Séparation des ions de lanthane(III) par la technique de point de trouble. Optimisation expérimentale et statistique

Abstract

Abstract The cloud point extraction experiments of La(III) ions using the C13E10 as non ionic surfactant were carried out. The experimental optimization was realized by the classical method when optimizing one experimental factor at the time. The results showed that the La(III) ions were extracted at 61.77% and stripped from the loaded coacervate phase at 90.26% in one-stage with the nitric acid solution of 10-1 M. The most influent experimental factors such as : initial concentration of feed phase (A), C13E10 concentration (B), quantity of sodium chloride salt (C) and pH of aqueous feed solution (D) were studied by the Taguchi’s DOE methodology using an orthogonal array L9 (3^4) and response surface methodology (RSM) using Box-Benheken Design (BBD). The comparison between the experimental results (61.77%) and those predicted (95.70%) by the Box-Behnken Design showed that not all the values were in good agreement. The study of the model by the method of Taguchi proves necessary. Statistical study based on the ANOM and ANOVA analysis showed that the factor D constituted a noise. These results were refined by using the Design-Expert 7 software where the predicted extraction yield of La(III) was in good agreement with that obtained experimentally (62.88% against of 61.77%), in which the standard deviation was of 1.81%. Therefore, the extraction and recovery of La(III) can be predicted with the best opportunity of the chosen model in our experimental conditions. The cloud point technique was tested for extraction of lanthanum(III), nickel(II) and cobalt(II) ions from their synthetic equimolar mixture using a polyethoxylated alcohol C13E10. Extraction optimization was determined by optimizing one parameter at a time. Lanthanum, cobalt and nickel were found to be extracted at 56.96%, 60.13% and 65.67%, respectively. As for the pre-concentration of the extracted metal ions, their elutions with nitric acid have shown that lanthanum is recovered at 100% in one step where two and four steps are necessary to recover 66.85% of nickel and 51.64% of cobalt respectively