Highly efficient photocatalytic treatment of mixed dyes wastewater via visible-light-driven AgI–Ag3PO4/MWCNTs

Abstract

A high-performance photocatalyst of AgI–Ag3PO4/multi-walled carbon nanotubes (MWCNTs) was fabricated by chemical precipitation method using KI, K2HPO4 and AgNO3 in the presence of MWCNTs. Its structure and physical properties were characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), UV–vis absorption spectra, X-ray photo-electron spectroscopy (XPS), photoluminescence spectra (PL) and photocurrent techniques. SEM, TEM and EDS analyses verified that AgI–Ag3PO4 is successfully loaded on MWCNTs. AgI–Ag3PO4/MWCNTs possess the absorption edge of red shift and small band gap energy, and could absorb more photons in the visible region. PL and photocurrent analyses illustrated that AgI–Ag3PO4/MWCNTs have the lowest emission peak intensity and the highest photoelectric current, compared with Ag3PO4, AgI and AgI–Ag3PO4. By using the photocatalytic degradation of mixed dyes wastewater of Orange II and ponceau 4R as a model reaction, the photocatalytic efficiencies of Ag3PO4, AgI, AgI–Ag3PO4 and AgI–Ag3PO4/MWCNTs were evaluated. The reaction results showed that AgI–Ag3PO4/MWCNTs have strong photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared AgI–Ag3PO4/MWCNTs could act as a high-performance catalyst for the photocatalytic degradation of mixed dyes wastewater and also suggested the promising applications.