Removal of hexavalent chromium by chemical modification of 4,4′-((1Z,11Z)-2,5,8,11-tetraazadodeca-1,8-diene-1,11-diyl)diphenol: kinetic and equilibrium modeling

Abstract

This study aimed to synthesize a new resin through immobilization of the 4,4′-((1Z,11Z)-2,5,8,11-tetraazadodeca-1,8-diene-1,11-diyl)diphenol (TRA) onto silica gel modified (Si-CPTS) with 3-chloropropyltrimethoxy silane (CPTS) and its application for the removal of chromium(VI) ions from aqueous solution as well as from industrial wastewater. The same applications were also made for industrial wastewater vapor. The objective purpose of this work was to investigate the influences of concentration, temperature, amount of metal ions, contact time and pH to sorption on the surface modified by TRA (Si-TRA). The newly synthesized Si-TRA is characterized with scanning electron microscope and elemental analysis and Cr(VI) heavy metal ions were used as sorbate. The sorption of Cr(VI) ion was evaluated by using batch methods. The value of adsorption of Cr(VI) ion was detected with an atomic absorption spectrometer. The maximum adsorption capacities and isotherm parameters were calculated from the Langmuir, Freundlich, and Dubinin–Radushkevich isotherm equations. Thermodynamic parameters such as free energy (ΔG°), entropy (ΔS°), and enthalpy (ΔH°) were also calculated from the sorption results. The modified structure used as adsorbent was successfully employed in the removal of Cr(VI) ions from the samples of industrial wastewater.