Extraction of humic acid by coacervate: Investigation of direct and back processes

• Published in: Journal of hazardous materials 2012-02, Vol.205-206, p.171-178
• Main Authors: Ghouas, H., Haddou, B., Kameche, M., Derriche, Z., Gourdon, C.
• Format: Article
• Language: English
• Subjects: Chemical and Process Engineering; Chemical engineering; Chemical Sciences; Cloud point; Coacervate; Engineering Sciences; Environmental Restoration and Remediation - methods; Ethylene Glycols - analysis; Ethylene Glycols - chemistry; Extraction; Humic acid; Humic Substances - analysis; Hydrogen-Ion Concentration; Phenols - analysis; Phenols - chemistry; Recycling; Surface-Active Agents - analysis; Surface-Active Agents - chemistry; Surfactant; Temperature; Water Pollutants - chemistry; Water Pollutants - isolation & purification
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.12.057

► Coacervate extraction was used, for humic acid extraction from aqueous solution. ► The surfactants used are alcohol polyethoxylate and alkylphenol polyethoxylate. ► Phase diagrams of binary (water/surfactant) and pseudo-binary systems were plotted. ► Best compromise between solute extraction percentage and volume fraction of coacervate was found. ► The possibility of recycling the surfactant has been proved. The two aqueous phases extraction process is widely used in environmental clean up of industrial effluents and fine chemical products for their reuse. This process can be made by cloud point of polyethoxylated alcohols and micellar solubilization phenomenon. It is commonly called “coacervate extraction” and is used, in our case, for humic acid extraction from aqueous solution at 100mg/L. The surfactants used are alcohol polyethoxylate and alkylphenol polyethoxylate. Phase diagrams of binary water/surfactant and pseudo-binary are plotted. The extraction results are expressed by the following responses: percentage of solute extracted, E (%), residual concentrations of solute and surfactant in dilute phase (Xs,w, and Xt,w respectively) and volume fraction of coacervate at equilibrium (ϕ). For each parameter, the experimental results are fitted to empirical equations in three dimensions. The aim of this study is to find out the best compromise between E and ϕC. The comparison between experimental and calculated values allows models validation. Sodium sulfate, cetyltrimethylammonium bromide (CTAB) addition and pH effect are also studied. Finally, the possibility of recycling the surfactant has been proved.