Lead sorptive removal using magnetic and nonmagnetic fast pyrolysis energy cane biochars

Energy cane biochar (ECBC) was prepared in a 72 s fast pyrolysis at 425 degrees C in an auger-fed reactor and ground into 250-600 pm diameter particles. This biochar was magnetized by fusing an iron oxide phase to the particles by mixing aqueous biochar suspensions with aqueous Fe3+/Fe2+ solutions, followed by NaOH treatment (MECBC). These biochars were characterized by Raman, FT-IR, X-ray, SEM, SEM-EDX, TEM, EDXRF, pHzpc, elemental analyses, SBET, and magnetic moment determinations. The SUET of energy cane biochar was negligible and increased to 37.13 m(2)/g after Fe3+/Fe2+/NaOH magnetization. The dry biochar contains 18.4% oxygen. This allows swelling in water and permits sorption inside the solid as well as on its pore surfaces, leading to high capacities at low surface areas. Maximum lead removal occurred at pH 4-5. Sorption isotherms exhibited increasing lead removal (Q, mg/g) as temperature increased for nonmagnetic [Q(25 degrees C)(0) = 45.70; 05.c - 52.01 and Q(45 degrees C)(0) -69.37) and magnetic [Q(25 degrees C)(0) -40.56; Q(35 degrees C)(0) -51.17 and [Q(25 degrees C)(0) = 51.75] biochars. Second order kinetics best fit the lead removal data. Furthermore, magnetic energy cane biochar was easily manipulated by low external magnetic field, thereby, allowing its easy recovery for further recycling and replacement from water. ECBC and MECBC were also successfully applied for Pb2 removal from contaminated ground water. Therefore, both chars can be used as potential green low cost sorbents for lead remediation to replace commercial activated carbon. (C) 2014 Elsevier Inc. All rights reserved.