(288b) Fractionation of Ionic Liquid and Monomeric Sugars during Biomass Pretreatment By Nanofiltration

Ionic liquids could be an emerging solvent for pretreatment of lignocellulosic biomass. They act by dissolving the biomass which allows for much better access of the enzymes used for hydrolysis of cellulose. Further, ionic liquids reduce the crystallinity of the cellulose leading to higher glucose yields during enzymatic saccharification. The high cost of ionic liquids means that efficient recovery and recycle of the ionic liquid is essential for an economically viable process. Here, we investigate the feasibility of developing nanofiltration membranes for ionic liquid recovery.

We have created nanofiltration membranes with different barrier properties. Our aim is to maximize the ionic liquid recovered in the permeate while obtaining as high a rejection of saccharides as possible. Using base ultrafiltration membranes as a support structure, we have used interfacial polymerization (IP) to create a dense polyamide layer. Common reactive monomers are diamines such as piperazine (PIP), m-phenylenediamine (MDP) and p-phenylemediamine (PPD) and acid chloride monomers such as trimesoyl chloride (TMC), isophthaloyl chloride (IPC) and 5-isocyanato-isophthaloyl chloride (ICIC). Here we focus on the reaction of TMC with PIP. Recent publications highlight the ability to tune the performance of these nanofiltration membranes by inclusion of novel monomers as well as inorganic additives. Here we have incorporated 3-aminophenylboronic acid (BA) in the IP layer to control the sugar selectivity and permeance of the membrane. We have also developed unique nanofiltration membranes using layer-by-layer deposition on base ultrafiltration membranes. Membrane performance has been determined using feed streams consisting of aqueous saccharide solutions, water, ionic liquid and saccharide solutions as well as real biomass hydrolysates.