磷酸活化活性炭对Cu^(2+)的吸附特征研究

Adsorption characteristics of Cu^(2+) onto carbon activation with H_3PO_4

寻求廉价而高效的吸附材料为目的,研究向日葵秸杆基活性炭对铜离子的吸附性能。以向日葵秸秆为原料,经H3PO4活化制备活性炭,通过静态实验研究了其对水溶液中Cu2+的吸附特性,考察了溶液pH值、吸附温度和离子强度对吸附的影响,探讨了吸附热力学、动力学和吸附机理。结果表明:溶液pH值为5～6时活性炭对Cu2+的去除效果最好;向50 mL 170 mg·L-1的溶液中加入0.5 g活性炭,温度为45℃、吸附时间为1 h时,对Cu2+的去除率可达98.3%;Langmuir方程能更好地描述Cu2+在活性炭上的等温吸附特征,静态吸附容量可达41.03 mg·g-1;吸附过程符合拟二级动力学过程,且为吸热的化学吸附过程,膜扩散为速率控制步骤,离子交换可能在吸附过程中起了重要作用。

For the purpose looking for cheap and high effective adsorption materials,the removal of Cu2＋ from aqueous solution by sunflower straw activation carbon had been studied.Cu2＋ adsorption characteristics in water solution has been studied in static experiments,with the activation carbon manufactured through activator H3PO4 and sunflower stalks as raw material.The influence of solution pH value,ionic strength and temperature was investigated.The adsorption kinetics,thermodynamic behavior and mechanism were also discussed.It is showed that the effect of removal of Cu2＋ is best when the value of pH is between 5 and 6;the removal ratio can reach to 98.3% when 0.5 g carbon activation is added into the Cu2＋ solution of 50 mL 170 mg·L-1,temperature is at 45 ℃,and the adsorption time is at 1 hour;Langmuir equation may be better to describe the adsorption characteristics of Cu2＋ onto carbon activation,and the static adsorption capacity is 41.03 mg.g-1;and the adsorption process accords with pseudo second order dynamics,and it is an endothermic adsorption-reaction with the control of film diffusion rate,and the adsorption of copper ions onto the carbons might be involved in an ion-exchange mechanism.