Remediation of Copper and Zinc from wastewater by modified clay in Asir region southwest of Saudi Arabia

To investigate the efficacy of modified clay minerals to remediate heavy metals from industrial wastewater, two natural clay sediments dominated by kaolinite were selected. Since the kaolinite clay has low cation exchange capacity, some modifications were made using unusual treatments thermal transformation and acid activation techniques were used to increase exchangeability properties for producing modified kaolinite. The increased exchangeability was demonstrated through various methods. Results of X-Ray diffraction analysis verified the transformation of Kaolinite as indicated from disappearing all the diffractogram peaks due to kaolinite. In infra-red spectroscopy, the presence of a broad band with little change in the intensity in the region coupled with broad Si-O bending vibration band and Si-O-Al compound vibration bands explain the extent of structural disorder as a response of modification treatment. From a mineral structural viewpoint, destruction through heat treatment exposes directed –OH bonds located between the tetrahedral and octahedral layers (amorphization). It has been observed that after an acidification treatment, the –OH groups become less stable and lead to the newly formed vacant sites during the modification treatments accommodate extra structural water; thereby; broadening the –OH bands in the I.R spectrum