Synthesis of trimethoprim vanillin anchored conjugate imprinted polymers for removal of bromocresol green and malachite green from aqueous media

Abstract

Bromocresol green (BCG) and malachite green (MG) are water-soluble toxic organic dyes with adverse health and environmental implications. This study presented a conjugate imprinted adsorbent (CIA) synthesized by incorporating trimethoprim vanillin ligand into a highly crosslinked polymer, designed for the efficient removal of BCG and MG from wastewater. Characterization of CIA involved X-ray powder diffraction, Fourier transform infrared, and scanning electron microscopic analyses. Batch adsorption processes were conducted to evaluate the adsorption characteristics of CIA, with focuses on the effects of contact time, initial dye concentration, pH, and temperature. The molecularly imprinted polymers (MIPs) achieved removal efficiencies of 99.27% and 98.99% at equilibrium for BCG and MG adsorption, respectively. The non-imprinted polymers (NIPs) demonstrated BCG and MG adsorption efficiencies of 51.52% and 62.90% at equilibrium, respectively. Kinetic and isotherm models were employed to elucidate the BCG and MG adsorption mechanisms. The thermodynamic results indicated non-spontaneous and spontaneous reactions for BCG and MG adsorption on MIPs under the examined temperature conditions. The adsorbent exhibited sustained high removal efficiency through five reuse cycles, with no apparent reduction in adsorption performance. Validation of the adsorbent using real textile wastewater samples achieved BCG and MG removal efficiencies of 85.5%–87.5%. The adsorbent outperformed previously reported materials in BCG and MG adsorption. The synthesized CIA is a promising adsorbent for BCG and MG dye removal, contributing to water sustainability.