Biomass derived gamma alumina decorated mesoporous carbon adsorbent for crystal violet removal from aqueous solution using batch system: Isotherm, thermodynamic and kinetic modelling

In this study, gamma alumina decorated mesoporous activated carbon (MAC@Al) adsorbent was prepared in order to remove the staining crystal violet dye found in nature. A biomass feedstock for the synthesis of mesoporous carbon was teak sawdust. Characterization techniques for gamma alumina decorated mesoporous carbon included elemental mapping, powder X-ray diffraction, FTIR, SEM, BET, Raman, XPS and EDAX. By characterizing the adsorbent with FTIR, SEM, XPS and EDAX, the adsorption of crystal violet dye was verified. Five distinct metal salts (Fe (III), Cr (III), As (V), Mg (II), and Ca (II)) were investigated for interference using an aqueous crystal violet dye solution. For the purpose of removing dye, batch mode analysis was used to determine temperature (298 K), dosage (1g/L), pH (neutral), pHzpc, contact time (30 min), and concentration (20-80 mg/ L). Bare activated carbon (BAC) and gamma alumina decorated bare activated carbon (BAC@Al) also were synthesised for comparing the aqueous crystal violet dye removal. The highest optimum removal of crystal violet using MAC@Al is 93.45 percent at pH 7 within 30 minutes for 80 mg/L. which is quite efficient compared to BAC and (BAC@Al) adsorbents discussed in this paper. The Ganga water is used for comparison of 40-ppm crystal violet dye removal using MAC@Al adsorbent within 2-30 min. The Freundlich out of all other isotherm model (Langmuir, Dubinin-Radushkevich) found best fitted showing the it-it interaction mostly with electrostatic and hydrogen bonding mechanism. Kinetically, removal is following pseudo second order kinetics as compared to pseudo first order and Elovich model. The highest adsorption capacity of dye removal was 14 mg/g for 40-ppm aqueous crystal violet dye at 298 K.