Performance of nanofiltration membranes for the recovery of lignin in the production of renewable fuels from kraft black liquor

Beskrivning

Kraft black liquor lignin is an underutilized resource from the pulp and paper industry with the potential of being a significant source of renewable fuels and chemicals. The SunCarbon process utilizes ultrafiltration to produce a lignin-rich retentate, which is subjected to lignin depolymerization to produce a renewable lignin-oil. Remaining is a lignin lean permeate, containing low molecular weight (MW) lignin, usually returned to the cooking chemical recovery cycle. However, recovery of the remaining lignin will both produce a concentrate of valuable low molecular weight lignin and produce a permeate clean enough to bypass the energy intensive evaporators and recovery boiler in the cooking chemical recovery cycle.
This work therefore evaluates nanofiltration for the separation and concentration of low MW lignin from the ultrafiltration permeate. Eight flat sheet membranes, two ceramic membranes and one hollow fibre membrane, with MW cut-offs ranging from 100 to 2000 Da were tested. The nanofiltration tests were conducted at 50 °C, 2.5-35 bar, and cross flow velocity of 0.3-0.5 m/s. The hollow fibre membrane showed a high flux of 82.3 L/m2·h, but only a 23.5% lignin retention. The SolSep NF09081 and Microdyn-Nadir NP030 membranes showed high lignin retentions (90.4% and 80.8%, respectively), but their fluxes were low (37 and 28.7 L/m2·h, respectively). Both high fluxes (72 and 165.9 L/m2·h, respectively) and high lignin retentions (83.7% and 71.4%, respectively) were obtained for the Koch Membrane System MPS36 and Microdyn-Nadir NP010 membranes. Overall, it was shown that the nanofiltration process can produce a permeate stream suitable for bypass of the evaporators and a concentrated lignin fraction which either can be used to produce valuable chemicals or blended into the lignin-oil.

Period	2020 dec. 7 → 2020 dec. 11
Evenemangstitel	12th International Congress on Membranes and Membrane Processes
Typ av evenemang	Konferens
Plats	London, StorbritannienVisa på karta
Omfattning	Internationell