Peptide-based surface modified silica particles: adsorption materials for dye-loaded wastewater treatment

Surface-modified silica particles were prepared via solid-phase grafting methodology, and their prospective utility in wastewater treatment was evaluated. The structure-activity relationship of the designed particles was investigated for silica surfaces grafted with various amino acid-based peptide molecules to determine the effect of the chemical nature on the adsorption capacity of these surface-modified silica particles. The successful grafting of the organic phase over the modified silica surface was confirmed on the basis of infrared absorption and solid-state C-13 NMR data, as well as thermogravimetric and elemental analyses. The organically modified silica particles effectively adsorbed anionic targets such as organic dyes and surfactants from aqueous medium, and the adsorption behaviour followed pseudo-second order kinetics, which conformed to the Freundlich or Langmuir adsorption isotherms. Furthermore, hydrophobic interaction of the aliphatic peripherals of the modified silica with the alkyl tail of the surfactant was the major force for adsorption of the surfactants onto the modified silica, whereas pi-pi and electrostatic interactions played a major role in the adsorption of anionic dye molecules.