Muñoz José Antonio, Gonzalo Anna, Valiente Manuel
Departament de Quimica, Química Analítica, Universitat Autonoma de Barcelona, Bellaterra, Spain.
Environ Sci Technol. 2002 Aug 1;36(15):3405-11. doi: 10.1021/es020017c.
Nowadays there is a great concern on the study of new adsorbent materials for either the removal or fixation of arsenic species because of their high toxicity and the health problems associated to such substances. The present paper reports a basic study of the adsorption of arsenic inorganic species from aqueous solutions using an open-celled cellulose sponge with anion-exchange and chelating properties (Forager Sponge). Consequences of preloading the adsorbentwith Fe(III) to enhance the adsorption selectivity are discussed and compared with the nonloaded adsorbent properties. The interactions of arsenic species with the Fe(III)-loaded adsorbent are accurately determined to clarify the feasibility of an effective remediation of contaminated waters. Arsenate is effectively adsorbed by the nonloaded and the Fe(III)-loaded sponge in the pH range 2-9 (maximum at pH 7), whereas arsenite is only slightly adsorbed by the Fe(III)-loaded sponge in the pH range 5-10 (maximum at pH 9), being that the nonloaded sponge is unable to adsorb As(III). The maximum sorption capacities are 1.83 mmol As(V)/g (pH approximately 4.5) and 0.24 mmol As(lII)/g (pH approximately 9.0) for the Fe(III)-loaded adsorbent. This difference is explained in terms of the different acidic behavior of both arsenic species. The interaction of the arsenic species with the Fe(III) loaded in the sponge is satisfactorily modeled. A 1:1 Fe:As complex is found to be formed for both species. H2AsO4- and H3AsO3 are determined to be adsorbed on Fe(III) with a thermodynamic affinity defined by log K = 2.5 +/- 0.3 and log K = 0.53 +/- 0.07, respectively. As(V) is, thus, found to be more strongly adsorbed than As(III) on the Fe(III) loaded in the sponge. A significant enhancement on As(V) adsorption selectivity by loading Fe(III) in the sponge is observed, and the effectiveness of the Fe(III)-loaded sponge for the As(V) adsorption is demonstrated, even in the presence of high concentrations of interfering anions (chloride, nitrate, sulfate, and phosphate).
由于砷类物质具有高毒性以及与之相关的健康问题，如今对于用于去除或固定砷类物质的新型吸附材料的研究备受关注。本文报道了一项关于使用具有阴离子交换和螯合特性的开孔纤维素海绵（Forager海绵）从水溶液中吸附无机砷类物质的基础研究。讨论了用Fe(III)预加载吸附剂以提高吸附选择性的结果，并与未加载吸附剂的性能进行了比较。准确确定了砷类物质与负载Fe(III)的吸附剂之间的相互作用，以阐明有效修复受污染水体的可行性。在pH值为2 - 9的范围内（pH = 7时吸附量最大），未加载和负载Fe(III)的海绵均能有效吸附砷酸盐，而在pH值为5 - 10的范围内（pH = 9时吸附量最大），负载Fe(III)的海绵仅能轻微吸附亚砷酸盐，未加载的海绵则无法吸附As(III)。对于负载Fe(III)的吸附剂，最大吸附容量分别为1.83 mmol As(V)/g（pH约为4.5）和0.24 mmol As(III)/g（pH约为9.0）。这种差异可根据两种砷类物质不同的酸性行为来解释。令人满意地建立了砷类物质与负载在海绵中的Fe(III)之间相互作用的模型。发现两种砷类物质均形成了1:1的Fe:As络合物。确定H2AsO4-和H3AsO3以log K = 2.5 +/- 0.3和log K = 0.53 +/- 0.07定义的热力学亲和力吸附在Fe(III)上。因此，发现As(V)比As(III)更强烈地吸附在负载于海绵中的Fe(III)上。观察到通过在海绵中负载Fe(III)对As(V)吸附选择性有显著提高，并且证明了负载Fe(III)的海绵对As(V)吸附的有效性，即使在存在高浓度干扰阴离子（氯离子、硝酸根离子、硫酸根离子和磷酸根离子）的情况下也是如此。
