Synthesis of Cellulose/Nano-hydroxyapatite Composite Hydrogel Absorbent for Removal of Heavy Metal Ions from Palm Oil Mill Effluents

Hydroxyapatite (HA) has been identified to have an outstanding ability to remove heavy metal ions. Hence, nano-hydroxyapatite-cellulose hydrogel composites were developed to investigate the effects of the HA produced from Marcia marmorata clam shell biomass in the composites on increasing the adsorption capacity of a hydrogel to remove heavy metals from industrial wastewater. The hydrogel performance in the removal of heavy metal ions was investigated using a palm oil mill effluent (POME), which is the industrial wastewater from a palm oil mill. The addition of nano-hydroxyapatite in the cellulose hydrogel matrix succeeded in increasing the hydrogel adsorption capacity in the extraction of heavy metal ions, such as Cu2+, Pb2+, Fe2+, Cd2+, and Zn2+. The resulting composite hydrogel with 1.5% of wt/v% of nano-hydroxyapatite managed to get rid of 70.24%, 57.74%, 48.56%, 27.33%, and 25.98% of Cu2+, Pb2+, Fe2+, Cd2+, and Zn2+ ions from POME, respectively. The success of this composite hydrogel in removing heavy metals is an important achievement in the field of industrial wastewater treatment, as it uses the nano-hydroxyapatite produced from the clam shell residual and cellulose powder as the raw materials for the synthesis of the composite instead of using chemicals that are harmful to the environment.