Salicylaldehyde and 3-hydroxybenzoic acid grafted NH2-MCM-41: Synthesis, characterization and application as U(VI) scavenging adsorbents using batch mode, column and membrane systems

Water sources with high uranium prevalence poses potential health risk to human health due to chemical and radio toxicity of uranium which causes severe diseases specifically nephritis, cell mutations, DNA damage and various types of cancer. Therefore, the development of efficient uranium scavenging water treatment techniques which provide safe water has earned immense attention globally. In this study, NH2-MCM-41(MCM-a) was synthesized by co-condensation method followed by its grafting using salicylaldehyde (MCM-s) and 3-hydroxybenzoic acid (MCM-hb). MCMs so obtained were characterized for their structural, morphological and surface features using small angle XRD, FESEM-EDX, FTIR and BET followed by systematic investigation of their scavenging adsorptive potential for U(VI) remediation using batch mode, column studies and membrane separation. The adsorption isotherm data were fitted well to the Langmuir model and the maximum adsorption capacity (mg/g) of three MCMs follows the order as: MCM-s (210.68) > MCM-hb (194.11) > MCM-a (159.99) at optimum conditions: pH (6.0), contact time (30 min) and adsorbent dose (0.4 g/l). The pseudo-second order kinetic model was appropriate for describing the chemisorption of U(VI) on the surface of all three MCMs and thermodynamic parameters revealed the feasible, spontaneous, endothermic and entropy driven nature of adsorption process. The rapid adsorption rate and high adsorption efficiency along with excellent regeneration ability allow the promising application of MCMs as packing materials and fillers in columns and membrane separation systems, respectively and used for successful remediation of uranium prevalent groundwater. (C) 2021 Elsevier B.V. All rights reserved.