Calcined Corn Cob-Kaolinite Mixture as Adsorbents for the Removal of Heavy Metal from Aqueous Solution

This research explores a low-cost composite adsorbent synthesized from calcined corn cobs and kaolinite for the extraction of lead (Pb2+) and cadmium (Cd2+) from polluted water. Corn cobs were dried and calcined at 150°C, then combined with kaolinite in a 3:2 weight ratio, followed by a thermal treatment at 300°C. The final product, termed Corn Cob-Kaolinite Mixture (CCKM), was tested in batch adsorption studies under different conditions (pH, initial ion concentration, contact time, dosage, and temperature). The adsorption characteristics were modeled using Langmuir and Freundlich isotherms. Results indicated a stronger correlation with the Langmuir model, with R2 values of 0.914 for Pb2+ and 0.952 for Cd2+, suggesting monolayer adsorption. These findings affirm the effectiveness and affordability of CCKM for treating heavy metal-contaminated water.