Urea-Functionalized mesoporous silica SBA-15 for heavy metal Adsorption: Synthesis, Characterization, and optimization

Abstract

This study investigates chromium, cadmium, and lead ions adsorption on mesoporous silica SBA-15 functionalized by the urea amine group (Urea-SBA-15). Parameters affecting adsorption by Urea-SBA-15 were the initial concentration of heavy metals, contact time, pH, adsorbent concentration, and temperature. Optimum adsorption performance was achieved at pH = 2.5 for Cr(VI), pH = 5 for Cd(II), and pH = 4 for Pb(II), a contact time of 2 h for Cr(VI) and Cd(II) and 1.5 h for lead, an adsorbent concentration of 2.5 g/L, temperature equal to 45 °C, and a heavy metals concentration of 25 ppm. The obtained results were consistent with Langmuir and pseudo-second-order models. The highest adsorption capability for Cr(VI), Cd(II), and Pb(II) were 26.83, 30.53, and 43.85 mg/g, respectively. Laboratory results showed that due to an increased adsorption capacity, the Urea-SBA-15 adsorbent is promising for heavy metal ions removal from water resources.