Process performance in lignin separation from softwood black liquor by membrane filtration

Separation phenomena in UF and NF in the recovery of organic acids from kraft black liquor

“…In this context, it is a little surprising how limited the number of studies published on this subject have been. There are several papers available on ultrafiltration (UF) of kraft black liquor to recover lignin as a concentrated fraction, but in these studies separation of hydroxy acids has not been considered at all [7][8][9]. However, ultrafiltration could enable the simultaneous recovery of both the lignin and organic acids into separate product fractions.…”

Biorefinery Process Combining Specel® Process and Selective Lignin Precipitation using Mineral Acids

“…Many applications could be developed using lignin as the main ingredient and also as a secondary ingredient such as dispersants, binders, emulsifiers, epoxy resins, or even foams (El Mansouri et al 2011;Arkell et al 2014;Tondi et al 2016). In addition, lignin can be used in the synthesis of new, more environmentally compatible polymeric materials, such as hydrogels, which are more suitable for various applications that range from biomedical to automotive (El-Zawawy and Ibrahim 2012;Thakur and Thakur 2015).…”

“…One method is acid precipitation, the second one is extraction with selective solvents, and the last method is separation using membrane technology, which is better known as ultrafiltration (Toledano et al 2010a;Hellstén et al 2013;Arkell et al 2014). Selective lignin precipitation is one of the most commonly used processes since the lignin is recovered by the simple addition of an inorganic acid to the black liquor (Toledano et al 2010b).…”

Lignin Degradation Processes and the Purification of Valuable Products

“…Ceramic membranes were preferred in these studies [91,92,96] due to their advantages over polymeric membranes, particularly their greater chemical and thermal stability which allows the filtration of acids, bases, solvents and hot feeds, and allows them to survive the harsh cleaning conditions that are often necessary to restore membrane permeability. Ceramic membranes also maintain physical stability during the filtration of abrasive media and generally last longer than polymeric membranes [99,100].…”

“…Therefore, the membrane-based fractionation of reaction mixtures from thermochemical lignin degradation processes could be used to separate non-degraded lignin from valuable mono-aromatic compounds [149]. The key advantages of ceramic membranes include their chemical and thermal stability, which allow the filtration of acids, bases, solvents and hot feeds, and make the membranes resistant to the harsh cleaning conditions that may be necessary to restore permeability [99,100]. These properties match the requirements of filtration processes involving reaction mixtures from thermochemical degradation, including extreme pH and the presence of harsh solvents.…”