Experimental Research On Treatment Of Straw Pulping Black Liquor By Membrane-Assisted Electrolysis

Experimental Research On Treatment Of Straw Pulping Black Liquor By Membrane-Assisted ElectrolysisZhongFei(College of Material Science and Technology, Nanjing University of Aeronautics And Astronautics, Nanjing)AbstractIn order to efficiently diminish the pollution of Straw Pulping Black Liquor (SPBL) and recover useful products from it, experimental researches have been done on basic theories, technical specification and influencing factors of disposing of SPBL by Membrane-Assisted-Electrolysis (MAE). After research, we got the following conclusions:1. Sodium Recovery From SPBLUnder experimental conditions, the influencing factors of sodium recovery from SPBL include performance of Ion-Exchange membrane, polar material, voltage and operation process etc. According to the results by researching, we made a technical scheme with three-stage processing, under best conditions, it cost 45 minutes to recover more than 90% sodium SPBL with average 3600kwh/t NaOH.2. Electrochemical oxidization and the change of CODcrThe oxidization of positive polar area in MAE technology leads to strong oxidization of reducible substances in SPBL. It is clearly seen from Infrared Spectrogram that aromatic rings of straw lignin and modified hemicelluloses can be damaged during electrolyzing. Moreover, the unoxidized lignin can be recovered near positive polar area, because of which the CODcr of SPBL can be greatly reduced and the biochemical property apparently improved. Under good experiment conditions, more than 90% CODcr can be reduced.3. Recovery of hydrogen and straw ligninDuring the process of SPBL, we can recover hydrogen generated from reaction near negative polar area; we also can recover straw lignin from SPBL near positive polar area. All of these can increase the practical value of MAE technology.4. ConclusionsIt turned out from experiments that MAE technology can not only diminish the pollution of SPBJ, but also can recover sodium and straw lignin from it, by which we can get both environmental and economical benefits. Above all MAE technology is a efficient method of SPBL' s treatment.