Use of Sr2Mg(BO3)2 in Congo red removal from aqueous solutions: Synthesis, adsorption, isotherm, kinetic study

Abstract

Sr2Mg(BO3)2 was prepared by a solution combustion method at 900 °C for 6 hour in air. The prepared adsorbent was characterized by X-Ray Diffraction (XRD). The XRD pattern of Sr2Mg(BO3)2 is in agreement with the ICDD File No: 01-076-9795. The particle morphology of the adsorbent was investigated by scanning electron microscope (SEM). The average size of particles is about 3–10 µm. The Congo red dye was removed from aqueous solution using Sr2Mg(BO3)2. The effect of time, initial concentration, pH, temperature and dosage on adsorption were investigated. The Freundlich model fitted according to equilibrium data and maximum adsorption capacity is 886.952 mg/g. According to theories of pseudo-second-order kinetics, the removal procedure involves chemical adsorption. According to the thermodynamic data, negative ΔG values indicated that adsorption of Sr2Mg(BO3)2 occurred spontaneously and negative ΔH values, the adsorption process was exothermic. Sr2Mg(BO3)2 is a useable material for Congo red dye removal.