黄壤对邻苯二甲酸二丁酯的吸附解吸特征及影响因素研究

Adsorption and Desorption of Dibutyl-Phthalate in Yellow Soil and Their Influencing Factors

采用紫外分光光度法研究黄壤对邻苯二甲酸二丁酯(DBP)的吸附—解吸特征、动力学特征,以及pH值、温度、离子强度等环境条件对吸附的影响.黄壤对DBP的等温吸附可以用Langmuir方程很好地表述,达到极显著相关,最大吸附量Qmax为0.564mg/g,吸附平衡常数为k=0.177 2;解吸量随着吸附量的增加而增大,黄壤对DBP的最大保有量为0.177mg/g;假二级动力学方程可以很好地描述黄壤对DBP的吸附动力学特征,颗粒内扩散模型表明黄壤对DBP的吸附过程中土壤颗粒内扩散并不是唯一的速率控制步骤;黄壤对DBP的吸附量在pH值为7.0时最低,为0.024mg/g,而在弱酸性范围内随着pH增大,吸附量降低,在弱碱性范围内,吸附量则随着pH增大而增大;温度对DBP的吸附有较大影响,在一定范围内,随着温度升高,吸附量下降,表明升高温度对吸附不利;随着离子强度的增大,黄壤对DBP的吸附量整体趋势是小幅增大.

UV-spectrophotometry was used to study the characteristics of DBP （di-n-butyl phthalate） ad sorption-desorption and adsorption kinetics on yellow soil and the effects of pH, temperature and ionic stren h on the adsorption process. The isothermal adsorption of DBP on yellow soil could well be de scribed by a Langumuir equation （adO. 01）, the maximum adsorption amount （Q ） being 0. 564 mg/g and the adsorption constant （k） being 0. 177 2. The desorption amount of DBP increased with the increase in DBP adsorption, the maximum conservation quantity being 0. 177 mg/g. The adsorption amount of DBP was the minimum tions, and increased wit （ h 0. 024 mg/g） at pH 7.0, decreased with increasing pH under weakly acid condi increasing pH under weakly alkaline conditions. The characteristics of isothermal adsorption kinetics of DBP on yellow soil could well be described with a pseudo-second-order kinetics equa tion. The particle internal diffusion model showed that the intra-particle diffusion was not the sole control ling with process. Temperature had great influence on DBP adsorption, and the adsorption amounts decreased rising temperature within a certain extent, indicating that high temperature was unfavorable to the adsorption reaction. On the whole, DBP adsorption amounts tended to increase moderately with increasing ionic strength.