Investigating the use of CaCO3 particles synthesized in the Ca(OH)2-CO2-H2O system for organic matter removal: adsorption efficiency and recyclability.

Abstract

In this study, we experimentally investigate the production and characterization of CaCO₃ particles through the carbonation process of Ca(OH)₂ and evaluate their potential application in removing organic matter. The CaCO₃ particles were characterized using BET, SEM-EDX, FT-IR, particle size, and XRD techniques. Adsorption of organic matter was studied using synthetic solutions and samples from two surface water sources. Experiments were conducted at room temperature with adsorbent dosages ranging from 1.3 to 21.5 g/L, initial dissolved organic carbon concentrations between 2.5 and 20 mg/L (initial loading: 0.1-14.6 mgDOC/gCaCO₃), and a contact time of at least 5 minutes. We observed a removal efficiency of 70-80% for DOC and 90-95% for UV₂₅₄ at a low concentration of organic matter (humic acids, 2.5 mgDOC/L). At a concentration of 5.0 mg DOC/L, we achieved (i) 70-90% DOC removal for humic acid, (ii) 50-65% DOC removal for one surface water sample with SUVA₂₅₄ of 2.4 L/mg·m, and (iii) 20-35% DOC removal for another surface water sample with SUVA₂₅₄ of 4.3 L/mg·m. Furthermore, we investigated the performance of the prepared particles in repeated usage for organics removal. In conclusion, our findings propose areas for future research including optimizing particle cycling within the reaction environment, exploring particle utilization in reactors such as an up-flow particle bed, and assessing potential applications in a membrane contactor. The environmentally friendly and non-toxic nature of CaCO₃ particles emphasizes their significance in future research and applications.