改性甘蔗渣对Cu^(2+)和Zn^(2+)的吸附机理

Adsorption mechanism for Cu^(2+) and Zn^(2+) by modified bagasse

研究了均苯四甲酸二酐(PMDA)和乙二胺四乙酸二酐(EDTAD)改性甘蔗渣对重金属离子Cu2+和Zn2+的吸附性能,包括吸附动力学和吸附等温线。结果表明,改性后的甘蔗渣对重金属离子Cu2+和Zn2+的吸附容量有显著提高,对Cu2+和Zn2+吸附等温线均符合Langmuir方程,吸附为单分子层吸附。根据Langmuir方程,PMDA和EDTAD改性甘蔗渣对Cu2+的吸附量分别为60.21和33.45 mg/g,对Zn2+的吸附量分别是70.53和36.53 mg/g。两种改性甘蔗渣对两种金属离子的吸附在30 min内均可完成,用准二级吸附动力学方程模拟动力学过程得到较好的线性相关性。以EDTA溶液为洗脱剂对吸附Cu2+和Zn2+的改性甘蔗渣进行洗脱再生,再生的吸附剂可反复使用。

The adsorption properties including adsorption kinetics and adsorption isotherm of the PMDA and EDTAD modified bagasse for heavy metal ions of Cu^2＋ and Zn^2＋ were investigated. Experimental results showed that the adsorption capacity of the PMDA and EDTAD modified bagasse was improved significantly. The adsorption data of the two metal ions both fitted Langmuir adsorption isotherm, which indicating that adsorption for met- al ions was a monolayer adsorption. According to Langmuir model, the adsorption capacities of the PMDA and EDTAD modified bagasse for Cua ＋ were 60.21 and 33.45 rag/g, and that for Zn^2＋ were 70.53 and 36.53 mg/g, respectively. Adsorption process could be finished within 30 rain, and could be fitted better with pseudo-second- order kinetic model than pseudo-second-order and intra-particle diffusion kinetic model. The adsorbed Cu^2＋ and Zn^2＋ on the modified bagasse could be effectively desorbed in an EDTA solution, and the regenerated bagasse could be reused with little loss of the adsorption capacity.