Rapid adsorptive removal of eosin yellow and methyl orange using zeolite Y
John Busayo Adeoye, David O. Balogun, Oghenefejiro Jeshurun Etemire, Princewill Nnaneme Ezeh, Yie Hua Tan, Nabisab Mujawar Mubarak
Abstract
Abstract In this study, zeolite Y was synthesised using a novel method. The heat generated from the reaction of H 2 SO 4 with metakaolin was used as a heat source instead of applying external heat for the dealuminated process. The synthesised zeolite Y produced was analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier-infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS) and Brunauer–Emmett–Teller (BET). Zeolite Y synthesis was mesoporous because of its pore diameter (30.53 nm), as shown in the BET results. Surface area and pore size decrease after adsorption due to dye deposition on the adsorbent’s surface. FTIR has bonds like O–H, C–H, –CH 3 , and –COOH responsible for adsorption. The maximum adsorption capacity of eosin yellow (EY) and methyl orange (MO) on to zeolite Y by the Langmuir isotherm was 52.91 mg/g and 20.62 mg/g respectively, at pH 2.5 and 8 for EY and MO dye. The batch adsorption studies were conducted, and the influence of different parameters (i.e., adsorbent dose, adsorption time, initial dye concentration, pH and temperature) was investigated. Experimental data were analysed by two linear model equations (Langmuir and Freundlich isotherms), and it was found that the Langmuir isotherm model best describes the adsorption data for methyl orange and Freundlich isotherm for eosin yellow, respectively. Adsorption rate constants were determined using linear pseudo-first-order and pseudo-second-order. The results showed that MO and EY dye adsorption onto zeolite Y followed a pseudo-second-order kinetic model. Thermodynamic studies show that adsorption was an exothermic reaction (enthalpy < 0) and feasible ( $$(Gibbs free energy)<0$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>G</mml:mi> <mml:mi>i</mml:mi> <mml:mi>b</mml:mi> <mml:mi>b</mml:mi> <mml:mi>s</mml:mi> <mml:mi>f</mml:mi> <mml:mi>r</mml:mi> <mml:mi>e</mml:mi> <mml:mi>e</mml:mi> <mml:mi>e</mml:mi> <mml:mi>n</mml:mi> <mml:mi>e</mml:mi> <mml:mi>r</mml:mi> <mml:mi>g</mml:mi> <mml:mi>y</mml:mi> <mml:mo>)</mml:mo> <mml:mo><</mml:mo> <mml:mn>0</mml:mn> </mml:mrow> </mml:math> ) at various temperatures under investigation.