9-89、15.3-153 和 15.7-157x10(-5)M 溶液浓度的吸附剂，在 pH 值为 6 时，吸附平衡时间为 20min，吸附剂用量为 0.2g，对吸附平衡进行了较好的描述。采用 Lagergren 和 Morris-Weber 动力学模型研究了金属离子在 RHA 上的传质和内扩散动力学。热力学参数的数值表明，吸附过程是放热的、自发的和可行的。采用 0.1M HCl 对 RHA 表面的金属成分进行了脱附研究。开发的吸附机制说明了吸附剂与吸附质之间的强相互作用，以及对稻壳废物的有效和环保的利用。
