Preparation and characterisation of biochars from elephant grass and their utilisation for aqueous nitrate removal: Effect of pyrolysis temperature
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Date
2020-09-21
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Biochar is a solid material obtainable from biomass pyrolysis and useful for pollution alleviation and soil
amendment. In this study, Biochars A and B were produced from elephant grass at pyrolytic temperatures of 400 ◦C and 600 ◦C, respectively, for removal of nitrate ion from aqueous solution. The physicochemical characteristics of the biochars were evaluated. The biochars were also characterised using Fourier Transform Infrared
(FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and X-ray Diffraction
(XRD). Operational variables such as pH, contact time, and concentration of nitrate ion were varied and optimum
variables were obtained. Kinetic and equilibrium data were subjected to kinetic (pseudo-first order, pseudosecond order, Avrami fractional order, Elovich and intraparticle diffusion) and equilibrium (Langmuir,
Freundlich, Liu, and Redlich-Peterson) models, respectively, to elucidate the interaction between the nitrate ion
and biochars. The yields of Biochars A and B were 41.40 % and 32.25 %, respectively. The two biochars
possessed good cation exchange capacity, water-holding capacity, carbon stability, and porosity. Avrami fractional kinetic order was the best model that explained the kinetic data. Maximum adsorption capacities obtained
from Liu model (the best equilibrium model) are 140.7 and 237.5 mg g− 1 for Biochars A and B, respectively.
Adsorption process was spontaneous and exothermic. There was a decrease in the disorderliness in the nitratebiochar system. Biochar B performed better than Biochar A for removal of nitrate ion from water. In summary,
the biochars produced from elephant grass excellently removed nitrate ion from solution and could be utilised for
water decontamination.
Description
Staff Publication
Keywords
Elephant grass, Biochar, Nitrate ion, Pyrolysis, Liu isotherm, Avrami fractional order
Citation
Adesemuyi, F. M., Adebayo, M. A., Akinola, A. O., Olasehinde, E. F., Adewole, K. A., & Lajide, L. (2020). Preparation and characterisation of biochars from elephant grass and their utilisation for aqueous nitrate removal: Effect of pyrolysis temperature. Journal of Environmental Chemical Engineering, 104507. doi:10.1016/j.jece.2020.104507