critical review of ionic liquids for the pretreatment of lignocellulosic biomass

Abstract

HOW TO CITE:Reddy P. A critical review of ionic liquids for the pretreatment of lignocellulosic biomass. S Afr J Sci. 2015;111(11/12), Art. #2015-0083, 9 pages. http://dx.doi.org/10. 17159/ sajs.2015/20150083 Ionic liquids have been the subject of active research over the course of the last decade and have in the past been touted as one of the most promising technologies for revolutionising the chemical and petrochemical industries. The sheer abundance of potential ionic liquid structures coupled with their tuneable physico-chemical properties has endeared ionic liquids to the scientific community across a broad range of disciplines with potential applications that include pharmaceuticals, electrolytes, thermal energy storage media and liquid mirror telescopes. Within the context of a biorefinery for the production of biofuels and other bio-based products from renewable resources, the unique abilities of some ionic liquids to selectively dissolve biomass components or whole native biomass have been demonstrated. This ability has sparked extensive investigations of ionic liquids for the pretreatment of different biomass types, particularly for the production of cellulosic biofuels. However, the esoteric nature of ionic liquids persists and constructing a fundamental framework for correlating ionic liquid structures with useful applications remains a significant challenge. In addition to the above, the more practical challenges of toxicity, high costs, high viscosities, low solids loading and complex recycling are key factors hindering the wide-scale uptake of ionic liquids as pretreatment solvents in a commercial biorefinery. This critical review provides insights from academic studies and the implications thereof for elevating ionic liquids from the status of 'promising' to 'commercialisable' in the pretreatment of biomass. It is vital that key hurdles for the commercialisation of ionic liquids in the form of high costs, high viscosities, poor water tolerance, toxicity, low solids loading and recovery/recycling be addressed.

Ionic Liquids in Biomass Processing

“…Since the pioneering work in this field by Varanasi et al., a number of research groups have explored this major application of ILs . The vast number of publications in this area for about a decade have been reviewed as well …”

“…[54] The vast number of publications in this area for about a decade have been reviewed as well. [55,56,57,58,59,60,61,62,63] The neutral ionic liquids as well as functionalized acidic and basic ionic liquids have been used in the pretreatment of biomass before cellulase enzyme catalyzed depolymerization. However the majority of examples are known with neutral ionic liquids.…”

Treatment of lignite and thermal coal with low cost amino acid based ionic liquid-water mixtures

“…Furthermore, as the coals contain significant amount of moisture, drying the ionic liquids was deemed uneconomical. Biomass processing with ionic liquid-water mixtures instead of neat ILs is common [7,13,31,32]. Aqueous solution of 65 wt% 1-butyl-3-methylimidazolium methylsulfate was as effective as 90 wt% [7], and concentration as low as 10 wt% ionic liquid was sufficient in the treatment of lignocellulosic biomass [14].…”

Mapeamento De Patentes E Artigos Sobre Tecnologias De Obtenção De Celulose Utilizando Líquidos Iônicos

“…Solventes alternativos, tais como os líquidos iônicos, são alternativas por serem de fácil manipulação, baixa volatilidade, baixa inflamabilidade e possibilidade de recuperação (SEOUD et al, 1997;LAN et al, 2011;GERICKE et al, 2012;PELETEIRO et al, 2015). Segundo revisão crítica de Reddy (2015), o uso de líquidos iônicos têm sido objeto de pesquisa ativa ao longo da última década e têm se mostrado como uma das tecnologias mais promissoras para revolucionar a indústria química e petroquímica. Isto pode ser atribuído à enorme abundância de estruturas líquidas iônicas em potencial, associadas a uma variedade de propriedades físico-químicas, possibilitando à comunidade científica uma ampla gama de aplicações, que incluem, além do pré-tratamento da biomassa lignocelulósica, produtos farmacêuticos, eletrólitos, armazenamento de energia térmica, mídia e telescópios de espelho líquido.…”