Gluconic acid produced from corn stover hydrolysate existed in
the form of sodium gluconate. The obtained sodium gluconate was
used as cement additive to prolong the setting time of cement
mortar by measuring its setting times and fluidity. The commercial
sodium gluconate produced from starch feedstock was used as
control. Final setting time indicates the time of cement mortar to
completely losing the plasticity and behaving rigorous structural
strength. Table 3 shows that the final setting time of cement mortar
with cellulosic sodium gluconate addition was almost same to
that with starch sodium gluconate (222 and 226 min, respectively).
Fluidity indicates the uniformity and stability of cement additive in
cement mortar indicated by circle diameter of cement mortar flow.
Table 4 shows that the fluidity of cellulosic sodium gluconate was
13.5% greater than the commercial sodium gluconate from starch.
The results indicate that the cellulosic sodium gluconate from corn
stover was comparable to the starch based sodium gluconate as the
cement additive for extending the setting time and fluidity of
cement mortar.
This study reported a dry dilute acid pretreated corn stover as
feedstock of high titer gluconic acid fermentation, in which no free
wastewater was generated from pretreatment operation, no detoxification
step was applied to inhibitor removal, and no extra nutrient
addition was required. The preliminary test of the obtained
cellulosic sodium gluconate demonstrated the competitive property
as cement additive to starch based commercial sodium gluconate
for extending the setting time and fluidity of cement
mortar. This environment friendly technology provided a promising
options for replacing starch feedstock for gluconic acid production
with lignocellulosic biomass.