Case Studies in Chemical and Environmental Engineering (Jun 2023)
Experimental, response surface methodology (RSM) and mass transfer modeling of heavy metals elimination using dolomite powder as an economical adsorbent
Abstract
This research aims to conduct a general study about the dolomite ability for the removal of heavy metals (Ag, Cu, Cd, Co, Ni, Ba, and Sr ions) in aqueous solutions. Desorption studies were performed for adsorbent recovery and reuse in adsorption processes. This research focused on the dependence of the adsorption capacity on the process parameters including pH in the range of 2–8, metal concentration in the range of 10–60 mg/L, the temperature in the range of 20–50 °C, and period of the domain of 5 min–6 hr. The dolomite powder was characterized using X-ray, scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR). The process optimization was analyzed using CCD, and RSM with three independent values of adsorbate (categoric), temperature, and concentration. The maximum adsorption of heavy metals was 60 mg/L and 293 K with a desirability of 0.976. The kinetic studies indicate that the pseudo-second-order (PSO) model for the adsorption of Ni, Ag, Co, Cu, Cd, and Ba ions indicated a better correlation with the experimental results. Thermodynamic factors implied that processes are spontaneous with heat releasing. The outcome showed that the temperature and concentration interaction in the designated range had a high effect on the maximum ability adsorption of metallic ions. Besides, the maximum adsorption for nickel-metal has occurred. The order of coefficient of mass transfer and flux of mass transfer obeys this arrangement: Cu > Sr > Cd > Ni > Ba > Ag > Co. This comparison demonstrates that the Cu ions have more tendency to migrate inside the pores, and Co ions have the least tendency to enter the pores. A comparison of the results revealed this case that Iranian dolomite has an appropriate potential in eliminating heavy metals in terms of capacity and economy.
