Optimization of Malachite Green Dye Adsorption Using Response Surface Methodology with CaO/PEG/Fe₃-O₄- Composite and Evaluation of Its Antibacterial Properties Ali Nurdin Hidayat1, Rajib Mulia Hakiki1, Della Ayu Eriza2, Nurlisa Hidayati2, Salni3, Poedji Loekitowati Hariani2
1Magister Program of Chemistry, Department of Chemistry, Faculty of Mathematics and Natural Sci-ence, Universitas Sriwijaya, Ogan Ilir 580056, Indonesia
2Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Sriwijaya, Ogan Ilir 580056, Indonesia
3Department of Biology, Faculty of Mathematics and Natural Science, Universitas Sriwijaya, Ogan Ilir 580056, Indonesia
Abstract
This study aims to synthesize and evaluate the performance of a CaO/PEG/Fe₃-O₄- composite as an adsorbent for the removal of Malachite green dye. The composite was characterized using XRD, BET, VSM, and SEM to determine its crystalline structure, specific surface area, magnetic behavior, and surface morphology. Adsorption optimization was carried out using Response Surface Methodology (RSM) based on a Central Composite Design (CCD) to investigate the effects of pH, initial dye concentration, and contact time on adsorption efficiency. The quadratic model showed a good correlation with an R2 value of 0.982. The optimum conditions were achieved at pH 10, a dye concentration of 10.71 mg/L, and a contact time of 120 minutes, resulting in a 94.28% removal efficiency. Furthermore, antibacterial tests against Escherichia coli and Staphylococcus aureus revealed significant inhibition zones, confirming the composite potential antimicrobial. Reusability tests demonstrated good stability, with only a 6.7% decrease in adsorption efficiency after five consecutive cycles.
Keywords: CaO/PEG/Fe₃-O₄-, adsorption, malachite green dye, optimization, antibacterial
