Maximizing yield of liquid-lignin from membrane filtration retentate of kraft black liquor

Membrane Operations in the Pulp and Paper Industry for the Recovery of Constituents: A State of the Art Review

“…Wood extractives are lipophilic compounds such as fatty acids, resin acids, sterols, steryl esters, and triglycerides [21]. They are present in pulping liquors either in their original forms or in a variation after undergoing hydrolysis or other transformation reactions [12].…”

“…They are present in pulping liquors either in their original forms or in a variation after undergoing hydrolysis or other transformation reactions [12]. Depending on the wood source, these extractives can account for up to 10 wt.% of the wood dry matter [21]. Turpentine, a fluid obtained from the resin of trees made up of terpenes, is a by-product of the kraft process and can be removed via MF or steam or air stripping.…”

“…Foulants and foulant mechanisms for different types of membranes have been extensively studied [21,22,36,37]. Fouling types, fouling mechanisms, and main foulants in membrane processes applied to process streams in the PPI are presented in table 2.…”

“…Ceramic membranes have a higher hydrophilicity as compared to other inorganic membranes and, therefore, achieve higher fluxes of BL. However, ceramic membranes have a lower lignin retention [21,25] and higher capital costs [58] in comparison with to polymeric membranes. To reduce costs by lowering energy consumption, air sparging has been proven to be effective for increasing hemicellulose retention from wheat bran in UF membranes; a transfer to streams from the PPI may be possible but has not been reported yet.…”

Lignin Fractionation Methods: Can Lignin Fractions Be Separated in a True Industrial Process?

“…The use of ultrafiltration technique was used for different purposes, such as study of the influence of molar mass on the lignin properties and also in-depth evaluations regarding the economic feasibility of including the process in the industrial sector. Regarding the lignin sources, it can be observed that, despite the use of different polymeric membranes, the yields presented in uncorrelated studies have similar values, as observed in study developed by Uloth et al 125 and Olivares et al 126 A point that highlights the lignin as a promising alternative to materials of petrochemical origin is the fact that the study of its economic feasibility in the inclusion in industrial processes is a topic addressed in investigations over decades, as observed in works highlighted in Table 4 by Uloth et al 125 A point that highlights lignin as a promising alternative to petrochemical-based materials is the fact that the study of its economic feasibility for inclusion in industrial processes is a topic that has been addressed in investigations over decades, as observed in the works highlighted in the table by Uloth et al 125 developed for a nationwide report on advances in pulping industries ahead of the times, later in Arkell et al 119 with the aim of optimizing the ultrafiltration process by reducing the sugar content in the permeate and finally in Li et al 129 aiming to favor an interaction between lignin and hemicelluloses to optimize the process related to the reduction of membrane fouling. It was also observed in the literature the comparison of the ultrafiltration process in relation to other lignin fractionation processes, as exposed by Toledano et al, 32 who brought to light the benefits and shortcomings presented by the ultrafiltration process in relation to the fractionation by precipitation from the variation of the acid gradient as to yield, purity and molar mass values obtained in the fractions of each process.…”