Ociński Daniel, Jacukowicz-Sobala Irena, Kociołek-Balawejder Elżbieta
Department of Industrial Chemistry, Wroclaw University of Economics, ul. Komandorska 118/120, 53-345, Wrocław, Poland.
Environ Sci Pollut Res Int. 2016 Dec;23(24):24527-24539. doi: 10.1007/s11356-016-6768-0. Epub 2016 May 10.
Water treatment residuals (WTRs) produced in large quantities during deironing and demanganization of infiltration water, due to high content of iron and manganese oxides, exhibit excellent sorptive properties toward arsenate and arsenite. Nonetheless, since they consist of microparticles, their practical use as an adsorbent is limited by difficulties with separation from treated solutions. The aim of this study was entrapment of chemically pretreated WTR into calcium alginate polymer and examination of sorptive properties of the obtained composite sorbent toward As(III) and As(V). Different products were formed varying in WTR content as well as in density of alginate matrix. In order to determine the key parameters of the adsorption process, both equilibrium and kinetic studies were conducted. The best properties were exhibited by a sorbent containing 5 % residuals, formed in alginate solution with a concentration of 1 %. In slightly acidic conditions (pH 4.5), its maximum sorption capacity was 3.4 and 2.9 mg g for As(III) and As(V), respectively. At neutral pH, the adsorption effectiveness decreased to 3.3 mg As g for arsenites and to 0.7 mg As g for arsenates. The presence of carboxylic groups in polymer chains impeded in neutral conditions the diffusion of anions into sorbent beads; therefore, the main rate-limiting step of the adsorption, mainly in the case of arsenates, was intraparticle diffusion. The optimal condition for simultaneous removal of arsenates and arsenites from water by means of the obtained composite sorbent is slightly acidic pH, ensuring similar adsorption effectiveness for both arsenic species.
在渗滤水除铁除锰过程中会大量产生水处理残渣（WTRs），由于其铁和锰氧化物含量高，对砷酸盐和亚砷酸盐具有优异的吸附性能。然而，由于它们由微粒组成，作为吸附剂的实际应用受到与处理后溶液分离困难的限制。本研究的目的是将化学预处理的WTRs包埋到海藻酸钙聚合物中，并研究所得复合吸附剂对As(III)和As(V)的吸附性能。形成了不同的产品，其WTR含量以及海藻酸盐基质的密度各不相同。为了确定吸附过程的关键参数，进行了平衡和动力学研究。含有5%残渣、在浓度为1%的海藻酸盐溶液中形成的吸附剂表现出最佳性能。在微酸性条件（pH 4.5）下，其对As(III)和As(V)的最大吸附容量分别为3.4和2.9 mg g。在中性pH下，亚砷酸盐的吸附效率降至3.3 mg As g，砷酸盐的吸附效率降至0.7 mg As g。聚合物链中羧基的存在在中性条件下阻碍了阴离子向吸附剂珠粒中的扩散；因此，吸附的主要限速步骤，主要是在砷酸盐的情况下，是颗粒内扩散。使用所得复合吸附剂同时从水中去除砷酸盐和亚砷酸盐的最佳条件是微酸性pH，确保两种砷物种具有相似的吸附效率。
