Design of experiments for Optimizing of extraction of organic compounds from spent acid of toluene nitration process

The removal of nitro-body compounds from spent acid of toluene nitration process was made by ethyl acetate solvent in an extraction method and adsorption by granule active carbon particles. The effects of three components of spent acid sample, extractant solvent and water for dilution of samples on the extraction efficiency were statistically modelled and optimized using mixture design of experiments by Minitab ۱۷ software. The multiple regression analysis and analysis of variance (ANOVA) showed that the predicted results obtained are in good agreement with the experimental data. In the optimized conditions, with one step extraction, nitro-bodies compounds can be extracted from spent acid with mean extraction efficiency of ۹۸.۵ wt.% and experimental relative error near to ۱.۴%. Also, the removal of nitro-body compounds from spent acid was investigated by adsorption by particles of active carbon. The Taguchi design was used for optimization of procedure. The experimental data indicated that the optimized values of variables of shuffle time of mixture, the amount of adsorbent of carbon particles and the dilution times of spent acid are ۹۰ min., ۰.۱ g/L and ۱۰ times, respectively. The p-values of coefficient's of predictors in extraction and adsorption methods are obtained < ۰.۰۵ that indicate in confidence level of ۹۵%, the null hypothesis is rejected and there are a meaningful dependence between predictors and responses of extraction and removal efficiencies, respectively.

کلیدواژه ها:

Spent acid ، mixture design ، Taguchi design ، optimization ، nitro-body compounds