Preparation of Magnetic Composite Polyaniline/Fe3O4−Hydrotalcite and Performance in Removal of Methyl Orange

Magnetic composite fabricated from polyaniline and Fe3O4-hydrotalcite (Pan/MHT) was successfully applicated for removal of methyl orange (MO) from wastewater. The structure and properties of Pan/MHT were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Brunauer-Emmett-Teller adsorption isotherm. Adsorption kinetic results indicated that the adsorption process followed pseudosecond-order kinetic model ( $R^2=0.999$ ), MO adsorption onto Pan/MHT was well described by Freundlich isotherm ( $R^2=0.994$ ), and the MO adsorption capacity of 2 Pan/MHT obtained the highest with $Q_e=156.25\text{mg}/\text{g}$ . Batch adsorption experiments were carried out using magnetic composite with the effects of initial MO concentration, solution pH, and adsorbent dosage. The results revealed that the magnetic Pan/MHT exhibited efficient adsorption of MO in the aqueous solution as a result of the affinity for organic dyes, microporous structure, and suitable surface area for adsorption (15,460 m2/g). The superparamagnetic behavior of Pan/MHT (with $H_c=18.56\text{Oe}$ , $M_s=23.38\times {10}^{-3}\text{emu}/\text{g}$ , and $M_r=0.91\times {10}^{-3}\text{emu}/\text{g}$ ) helps that it could be separated from the solution and performs as an economical and alternative adsorbent to removal and degrade azo dye from wastewater. Pan/MHT was also investigated to reuse after desorption of MO in 0.1 M HCl, and the results show that 2 Pan/MHT can be reused for 4 cycles with $Q_e=79.66\text{mg}/\text{g}.$