ALKALI MODIFICATION: AN APPROACH TO IMPROVE SURFACE PROPERTIES OF BIOCHAR FROM EASILY AVAILABLE FEEDSTOCKS

Abstract

Biochar is a stable carbon-rich material whose potentials can be greatly
enhanced by modification with simple treatments. Easily available two different
biochars such as rice stubble biochar (RSB) and saw dust biochar (SDB) were
slowly pyrolyzed (450±50°C) and modified with KOH as RSB-M and SDB-M
respectively. Represented biochars were analyzed to know their physicochemical
characteristics and nutrient contents. Results revealed that nutrient contents such
as total N, P and S of RSB and SDB were found maximum whereas RSB-M and
SDB-M showed the lowest nutrient contents. All the biochars possessed pH
value higher than 7. In case of organic C, the values of RSB-M (19.97%) and SDBM
(17.83%) were the highest and RSB (17.32%) and SDB (14.80%) were the
lowest. All the biochars showed very low concentration of heavy metals (such as
Cr, Cd, Pb and Ni). Water holding capacity, average particle size and surface
area were higher in the RSB-M and SDB-M compared to unmodified RSB and
SDB. These findings showed that alkali-modified biochars had better surface
properties than unmodified biochars.