Propionic acid recovery from dilute aqueous solution by emulsion liquid membrane (ELM) technique: optimization using response surface methodology (RSM) and artificial neural network (ANN) experimental design

Abstract

ABSTRACT Carboxylic acids are present in very dilute form in aqueous solutions which poses difficulty in its recovery. Emulsion liquid membrane (ELM) technique which integrates solvent extraction and stripping was experimentally explored for propionic acid recovery existent in very dilute aqueous solutions. The ELM process was carried out using trioctylamine (TOA) as a carrier in 1-decanol, sorbitan monooleate (Span 80) as a surfactant in heptane, and sodium carbonate (Na2CO3) as a stripping agent. The interactive effects of the different parameters on the propionic acid extraction efficiency were investigated. A comparative study utilizing Response surface methodology (RSM) and artificial neural network (ANN) was carried out. The statistical models were employed in the experimental design, optimization, construction and interpretation of response/output surface plots to analyze the effect of input variables on extraction efficiency. From the results obtained, both models gave statistically significant predictions of the response values. Results confirmation tests were completed to validate the predicted optimal operating conditions which include: propionic acid concentration = 0.082 kmol/m3, Na2CO3 concentration = 0.13 kmol/m3, fraction of TOA = 7.45%v/v, extraction time = 12 mins, treat ratio = 1.17 v/v with the experimental response. The optimum solution achieved by RSM led to an experimentally determined extraction efficiency of 92.28% which was in close proximity with the numerical predicted value of 93.68%.