Performance of algal activated carbon/Fe3O4 magnetic composite for cationic dyes removal from aqueous solutions

Abstract

The activated carbon of Sargassum oligocystum (ACSO) was composited with Fe3O4 nanoparticle (=ACSO/Fe3O4) by a simple method and used as a recyclable and effective adsorbent for the removal of methylene blue (MB) and methyl violet (MV) from aqueous solutions. ACSO/Fe3O4 was characterized using different physicochemical methods. The value of saturation magnetization and Brunauer–Emmett–Teller (BET) surface area for ACSO/Fe3O4 was obtained 26.57 emu/g and 126.77 m2/g, respectively. The optimal adsorption conditions, including initial pH (7), the amount of ACSO/Fe3O4 (0.15 g/100 mL), and contact time (50 min) were determined. At optimized conditions and the ultrasonic wave of 45 kHz more than 98% of the cationic dyes were removed. The adsorption process data matched well with pseudo-second-order and Freundlich isotherm models. Intra-particle diffusion model showed that the adsorption of cationic dyes onto ACSO/Fe3O4 magnetic composite is two-stage and the speed of the first stage is faster than the second one. Furthermore, the maximum adsorption capacity of the ACSO/Fe3O4 magnetic composite toward MB and MV reached as high as 60.60 mg/g and 59.88 mg/g, respectively. Finally, seven times reusing of ACSO/Fe3O4 and removing dye from a real wastewater has made it a promising and attractive option for further practical applications.