3.1 Phase transition
MDSCTM allows for separation and evaluation of
thermodynamic and kinetic processes within the regions of glass and
melting transitions as shown in equation (1). Endothermic or exothermic
enthalpy relaxation may occur within the glass transition range owing to
changes in the temperature of the sample. There was no glass transition
(Tg ) on total heat flow and non-reversible heat
flow profiles except on reversible heat flow profiles for all biomass
samples tested. There was glass transition (Tg )
at a temperature of 239 K and the enthalpy change of 12.586 J/g with an
endothermic peak temperature of 292.333 K for BA sample, and aTg of 211 K, an enthalpy change of 22.096 J/g at
an endothermic peak temperature of 287 K for BCN samples on the
reversible heat flow profiles which was an indication of a structural
transformation of the samples studied, i.e. BA and BCN samples; that is
reversible with any temperature changes
[29,
30]. The lowerTg for BCN samples is an indication of a rapid
breakdown of aromatic constituents in Beta vulgaris supplemented
biomass owning to the residual free cyanide within the synthetic
wastewater used, thereby enhancing microbial growth during the free
cyanide biodegradation process. In addition, melting transition
(Tm ) was observed on the reversing heat flow
profiles for all samples studied – see Table 1.
Table 1: Effect of
melting temperature on the samples