Efficient and feasible
pretreatment of lignocellulosic biomass
waste is an important prerequisite step to promote subsequent enzymatic
hydrolysis and enhance the economics of biofuels production. This
study focuses on the pretreatment of wheat straw (WS) with triethylbenzyl
ammonium chloride/lactic acid (TEBAC/LA)-based deep eutectic solvents
to enhance biomass fractionation and lignin extraction. Effects of
pretreatment time, temperature, and TEBAC/LA molar ratio on pretreatment
were evaluated systematically. Results suggested that 89.06 ±
1.05% of cellulose and 71.00 ± 1.03% of xylan were hydrolyzed
with enzyme loadings of 35 FPU cellulase and 82 CBU β-glucosidase
(per gram of dry biomass) after pretreatment by TEBAC/LA (1:9) at
373 K for 10 h. A total monosaccharide yield of 0.550 g/g WS (91.27%
of the theoretical yield) was achieved with 79.73 ± 0.93% of
lignin removal. Furthermore, the 1H–13C two-dimensional heteronuclear single quantum correlation (2D-HSQC)
NMR spectroscopy showed that the regenerated lignin (75.69 ±
1.32% purity) was mainly composed of the syringyl units and the guaiacyl
units. Overall, the results in this study provide an effective and
facile pretreatment method for lignocellulosic biomass waste to enhance
enzymatic hydrolysis saccharification.
Levulinic acid (LA) is a versatile
platform chemical in the modern
concept of the biorefinery and can be used to synthesize a broad range
of desirable chemicals and fuel additives. Unfortunately, because
LA released from biomass hydrolysate is accompanied by formic acid
(FA) and 5-hydroxymethylfurfural (5-HMF), it is also important to
investigate the binary and ternary adsorption equilibrium, as well
as competitive dynamic fixed-bed column adsorption from the viewpoint
of industrial application. Batch adsorption experiments showed that
the affinity of SY-01 resin toward FA–LA–5-HMF were
in the order of 5-HMF > LA > FA under noncompetitive and competitive
systems. The highest adsorption capacity were 7.54 mg/g wet resin
for FA, 103.51 mg/g wet resin for LA, and 107.73 mg/g wet resin for
5-HMF. Interestingly, the presence of FA has a synergistic effect
on the adsorption of LA and 5-HMF onto SY-01 resin in a binary- or
ternary-mixtures system, leading to a slight increase in adsorption
uptakes. Furthermore, a mathematical model based on the general rate
model coupled with the noncompetitive single-component and competitive
multicomponent Langmuir isotherm was successfully developed to simulate
the breakthrough curves of FA–LA–5-HMF from single,
binary, as well as ternary-component mixtures. The proposed methodology
for fixed-bed column multicomponent competitive adsorption model can
be successfully implemented to completely design the separation unit
of LA from aqueous solution or biomass hydrolysate. Furthermore, it
also has the potential to expand the application to the actual biomass
hydrolysate, saving a lot of manpower and material resources.
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