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Detoxification of dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate by soluble polyelectrolyte flocculants
- Deng, Fang, Aita, Giovanna M.
- Industrial crops and products 2018 v.112 pp. 681-690
- acetic acid, adsorption, ammonia, bagasse, chlorides, electrolytes, energy cane, flocculants, flocculation, formic acid, furfural, hydrolysates, hydroxymethylfurfural, levulinic acid, pH, phenolic compounds, polyethyleneimine, pretreatment, recycling, sugars
- This study investigated the detoxification of dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate using polyelectrolyte flocculants. Non-sugar compounds such as formic acid, acetic acid, levulinic acid, furfural, 5-hydroxymethylfurfural (HMF), and phenolic compounds can be generated during pretreatment, which have negative effects on downstream processes. Flocculation was carried out to remove these non-sugar compounds while retaining the fermentable sugars. The flocculants polyethylenimine (PEI) and poly-diallyldimethylammonium chloride (pDADMAC) were used and parameters including flocculant dose and hydrolysate pH were evaluated. The recyclability of PEI and recovery of non-sugar compounds were also assessed. Optimum conditions for both PEI and pDADMAC were 15 g/L dose at unadjusted pH 4.5. At these conditions, PEI outperformed pDADMAC by having greater adsorption efficiencies towards non-sugar compounds with minimal sugar losses. PEI removed 43% organic acids, 73% total phenolic compounds and 100% furans with less than 10% total fermentable sugar losses. However, after two cycles, only 20% of the adsorbed organic acids and total phenolic compounds, and 80% of the furans were recovered. Sugar losses of less than 10% were observed throughout the recycling process. PEI can significantly remove the non-sugar compounds from dilute ammonia pretreated energy cane bagasse enzymatic hydrolysate with minimum sugar losses. However, recycling of PEI and recovery of adsorbed non-sugar compounds are not recommended for more than two cycles.