Utilization of Coral Skeleton as Raw Material for Making Ca-Alginate Silica Membrane for Seawater Desalination

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

The calcium content in coral skeleton has the potential as a raw material for the synthesis of calcium alginate silica membrane for the absorption of Na+ and Cl^- ion levels in seawater. This research aims to synthesize Ca-alginate silica membrane by utilizing coral skeleton waste on the coast of Wedi Awu Beach and membrane application to seawater for seawater desalination process. This research stage consists of coral skeleton sampling, characterization of coral powder using XRF instrument, synthesis of Ca-alginate silica membrane with CaCh solution concentration of 0.5, 1, and 2 M, optimization of concentration and contact time, membrane characterization using XRF and FTIR instruments, and membrane application to seawater. The content of CaO in coral is also shown in the results of FTIR analysis at wave number 714.42 cm^-1. Symmetrical and asymmetrical Si-O-Si absorption peaks are also shown from the results of FTIR analysis, namely at wave numbers 1185.55 cm-1 and 835.09 cm^-1. The optimization results of Ca-alginate silica membrane concentration against NaCl standard solution were obtained at a concentration of 0.5 M CaCl2 solution with an optimum contact time of 30 minutes. The results of the percentage of adsorption of Ca-alginate silica membrane on seawater obtained absorption of Na⁺ and Cl^- ions of 61.7% and 36%, respectively.