مشخصات پژوهش

The wet procedure is one of the prominent methods to produce phosphoric acid but unfortunately, remain the undesired components such as heavy metals in the final product. The aim of this work is to employ 4A zeolite adsorbent for the adsorption of lead and arsenic from the wet-process phosphoric acid. The Taguchi methodology was used to improve the processing quality and optimize design factors. Three operational factors of the concentrations of lead and arsenic, adsorbent dosage, and pH were chosen as variables of the experimental design. The batch adsorption method was applied to remove heavy metals. The results make it clear that the adsorption process of heavy metals is significantly affected by the pH of the solution, the heavy metals concentration, and lastly, by the adsorbent dosage. The adsorption mechanism has been surveyed using two adsorption isotherm models (the Langmuir and the Freundlich isotherm). The consequence demonstrated that the Langmuir model more excellently and effectively illustrates the experimental results compared to the Freundlich model. The equilibrium time for removal of arsenic and lead was found to be 140 min and 100 min, respectively. Using the experiment setting optimized by the Taguchi method, a 99% reduction in both pollutant concentrations was achieved by the adsorption process. By using analysis of variance and signal-to-noise ratio, the impact of the effect of each parameter on the response and the error rate based on a 95% confidence interval were obtained.