Magnetized algae-silica hybrid from Porphyridium sp. biomass with Fe3O4 particle and its application as adsorbent for the removal of methylene blue from aqueous solution

Abstract

Algae-silica hybrid material from biomass Porphyridium sp. (AS) has been modified by coating Fe3O4 particles (MPs) via a sol-gel process using tetraethyl orthosilicate (TEOS) to produce algae-silica-Fe3O4 (AS-MPs). The AS-MPs produced were applied as adsorbent for the adsorption of methylene blue (MB). Identification of functional groups was performed by infrared spectrometer (IR) indicating that in AS-MPs there were active organic group derived from Porphyridium sp., silanol, and siloxane. Diffraction pattern of the AS-MPs material analyzed by X-ray diffraction (XRD) showed that the material has peak with higher intensity at 2θ = 30.04 and 35.52o. Analyst results using a particle size analyzer (PSA) showed that the average particle size distribution of the AS-MPs material was 1.40 µm. In addition the results of the analysis using Scanning Electron Microscopy (SEM), material of AS-MPs has a more heterogeneous surface morphology. The models of MB adsorption by AS and AS-MPs tend to follow the pseudo second-order kinetics model and Freundlich adsorption isotherm. The adsorption of MB solution by AS-MPs produces rate constants (k2) of 0.003 g/mg·min and adsorption capacity (qm) of 96.927 mg/g under the experiment conditions of dose of adsorbent 2.5 mg/L, interaction pH of 6, contact time of 60 min, and temperature of 27 °C. The AS-MPs material obtained from the results of this study can be used as an effective adsorbent because it can remove MB dyestuff in solution, it is chemically stable in acidic and neutral media, and it can be used repeatedly