Synthesis and surface modifications of mesoporous silica adsorbent for selective removal of chromium (Cr 3+ ) ions from wastewater

A salicylaldehyde-based Schiff base ligand functionalized mesoporous silica nanoparticles (SBA-15@SB NPs) were prepared for selective adsorption of chromium (Cr3+) ions from aqueous solution. The prepared SBA-15@SB NPs were characterized using X-ray diffraction (XRD), N2 sorption, SEM, TEM, zeta potential, particle size analysis, and thermogravimetric analysis. The selective metal ion adsorption capacity of SBA-15@SB NPs was determined using various competitive divalent metal ions (Ni2+, Zn2+, Mn2+, and Mg2+), and trivalent metal ions (Al3+, Fe2+, and In3+), respectively, at different experimental conditions such as varied solution pH (pH 3, 5, 6.5, 7.0, and 9.0), concentration of metal ions (50, 100 and 150 mg/L), adsorbent amount (0.025, 0.05, 0.075, 0.1 and 0.15 g), respectively. At pH 6.5, the synthesized SBA-15@SB NPs showed a high adsorption ability and selectivity toward Cr3+ ions, adsorbing over 90% of the initial Cr3+ ion solution (100 mg/L) in about 210 mg/g.