Manganese (Ii)-Anderson Polyoxometalate Mediated Bioethanol Production from Sugarcane Cake

Abstract

Recalcitrant lignin compounds inhibit bioethanol production from biomass. The lignin bind cellulose and hemicellulose in biomass suppressing the fermentation process. Current delignification techniques have an average efficiency of 30% hence affecting the economics of bioethanol production from biomass. In the current work, we report a Manganese(II)-Anderson Polyoxometalate salt (Mn(II)-Anderson POM) , one of the discrete anionic metal oxide salts having a unique Lewis base and Lewis acid properties, to degrade lignin in sugar cane cake root stalk biomass. The results show the Mn(II) - Anderson POM salt to degrade lignin up to 46.97% effectively. Furthermore, upon fermentation of the pretreated cake, bioethanol concentration was 42.12% whereas the positive control (NaOH delignification) had bioethanol concentration of 26.9% using a salt concentration of 3% at 50℃ treating it for a duration of 4 hours. An increase in salt concentration from 1%, 2% and 3% gave significant increase in extracted lignin for both NaOH and POM salts pretreated samples. Similar results were obtained when temperature was varied from 30℃, 40℃, 50℃ and 60℃; and also, time from 2hrs, 3hrs and 4hrs. The quantity and quality of bioethanol obtained followed a similar trend. However, it is noted that in all cases, Mn(II)-Anderson Polyoxometalate salts performed better than NaOH pretreated samples. Specifically, an increase in bioethanol quality (46.13%) after pretreatment with Mn(II)-Anderson POM salt at a concentration of 3%, time 4hrs and temperature 60℃ as compared to NaOH (41.3%) at the same pretreatment parameters is noted