Dias Fabiana F, Allen Herbert E, Guimarães José Roberto, Taddei Maria Helena T, Nascimento Marcos R, Guilherme Luiz Roberto G
Brazilian Nuclear Energy Commission (CNEN), Rodovia Poços de Caldas/Andradas, km 13, 37701-970, Poços de Caldas, MG, Brazil.
J Environ Monit. 2009 Jul;11(7):1412-20. doi: 10.1039/b900545e. Epub 2009 May 29.
This paper presents an evaluation of the environmental behavior of arsenic species in soils (F. F. Dias, Master Thesis, University of Delaware, 1997). The results obtained were used to determine adsorption constants that were incorporated in mathematical models using forward and backward stepwise linear regression to correlate data. The amount of adsorption was significantly different depending on soil properties, such as organic matter, iron oxide content, and surface area. Arsenic speciation on the soil surface was deduced from desorption data, with As(V) being more strongly retained in the soil. As(III) was oxidized on the soil surface and desorbed as As(V); an important factor since As(V) is less toxic. In order to develop an adequate adsorption model, Langmuir and Freundlich isotherms were obtained for each soil without pH alteration. Results indicated that the maximum amount of As(V) adsorbed was greater than the amount of As(III) adsorbed. Adsorption edges for As(III) and As(V), with pH varying from 3 to 10, were obtained at concentrations that ranged from 0.1 to 200 mg L(-1). The soils studied exhibited an L-type Langmuir isotherm. Maximum As(III) adsorption occurred around pH 6 to 9, while maximum As(V) adsorption occurred in the 4 to 5 pH range. Experiments to determine arsenic kinetics were carried out and showed that adsorption and desorption equilibrium was reached within 48 hours for both species.
本文介绍了对土壤中砷形态环境行为的评估（F.F.迪亚斯，硕士论文，特拉华大学，1997年）。所得结果用于确定吸附常数，这些常数被纳入数学模型，使用向前和向后逐步线性回归来关联数据。吸附量因土壤性质（如有机质、氧化铁含量和表面积）的不同而有显著差异。从解吸数据推断土壤表面的砷形态，其中As(V)在土壤中保留得更强。As(III)在土壤表面被氧化并以As(V)形式解吸；这是一个重要因素，因为As(V)毒性较小。为了建立一个合适的吸附模型，在不改变pH值的情况下，为每种土壤获得了朗缪尔等温线和弗伦德利希等温线。结果表明，吸附的As(V)的最大量大于吸附的As(III)的量。在pH值从3到10变化、浓度范围为0.1至200 mg L(-1)的条件下，获得了As(III)和As(V)的吸附边界。所研究的土壤呈现出L型朗缪尔等温线。As(III)的最大吸附发生在pH值6至9左右，而As(V)的最大吸附发生在pH值4至5范围内。进行了测定砷动力学的实验，结果表明两种形态在48小时内均达到吸附和解吸平衡。
