Heavy Metals Removal from Polluted Water by Cement Kiln Dust

Two laboratory experiments were conducted in the Desert Studies Center laboratories during the spring season of 2024 to evaluate the efficiency of Cement Kiln Dust (CKD) in removing lead and cadmium from polluted water. The first experiment represents the thermally isotropic adsorption of heavy metals on the cement kiln dust (CKD) surface. The experiment included three diameters of CKD particles, i.e., 0.3, 1.18, and 2 mm, treated with four concentrations of cadmium and lead, namely 20, 40, 80, and 160 mg.L⁻¹ for each element (cadmium and lead). The amount of the adsorbed metals on the surface of CKD was calculated according to the Langmuir equation. In contrast, the second experiment represents the effect of contact time between the heavy metals and CKD particles for the same aforementioned diameters and concentrations. The results of the isothermal adsorption experiment showed that the adsorbed amount increased with increasing the added concentrations of heavy metals. The adsorbed quantity of cadmium is superior to that of lead. Also, the adsorption capacity of cadmium was higher compared to the lead adsorption capacity. In this context, the adsorption capacity reached 2880.00 and 2735.58 mg.kg⁻¹ for cadmium and lead, respectively. Regarding the second experiment, the results showed that the amount of cadmium and lead adsorbed on the CKD particle’s surface increased with time, where the highest amount of cadmium and lead adsorption was 39.94 and 34.93%, respectively, for shaking of 4 h. It is recommended to apply the experiment in real-world projects.