花生壳、大豆壳和柚子皮对Cr^(3+)、Cu^(2+)和Ni^(2+)的吸附研究

Adsorption of Cr^(3+),Cu^(2+) and Ni^(2+) using peanut hull,soybean shell and grapefruit peel

采用农林废弃物花生壳、大豆壳、柚子皮对重金属离子Cr3+、Cu2+和Ni 2+进行吸附研究,探讨反应时间、吸附剂用量、pH、重金属离子初始浓度以及温度对吸附的影响。结果表明:柚子皮对Cr3+、Cu2+、Ni 2+的吸附效果优于花生壳和大豆壳,其在20℃、pH 5.00、10.0mg/kg条件下,反应360min,Cr3+、Cu2+、Ni 2+的吸附率分别可达83.20%、84.50%、59.10%;花生壳、大豆壳和柚子皮对Ni 2+的吸附率远低于Cr3+和Cu2+;花生壳、大豆壳和柚子皮对Cr3+、Cu2+、Ni 2+的吸附动力学可以用准二级动力学方程描述;吸附率随初始重金属离子浓度增加而降低,其吸附等温线可以用Langmuir方程描述;在一定范围内,吸附率随吸附剂用量增加而增加;溶液初始pH在2～5时,吸附率随pH增大而增加;Cu2+、Ni 2+的吸附量随温度的上升而逐渐减少,但Cr3+的吸附量随着温度的上升而略增加。

Peanut hull, soybean shell, grapefruit peel were used to adsorb Cr3＋ , Cu2＋ , and Ni2＋ from simulative heavy metal polluted water. Adsorption as function of reaction time, absorbents dosage, initial pH, initial metal continents, or temperature was investigated. Grapefruit peel showed the best adsorption ability for the three metals, and it removed 83. 20% of Cra＋ , 84.50o//00 of Cuz＋ and 59.10% of Ni2＋ from the solution （pH 5.00, containing 10.0 mg/kg Cr3＋ , 10.0 mg/kg Cu2＋ and 10.0 mg/kg Ni2＋ ） at 20℃ , with reaction time of 360 min. Compared to Cr3＋ and Cu2＋ , Ni2＋ was more difficult to be removed by the three absorbents. The adsorption kinetics of Cr3＋ , Cu2＋ , and Ni2＋ by the three absorbents could be well described with pseudo-second-order equation. Adsorption efficiency decreased with the increasing initial metal contents, and the isotherms was well fitted with Langmuir equation. Ad sorption efficiency increased with the increasing amount of absorbents and then came to a platform. Enhanced pH also resulted in greater amount of metals adsorption. Adsorption efficiency of Cu2＋ and Ni2＋ decreased with the increase of the temperature, while there was considerable increase regarding the adsorption efficiency of Cr3＋ , especially for peanut hull.