Using rice straw to prepare magnetic carbon material for arsenic removal

Abstract

Magnetic carbon material has been successfully synthesized from rice straw, FeCl₃ and KOH by hydrothermal carbonization method at low temperature. Batch studies were conducted to examine the adsorption kinetics and adsorption capacity of magnetic carbon material (MC) for As(V). The obtained materials were characterized using XRD, SEM, EDX, FT-IR, BET, and VSM. It shows that the obtained materials have high specific surface area (171 m²/g) and magnetization (33 emu/g). The pseudo-second order rate equation was found to describe better the kinetics of arsenic adsorption than the pseudo-first order. Although the two models both describe the experimental data well, the isotherm data for As(V) removal fitted better with the Langmuir equation compared with the Freundlich model. With an initial arsenic concentration of 400 µg.L^-1, the content after adsorption treatment was lower than the allowable arsenic limit in drinking water (10 µg/L) as prescribed by the World Health Organization (WHO). Therefore, the sample had a high surface area, magnetic properties and removal of arsenic ion from aqueous solution, appearing to be a potential adsorbent.