Air infiltration in mass scale industrial applications of
bio char production is inevitable. The presence of oxygen during the
carbonization process is detrimental to the production of biochar yield
and properties. The experiment was carried out on several wood
species in a fixed-bed pyrolyser under various fractions of oxygen
ranging from 0% to 11% by varying nitrogen and oxygen composition
in the pyrolysing gas mixtures at desired compositions. The bed
temperature and holding time were also varied. Process optimization
was carried out by Response Surface Methodology (RSM) by
employing Central Composite Design (CCD) using Design Expert 6.0
Software. The effect of oxygen ratio and holding time on biochar yield
within the range studied were statistically significant. From the
analysis result, optimum condition of 15.2% biochar yield of
mangrove wood was predicted at pyrolysis temperature of 403 oC,
oxygen percentage of 2.3% and holding time of two hours. This
prediction agreed well with the experiment finding of 15.1% biochar
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