不同类型土壤中As(Ⅴ)解吸行为的研究

为了解As(Ⅴ)在土壤中的解吸行为及不同类型试剂(NaOH、NaCl、NaHCO3、柠檬酸、草酸及磷酸盐缓冲液)对所吸附砷的解吸效果,对As(Ⅴ)在不同类型土壤中的解吸热力学和动力学效果进行了研究.结果表明,NaOH和磷酸盐缓冲液对几种土壤吸附砷的解吸效果较好,解吸率分别在47.3%～73.0%和35.4%～66.6%...

The arsenate adsorption behavior of seven Chinese soils

The arsenate desorption were studied using seven Chinese soils, batch experiments and different extractants (sodium hydroxide, sodium chloride, sodium bicarbonate, citric acid, oxalic acid and phosphate buffer solution). Also the desorption behavior of As(V) on soils were studied. The results showed that NaOH and phosphate buffer solutions were most effective to extract As(V) from soils with 47.3%~73.0% and 35.4%~66.6% of As(V), respectively. Except for black soil, the extractability of the citric acid and oxalic acid solutions were moderate among soils. For the solutions of NaHCO3 and NaCl, only 10.3%~42.1% and 2.3%~32.2% of As(V) were extracted, respectively. Among seven soils, As(V) desorbed from red soil developed from the Quaternary red clay soil and red soil developed from granite were the highest, with the desorbed amount of 0.004~0.135 mg•g-1 and 0.009~0.101 mg•g-1, respectively, followed by yellow soil and black soil. The amounts of As(V) adsorbed on purple soil, red soil developed from purple sandy shale and fluvo-aquic soil were released less, especially on fluvo-aquic soil, with the desorbed amount of 0.012~0.027mg•g-1. The results of isotherm experiments with NaOH as an extractant showed that the adsorption and desorption amounts of As(V) on different soils increased with the increase of initial As(V) concentration, and a significant positive relationship was found between adsorption and desorption amounts. With time, As(V) on the soils desorbed rapidly within 1 h, reaching 43.9%~65.1% of the desorption equilibrium within 5 minutes. After 2 h, the desorption curves changed slightly, reaching 78.4%~91.8% of equilibrium desorption amount.