Preparation and characterization of novel bi-functionalized xerogel for removal of methylene blue and lead ions from aqueous solution in batch and fixed-bed modes: RSM optimization, kinetic and equilibrium studies

Abstract

A new bi-functionalized xerogel is fabricated and then was identified by 29Si CP MAS NMR, SEM, FTIR, and nitrogen adsorption–desorption approaches. As-prepared xerogel efficiency for simultaneous uptake of methylene blue (MB) and Pb2+ ions from aqueous solution is investigated. Individual and combination effects of operating variables (xerogel mass, contact time and initial MB and Pb2+ ion concentration) on the retention performance is achieved with central composite design (CCD) and upgraded through response surface method (RSM). Batch equilibrium outcomes uncovered that MB and Pb2+ ions adsorption onto hybrid composite could be all around depicted by Langmuir isotherm model contrasted with Freundlich equation. Howbeit, the column trials reported that the breakthrough capacities of MB and Pb(II) are observed to be 512 mg.g−1 and 400 mg.g−1 respectively. XPS and FTIR investigations uncovered that the main mechanism of lead uptake ought to be credited to the chelation with –NH2 and ion exchange with –SH groups in the xerogel frameworks. While the MB adsorption system is proposed to be electrostatic attractions, π-π stacking interactions and hydrogen bonds. The work undertaken in this research highlights the major role of the as-synthesized xerogel for treatment of industrial wastewater.