A novel magnetic reusable nanocomposite with enhanced photocatalytic activities for dye degradationby Tina Harifi, Majid Montazer

Separation and Purification Technology


Filtration and Separation / Analytical Chemistry


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Accepted Manuscript

A novel magnetic reusable nanocomposite with enhanced photocatalytic activities for dye degradation

Tina Harifi, Majid Montazer

PII: S1383-5866(14)00390-6

DOI: http://dx.doi.org/10.1016/j.seppur.2014.06.042

Reference: SEPPUR 11842

To appear in: Separation and Purification Technology

Received Date: 22 March 2014

Revised Date: 27 June 2014

Accepted Date: 28 June 2014

Please cite this article as: T. Harifi, M. Montazer, A novel magnetic reusable nanocomposite with enhanced photocatalytic activities for dye degradation, Separation and Purification Technology (2014), doi: http://dx.doi.org/ 10.1016/j.seppur.2014.06.042

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A novel magnetic reusable nanocomposite with enhanced photocatalytic activities for dye degradation

Tina Harifia and Majid Montazera* a Department of Textile Engineering, Functional Fibrous Structures & Environmental

Enhancement (FFSEE), Amirkabir University of Technology, Tehran, Iran *Corresponding author: Majid Montazer, Textile department, Amirkabir University of

Technology, Functional Fibrous Structures & Environmental Enhancement (FFSEE), Hafez

Avenue, Tehran, Iran

Email: tex5mm@aut.ac.ir

Phone: 009821 64542657

Fax: 009821 66400245 2


In this research, a magnetically separable Fe3O4 loaded TiO2 nanocomposite with enhanced photocatalytic activity was synthesized through a novel simple strategy. The proposed method benefits from simplicity and involves no multi steps or high temperature. Scanning electron microscopy, x-ray diffraction, transmittance electron microscopy, energy dispersive x-ray spectroscopy, nitrogen adsorption-desorption isotherms, vibrating sample magnetometry and

Mossbauer spectroscopy were performed to investigate the properties of the prepared magnetic photocatalyst. Moreover, the photocatalytic efficiency of the prepared nanocatalyst was evaluated with decomposition of Methylene Blue under UV light illumination. One factor response surface methodology was applied to study the influence of Fe2+/TiO2 molar ratio in the prepared nanocomposite. The results suggested the potential of the proposed facile method in producing a nanocatalyst with high dye photodegradability and no adverse effects on the aquatic environment. The prepared nanocomposite indicated excellent photodegradation of Methylene

Blue, 1.6 times superior to nano TiO2 Degussa P25. Due to the existence of magnetite particles on the surface of TiO2, the transferred charge carriers are accessible to the oxidants or reductants and initiate the redox reactions. Fe3O4 nanoparticles may retard the electron-hole recombination rate evidenced by photoluminescence spectroscopy. Moreover, repeated usage of the photocatalyst proved its liability to be collected and reused.

Keywords: Fe3O4 loaded TiO2 nanocomposite; Magnetically separable; Photocatalytic efficiency; Response surface methodology; Reusability. 3 1. Introduction

With the advent of nanomaterials and their various applications, there have been many efforts overcoming their associated drawbacks [1]. Nanocomposites with different functionalities are attractive candidates for high performance nanomaterials [2].

It is important to avoid the propagation of nanoparticulate contamination into the aquatic environment and effective methods are required to remediate nanoparticles environmental problems [3]. TiO2 nanoparticles have fascinated researchers for their great efficiency in photocatalytic processes [4-14], however, recollecting such nanomaterials from wastewater involves difficulties restricted their performance [15, 16]. The existence of nano TiO2 in suspension after photocatalytic reaction threatens the environment and poses risk to human health [17]. Filtration, centrifuge and immobilization of nanoparticles on supported materials are some of the suggested solutions that require additional separation step and further expenses [18].

The idea of using magnetic force, as a long-range attraction, for nanoparticles separation has been widely investigated [19-23]. Magnetic separation is a convenient approach capable of purifying a large amount of wastewater within a short time [24]. Attempts have been made to impart magnetic property into nanomaterials removing them by use of external magnetic field, preventing effluent contamination and damage to the environment [25-29].

Iron oxides, such as maghemite (γ-Fe2O3) and magnetite (Fe3O4), are the most useful materials with ferromagnetism [30, 31]. Superiority of nanostructured iron oxides to their bulk is due to the higher surface area, better distribution and higher rate of reactivity [32]. Different methods have been proposed for preparing iron oxides and magnetic nanomaterials with iron oxides incorporation [33, 34], among which co-precipitation is the most convenient and low-cost method [35-39]. 4

Coating of magnetite by titania has been investigated, aiming at modifying different properties of the applied materials obtaining some required specifications [16, 40]. TiO2/Fe3O4 nanocomposite with photocatalytic activity and magnetic property has been synthesized in previous studies [25, 26, 28, 29]. Preparing the composite particles with photocatalytic efficiency comparable to the manufactured TiO2 along with magnetism at a high level is dependent on many factors such as molar ratio of TiO2 to Fe3O4 and the preparation technique [28, 41]. A SiO2 membrane was effectively added between Fe3O4 core and TiO2 shell to reduce the adverse effects of Fe3O4 on the photocatalytic activity of TiO2 [16, 25]. Loading silver on TiO2/SiO2/Fe3O4 composite was also efficient in enhancing the photocatalytic activity [16]. A new sonochemical method for the synthesis of Fe3O4/TiO2 photocatalyst as an effective and conveniently recyclable nanomaterial has been recently reported [42]. Mesoporous Fe2O3-doped TiO2 fibers with high photocatalytic activity towards decomposition of methylene blue have been prepared [43]. A novel magnetic