Kinetic and Isotherm Study of 2,4,6-Trichlorophenol’s Fast Adsorption from Aqueous Solutions by Synthesized Magnetite-Bentonite Nanocomposite

Organic pollutants in water have been the main contaminations of concern for man. 2,4,6-Trichlorophenol (TCP), is a toxic carcinogen phenolic derivative which exists in effluents of chemical industries and the removal of this pollutant is critical. As the removal of TCP from industrial effluents is important, various techniques have been applied such as adsorption, chemical oxidation, chemical coagulation, and anaerobic biodegradation. In adsorption technique, nanobentonite is considered as a suitable adsorbent due to the low cost, small size of particles, large surface area, naturally available, and intense adsorption capacity. To separate adsorbent particles easily through an external magnetic field, magnetic nanomaterials, such as Fe₃O₄, can be fixed on nanobentonite. In this research, magnetized bentonite nanocomposite was synthesized for fast adsorption of TCP from aqueous solutions. The adsorbent was characterized by a Vibrating-Sample magnetometer (VSM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR), X-Ray diffraction (XRD) and Zetasizer Nanoparticle analyzer and the effect of adsorbent dose; pH and contact time parameters on the adsorption process of TCP were evaluated. Moreover, the isotherms and adsorption kinetics were studied. The pH 5 was considered as the optimal pH. The results of kinetic experiments showed that by increasing the contact time, the adsorption efficiency was increased and the equilibrium contact time was found to be about 60 minutes. In optimal pH and equilibrium time (60 min) conditions with the adsorbent dose of 1 g/L, the percentage of adsorption by magnetized nanobentonite was achieved 96.777% while unmodified bentonite adsorbed 68.25% of TCP in equilibrium time of 3 h. The experimental data of adsorption indicated more conformity with the pseudo-second-order and Langmuir isotherm models. As a deduction, nanobentonite with high adsorption capacity was prepared from bentonite mines of Iran and magnetized by Fe₃O₄ leading to easy and fast separation of nanocomposite TCP from the solution.