Content area
Full text
INTRODUCTION
Dyes are important industrial materials widely used in many fields such as leather, textile, plastics and paper (Wang et al. 2015). However, dye wastewaters feature high toxicity. The widespread disposal of dye wastewaters has caused serious contamination in many countries and has led to health risks to human life (Chaleshtori et al. 2013; Zhang et al. 2015). To eliminate the pollution, dye wastewaters must be treated to remove toxic constituents before disposal.
Shown in Figure 1 is the molecular structure of bromocresol green (BCG), one of the most commonly used triphenylmethane dyes, with three benzene rings that are difficult to degrade (Nezamzadeh-Ejhieh & Moazzeni 2013). Up to now, some conventional treatment methods such as photocatalysis and adsorption procedures have been adopted to removal of BCG wastewater (Ghaedi et al. 2012; Zarei-Chaleshtori et al. 2014). However, the photocatalysis method requires high investment costs, and the adsorption method is not always sufficient to achieve the discharge limits. Therefore, looking for some environment-friendly methods with high BCG removal efficiency is always a crucial and glamorous task.
Caption: Figure 1: Molecular structure of BCG.
Electrochemical oxidation methods include electro-fenton, electrocoagulation and electrocatalytic, etc. Compared with the traditional methods of wastewater degradation, electrochemical oxidation offers higher efficiency and environmental compatibility (Brillas & Martínez-Huitle 2015). It has been widely applied in electrolysis industries and the degradation of organic wastewaters, especially electrocatalytic on a dimensionally stable anode (DSA) (Labiadh et al. 2016). The commonly used DSAs include Ti/RuO2, Ti/IrO2, Ti/PbO2, Ti/TiOxHy/Sb-SnO2 and Ti/SnO2-RuO2 electrodes (Giraldo et al. 2015; Santos et al. 2015; Akbarpour et al. 2016; Dai et al. 2016; Li et al. 2016). Among these electrodes, the Ti/SnO2-RuO2 electrode has attracted great interest because of its low cost, easy preparation and high cost-efficiency (Zhao et al. 2013a).
In this work, a Ti/SnO2-RuO2 electrode was prepared successfully and the degradation process of BCG was investigated in detail. The electrode morphology, crystal structure and element analysis were investigated by scanning electron microscopy, X-ray diffractometer and X-ray fluorescence spectrometer, respectively. The optimal removal efficiency of BCG reached over 90%. The work demonstrated that BCG was degraded effectively on a Ti/SnO2-RuO2 electrode.
METHODS
Reagents and materials
BCG, NaCl, Na2SO4, NaOH, C2H2O4·2H2O, H2SO4, HCl, C2H5OH, C3H7OH, C3H6O, SnCl2·2H2O, RuCl3·3H2O, Ag2SO4, K2Cr2O7, FeSO4·7H2O, (NH4)2Fe(SO4)2·6H2O and C12H8N2·H2O...