Removal of copper ion using rice hulls

Rice hulls which have some functional groups like hydroxyl, carboxyl and amino groups were used as an adsorbent to remove copper ions. The functional groups and composition of elements in rice hulls were confirmed by the FT-IR and elemental analysis. Rice hulls had a high uptake capacity of 0.18 mmol/g-dry mass for copper ion at pH 4 and regression curve using Langmuir isotherm equation fit well with the experimental data. The effects of pH, loading amount, time, and organic material (NTA) on uptake capacity of copper ions were investigated. The optimal pH for copper ion uptake was the 4 and rice hulls could remove copper ions of about 33% with 5.0 g of loading amount. Adsorption process of copper ions was almost completed in 30 min and effect of NTA on copper uptake capacity was very small in low concentration (<100 mg/L).