Gd0.5Y0.5CrO3 perovskite-type oxide nanopowder: a novel adsorbent to remove organic dye from aqueous media

Nanoparticles of perovskite-type Gd0.5Y0.5CrO3 were prepared by the sol-gel method and tested for dye removal from aqueous media. The structure and morphology of Gd0.5Y0.5CrO3 nanopowders were characterised using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, the Brunauer-Emmett-Teller technique, thermal gravimetric analysis-differential thermal analysis and infrared spectroscopy. The ability of calcined nanoparticles to remove bromothymol blue (BTB) dye from aqueous solution was assessed. Adsorption experiments were carried out systematically by batch experiments to investigate the influence of different factors, such as contact time, initial concentration of dye, various adsorbent doses and pH of the solutions. The dye removal efficiency was found to be decreased with an increase in initial pH of the dye solution and Gd0.5Y0.5CrO3 nanoparticles exhibited good dye removal efficiency at acidic pH, optimized at pH 2. Kinetic adsorption data were studied using three most popular isotherm models, namely Langmuir, Freundlich and Redlich-Peterson. A non-linear method was used for comparing the best fit of the isotherms. The best fit was found for the Redlich-Peterson isotherm. The maximum predicted adsorption capacity was 366.67 mg(-1) for BTB. In addition experimental results indicated that the adsorption kinetic data followed a pseudo second-order rate for the tested dye.