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BioMed Research International
Volume 2013 (2013), Article ID 934171, 11 pages
Research Article

Optimization of Sulfide/Sulfite Pretreatment of Lignocellulosic Biomass for Lactic Acid Production

1Department of Chemistry, GC University, Katchery Road, Lahore 54000, Pakistan
2Office of Research, Innovation and Commercialization, COMSATS Institute of Information Technology, Chak Shahzad, Park Road, Islamabad 45600, Pakistan

Received 25 March 2013; Revised 24 June 2013; Accepted 24 June 2013

Academic Editor: Alain Dufresne

Copyright © 2013 Muhammad Idrees et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Potential of sodium sulfide and sodium sulfite, in the presence of sodium hydroxide was investigated to pretreat the corncob (CC), bagasse (BG), water hyacinth and rice husk (RH) for maximum digestibility. Response Surface Methodology was employed for the optimization of pretreatment factors such as temperature, time and concentration of Na2S and Na2SO3, which had high coefficient of determination ( ) along with low probability value ( ), indicating the reliable predictability of the model. At optimized conditions, Na2S and Na2SO3 remove up to 97% lignin, from WH and RH, along with removal of hemicellulose (up to 93%) during pretreatment providing maximum cellulose, while in BG and CC; 75.0% and 90.0% reduction in lignin and hemicellulose was observed. Saccharification efficiency of RH, WH, BG and CC after treatment with 1.0% Na2S at 130°C for 2.3–3.0 h was 79.40, 85.93, 87.70, and 88.43%, respectively. WH treated with Na2SO3 showed higher hydrolysis yield (86.34%) as compared to Na2S while other biomass substrates showed 2.0–3.0% less yield with Na2SO3. Resulting sugars were evaluated as substrate for lactic acid production, yielding 26.48, 25.36, 31.73, and 30.31 gL−1 of lactic acid with 76.0, 76.0, 86.0, and 83.0% conversion yield from CC, BG, WH, and RH hydrolyzate, respectively.