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 °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.