Original Research Paper Magnetically separable, bifunctional catalyst MgFe 2 O 4 obtained by epoxide mediated synthesis Vikash Kumar Tripathi, Rajamani Nagarajan ⇑ Materials Chemistry Group, Department of Chemistry, University of Delhi, Delhi 110007, India article info Article history: Received 18 November 2015 Received in revised form 23 February 2016 Accepted 18 April 2016 Available online 27 April 2016 Keywords: Sol–gel processes Spinel phases X-ray diffraction Oxidation Reduction abstract Epoxide mediated sol–gel synthesis of magnesium ferrite (MgFe 2 O 4 ) starting from MgCl 2 and Fe(NO 3 ) 3 has been carried out and the product has been subjected to various characterizations such as high reso- lution powder X-ray diffraction (PXRD), SEM, TEM and HR-TEM with EDX analysis, SAED measurements, FTIR, Raman and UV–visible spectroscopy techniques. Cubic spinel structure emerged on calcining the xerogel (for just 2 h) at temperatures as low as 500 °C with an average crystallite size of 8 nm. Heating xerogel at higher temperatures (700 and 900 °C for the same duration) yielded products with average crystallite size of 27 and 41 nm, respectively. The existence of Mg 2+ , Fe 2+ and Fe 3+ in tetrahedral and octa- hedral sites of the spinel structure have been evidenced from the presence of bands at 211, 322, 470, 541 and 701 cm À1 in the Raman spectrum of the sample. Optical band gap of 1.94 eV has been deduced from UV–visible spectroscopic analysis. MgFe 2 O 4 (obtained at 900 °C) showed a typical super paramagnetic behavior with a saturation magnetization of 22.021 emu/g at room temperature. It showed BET surface area of 21.28 m 2 /g with an average pore size of 12.19 nm. It was demonstrated to be an efficient catalyst for the oxidation of Xylenol Orange (XO) dye and the reduction of p-nitrophenol to p-aminophenol. Ó 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. 1. Introduction The technological capabilities offered by the spinel structured oxides have invited extensive investigations from fundamental synthetic aspects to advanced applications for the development of functional devices [1]. Magnesium ferrite, MgFe 2 O 4 , is an impor- tant member of the spinel family as it is a soft magnetic n-type semiconductor finding extensive use in catalysis, adsorption, sen- sor, medical field and as oil paint [2–12]. It is a widely accepted fact that the cation distribution in MgFe 2 O 4 is strongly dependent on the followed synthetic approach as well as the various optimiza- tion parameters employed. Apart from the traditional heat and beat approach, MgFe 2 O 4 has been synthesized by co- precipitation, sol–gel, micro-emulsion process, sonochemical, mechano-chemical, molten salt and combustion synthesis routes [13–22]. They have been proved to be quite advantageous in reduc- ing the calcination temperature and in turn prevent agglomeration of crystallites to a larger extent. Among several physical and chemical routes, molecular precursors are excellent starting materials for the formation of nanostructured oxides where the single entity can act as a building block for the controlled formation of specific nanostructures. The molecule to material approach has the advantage of capturing the kinetically stable phases which are otherwise inaccessible as it is a bottom up approach [23]. Sol–gel method, involving hetero- bimetallic alkoxides or their derivatives with other ligands, has been demonstrated to produce mixed metal oxides of high purity and homogeneity requiring very low calcination temperatures [24–27]. Limitations of this method include the stringent handling conditions of air and moisture sensitive precursors which are expensive. Also, in many cases, the unavailability of stable and suitable precursors for the mixed metal ions in the desired stoi- chiometry coerced researchers to explore for alternate ways of conducting the sol–gel process. Other problem associated with the sol–gel synthesis from alkoxide mixture is the different hydrol- ysis susceptibilities of the individual components leading to com- ponent segregation and mixed phases in the final materials. To achieve homogeneous mixed oxides with predetermined composi- tions, the difference in reactivity has been minimized by many ways such as controlled prehydrolysis of the less reactive precur- sor, by chemical modification of the precursors, by using single- source heterobimetallic alkoxide precursors, or by non-hydrolytic sol–gel processes. Non-alkoxide sol–gel process, involving http://dx.doi.org/10.1016/j.apt.2016.04.013 0921-8831/Ó 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. ⇑ Corresponding author. E-mail address: rnagarajan@chemistry.du.ac.in (R. Nagarajan). Advanced Powder Technology 27 (2016) 1251–1256 Contents lists available at ScienceDirect Advanced Powder Technology journal homepage: www.elsevier.com/locate/apt