芹菜渣对Cr^(6+)的吸附实验

Study on biosorption of Cr^(6+)by celery residue

首次以芹菜渣为生物吸附剂,采用静置吸附法研究了其对Cr^(6+)的吸附作用、吸附过程的影响因素、热力学和动力学行为。结果显示:芹菜渣对Cr^(6+)的吸附率随其粒径的减小而增大;Cr^(6+)初始浓度相同时,吸附率随芹菜渣加入量的增加而增大,芹菜渣加入量相同时,吸附率随Cr^(6+)初始浓度的增加而增大。正交实验得到3因素对吸附效果的影响程度顺序为:pH>温度>时间,最优吸附条件为pH2、吸附温度40℃、吸附时间2h。对于50mg/L的Cr^(6+)溶液,芹菜渣为吸附剂时的最佳固液比为10g/L;芹菜渣对Cr^(6+)的吸附以单分子层吸附为主,吸附过程先为快速吸附,当吸附时间超过90min时为慢速吸附;芹菜渣对Cr^(6+)的吸附热力学情况可用Freundlich吸附等温式描述,吸附动力学情况可用二级动力学模型描述;对于中低浓度(≤30mg/L)的Cr^(6+)溶液,芹菜渣的吸附效果好于活性炭。

By adsorption,adsorption and adsorption mechanism of Cr^（6＋）were studied by celery residue,firstly.Experimental results showed that the adsorption rate of Cr^（6＋）increased with the decreasing of the size of celery residue.Under the same Cr^（6＋）initial concentration,with the addition of more celery residue,Cr^（6＋）adsorption rate increased.Under the same addition amount of celery residue,with the addition of Cr^（6＋）initial concentration,adsorption rate increased.Orthogonal tests showed that：the optimum adsorption conditions for the wastewater pH was 2,the temperature was 40℃ and soaking time was 2 hours,influence degree for 3 factors from big to small was pH,temperature and soaking time.The best solid to liquid ratio of Cr6＋（50mg/L）adsorption by celery residue was 10g/L.Celery residue on Cr^（6＋）adsorption with single molecule layer absorption dominant,and adsorption isotherm was fit to Freundlich adsorption isotherm.The adsorption rate for celery residue to Cr^（6＋）was quick at first,and then became slow after more than 90min.Second kinetic model could describe the adsorption kinetics of celery residue much better.In the low concentration of Cr^（6＋）solution（≤30mg/L）,the adsorption of celery residue was better than that of activated carbon.