Recaustization of kraft black liquor via bipolar electrodialysis. Final report.

摘要

The US Department of Energy in conjunction with HPD Inc. supported a research program to perform a laboratory feasibility study with various black liquor samples for the recaustization of these samples via bipolar electrodialysis. The research was conducted at the HPD pilot plant facility in Plainfield, Illinois, beginning in April 1989. This report is a summary of the work completed through November 1989. The program was designed to operate the electrodialyzer in order to obtain performance and engineering data such as current efficiency, power consumption per gram of NaOH produced, and assess fouling and/or membrane durability. Prior to the electrodialysis laboratory runs, the black liquor samples were pretreated in order to remove as much lignin as possible. The black liquor samples were air oxidized, acidified to pH = 9.0 and pH = 2.0 and later filtered via a Buchner funnel under vacuum. The filtrate was then utilized to become the feed to the electrodialysis stack. Initial test runs were performed with synthetic solutions of either sodium sulfate or sodium bicarbonate in order to determine acceptable operating current, power, current efficiencies, and fouling behavior. A second set of test were conducted with a series of four Southern Kraft black liquor samples. Based on the results of this study, it was determined that the use of bipolar electrodialysis for producing a caustic stream and an acidified black liquor stream is feasible and was demonstrated. 9 refs., 27 figs., 32 tabs.