Hlavay József, Polyák Klára
Department of Earth and Environmental Sciences, University of Veszprém, 8201 Veszprém, P.O. Box 158, Hungary.
J Colloid Interface Sci. 2005 Apr 1;284(1):71-7. doi: 10.1016/j.jcis.2004.10.032.
A novel type adsorbent was prepared by in situ precipitation of Fe(OH)3 on the surface of activated Al2O3 as a support material. The iron content of the adsorbent was 0.31+/-0.003% m/m (56.1 mmol/g); its mechanical and chemical stability proved to be appropriate in solutions. The total capacity of the adsorbent was 0.12 mmol/g, and the pH of zero point of charge, pH(zpc) = 6.9+/-0.3. Depending on the pH of solutions, the adsorbent can be used for binding of both anions and cations, if pH(eq) < pH(zpc) anions are sorbed on the surface of adsorbent (S) through [SOH2+] and [SOH] groups. A graphical method was used for the determination of pH(iep) (isoelectric points) of the adsorbent and values of pH(iep) = 6.1+/-0.3 for As(III) and pH(iep) = 8.0+/-0.3 for As(V) ions were found. The amount of surface charged groups (Q) was about zero within the a pH range of 6.5-8.6, due to the practically neutral surface formed on the adsorption of As(V) ions. At acidic pH (pH 4.7), Q = 0.19 mol/kg was obtained. The adsorption of arsenate and arsenite ions from solutions of 0.1-0.4 mmol/L was represented by Langmuir-type isotherms. A great advantage of the adsorbent is that it can be used in adsorption columns, and low waste technology for removal of arsenic from drinking water can be developed.
通过在作为载体材料的活性Al2O3表面原位沉淀Fe(OH)3制备了一种新型吸附剂。该吸附剂的铁含量为0.31±0.003% m/m(56.1 mmol/g);其机械和化学稳定性在溶液中被证明是合适的。吸附剂的总容量为0.12 mmol/g,零电荷点pH值,pH(zpc)=6.9±0.3。根据溶液的pH值,该吸附剂可用于结合阴离子和阳离子,如果pH(eq)<pH(zpc),阴离子通过[SOH2+]和[SOH]基团吸附在吸附剂(S)表面。采用图解法测定吸附剂的pH(iep)(等电点),发现As(III)的pH(iep)=6.1±0.3,As(V)离子的pH(iep)=8.0±0.3。由于As(V)离子吸附形成的表面几乎呈中性,在pH值为6.5 - 8.6的范围内,表面带电基团的量(Q)约为零。在酸性pH值(pH 4.7)下,Q = 0.19 mol/kg。0.1 - 0.4 mmol/L溶液中砷酸盐和亚砷酸盐离子的吸附符合朗缪尔型等温线。该吸附剂的一个很大优点是它可用于吸附柱,并且可以开发用于去除饮用水中砷的低废物技术。