Effects of Temperature and pH on Adsorption Isotherms for Cupric and Cadmium Ions in Their Single and Binary Solutions Using Corncob Particles as Adsorbent

Abstract

ABSTRACTThe effect of temperature on the adsorption isotherms for cupric and cadmium ions by corncob particles was investigated. The uptake of the two types of ions by corncob particles increased with temperature in the ranges between 25°C and 65°C and between 15°C and 65°C for copper and cadmium, respectively. In addition, a study on the competitive adsorption of copper and cadmium ions from their mixture by the adsorbent was also conducted. The tests showed that the uptake of copper ions in the mixture increased with increasing the total metal ion concentration. However, the uptake of cadmium ions from the mixtures first increased, reached a maximum point, and then decreased with increasing the total metal ion concentration resulting in inversed U-shape isotherms. To describe these inversed U-shape isotherms, a new competitive adsorption model with interaction factors was proposed and its constants were estimated. From the tests, it can be concluded that the cupric ions had stronger affinity than the cadmium ions for the corncob particles during the competitive adsorption.