Extraction of Lignosulfonate using TOA-Kerosene-PVDF in Supported Liquid Membrane Process

Abstract

Lignosulfonate is a major byproduct from the sulphite pulping process which is the most abundant biopolymer and largely unused. Although lignosulfonate is nontoxic, it impacts brownish black colour to water and makes the water unsuitable for reuse. However, lignosulfonate have a wide range application, such as production of vanillin, animal feed pellets binder and pesticides. Therefore, an efficient separation technique of lignosulfonate from the wastewater is necessary in order to meet the wastewater treatment requirement and as a source of valuable material for industrial applications. In this study, lignosulfonate was extracted from aqueous solution through flat sheet supported liquid membrane (SLM) using trioctylamine (TOA) as carrier. SLM has great potential for the separation lignosulfonate as it offers advantages such as simultaneous extraction and stripping steps, low consumption of carrier and high selectivity. The important parameters governing the extraction process are the types of support material, types of solvents, types of stripping agent, feed phase flow rate and pH were investigated. The favorable condition for extraction was obtained by using TOA-Kerosene-PVDF membrane system, 0.5M NaOH as stripping agent, 100 mL/min of flow rate and feed at pH 2 with 37.5% of lignosulfonate removal. The result demonstrated that the membrane support remains stable for more than 9 hours, hence demonstrating promising separation technique for lignosulfonate.

Screening of Reactive Extractants for the Lignosulfonate Extraction from Lignosulfonate Model Solution and Spent Sulfite Liquor

“…Based on the prices of the suppliers, the amines can be categorized into 3 classes: expensive (DEA, TDA), cheap (OA, ALIQ), and in the middle (DA, DHA, DOA, THA, TOA). TOA was selected as the first amine because it is a commonly applied reactive extractant for LS isolation. ,,, This decision is also reasonable from an economic point of view. For the second amine, the results for crud formation and overall efficiency with the spent liquor were used as the basis of decision making.…”

“…Because of the anionically charged sulfonate groups, LSs are highly water soluble and the simple precipitation by pH change, as it is practiced for Kraft lignin, is not possible. ,− Two state-of-the-art isolation processes for LSs are the Howard method, which is the precipitation of calcium LS with excess lime, and the second process is ultrafiltration of spent liquor . The drawbacks of these methods are the high chemical or high energy demands and insufficient removal of impurities present in the spent liquor, for example, hemicelluloses and sugars. ,− Because more advanced applications of LSs require high purity of the raw material, alternative methods, such as electrolysis, ion-exchange resins, or amine extraction, are under investigation for the isolation of LSs. ,,, …”

“…1,13−15 Because more advanced applications of LSs require high purity of the raw material, alternative methods, such as electrolysis, ion-exchange resins, or amine extraction, are under investigation for the isolation of LSs. 1,13,15,16 In amine extraction of LSs, the LSs are transferred into a water insoluble LS−amine complex and accumulate in the organic solvent phase. The proposed reaction mechanism is shown in eqs 1 and 2, where org refers to species in the organic solvent phase.…”

“…1907/2006). Ke Xian et al 13 investigated the LS isolation in a supported liquid membrane setup with trioctylamine− kerosene as the solvent phase and achieved an overall efficiency of more than 35% for a feed concentration of 100 ppm.…”

Comparison of Supported Ionic Liquid Membranes and Polymeric Ultrafiltration and Nanofiltration Membranes for Separation of Lignin and Monosaccharides

“…A liquid membrane is just a liquid barrier that separates two liquid phases of different composition and allows the transport of at least a solute between them [37]. For the separation of lignosulphonates, the proposed liquid membranes were formulated with organic amines as carriers for facilitated transport [38], such as trioctylamine or trilaurylamine, dissolved in dichloroethane, 1-decanol or sunflower oil [39][40][41][42][43][44][45]. In the case of Kraft lignin, Aliquat 336 dissolved in kerosene was mentioned as an effective liquid membrane [46].…”