Optimization of alkali, acid and organic solvent pretreatment on rice husk and its techno economic analysis for efficient sugar production

Anuradha, A.; Sampath, Muthu Kumar

doi:10.1080/10826068.2022.2078982

Cited by 3 publications

(1 citation statement)

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“…When compared to acid or oxidative reagents, alkali pretreatment is the most efficient approach for rupturing the ester linkages between lignin, hemicellulose, and cellulose and limiting breakage of the hemicellulose polymers. According to previous studies, pretreatment with NaOH effectively increases the accessibility of enzymes to the cellulose while removing lignin and a small fraction of the hemicelluloses [11]. The majority of alkali pretreatment processes used in rice straw biogas production require heating and a substantial use of chemicals.…”

Section: Introductionmentioning

confidence: 99%

Sodium Hydroxide Hydrothermal Extraction of Lignin from Rice Straw Residue and Fermentation to Biomethane

et al. 2023

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The purpose of the NaOH pretreatment of rice straw with a recycling strategy was to enhance the economic efficiency of producing biomethane. Anaerobic digestion is used for converting rice straw into biogas. In this work, 5% NaOH and rice straw mixed samples were autoclaved at 121 °C for 20 min for lignin removal. The NaOH black liquor was separated using filtration for the subsequent treatment cycle. The NaOH liquor was utilized in one more subsequent recycling procedure to test its ability to remove lignin from the rice straw. The 5% NaOH treatment results in a reduction in rice straw (RC) lignin of 73.6%. The lignin content of the recycled NaOH-filtrated rice straw samples (RCF1) was reduced by 55.5%. The 5% NaOH-treated rice straw sample yields a total cumulative biogas of 1452.4 mL/gVS, whereas the recycled NaOH-filtered (RCF1) samples generate 1125.2 mL/gVS after 30 days of incubation. However, after 30 days of incubation, the untreated rice straw (RCC) bottle produced a total of 285.5 mL/gVS of biogas. The total increase in methane output after NaOH treatment is 6–8 times greater, and the biogas yield improves by 80–124%. We show here that the recycled NaOH black solution has still the effectiveness to be used for successive pretreatment cycles to remove lignin and generate methane. In the meantime, the NaOH black solution contains useful materials (lignin, sugars, potassium, and nitrogen) that could be purified for commercial purposes, and more importantly recycling the NaOH solution decrease the chances of environmental pollution. Thus, recycling NaOH decreased chemical consumption, which would provide net benefits instead of using fresh NaOH solution, had a lower water consumption, and provided the prospect of producing an optimum yield of methane in anaerobic digestion. This method will decrease the chemical treatment costs for biomass pretreatment prior to anaerobic digestion. Recycling of NaOH solution and the integration of pretreatment reactors could be a novel bioprocessing addition to the current technology.

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Section: Introductionmentioning

confidence: 99%