Efficient removal of chromate ions from aqueous solution using a highly cost-effective ferric coordinated [3-(2-aminoethylamino)propyl]trimethoxysilane–MCM-41 adsorbent

Abstract

The present investigation involves synthesis and characterization of MCM-41–AEAPTMS–Fe(III)Cl using coordinated Fe(III) on MCM-41–AEAPTMS for efficient removal of hazardous Cr(VI) ions from aqueous solution. The adsorbent MCM-41–AEAPTMS–Fe(III)Cl was characterized using small-angle X-ray diffraction (SAX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier-transform infrared (FT-IR) and Brunauer–Emmett–Teller (BET) surface analyzer techniques. The BET surface area was found to be 87.598 m² g⁻¹. The MCM-41–AEAPTMS–Fe(III)Cl effectively adsorbs Cr(VI) with an adsorption capacity acquiring the maximum value of 84.9 mg g⁻¹ at pH 3 at 298 K. The data followed pseudo-second-order kinetics and obeyed the Langmuir isotherm model. The thermodynamic data proved the exothermic and spontaneous nature of Cr(VI) ion adsorption on MCM-41–AEAPTMS–Fe(III). Further, the higher value of ΔH° (−64.339 kJ mol⁻¹) indicated that the adsorption was chemisorption in nature.