Tailored Synthesis of Ca(OH) ₂ with High Specific Surface Area from Quicklime for Removal of Cd(II) from Solution

Abstract Lamellar Ca(OH) 2 with high specific surface area (SSA) and enhanced Cd(II) removal efficiency was synthesized via a lime digestion method using quicklime as the raw material and triethanolamine (TEA) as an activator. It is found that TEA plays a crucial role in forming high SSA lamellar Ca(OH) 2 and improving removal efficiency of Cd(II) in aqueous solution. Digesting in the presence of 15% TEA yields the Ca(OH) 2 exhibiting an SSA of 62.666 m 2 g −1 , pore volume of 0.2106 cm 3 g −1 , and average pore size of 11.664 nm. Moreover, the incorporation of TEA inhibits Ca(OH) 2 crystallization, leading to TEA molecule intercalation within the crystal structure and a morphological transition from hexagonal prismatic blocks to lamellae. Consequently, the prepared Ca(OH) 2 shows a 99.99% Cd(II) removal efficiency and the residual Cd(II) below 0.004 mg L −1 in supernatant, meeting China's drinking water standard. The primary mechanism underlying the removal of Cd(II) is proved to be chemisorption, accompanied by both monolayer and multilayer physical adsorption. These results suggest the feasibility of synthesizing high‐SSA Ca(OH) 2 via a scalable lime digestion process and providing a cost‐effective Ca(OH) 2 adsorbent for Cd(II)‐contaminated water treatment.