Polymer-Based Aqueous Biphasic Extraction Technology for Reaction Engineering of the Alkaline Paper Pulping ProcessEPA Grant Number: R826732
Title: Polymer-Based Aqueous Biphasic Extraction Technology for Reaction Engineering of the Alkaline Paper Pulping Process
Investigators: Rogers, Robin D. , April, Gary C. , Huddleston, Jonathan G. , Wiest, John M.
Institution: The University of Alabama
EPA Project Officer: Richards, April
Project Period: October 1, 1998 through September 30, 2001 (Extended to December 30, 2002)
Project Amount: $350,139
RFA: Technology for a Sustainable Environment (1998) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , Pollution Prevention/Sustainable Development
High quality cellulose pulps are produced by hydrolysis and sulfonation to effect removal of lignins from cellulosic materials followed by bleaching. The danger of dioxin production at this stage results in extended cooking times lowering the strength and yield of the pulp and increasing the consumption of cooking liquor. The objectives of this project are to utilize environmentally benign polymer-based separations of reaction products during the pulping reactions and thus, reduce the consumption of chemical feedstock and the extent of the reaction to only that required to release and solubilize the lignins from the pulp. Waste of reagents through further hydrolysis and sulfonation of already solubilized lignins would be avoided leading to the production of a lower degree of sulfonation in the lignin byproducts and thereby reducing the scale and energy demands of the recausticizing recycle.
Preliminary results on the separation of lignins and cellulosic fibers show that polyethylene glycol-based aqueous biphasic systems may be used to separate these products of the Kraft alkaline pulping process on the basis of their widely different surface properties. In the work proposed here, the appropriate conditions and phase modifiers will be determined which will minimize the need for solute or solvent addition to promote this separation. A variety of environmentally benign aqueous polymers will be investigated for their ability to promote phase separation of the reaction mixture or solid phase adsorption of the lignins. An additional aspect of this project will investigate the utility of the separated lignin byproduct as a useful polymer in environmental separations.
It is expected that the project will result in a novel reactive extraction process for the efficient production of cellulose pulp based on the strong tendency of lignin materials to partition to relatively hydrophobic phase separated aqueous phases composed of minimal concentrations of added polymers sufficient to promote the phase separation of the lignin and cellulosic materials.
Improvements in Risk Assessment or Risk Management: The development of a solvent extraction process requiring no organic solvents for its generation is expected to result in a safe, environmentally benign pulping process which will improve the efficiency of the separation of lignins from cellulosics, resulting in a reduction in the consumption and more efficient recycling of caustic chemicals. The degree of sulfonation of the separated lignins will be reduced resulting in lower emissions of sulfur compounds during incineration and reduced requirement for a recausticizing recycle. More efficient removal of lignins may also be expected to benefit the requirement for, and efficiency of, subsequent bleaching operations.