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Miscanthus Biomass for the Sustainable Fractionation of Ethanol–Water Mixtures

Dehabadi, Leila, Mahaninia, Mohammad H., Soleimani, Majid, Wilson, Lee D.
ACS sustainable chemistry 2017 v.5 no.4 pp. 2970-2980
Miscanthus, adsorption, biofuels, biomass, biopolymers, biosorbents, cellulose, chemical treatment, ethanol, fractionation, fuel production, grinding, hemicellulose, hydrolysis, lignin, lignocellulose, mineral content, models, nuclear magnetic resonance spectroscopy, particle size, sorbents, value added, water uptake
Miscanthus is a rich source of lignocellulosic biomass with low mineral content suitable for applications that range from biofuel production to value-added biomass-derived products including a sustainable biosorbent. Herein, Miscanthus and its modified forms were used for the fractionation of water (W) and ethanol (E) mixtures that were analyzed by an in situ analytical method, referred to as quantitative NMR (qNMR) spectroscopy. Miscanthus was pretreated by hydrolysis and subsequent grinding to yield materials with variable biopolymer content (cellulose and lignins) and particle size. The Miscanthus materials were evaluated as sorbents in binary water–ethanol (W-E) mixtures. The maximum biomass adsorption capacity (Qₘ; g g–¹) with water (Qₘ,W) and ethanol (Qₘ,E) fractions were determined by the best-fit Sips model parameters listed in parentheses: raw Miscanthus biomass (Qₘ,W = 8.93 and Qₘ,E = 4.15) and pretreated Miscanthus biomass (Qₘ,W = 4.73 and Qₘ,E = 3.22, g g–¹). The fractionation properties of Miscanthus and its biopolymer constituents show molecular selectivity [Rₛₑₗₑcₜᵢᵥᵢₜy = Qₘ,W/Qₘ,E] between W and E. The Rₛₑₗₑcₜᵢᵥᵢₜy values are given in parentheses, as follows: untreated Miscanthus (3:1), pretreated Miscanthus (1.5:1), and lignins (1:5.4). The pretreated Miscanthus was prepared by acid and base hydrolysis for the removal of hemicellulose and lignins, respectively, leading to cellulose enrichment. The raw and pretreated Miscanthus have preferential water uptake properties that relate to the relative biopolymer composition. To test the reusability and regeneration of Miscanthus, the biosorbent was tested over four adsorption–desorption cycles. This work contributes to a greater understanding of chemical treatment effects on biomass adsorption properties and evaluation of the adsorptive contributions of biopolymer components for the fractionation of water–ethanol mixtures.