Synthesis, characterization and adsorption properties of a novel biomagnetic composite for the removal of Congo red from aqueous medium

A novel biomagnetic composite (MnFe2O4/PW) was synthesized and used for the removal of Congo red (CR) from aqueous solutions. Adsorption of CR on the composite adsorbent was studied as a function of time (5-300 min), initial CR concentration (100-200 mg/L), composite dose (0.05-0.1 g), pH (6-10), and temperature (25-55 degrees C). The properties of the biomagnetic composite were measured by BET, SEM, SEM-EDX, FTIR, XRD, and VSM techniques. The kinetics and isotherm studies were carried out under optimum removal conditions of CR by MnFe2O4/PW. The kinetics and equilibrium data fitted to the pseudo-first-order kinetics and Langmuir isotherm models. Using CR as model pollutant, the prepared composite adsorbent showed good adsorption capacity of 86.96 mg/g. Thermodynamic analysis showed that the adsorption was favorable, spontaneous and endothermic. The adsorbent could be regenerated using 50% of ethanol-water solution, remaining 87.36% of its original capacity after the first regeneration cycle and reaching 65.68% of the original capacity after the fifth cycle. This study shows that the synthesized biomagnetic composite could be utilized as an efficient and magnetically separable adsorbent for the dye removal applications. (C) 2015 Elsevier B.V. All rights reserved.