Selective Adsorption and Photocatalytic Degradation of Dyes Using Polyoxometalate Hybrid Supported on Magnetic Activated Carbon Nanoparticles under Sunlight, Visible, and UV Irradiation

Abstract

In this study, magnetic activated carbon (MAC) nanoparticles were coated with an organic hybrid of silicotungstic acid that makes MAC suitable for adsorption and photocatalytic degradation of dyes. The prepared composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermal analyses, scanning electron microscopy, vibrating sample magnetometer, and N 2 adsorption-desorption isotherms. Dye adsorption and photocatalytic properties of composite were examined by studying the decolorization of model dyes methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and their mixture solutions. The results show that the composite can selectively adsorb MB molecules from binary mixtures of MB/MO or MB/RhB, and its adsorption capacity is enhanced as compared with the MAC. The composite is also, unlike MAC, a good photocatalyst in the degradation of dyes under sunlight, visible, and UV irradiation and can be separated by magnet, recovered and reused. Removal is via combination of adsorption and then photocatalytic degradation through direct oxidation by composite or indirect oxidation by• OH radicals. While the sunlight is not able to degrade alone MO and RhB solution in the presence of composite, it degrades the MO and RhB mixed with MB solution.

Shift the Photocatalytic Activity of P25 TiO2 Nanoparticles toward the Visible Region upon Surface Modification with Organic Hybrid of Phosphotungstate

“…Evaluation of the Photocatalytic Activity. Solar photocatalytic experiments were performed similar to our previous works [14,15]. 100 mL RhB (15 mg L -1 ) and a specific amount of the photocatalyst were transferred to a beaker, capped by cellophane, and exposed to sunlight in September 2017 between 11 am and 3 pm at the Payame Noor University, Ardakan, Yazd, Iran (GPS coordinates: 32°29 ′ N, 53°59 ′ E).…”

“…One other is modification with polyoxometalates (POMs), but pure POMs cannot shift the photocatalytic activity of pure P25 TiO 2 toward the visible region, and it is necessary to join them to valuable metallic or nonmetallic moieties [9][10][11][12][13]. In this work and in the following of our previous works [14,15], we have utilized the combination of dye sensitization and POMs, i.e., the adsorbed MB on phosphotungstate-hexamethylenetetramine hybrid (PTA-HMT-MB) as sensitizer. To our knowledge, the coating of P25 TiO 2 with a colored organic hybrid of POMs has not been reported yet.…”

Graphene/silver-based composites and coating on dead coral for degradation of organic pollution using the Z-scheme mechanism

“…Nowadays, water treatment is a fundamental global challenge due to the lack of safe drinking water, extensive population growth, 1 and the development of water-polluting industries (e.g., oil reneries, textile and dyestuff factories, hospitals). 2 Biological (viruses, bacteria, and fungi), 3 mineral (nitrate, sulfate, and heavy metal), and organic contaminants (medicinal, dung, dyestuffs, oil, larvicides) are three major pollutants of water. Natural organic matter (NOM) causes an unpleasant odor, taste, and a change in the color of the water; in addition, this wide-ranging family prevents cation removal by forming complex compounds.…”

“…[5][6][7] As a subset of AOPs, photocatalysis is an eco-friendly approach for the degradation of organic pollutants in water that is based on the application of clean solar energy. 2,[7][8][9][10][11] In this approach, with regard to the exposure of the semiconductor to light with hn $ E g , electrons are excited from the valence band (VB) to the conduction band (CB), while an electron (e À )-hole (h + ) pair is photogenerated (i.e., a charge carrier). When the charge carriers have arrived at the surface of the photocatalyst, organic materials can be oxidized or reduced, and active superoxide (O 2 À ) or hydroxyl radical (cOH) and hydrogen peroxide (H 2 O 2 ) are produced.…”

Experimental study on silver nanoparticles: synthesis, photo-degradation and analysis

“…These nondecomposable textile dyes, which are around 15% (one thousand tons) per year are released into water bodies via textile waste effluents [2]. These compounds are highly toxic, carcinogenic, mutagenic and nonbiodegradable and are harmful for aquatic life and humans [3]. The coloring materials/dyes also absorb sunlight strongly, which slow down photosynthetic activity of aquatic plants, and threatening badly the entire ecosystem [4].…”