Preparation and characterization of corn cob activated carbon coated with nano-sized magnetite particles for the removal of Cr(VI)

• Published in: Bioresource technology 2013-04, Vol.134, p.94-100
• Main Authors: Nethaji, S., Sivasamy, A., Mandal, A.B.
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Adsorption isotherm; Adsorption mechanism; Agronomy. Soil science and plant productions; Batch Cell Culture Techniques; Biodegradation, Environmental; Biological and medical sciences; Bioreactors; Charcoal - chemistry; Chemisorption; Chromium - isolation & purification; Continuous column studies; Diffusion; Ferrosoferric Oxide - chemistry; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Isotherms; Kinetics; Magnetite; Magnetite nanoparticles; Magnetized activated carbon; Mathematical analysis; Mathematical models; Nanoparticles - chemistry; Particle Size; Surface chemistry; Temperature; Use of agricultural and forest wastes. Biomass use, bioconversion; Water Pollutants, Chemical - isolation & purification; Water Purification - methods; Zea mays - chemistry
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2013.02.012

► Activated carbon coated with magnetite nanoparticles was synthesized from biomass. ► Nano magnetization achieved in a single step process and well characterized. ► Adsorbent showed better superparamagnetism compared to reported elsewhere. ► New nano magnetite adsorbent effectively removed toxic hexavalent chromium. ► Continuous column reactor was designed and the parameters evaluated. Activated carbon prepared from corn cob biomass, magnetized by magnetite nanoparticles (MCCAC) was used for the adsorption of hexavalent chromium from aqueous solution. The adsorbent was characterized by SEM, TEM, XRD, VSM, surface functionality and zero-point charge. The iron oxide nanoparticles were of 50nm sizes and the saturation magnetization value for the adsorbent is 48.43emu/g. Adsorption was maximum at pH 2. Isotherm data were modeled using Langmuir, Freundlich and Temkin isotherm. The prepared MCCAC had a heterogeneous surface. The maximum monolayer adsorption capacity was 57.37mg/g. Kinetic studies were carried out and the data fitted the pseudo second-order equation. The mechanism of the adsorption process was studied by incorporating the kinetic data with intraparticle diffusion model, Bangham equation and Boyd plot. The adsorption was by chemisorption and the external mass transfer was the rate-determining step. A micro column was designed and the basic column parameters were estimated.