Catalytic reduction of 4-nitrophenol on the surface of copper/copper oxide nanoparticles: a kinetics study
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ORIGINAL ARTICLE
Catalytic reduction of 4‑nitrophenol on the surface of copper/copper oxide nanoparticles: a kinetics study Mahdi Najafi1 · Saeid Azizian1 Received: 30 April 2020 / Accepted: 10 June 2020 © King Abdulaziz City for Science and Technology 2020
Abstract Metal and metal oxide nanoparticles are very suitable for catalytic activities in organic electron transfer processes. Among these, copper is one of the most important materials that have catalytic activity and the synthesis of copper/copper oxide nanoparticles ( Cu/Cu2 O NPs) is more cost-effective than other noble metals. In this study, a combination of copper nanoparticles with different degree of oxidation has been synthesized by electrochemical method. The efficiency of synthesized material for the catalytic reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride was studied. The morphology, particle size, and crystalline structure of the synthesized catalyst was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. The kinetics of reaction was followed by UV–Visible spectroscopy and the effect of different parameters such as initial concentrations of 4-nitrophenol, sodium borohydride and catalyst dosage on the reaction rate was studied. The recyclability of the prepared catalyst was investigated as well. The reaction order of the catalyst dosage was investigated by graphical analysis method. Finally based on Langmuir–Hinshelwood (L–H) mechanism the rate of reaction was modeled. Keywords Copper · Copper oxides · 4-nitrophenol · Sodium borohydride · Catalytic reduction · Nanoparticles
Introduction 4-nitrophenol (4-NP) is one of the most common phenolic compounds, which is highly toxic and hazardous (Fedorczyk et al. 2015; Dinesh and Saraswathi 2017). This pollutant is generally found in sewage from different industries including dye, medicines, paper, insecticide, etc. (Mane Gavade et al. 2016; Narkkun et al. 2019) factories. Therefore, it should be eliminated before release to the environment (Narkkun et al. 2019; Fadillah et al. 2019). Various methods have been developed to remove this pollutant from aqueous environments (Fadillah et al. 2019), including simultaneous nitrification and denitrification (Kulkarni 2013), electrochemical oxidation (Gu et al. 2010), photocatalytic degradation (Sahu et al. 2020a) and biodegradation (Paisio et al. 2014; Karlová et al. 2016). The mentioned methods may have low efficiency, slow rate or need special equipments (Dhorabe et al. 2016; Bhatia and Nath 2020). On the other hand, the * Saeid Azizian [email protected] 1
Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, 65167 Hamedan, Iran
reduction of 4-NP in the presence of catalyst is a fast and convenient method (Denrah and Sarkar 2019; Yang et al. 2014). 4-aminophenol (4-AP) is the product of 4-NP reduction in the presence of sodium borohydride (Wunder et al. 2010); this product can be used in anti-corrosion, beauty products, pharmaceuticals, and primary substances o
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