Post-synthetic modification of MIL-125 with bis-quinoline Mannich bases for removal of heavy metals from wastewater

Ti-based metal-organic frameworks (NH2 -MIL-125) were post synthetic modified through a facile strategy using bis-quinoline Mannich bases producing MIL-125-HQ. The modified material (MIL-125-HQ) was used as an absorbent for uptake of the heavy metals from wastewater. H-1 NMR, FTIR, CHN and SEM-EDX analysis showed successful incorporation of hydroxyl quinoline moiety into the NH2-MIL-125 upon chemical reaction. The modified MIL-125-HQ showed high affinity for Pb(II) ions from water, and the amount of Pb(II) ions decrease sharply from 500 mg/L to 60 mg/L, within merely 30 min of exposure at pH7, 298 K and 2 g/L MIL-125-HQ. The maximum adsorption capacity of MIL-125-HQ for Pb(II), Cd(II), Cu(II) and Cr(III) was determined to be 262.1, 102.8, 66.9 and 53.9 mg/g, respectively.