The study of Zn~(2+) and Cd~(2+) adsorption on activated carbon modified with KMnO_4

The adsorption capacity of modified activated carbon(MAC) with KMnO4 to Zn2+ and Cd2+ was studied.The effect of pH,adsorption time and adsorbent dosage on adsorption rate of Zn2+ and Cd2+ was investigated,respectively.The adsorption isotherms were also studied.The results show that there is a high adsorption rate of Zn2+ and Cd2+on the MAC.The adsorption capacity of the MAC to Zn2+ is higher than Cd2+ with the increase of pH.The adsorption speed of Cd2+ on the MAC is more quickly than Zn2+.Their equilibrium time is 60 min and 120 min,respectively.The adsorption behaviors are in accordance with Langmuir model at 25℃ and pH 7.0.On the same condition,the saturated adsorption amounts of Zn2+ and Cd2+ are 10.80 mg/g and 4.564 mg/g,and the adsorption amounts are 1.2 and 1.4 times compared with that of the unmodified activated carbon,respectively.Moreover,the adsorption amounts of Zn2+ and Cd2+ on the MAC are significantly improved with the increase of temperature.