Cellulose Molecular Dissolution and Emulsification for Enhanced Enzymatic Hydrolysis

Yachin Cohen, Chemical Engineering, Technion, Haifa, Israel
Gilad Alfassi, Chemical Engineering, Technion, Haifa, Israel
Sofia Napso, Chemical Engineering, Technion, Haifa, Israel
Dmitry Rein, Chemical Engineering, Technion, Haifa, Israel
Rafail Khalfin, Chemical Engineering, Technion, Haifa, Israel
Lev Vaikhanski, Chemical Engineering, Technion, Haifa, Israel

Cellulose is the most abundant renewable material in nature, yet only a minute fraction of its annual natural production is utilized as raw material or source for biofuel. Its processing requires harsh solvents or procedures considered to be detrimental to the environment.
Our current research achieved two basic discoveries: using mixtures of an ionic liquid and a polar organic solvent we show that the cellulose molecules are dissolved essentially as individual chains, as evident from neutron and x-ray scattering patterns augmented by cryo-transmission electron microscopy imaging. Furthermore, the dissolved cellulose chains readily form a unique encapsulation coating of oil droplets in emulsion. These newly discovered characteristics lead to potential applications in several directions, such as utilization of native cellulose as a unique coating for functional hydrophobic molecules (e.g. pharmaceuticals, phase-change materials, etc.) Furthermore, we show that cellulose hydrogel particles in aqueous suspension exhibit significantly higher rates of glucose production in enzymatic decomposition, relative to other pretreatment effects. In particular, the hydrolysis rate of cellulose-coated emulsion can be three orders of magnitude faster than that of microcrystalline cellulose. Using a conventional cellulase complex, we achieved about 70% conversion of cellulose to glucose in less than 5 minutes. This process was applied successfully to waste sludge of a local paper industry. Recently we have also found conditions by which similar effects are achieved with much less expensive solvents such as 4% aqueous sodium hydroxide.
The use of cellulose-coated emulsions in enzymatic hydrolysis and subsequent fermentation and esterification may impact on achievement of a sustainable bio-fuel process.