Synthesis and Application of Calcium-Alginate-Chitosan as a Seawater Desalination Product

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Negeri Malang, Jl. Semarang 5, Malang 65145, Indonesia

^* Corresponding author: anugrah.ricky.fmipa@um.ac.id

Abstract

Water is one of the primary needs of society in the modern era. The demand for freshwater has been increasing year by year but is not proportional to the amount of available water. This research aims to synthesize calcium-alginate-chitosan beads using natural coral skeleton waste as a source. Calcium-alginate-chitosan beads function to absorb NaCl levels in seawater. The method used in this study is a cross-linking reaction between polymers with variations of CaCh, namely 0.5 M, 1 M, and 2 M for the formation of calcium-alginate-chitosan. Furthermore, the synthesis results were characterized using FTIR to determine the functional groups of the beads. Calcium-alginate-chitosan beads will be optimized with laboratory-scale NaCl compounds at variations of 15, 30, and 60 minutes. XRF analysis of coral powder showed the percentage of calcium in the form of CaO before calcination to be 94.63% and after calcination to be 94.76%. FTIR characterization was carried out on coral powder and calcium-alginate-chitosan beads. The levels of [Na+] and [Cl^-] were analyzed using ICP-OES, argentometric titration, and AAS instrument analysis. The application of calcium-alginate-chitosan beads in optimal conditions was carried out using seawater. The results showed that the optimal conditions for calcium-alginate-chitosan beads were at a concentration of 0.5 M with a contact time of 30 minutes. Applications conducted on standard NaCl obtained adsorption percentages of [Na+] of 95.75% and [Cl^-] of 99.41%, while applications conducted on seawater obtained adsorption percentages of [Na+] of 68.04% and [Cl^-] of 37.8%.