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Synthesis of Hedgehog-like F-TiO2(B)/CNT Nanocomposites for Sonophotocatalytic and Photocatalytic Degradation of Malachite Green (MG) under Visible Light: Kinetic Study Yasaman Panahian, and Nasser Arsalani J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.7b02580 • Publication Date (Web): 10 Jul 2017 Downloaded from http://pubs.acs.org on July 12, 2017

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The Journal of Physical Chemistry

Synthesis

of

Hedgehog-like

F-TiO2(B)/CNT

Nanocomposites

for

Sonophotocatalytic and Photocatalytic Degradation of Malachite Green (MG) under Visible Light: Kinetic Study Yasaman Panahian, Nasser Arsalani* [email protected], [email protected]

Research Laboratory of Polymer, Department of Organic and Biochemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran

1 ACS Paragon Plus Environment


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Abstract The present study describes the preparation of hedgehog-like F-doped titanium dioxide bronze (FTiO2(B)) and its nanocomposites containing single walled and multi walled carbon nanotubes (SWCNT, MWCNT) by using combined ball milling – hydrothermal processes. Then, sonophotocatalytic and photocatalytic degradation of malachite green (MG) dye from aqueous solution using prepared materials was performed. The results show that F-TiO2(B)/SWCNT displays a good sonophotocatalytic and photocatalytic performance among other products under visible light. In addition, they indicated that the efficiency of malachite green degradation is more than 95% and 91% for sonophotocatalytic and photocatalytic, respectively. Also, they demonstrate that the photocatalytic efficiency of catalysts increases in the presence of ultrasound and the sonophotocatalysis process followed a second-order kinetics. The catalysts have been characterized by transmission electron microscopy (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The analyzed data confirmed the presence of CNTs and Fluorine (F) as dopant in all nanocomposites. The presented hybrid method reduce band gap from 3.02 for F-TiO2(B) to 2.7 ev for F-TiO2(B)/SWCNT nanocomposite.


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1. Introduction Having potential application in paper, leather, cosmetics, plastics, clothing, drugs, electronics, and printing industries, dyes are the major class of organic pollutants 1-4. Wastewaters discharged from these industries containing dyes cause critical environmental problems. Hence, it is important to explore an effective method of the wastewater treatment to remove dyes from industrial waste streams before they are delivered to the environment 5-7. In recent years, different technologies such as biological, adsorption, membrane, coagulation– flocculation and advanced oxidation processes (AOPs) 8,9 have been employed to decontaminate dye traces from wastewater. Between these possible technologies, advanced oxidation processes (AOPs) (like heterogeneous photocatalysis, ozonization, sonolysis, radiolysis, or Fenton - like processes) have been considered as the most feasible techniques for the removal of most pollutants from the contaminated water due to their low cost and high effectiveness for the removal of the resistant organic pollutants 10-12. Among AOPs, heterogeneous photocatalysis via combination of TiO2, visible light and ultrasound as one of the effective technologies are very appealing for wastewater treatment 13. The literature reported that the combining AOPs from photocatalytic and other techniques particularly for the wastewater treatment have recently been considered as an effective technology 14,15. Nowadays the combination of photocatalytic and ultrasonic irradiation, i.e. the so-called sonophotocatalysis has received considerable attention among scientists due to its synergistic effect on the photodegradation

16

. Actually, sonophotocatalysis mentions the simultaneous

application of ultrasound and light in a system containing an oxide semiconducting materials, such as TiO2, ZnO and CdS 17.



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Among the numerous oxide semiconducting materials, titanium (IV) dioxide (TiO2) has been identified as an excellent material for photocatalytic reaction because of its non-toxicity properties, low cost, strong oxidizing power, availability and long-term photostability 18-22. But owing to the large energy band gap of TiO2 (Eg= 3.2 eV), it can be activated only by ultraviolet (λ < 380 nm) and this point limits its practical applications. One way to solve this problem is developing modified TiO2 with higher visible-light-driven (VLD) photocatalytic ability by doping such as different atoms and combination of different carbonaceous nanomaterials such as carbon nanotubes (CNTs) activated carbon, graphene and fullerene 23-27. To the best of our knowledge, there has been no study conducted until now for the sonophotocatalytic degradation of malachite green dye on F-TiO2(B) and F-TiO2(B)/CNT nanocomposites under visible light, and its kinetic study. So, in this study, for the first time we have designed and synthesized F-doped titanium dioxide bronze /carbon nanotubes composites, by using appropriate methods that combine ball milling – hydrothermal. Also, studying their photocatalytic and sonophotocatalytic degradation properties on malachite green degradations under visible light is performed and kinetic study is characterized as well.


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2. Experimental section 2.1. Materials Malachite green (MG), a commercial dye (Boyakhsaz Co, Iran), was chosen as the model compound. The structure and other characteristics of this dye were presented in table 1. TTIP (titanium tetra isopropoxide) was produced by Merck with the purity of 98 wt%, for use as a precursor. The SWCNT (single‑walled carbon nanotube) (diameter 1–2 nm) and MWCNT (multi ‑walled carbon nanotube) (diameter

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