Removal of Copper and Cobalt(II) Ions from Sewage Using Natural and Modified Bentonite: Kinetics Studies

In the present study, the adsorption capacities of natural activated clay (bentonite) and Na-form of heat-treated bentonite for copper and cobalt ions from sewage at 20–65°C temperature range were examined and compared. The modification of the natural clay was performed by treatment with hydrochloric acid and subsequent neutralization of the resultant solution by sodium hydroxide. The morphology and structural properties of Natural and Na-form of heat-treated bentonite were investigated by XRD, SEM, and FTIR. The equilibrium adsorption capacity of both natural and Na-form heat-treated bentonite at various temperatures were determined samples. XRD showed, there is the montmorillonite in studied bentonite and modified bentonite samples. SEM analysis indicated the montmorillonite is formed in format of large and small bowls and leaf shape in 2 samples. The study showed that increasing the temperature results in the increase of the adsorption efficiency of the adsorbents because swelling and dehydration are reduced. Also, the adsorption efficiency of bentonite samples for the Cu²⁺ ions was greater than Co²⁺ ions in all the examined solution concentration and temperatures. Na modified bentonite had higher equilibrium distribution coefficient, gross capacity values, and metal ion adsorption selectivity.