Evaluation of Clay Brick and Laterite Brick as Low-Cost Adsorbents for the Removal of Cd2+ and Pb2+ in Aqueous Solutions

Adsorption is recognized as a low-cost and effective method for treating C admium and Lead in wastewater. Therefore, this study focu sed on investigating the potential of construction demolition wastes (CDWs), laterite bricks (LB), and clay brick (CB) to re move Cd and Pb in synthetic wastewater. A series of batch a dsorption experiments were conducted to study the adsorption characteristics and capacities. The results revealed that the ma ximum adsorption capacity of CB and LB reached 210.85 mg/g and 210.72 mg/g for Pb²⁺, respectively. The maximum adsorption capacity of Cd²⁺ by CB and LB was 4.52 mg/g and  4.51 mg/g. From adsorption isotherms, the Langmuir and Freundlich models fitted well for 0 ≤ Ci ≤ 1000 mg/L of Cd²⁺ adsorption on both CB and LB. Adsorption of Pb²⁺ onto CB and LB is well  captured by all isotherm models tested. A similar pattern of adsorption was observed among all particle sizes of CB and LB  (<0.5, 0.5-1.0, and 1.0–2.0 mm), indicating that the particle size  of tested adsorbents is not affecting the adsorption isotherms of Cd²⁺ and Pb²⁺. However, the particle size ranges used in this  study lay within a narrower range, which might be the reason  for not showing any difference in adsorption among the different size fractions. Therefore, it is concluded that both CB and  LB are effective and environmentally friendly adsorbents to remove Pb²⁺ and Cd²⁺in wastewater.