东北地区农田土壤对Cd^(2+)的吸附特性研究

Adsorption Characteristics Research on Cd^(2+)in Farmland Soil in Northeast China

以东北农田黑土土壤为吸附剂,研究对Cd 2+的吸附动力学、热力学吸附过程及影响因素.结果表明:土壤吸附Cd^(2+)在60 min内达到吸附平衡,准二级动力学模型模拟吸附动力学过程效果最好(R^(2)=0.9993).通过Web-Morris颗粒内扩散模型和Boyd模型分析,发现吸附过程完全受土壤颗粒内扩散控制,吸附速率由膜扩散控制.采用Langmuir方程拟合吸附等温线效果最好,以单分子层吸附为主.土壤吸附剂用量为2.0 g时,对Cd^(2+)的吸附量最大,为2.35 mg·g^(-1).当pH为3.0~8.0的范围内,土壤对Cd^(2+)的吸附量随着溶液pH的增加而增加.

The adsorption kinetics,thermodynamic process and influencing factors of Cd^(2+)by black soil in northeast China were studied.The results showed that the Cd 2+adsorption by soil reached adsorption equilibrium within 60 min,and the adsorption kinetics process simulation effect by quasi-second-order kinetic model was the best(R 2=0.9993).According to the analysis of web-morris intra-particle diffusion model and Boyd model,the adsorption process was controlled by the soil intra-particle diffusion,and the adsorption rate was impacted by the membrane diffusion.The adsorption isotherm fitting result was better by Langmuir equation,and the adsorption process was dominated by monolayer adsorption.When the soil adsorbent dosage was 2.0 g,the maximum adsorption capacity of Cd^(2+)was 2.35 mg·g^(-1).Soil adsorption capacity of Cd^(2+)increased with the increase of solution pH value in the pH range of 3.0~8.0.