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Pretreatment of agroindustry waste by ozonolysis for synthesis of biorefinery products 311

the sugar yield for wheat and rye straw when the reaction time was fixed.
Wan Omar and Amin (2016) revealed that the interaction between ozone flow rate
and reaction time could lead to a decrease in lignin degradation due to the longer
reaction time although the ozone flow rate was increased. Thus the optimal ozone
flow rate might help one to reduce the ozone gas and solid biomass mass transfer
limitation. The ozone concentration in the reactor can be precisely controlled by the
ozone generation rate, therefore preventing the reaction from being ozone-limited.

14.2.2.2 Effect of particle size

Significant effect of particle size of the lignocellulosic biomass can be seen on
process parameters, thus being considered an important parameter for an optimal
ozonolysis process. A very small particle could facilitate the sugar released yield
but ultimately causing additional cost for grinding and sieving process. Shi et al.
(2015b) used particles ranges from 160 to 21 μm of corn straw in a fixed-bed reac-
tor by combining two clean pretreatment of ozonolysis and planetary ball mill and
obtained the highest glucose conversion at 64 μm. The size reduction of raw materi-
als could increase the glucose release and delignification efficiency because much
finer particles can agglomerate more easily, resulting in a smaller reaction area
with ozone and raw materials.
Ozonolysis pretreatment of maize stover in particle sizes of 20, 40, 80, 150, and
less than 300 μm has been studied by Li et al. (2015b). The optimal moisture con-
tent varies with particle sizes. For a maximizing delignification rate the optimal
moisture content was 60% for 300 μm of particle sizes and an optimal moisture
content of 45% for other particle sizes. Moisture and particle sizes have an interac-
tive effect, and the relation between glucose yield and delignification rate is shown
in Fig. 14.3C. A delignification of 75% and a glucose conversion of 80% were
achieved with particle sizes lower than 300 μm(Li et al., 2015b).
The wheat straw particle sizes of 0.5, 1.0, and 2.0 mm have been studied by
Schultz-Jensen et al. (2011) in a fixed-bed reactor where the glucan conversions
were 23%, 50%, and 19.4%, while the xylan conversions were 57.5%, 75%, and
45%. At 2 mm particle sizes the reaction kinetic was slowed due to a lower surface
area for ozone interaction with subtract (Schultz-Jensen et al., 2011). Meanwhile
with the 0.5 mm particle, the sugar conversion decreased due to agglomeration
effect. On the other hand, de Barros Rda et al. (2013) studied the enzymatic sac-
charification of sugarcane bagasse and straw by combining wet disk milling and
ozonolysis pretreatment in particle sizes less than 2 mm (de Barros Rda et al.,
2013). The increased yields were attributed to the larger surface area due to the par-
ticle size reduction. Neely (1984) found that the reaction time can be reduced by
reducing the particle sizes from 1000 to 106 μm.
Wheat and rye straws were studied by Garcı ´a-Cubero et al. (2009) in a fixed-bed
reactor with particle size of ,1 and 3 5 mm and found that the delignification and
sugar yields did not significantly change with particle size. While studying sugar-
cane bagasse, Souza-Corrˆ ea et al. (2014) found that reducing particle sizes (from 2
to 0.08 mm) gave a small improvement of delignification efficiency from 75% to
80% (Souza-Corrˆ ea et al., 2014). The most significant change was found below