Adsorption and catalytic removal of methyl orange from water by PIL-GO/TiO2/Fe3O4 composites

In this paper, an organic-inorganic hybrid material was synthesized via a simple but effective method, the novel material PGO-TiO 2 /Fe 3 O 4 (PGTF) was produced by loading TiO 2 and Fe 3 O 4 onto polymeric ionic liquid(PIL) functionalized graphene oxide(GO). The successful synthesis of PGTF and related structural feature were confirmed by a series of characterizations. The results of UV diffuse reflectance (DRS) demonstrated that the incorporation of PGO-Fe 3 O 4 to TiO 2 shifted the light absorption of TiO 2 from ultraviolet (UV) to visible region. The band gap energy of the PGTF reduced to1.92 eV as compared to TiO 2 (3.12 eV). Different materials were used to remove methyl orange (MO) from the aqueous solution. The results showed that PGTF had a superior capacity to remove dye due to the synergistic effects of adsorption and photocatalysis . The excellent adsorption properties may result from the high specific surface area of GO and the –NH 2 in the PIL. The polyionic liquid absorbed electrons due to the electrostatic action of the cation head in the polyionic liquid and GO which had high conductivity favored electron transport . The photocatalytic effectiveness increased as a result of the separation of photoexcited electron-hole pairs. The Langmuir model was investigated to evaluate the adsorption equilibrium behavior of MO dyes by PGTF. The maximum adsorption capacity( Q m ax ) was 67.88 mg/g for MO dyes. The pseudo-second-order kinetic model, with a correlation coefficient of 0.999, provided a good fit for the adsorption kinetic processes. The adsorption rate constant K 2 obtained by this model is 0.0072 g/(mg*min). The degradation rate constant of PGTF for MO in the photocatalytic stage was 0.00881 min −1 , which exhibited 3.7, 7.5 and 3 times higher than that of TiO 2 , FT and GTF. The main reactive species in the degradation process were O 2 − 、·OH、h + . PGTF had excellent repeatability because of the presence of Fe 3 O 4 . They can be easily separated from the water. These results indicated that the PGTF composites hold great potential for removing MO from wastewater.