Synthesis and application of ZSM-5/Graphene composite for photocatalytic degradation of industrial dyes

Abstract

Various materials and technologies are being employed to address the concern of increased wastewater generation. In this work, the synthesis of ZSM-5 (Zeolite Socony Mobil-5) and graphene (GR) composite, their characterisation, and application for the removal of dyes are presented. Two composites of ZSM-5 and GR composites were prepared via the hydrothermal method by varying the loading amount of GR, i.e. 1% and 5%, and labelled as GZ1 and GZ5. The parent and composite materials were characterised using field emission scanning electron microscope (FE-SEM), x-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), x-ray photoelectrons spectroscopy (XPS), Raman, and Fourier transform infrared (FTIR). The materials were then employed for the photodegradation of methyl orange (MO) dye. The adsorption efficiencies for ZSM-5, GR, GZ1, and GZ5 were found as 0%, 17.8%, 0%, and 16% respectively. According to photodegradation results, the GZ1 composite exhibits the maximum degradation efficiency of 75.3% for 20 ppm of MO, within 180 min of light exposure. The scavenger studies were performed to evaluate the role of active oxygen species (AOS) in the photocatalysis mechanism. All studies were performed with the catalyst dosage of 0.5 mg ml⁻¹. The degradation efficiencies for GR, GZ5, and Z5 were reported as 34.2%, 20.8%, and 17.5%, respectively. On increasing the irradiation time to 240 min, the degradation efficiency of GZ1 reached 92%. The removal efficiencies for MO (7 ppm) and methyl blue (5 ppm) in a 12-ppm dye mixture were observed to be 98% and 97.2% respectively within 180 min of light exposure with GZ1 composite.