Mild Acid-Alkali Modification of Ceramsite: a Low-Cost Adsorbent for Lead Removal

In order to improve the adsorption capacity of waste-based ceramsite, this study proposed to use acid-alkali surface modification to enhance the adsorption capacity of ceramsite for heavy metals. In acid treatment, the ceramsite surface generated a composite pore structure, thus the specific surface area of ceramsite is significantly increased through acid treatment. In alkaline treatment, hydroxyl functional groups were loaded on the surface of the ceramsite, therefore the adsorption capacity for heavy metals was significantly improved. The surface of modified ceramic particles carries a negative charge, which is beneficial for the adsorption of cations. Taking lead ions as an example, the adsorption performance of ceramic particles on heavy metals was tested, and the maximum adsorption capacity reached 33.2 mg/g. Furthermore, the modified ceramic particles exhibit good desorption and regeneration properties. The modified ceramsite offers advantages in terms of raw material sources and production costs compared to natural zeolite.