Optimization and modeling of Pb(II) adsorption from aqueous solution onto phosphogypsum by application of response surface methodology

In this work, we have proposed a method of phosphogypsum (PG) recovery by attempting to use it as an adsorbent of heavy metal ions from aqueous solutions, while trying to study the different quantitative and qualitative characteristics. The PG was synthesized and characterized with X-ray diffraction (XRD) and Fourier transform infrared (FTIR). The effects of the initial concentration of lead (X1), pH of the solution (X2), and temperature (X3) on the amount of Pb(II) adsorbed were investigated. Thermodynamic parameters were calculated. The modeling of the adsorption tests by the experimental design method as well as the optimization of the parameters by the response surface methodology (RSM) is given in this article. The results obtained show that amount of Pb(II) adsorbed increases with Pb concentration and decreases as pH of the solution and temperature increase. It was found that the processes conforming to second-order kinetics and the optimal adsorption capacity of lead on PG are at a lead concentration of 109.64 mg/L, 5.25 of pH, and 70 degrees C for temperature. The adsorption process was found to be exothermic and spontaneous.