Loblolly pine pretreatment by ionic liquid-glycerol mixtures

Abstract

Glycerol was used as a cosolvent with the two ionic l i q u i d s 1 -e t h y l -3 -m e t h y l i m i d a z o l i u m f o r m a t e ([C2mim][O2CH]) and 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) to pretreat loblolly pine at 140°C. Enzymatic hydrolysis was then performed on raw and pretreated pines to establish pretreatment efficacy. With pretreatment, glucose yield from enzymatic hydrolysis was improved from 2 % for raw pine up to 43 %, while yields of mannose/xylose combined improved from 4 % up to 77 %. Pine pretreated with a 50 % [C2mim][O2CH]-50 % glycerol mixture exhibited a pulp-like structure, likely formed from removal of the lignin that binds cell walls together. Using this 50 % mixture of [C2mim][O2CH] and glycerol for pretreatment gave a slightly lower glucose yield than a 75 % mixture of [C2mim][O2CH] and glycerol but gave a mannose/xylose yield twice as high. Klason lignin and Fourier transform infrared spectroscopy (FTIR) analysis indicated that [C2mim][O2CH]-glycerol pretreatment preferentially dissolves lignin. FTIR analysis also suggested increased amorphous cellulose content with this pretreatment. Using the anti-solvent ethanol, a lignin-rich substance was precipitated from the solvent mixtures.

Ionic Liquids Separating Rubber Latex from Guayule

“…Guayule stems were collected from two-year-old plants of improved germplasm (CAL-7), generously provided by Dr. Hussein Abdel-Haleem from the US Arid-Land Agricultural Research Center at Maricopa Agricultural Center, Maricopa, AZ, USA. CAL-7 was developed by the University of California and released for its high rubber content [ 14 , 15 ]. It has a rubber content of approximately 10% [ 16 ].…”

“…Some ILs have been reported to be of low hazard to the environment, such as 1-ethyl-3-methylimidazolium acetate (Emim Ac), a low toxicity IL (LD50 > 2000 mg kg −1 ) [ 14 ]. If halogens and sulfur are avoided when synthesizing ILs, then their decomposition products are reported to be relatively harmless [ 15 ]. Nevertheless, full life cycle analyses need to be conducted even on these ILs [ 16 ].…”

Multi-Scale Structural Studies of Sequential Ionic Liquids and Alkali Pretreated Corn Stover and Sugarcane Bagasse

“…The spectra were recorded in a Vertex 70 spectrophotometer (Bruker OPTIK, GmbH) in the frequency range of 4000 cm −1 -400 cm −1 at 4 cm −1 resolution with 32 scans per sample. Lynam and Coronella [21] gave the concept of pretreatment index (Ip) which is the ratio of the intensities of the FTIR peaks at 896 cm −1 (amorphous cellulose) and 1515 cm −1 (lignin) divided by the same ratio for the raw biomass. The estimation of respective pretreatment's effectiveness is provided by the same [22].…”

Corn Stover Pretreatment by Ionic Liquid and Glycerol Mixtures with Their Density, Viscosity, and Thermogravimetric Properties

“…Pretreatment in [C2mim]­[OAc] has been reported to increase glucose yield after enzymatic hydrolysis . If halogens and sulfur are avoided in ILs, then their decomposition products are relatively benign . Reducing the cost of IL pretreatment by dilution with low-cost and nonhazardous cosolvents would make biomass conversion more feasible, since pretreatment is a large part of the overall conversion cost …”

“…This less expensive form of glycerol has been used to pretreat wheat straw before subsequent enzymatic hydrolysis, resulting in improved sugar yields . Lynam and Coronella have added glycerol to [C2mim]­[OAc] and [C2mim]­[O2CH] to pretreat loblolly pine and rice hulls. , …”