Abstract
In this study, we compared the GR51PP (hydrophobic/polysulfone) membrane with a series of hydrophilic (regenerated cellulose) membranes with the aim of increasing the retention of products and decreasing membrane fouling. The raw material used was a sodium-based spent sulfite liquor from the sulfite pulping process of spruce and pine. The results show that the hydrophilic membranes were superior to the hydrophobic membranes in terms of higher fluxes (up to twice the magnitude), higher product retentions and less fouling (up to five times lower fouling). The fouling was probably caused by pore blocking as observed in earlier studies. However, the hydrophilic membranes had a lower affinity for lignin, which was indicated by the lower retention and fouling. This also resulted in a separation degree, which was higher compared with the hydrophobic membrane, thus yielding a higher galactoglucomannan (GGM) purity. 2D HSQC NMR results show that no major structural differences were present in the hydrophilic and hydrophobic retentates. A techno-economical evaluation resulted in the RC70PP being chosen as the most cost-efficient membrane in terms of flux and product recovery.
Highlights
Spent sulfite liquor (SSL) is a waste stream that is generated in the sulfite pulping process, where it is usually incinerated for the production of power and heat [1]
The results showed that a high molecular weight cutoff (MWCO) polysulphone membrane was optimal in terms of flux and rejection
SSL decomposition solutions contain of the lignosulfonates
Summary
Spent sulfite liquor (SSL) is a waste stream that is generated in the sulfite pulping process, where it is usually incinerated for the production of power and heat [1]. Studies concerning the different wood components have shown that a part of the lignin is covalently bound to polysaccharides, forming the so-called lignin-carbohydrate-complexes (LCC) [3]. This makes the different plant-based waste streams very complex in terms of composition, which depends both on the used biomass raw material and the extraction method. SSL from spruce contains mainly lignosulfonates (LS), galactoglucomannan (GGM), arabinoglucuronoxylan and LCC [4] It was further discovered by Giummarella et al [5] that the main bonds between lignin and a carbohydrates are benzyl ether to xylan and phenyl-glycosidic to mannan. The LCCs were shown to have a high molecular weight and were insoluble in dioxane/water mixtures
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
