Technoeconomic Assessment of a Biomass Pretreatment + Ionic Liquid Recovery Process with Aprotic and Choline Derived Ionic Liquids

Abstract

Ionic liquids have shown promising results in biomass pretreatment; however, an extensive water washing step is necessary. This fact increases not only the processing costs but also those associated with the ionic liquid recovery step. In this work, Eucalyptus globulus wood pretreated with two acetate-based ionic liquids, namely 1-ethyl-3-methylimidazolium acetate and choline acetate, has been washed with increasing volumes of water in order to analyze the influence of the amount of washing water used on the subsequent enzymatic hydrolysis stage and on the IL recovery costs. Vapor−liquid equilibria data of recovered ionic liquid/water mixtures have been determined to simulate the IL recovery step with Aspen Plus, calculating the operating costs using the Aspen Plus Economics Analyzer afterward. [Emim][OAc] was more efficiently washed and more effective toward wood pretreatment than [Ch][OAc]. Both IL/water systems were successfully modeled, and simulation studies showed that incremental volumes of water led to higher operating costs in the IL recovery step that are compensated with less IL makeup costs. Therefore, this work offers a technoeconomical analysis of the IL recovery step in a real biorefinery pretreatment process as a function of the volume of water used in the pretreated wood washing stage.

Sustainable keratin recovery process using a bio-based ionic liquid aqueous solution and its techno-economic assessment

“…The necessity of several washing steps is probably due to the high viscosity of [N 111(2OH) ][C 1 CO 2 ], which maintains a strong hydrogen bonding network with keratin. 52 Approximately (93 ± 4) wt% to (86 ± 2) wt% of keratin was recovered along the 4 cycles, indicating that the reused IL does not have a significant impact at keratin recovery efficiency. The integrity of the recycled IL was confirmed by 1 H and 13 C NMR, as shown in the ESI (Fig.…”

“…Regarding the price of [N 111(2OH) ][C 1 CO 2 ], it is not considered a limiting factor since it can be easily synthesized using acetic acid and cholinium hydroxide in an acid-base reaction, which makes this IL more accessible. 52 Nevertheless, the operating costs associated with its recovery significantly impact the process. The main contribution to the cost is the steam used to regenerate the IL in the multiple effect evaporator and the capital required for a plant with large flow rates with relatively low productivity (Table S8 in the ESI †).…”

History repeats itself again: Will the mistakes of the past for ILs be repeated for DESs? From being considered ionic liquids to becoming their alternative: the unbalanced turn of deep eutectic solvents

“…Of note is also the recent comparative techno-economic analysis of Eucalyptus globulus wood pretreatment carried out either with [C 2 C 1 im]OAc or [Ch] OAc. 366 In particular, the amount of water needed to remove residual IL from dissolved cellulose during the washing step, the effect on the subsequent enzymatic hydrolysis and the IL recycling step all indicate the possibility of lower operating costs for the imidazolium-containing IL. Despite these findings, additional features such as the potential environmental footprints and the overall toxicity should be considered in future developments.…”

A Critical Review on Water Overconsumption in Lignocellulosic Biomass Pretreatment for Ethanol Production through Enzymic Hydrolysis and Fermentation

“…One of the economic challenges could be associated with water and chemicals overconsumption. For example, Ovejero-Peŕez et al 148 demonstrated that increasing water washing volumes of the pretreated biomass increased production costs, but washing with 5.5 g water/g ionic liquid was approved to be the most economic option as it achieved a minimal total ionic liquid recovery cost of $16/kg of biomass. Increasing solid loading for biomass pretreatment might be able to reduce water use to some extent, but the resulting side effects including ineffective pretreatment performance, more byproduct generation, and high viscosity cannot be ignored.…”