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

• Published in: Journal of colloid and interface science 2015-06, Vol.448, p.238-250
• Main Authors: Mohan, Dinesh, Singh, Prachi, Sarswat, Ankur, Steele, Philip H., Pittman, Charles U.
• Format: Article
• Language: English
• Subjects: Adsorption; Biochar; Charcoal - chemistry; Electrochemical Techniques; Energy cane biochar; Ferric Compounds - chemistry; Lead - isolation & purification; Lead adsorption; Magnetic energy cane biochar; Magnets - chemistry; Metal removal; Sorption; Water Pollutants, Chemical - isolation & purification; Water Purification - methods
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2014.12.030

[Display omitted] Energy cane biochar (ECBC) was prepared in a 72s fast pyrolysis at 425°C in an auger-fed reactor and ground into 250–600μm 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 SBET of energy cane biochar was negligible and increased to 37.13m2/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 (Q0, mg/g) as temperature increased for nonmagnetic [Q025°C=45.70; Q035°C=52.01 and Q045°C=69.37] and magnetic [Q025°C=40.56; Q035°C=51.17 and Q045°C=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.