Efficient removal of organic pollutants from aqueous media using newly synthesized polypyrrole/CNTs-CoFe2O4 magnetic nanocomposites

In this study, the polypyrrole/CNTs-CoFe2O4 magnetic nanohybrid (CNTs-CoFe2O4@PPy) was prepared and then used as adsorbent and catalyst to remove anionic and cationic dyes. The hybrid material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), elemental analysis, BET surface area, Fourier transform infrared (FTIR) spectroscopy and vibrating sample magnetometer (VSM). Adsorption behaviors of the as-prepared composites for anionic dyes such as Methyl Blue (MB), Methyl Orange (MO) and Acid Fuchsin (AF) were conducted where the effects of solution pH, initial dye concentration, contact time and ionic strength were systematically studied. The equilibrium adsorption data of MB, MO and AF were well fitted to the Langmuir isotherm model, yielding the maximum monolayer adsorption capacity of 137.00, 116.06 and 132.15 mg/g, respectively. Adsorption kinetics was best described by the pseudo-second order model. The introduction of CoFe2O4 into CNTs-CoFe2O4@PPy hybrid could not only provide an effective magnetic separation performance, but also act as catalyst to activate peroxymonosulfate (PMS) for the degradation of cationic dye, Methylene Blue (MEB), from aqueous solution. The results showed that CNTs-CoFe2O4@PPy presented higher catalytic activity, better stability and reusability for the decolorization of MEB, resulting in an almost complete removal of 50 mg/L MEB after 30 min with 1.0 g/L catalyst and 4 mmol/L PMS. The characteristics of high adsorption capacity, effective separation, excellent catalytic activity and good reusability would make CNTs-CoFe2O4@PPy a promising candidate for wastewater treatment.