Alkaline sulfite pretreatment of corncob residue and its reaction kinetic model
【Abstract】Corncob residues (CCR) were obtained from corncobs by using acid hydrolysis for extraction of xylose. Due to the high content of lignin and low content of hemicellulose in corncob residues, the alkaline sulfite pretreatment was used to treat the corncob residue. The effects of pH, liquid/solid ratio, temperature and the dosage of sodium sulfite on the cellulose retained, delignification, substrate enzymatic digestibility (SED) and yield of lignosulfonate in pretreatment spent liquor were investigated. The results showed that with 10% (mass) sodium sulfite (Na2SO3) and 5% (mass) sodium hydroxide (NaOH) on CCR and 1 h pretreatment at 160 °C, the alkaline sulfite pretreatment could make 86.1% of lignin removed and 82.4% of cellulose recovered in pretreatment liquid/solid ratio of 6/1. The SED of CCR increased from 46.4% to 85.1% after 72 h hydrolysis [cellulase loading of 5 FPU·(g glucan)−1], and the yield of lignosulfonate in pretreatment spent liquor was 31.5g·(100 g CCR)−1 under the same pretreatment condition. Lignin factor (LF) was proposed to predict the lignin content of the pretreated CCR to guide the scale up test and engineering application. The delignification kinetics and prediction equation for SED of CCR were established based on the experimental data. The error of SED predicted and SED measured was within 10%.
【Keywords】 biomass; alkaline sulfite pretreatment; mathematical modeling; prediction; reaction kinetics;
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