Fluoride removal from ground water using magnetic and nonmagnetic corn stover biochars

Slow pyrolysis corn stover biochar was prepared at 500 degrees C in an ingeniously developed reactor. Biooil was also collected. Corn stover biochar was magnetized by mixing aqueous biochar suspension with aqueous Fe3+/Fe2+ solution, followed by NaOH treatment. Corn stover biochar (CSBC) and magnetic corn stover biochar (MCSBC) were characterized by pHzpc, S-BET; X-ray, FT-IR, SEM, SEM-EDX, TEM, EDXRF and Raman analyses. Magnetic moment of MCSBC was also measured. Both the biochars were utilized for fluoride removal to replace the existing commercially available costly adsorbents. Maximum fluoride removal was achieved at pH 2.0. Adsorption studies were carried out at 25, 35 and 45 degrees C. Fluoride removal on CSBC and MCSBC was decreased with rise in temperature [CSBC: Q(25)(0) = 6.42 mg/g; Q(35)(0) = 5.17 mg/g; Q(25)(0) = 4.99 mg/g and MCSBC: Q(25)(0) = 4.11 mg/g; Q(35)(0) = 3.45 mg/g; Q(25)(0) = 3.41 mg/g]. Pseudo-first order kinetics best fit the fluoride adsorption data. Both biochars successfully remediated fluoride from contaminated ground water. (C) 2014 Elsevier B.V. All rights reserved.