Application of response surface methodology for modeling and optimization of the extraction and separation of Se(IV) and Te(IV) from nitric acid solution by Cyanex 301 extractant

Abstract

The objective of this study is to develop a mathematical model based on the response surface methodology (RSM) for Liquid-liquid extraction and separation of Selenium and Tellurium from the aqueous nitric acid solution using Cyanex 301 as a potential organic extractant. For this purpose, three independent variables, i.e. nitric acid concentration (1–5 mol L−1), Cyanex 301 concentration (0.02–0.1 mol L−1), and extraction temperature (15–55 °C) were considered to evaluate their impacts on the responses of the percentage extractions (%E) of selenium and tellurium based on central composite design (CCD) approach. After conducting the experiments and statistically analyzing the results, correlations were proposed for selenium and tellurium extraction based on quadratic models. The results indicated that the Cyanex 301 concentration was the most paramount variable in extraction separation of Selenium and Tellurium. According to the obtained results the optimal condition for selective extraction of Se(IV) over Te(IV) was obtained at HNO3 concentration 2.7 mol L−1, Cyanex 301 concentration 0.06 mol L−1, and extraction temperature 25 °C. The optimum predicted extraction percentage of Se(IV) and Te(IV) was 99.77% and 28.47%, respectively and the actual values were 99.72%, and 28.12%, respectively. Also, the predicted and real separation factor was found to be 1089.87 and 910.37 respectively. These results showed the suitability of the implemented model and the prosperous application of RSM based on CCD in optimizing the selective extraction conditions of Se(IV) from Te(IV) in nitric acid medium.