Multiple nitrogen functionalized magnetic nanoparticles as an efficient adsorbent: synthesis, kinetics, isotherm and thermodynamic studies for the removal of rhodamine B from aqueous solution

The continuous demand for clean and affordable water needed for the survival of man is now a major challenge globally. Therefore, the treatment of wastewater generated from printing, textile and dyeing industries containing soluble dyes like rhodamine B (Rh-B) is of utmost important. This study investigates the efficiency of new multifunctionalized superparamagnetic nanoparticles (MNP-Tppy) for the removal of cationic Rh-B from aqueous solution. To afford MNP-Tppy, the surface of MNP was covalently functionalized with terpyridine ligand to enable an anionic charge on the adsorbent. The results of characterization including Brunauer-Emmett-Teller (BET) analysis, thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscope (SEM) and fourier transform infra-red spectroscopy (FTIR) indicate that this superparamagnetic nanoparticle functionalized with multiple nitrogen atoms was successfully synthesized. Adsorption experiments involving the effect of pH, time, temperature, adsorbent dose and adsorbate concentration show that the maximum adsorption of Rh-B using MNP-Tppy was observed at pH 9 and removal was observed to increase as solution pH increases. Similarly, time variation shows that adsorbate removal increases as adsorption time increases until the removal attained equilibrium at 15 min. Kinetic studies conducted among four kinetic models using the data obtained from effect of time indicate that the adsorption process can best be described by the pseudo-second order model. Isotherm studies conducted at three different temperatures revealed that Langmuir isotherm model fitted well for the equilibrium data with q(m) value of 113.64 mg g(-1) and thermodynamic studies showed that the adsorption process involving the removal of Rh-B from aqueous solution by MNP-Tppy is spontaneous, endothermic and realistic in nature. Lastly, Reusability experiments indicate that MNP-Tppy can be regenerated and re-used.