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.