Abstract
A novel graphite-phase carbon nitride (g-C3N4)/bismuth ferrite (BiFeO3)/carbon nanotubes (CNTs) ternary magnetic composite (CNBT) was prepared by a hydrothermal synthesis. Using this material, Cr(VI) and methylene blue (MB) were removed from wastewater through synergistic adsorption and photocatalysis. The effects of pH, time, and pollutant concentration on the photocatalytic performance of CNBT, as well as possible interactions between Cr(VI) and MB species were analyzed. The obtained results showed that CNTs could effectively reduce the recombination rate of electron-hole pairs during the photocatalytic reaction of the g-C3N4/BiFeO3 composite, thereby improving its photocatalytic performance, while the presence of MB increased the reduction rate of Cr(VI). After 5 h of the simultaneous adsorption and photocatalysis by CNBT, the removal rates of Cr(VI) and MB were 93% and 98%, respectively. This study provides a new theoretical basis and technical guidance for the combined application of photocatalysis and adsorption in the treatment of wastewaters containing mixed pollutants.
Highlights
With the development of many industrial technologies, pollutants discharged into the environment have become increasingly toxic and chemically complex [1]
The material microstructure was characterized by a QUANTA250 field emission scanning electron microscope (FE-SEM; FEI, Hillsboro, OR, USA), the samples were directly attached to the conductive adhesive, were tested with the ETD morphology mode under a 20 KV working voltage and 0◦
The photocurrent responses of the studied materials were measured using a photochemical workstation (CHI 660E) with a conventional three-electrode model [28]. g-C3 N4, BiFeO3, carbon nanotubes (CNTs), C3 N4 /BiFeO3 (CNB), and CNBT samples were examined by a current-time method, in which the Pt and Ag/AgCl electrodes served as the counter and reference electrodes, respectively
Summary
With the development of many industrial technologies, pollutants discharged into the environment have become increasingly toxic and chemically complex [1]. Bismuth ferrite (BiFeO3 ) is a photocatalytic material with a wide range of potential applications, which possesses a narrow band gap and is responsive to visible light [22]. It can simultaneously exhibit ferroelectric and magnetic properties at room temperature [21]. Combining g-C3 N4 , BiFeO3 , and CNTs to form a ternary magnetic composite may increase the specific surface area and number of active sites [27], and reduce the recombination rate of photogenerated carriers, improving the photocatalytic properties of the resulting material. The influences of the solution pH, pollutant concentration, and reaction time on the adsorption and photocatalytic processes were determined, and possible mechanisms of the adsorption and photocatalytic reactions were suggested
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