All-iron ions mediated electron transfer for biomass pretreatment coupling with direct generation of electricity from lignocellulose.

[Display omitted] • All-iron ions mediated biomass pretreatment coupling with direct biomass fuel cell. • Ferric ions as electron carriers under acidic condition. • Ferricyanide ions as electron carriers under alkaline condition. • Ferric nitrate activated by HNO 3 as cathode electron carriers. • Fermentable sugars production with co-generation of electricity from bagasse. A coupled process of biomass pretreatment for increasing cellulose digestibility and direct conversion of biomass to electricity has been developed with ferric or ferricyanide ions as the anode electron carriers, and Fe(NO 3) 3 activated by HNO 3 as the cathode electron carriers. Pretreated substrates are subjected to enzymatic hydrolysis for release of fermentable sugars, while the pretreatment liquor is employed as anolyte for electricity generation in a liquid flow fuel cell (LFFC). Pretreatment of sugarcane bagasse with 2 M FeCl 3 in anode reactor removes ∼ 100% hemicelluloses and obtains 76% enzymatic glucan conversion (EGC), while pretreatment with 0.1 M K 3 [Fe(CN) 6 ] in 0.5 M KOH achieves 78% lignin removal, 95.8% EGC and 85.1% xylan conversion. From 1000 g bagasse, 171.3 g fermentable sugars is produced with co-generation of 101.4 W·h electricity based on FeCl 3 pretreatment, while 519 g fermentable sugars and 28.9 W·h electricity are obtained based on K 3 [Fe(CN) 6 ] pretreatment. [ABSTRACT FROM AUTHOR]