Professor, Department of Chemistry, Faculty of Mathematic and Natural Sciences, University of Lampung, Indonesia

Speech Title: Synthesis of algal-silica-magnetite hybrids from red algae biomass as methylene blue adsorbent in aqueous solution

Abstract: The synthesis of algae-silica-magnetite hybrid materials from Porphyridium sp. red algae biomass (AS) has been done through a sol-gel process using tetraethyl orthosilicate (TEOS) as a precursor to produce an algae-silica-magnetite material (AS-MPs). The identification of functional groups performed by infrared spectrophotometers (IR) shows that in AS-MPs there are organic active groups derived from red algae biomass, silanol and siloxane from the silica matrix, and Fe-O from magnetite particles (MPs). The diffraction pattern of AS-MPs material analyzed by X-ray diffraction (XRD) shows that the material has a large intensity peak at 2θ = 30.04 and 35.52 while the analysis using Scanning Electron Microscopy (SEM) shows the material surface is heterogeneous. Methylene blue (MB) dye adsorption patterns by AS and AS-MPs tend to follow the second order pseudo kinetics model and Freundlich adsorption isotherm. Adsorption of MB solution by AS-MPs at dose of adsorbent 2.5 mg/L, interaction pH of 6, contact time of 60 min, and temperature of 27 °C yielded rate constants (k₂) and adsorption capacity (q_m) each of 0.003 g/mg•min and 96.927 mg/g. The AS-MPs material is an effective adsorbent for removal of the dye of MB in solution, chemically stable against acid and neutral media and can be used repeatedly.