원문정보
초록
영어
Increasing the accessibility of enzymes to cellulose of lignocellulosic biomass has long been
a challenge in bioconversion of lignocellulose into biofuels. In this study, rice straw
produced in S. Korea was pretreated by aqueous ammonia at moderate temperatures to
improve the enzymatic hydrolysis. By selecting the degree of delignification and enzymatic
digestibility as target maximizing functions, pretreatment process conditions of temperature,
time, concentration of ammonia, and solid-to-liquid ratio (S/L ratio) were optimized by using
a response surface methodology (RSM). The tested ranges of reaction conditions were as
follows: a temperature of 50-70°C, a reaction time of 4-12 h, and an ammonia concentration
of 12-28 wt.% at a fixed S/L ratio of 1:6. The effects of ammonia soaking process on the
structure of rice straw were also investigated by crystallinity index and scanning electron
microscopy. These results indicated that the theoretical glucose yield of the aqueous
ammonia-pretreated rice straw by commercial cellulase was significantly increased in
comparison with untreated rice straw approximately from 20 to 70% of theoretical maximum
of glucose hydrolysis yield. The experimental and RSM optimization results showed that
the reaction time and temperature were significant on the degree of lignin removal and
enzymatic digestibility of the pretreated rice straw. The optimum reaction conditions for
achieving the maximum enzymatic digestibility was determined to be 69°C, 10 h, 20.5 wt.%
at a S/L ratio of 1:6.