Abstract:
Biochar produced by decomposing variety of biomass feedstock is a carbon rich
product that act as an efficient material for various applications such as contaminant
management in soil and water, soil amendment in agriculture etc. Biochar obtained
from biomass such as wood, manure and leaves have been studied worldwide for
their adsorptive capacity, but reports on use of rice straw for such applications are
limited. Hence the objective of the present study is to produce biochar using locally
available rice straw.
Samples of rice straw were chemically decomposed at 400 °C with H3PO4. In order
to find a suitable surface modifier to increase the surface porosity and acidity, the
resulted biochar materials were treated separately with oxidizing agents such as
HNO3, KOH and H2O2. The pore size distribution of modified and the control
samples were studied using scanning electron microscopy (SEM) technique. The
functional groups available on biochar prior to and after chemical modifications were
analyzed using the Fourier transform infrared spectroscopic (FTIR) technique.
The FTIR spectral analyses disclosed significant increase in concentrations of the
functional groups (carboxylic, alcoholic hydroxyl, phenolic hydroxyl and carbonyl)
available on the surface of the KOH treated sample. The SEM analysis revealed about
40% increment in pore diameter of the rice straw biochar that was modified with
KOH and H2O2 in contrast to non-modified biochar. Hence, according to the present
study, the surface of the decomposed rice straw can be effectively modified with
KOH to increase its surface porosity and functionality.
