Catalytic wet peroxide oxidation of phenol solution over Fe–Mn binary oxides diatomite composite Bui Hai Dang Son 1 • Vo Quang Mai 2 • Dang Xuan Du 2 • Nguyen Hai Phong 1 • Nguyen Duc Cuong 3 • Dinh Quang Khieu 1 Ó Springer Science+Business Media New York 2016 Abstract Mn–Fe binary oxides incorporated into diato- mite (denoted as FM-diatomite) was prepared by the redox reaction of KMnO 4 and FeSO 4 with pH ranging from 3 to 9. The catalytic activities of FM-diatomite were studied for phenol oxidation and were compared with iron oxide modified diatomite (F-diatomite) and manganese oxide modified diatomite (M-diatomite). The obtained catalysts were characterized by scanning electron microscope, powder X-ray diffraction, energy dispersive spectroscopy, transmission electron microscope, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption iso- therms. The results show that Fe–Mn binary oxides were highly dispersed on the diatomite surface in which man- ganese oxide and iron oxide displayed multiple oxidation states including Mn 4? , Mn 3? , Fe 2? and Fe 3? . The phenol oxidation by H 2 O 2 through the use of Mn–Fe-diatomite as a catalyst was conducted. FM-diatomite exhibited as an excellent catalyst for the total oxidation of phenol and main intermediates (catechol and hydroquinone). The conversion of phenol and main intermediates by means of FM-di- atomite was 100 % under 50 min while that by F-diatomite also was 100 % after 110 min but other intermediates still remained. While phenol conversion by M-diatomite was close to zero due to speedy hydroperoxide decomposition over the manganese oxide catalyst. These results show that there was a synergized effect of iron and manganese oxide present in FM-diatomite. Keywords Diatomite  Fe–Mn binary oxides  Catalysis  Catechol  Hydroquinone 1 Introduction Much wastewater in the chemical processing industry con- tains high concentrations of organic materials which are difficult to be oxidized biologically [1]. Phenol and phenol derivatives are among most abundant organic pollutants, which are toxic even at low concentrations and resistant to biodegradation [2]. Several processes, used for treatment, have been applied efficiently to the degradation of phenol derivatives. The biological processes have widely been used to oxidize the poisonous stream entirely, since the present microorganisms are fully adapted to its concentration and toxicity. However, outflows containing phenol compounds in high concentrations can be inadequate to the biological treatment [3]. Catalytic Wet Air Oxidation (CWAO) is an efficient and promising oxidative pollution removal process that has been proved successful in the research on wastewater treatment. However, the CWAO usually requires rather critical conditions including high pressure and temperature, and the implementation of this technology is not cost-ef- fective [4]. The process of catalytic wet peroxide oxidation (CWPO) has provided an alternative for the treatment of wastewater with high-poisonous organic compounds. Hydrogen peroxide is a strong oxidant (E 0 = 0.87–1.80 V) [5] and it does not produce harmful by-products and, there- fore, is a non-toxic and ecologically friendly oxidant. Wang et al. [6] reported that Schwertmannite (Sch), an Fe(III)- oxyhydroxysulfate mineral, exhibited as a catalyst of CWPO & Dinh Quang Khieu dqkhieu@hueuni.edu.vn 1 College of Science, Hue University, No. 77, Nguyen Hue, Phu Nhuan Ward, Hue City, Vietnam 2 Faculty of Natural Science, Saigon University, 273 An Duong Vuong, Ho Chi Minh City, Vietnam 3 Faculty of Hospitality and Tourism, Hue University, 22 Lam Hoang, Hue City, Vietnam 123 J Porous Mater DOI 10.1007/s10934-016-0296-7