Separation of sodium lactate from Span 80 and SDS surfactants by ultrafiltration

Abstract

The ultrafiltration process for separation of sodium lactate from sorbitan monooleate (Span 80) and sodium dodecyl sulfate (SDS) surfactants using ZrO 2 flat-disc ultrafiltration membranes was studied in this work. The study is focused on the influence of the nominal molecular weight limit of the membrane (NMWL), the transmembrane pressure (TMP), and initial lactic acid concentration (C A) on the permeate flux (J p) and rejections observed to ion lactate (R A) and SDS (R S) using a full central composite experimental design and response surface methodology. Experiments were conducted in four stages: a first stage of lactic acid extraction with niosomes formulated with Span 80 (20 mol/m 3) and SDS (4 mol/m 3), a second backextraction stage conducted by NaOH addition until pH > 12 for niosomes breaking and sodium lactate releasing, and a third and fourth ultrafiltration stages at 25 o C to separate the lactate ions from the mixed surfactants. Membrane NMWL, TMP and their interactions presented statistically significant influence on the permeate flux. Rejections to lactate ion and SDS were lower than 4.5% and higher than 86%, respectively, whereas Span 80 rejection was 100% in all range of experimental conditions tested. The optimal conditions were established for maximum values of permeate flux, and they were obtained for a 2 bar TMP and 15 kDa NMWL membrane. Under these conditions, the rejections of SDS surfactant and lactate ion were 87.3% and 4.31%, respectively, with a permeate flux of 42.63 L/m 2 h. The antagonistic effect between permeate flux and SDS rejection is also proved.

Stability and characterization studies of Span 80 niosomes modified with CTAB in the presence of NaCl

“…They can be an alternative to liposomes due to their biological compatibility, high purity, greater chemical stability, low toxicity, low cost and better handling and storage [1][2][3][4]. Also, the use of niosomes as extraction agents of solutes present at very low concentration in aqueous solutions is a new application in the field of sustainable processes that has been explored in previous works [5][6][7].…”

“…Sorbitan monooleate (Span 80) is an attractive surfactant because it is generally recognized as safe (GRAS) by FDA, biodegradable, biocompatible and non-toxic, features that make it ideal for use in pharmaceutical, cosmetic and food industry. It has a HLB value of 4.3 and can form stable niosomes with addition of small quantities of additives as ionic surfactants [7] or cholesterol, widely used in formulations to increase the membrane rigidity [14]. However, the study on its surface and bulk behavior has hardly been investigated.…”

Reactive Extraction of Lactic Acid using Environmentally Benign Green Solvents and Synergistic Mixture of Extractants

“…The industrial and traditional technique of LA separation is precipitation, which uses calcium hydroxide and large amounts of sulfuric acid and further produces solid waste, i.e., calcium sulfate (environmentally unfriendly) as a by-product [8,9]. In order to reduce the cost, various extraction methods (such as adsorption [10], membrane separation [11,12], electrodialysis [13,14], ultra ltration [15], and extraction [16,17]) have e caciously been applied to the extraction of LA. All these methods possess several speci c disadvantages (such as poor extraction e ciency (%), being uneconomical, the generation of huge amount of wastewater, high complexity, high energy consumption, and large production of by-products) [13].…”

Vegetable Oil–Ionic Liquid-Based Emulsion Liquid Membrane for the Removal of Lactic Acid from Aqueous Streams: Emulsion Size, Membrane Breakage, and Stability Study

“… 2 Because of the increasing demand for LA, its recovery from aqueous streams is becoming highly important. Various extraction methods, including solvent extraction, 3 ultrafiltration, 4 nanofiltration membrane, 5 membrane reactor, 6 and adsorption, 7 have been applied for the removal of LA from water streams. Despite their widespread use, the aforementioned methods often suffer from drawbacks such as low extraction efficiencies and the employment of organic solvents that are extremely hazardous to the environment.…”