Cr (VI) Adsorption Using synthesis Novel UIO-66-MnFe2O4-TiO2 Magnetic Nanoparticles by Experimental Design

One of the major problems we face with the growth of various industries around the world is the environmental pollution of heavy metals. One of the most toxic heavy metals that is problematic even at low concentrations is Cr (IV).

In this study, the removal of this toxic heavy metal was investigated with high efficiency by UIO-66-MnFe2O4-TiO2 magnetic adsorbent. For this purpose, magnetic nanocomposite (UIO-66-MnFe2O4-TiO2) was synthesized based on metal-organic framework (MOF) for adsorption of Cr (IV). The choice of the hydrothermal method for the synthesis of UIO-66 in addition to its simplicity resulted in the production of pure and efficient UIO-66, which produced very high efficiency during the experiments. MnFe2O4 nanoparticles were used to magnetize the adsorbent. To increase the magnetic properties and increase the loading efficiency of the MnFe2O4 nanoparticles, TiO2 nanoparticles were used to increase the loading rate on the adsorbent. XRD, SEM, FT-IR, BET, VSM and EDX tests were used to the characterization of the adsorbent properties.

Effect of four effective variables during adsorption experiments such as adsorbent content (0.05 to 0.25 g), pH (2 to 6), adsorption time (15 to 75 min), initial metal ion concentration (200 to 1000 mg / l) at five levels (+2 to +2) were investigated using experimental design with response surface methodology (RSM) and central composite design (CCD). The best conditions were determined for the independent variables for the initial metal concentration of 552 mg /l. The optimum pH was obtained 4 during the experiment. Finally, the optimum values were achieved for adsorption parameters such as adsorption time and adsorbent amount were 42.3 min and 0.143 gr, respectively, and also the maximum adsorption rate was obtained 98%. Investigation of the adsorption isotherm kinetics showed that the pseudo-second-order model and Langmuir isotherm fit the Cr (IV) data well. After the adsorption process, the adsorbent can be removed from the environment by a magnetic field.