Magnetic microspheres based on glycidyl methacrylate and divinylbenzene modified with different amines for removing chromium VI from aqueous media

Abstract Magnetic microspheres of poly(glycidyl methacrylate- co -divinylbenzene) were produced via suspension polymerization. These microspheres were functionalized with ethylenediamine, diethylenetriamine and triethylenetetramine. Microspheres with good morphological control and superparamagnetic behavior were obtained. The Cr (VI) adsorption by the amino functionalized microspheres was pH dependent, achieving better removal results at pH 2. The adsorptive process was best described by the pseudo-second order model. The model confirmed that chemisorption is the main mechanism of adsorption control. The equilibrium isotherm study indicated the best suitability for the Langmuir model. The maximum sorption capacity was 77.35 mg. g − 1 from the microsphere functionalized with diethylenetriamine, at pH 2, 318.15 K. The adsorbents had ΔH around 40–45 kJ / mol and ΔS between 148–159 J / mol.K. The results indicated an endothermic process, of chemical nature, and with negative ΔG values.