A composite adsorbent of superparamagnetic nanoparticles with sludge biomass derived activated carbon for the removal of chromium (VI)

Superparamagnetic nanoparticles/sludge biomass derived activated carbon composite was prepared and characterized using FT-IR, XRD, FE-SEM, HR-TEM, and Vibrating Sample Magnetometer (VSM). The surface area, porosity and pore volume were evaluated using BET method. The composite adsorbent had a specific surface area of 119.56 m2/g and saturation magnetization value of 2.35 emu/g. The iron oxide nanoparticles were in the size range of 15–30 nm. The composite adsorbent was utilized for the removal of Cr (VI) from aqueous solution. Langmuir, Freundlich and Temkin model isotherms were employed to study the adsorption phenomena. Monolayer adsorption capacity of the adsorbent for Cr (VI) was 80.21 mg/g at pH 2.0. Thermodynamics of the adsorption process was studied and the prepared composite adsorbent showed better stability and recyclability for multiple use.