To improve the electro-catalytic degradation efficiency of the cathode in electrochemical advanced oxidation processes , MnO 2 modified Nano-graphite (MnO 2 /Nano-G) and Pd loaded Foam-Ni (Foam-Ni/Pd) composites were prepared by the chemical redox and electro-deposition methods, respectively, and a two-layer type MnO 2 /Nano-G|Foam-Ni/Pd composite cathode was prepared with the chitosan as a binder. The composites were characterized by X-ray diffraction, scanning electrons microscopy and X-ray photoelectron spectroscopy. Results showed that the mix-crystal structural MnO 2 (α-MnO 2 and γ-MnO 2 ) nanorods with length of 80–200 nm and width of 20–50 nm were uniformly loaded on the Nano-G surface, and the three-dimensional Pd° metal trees/crystals were tightly deposited on the Foam-Ni substrate. The as-prepared cathode was applied to the electro-catalytic degradation of phenol wastewater, and the reaction parameters were optimized. Compared with MnO 2 /Nano-G|Foam-Ni and Nano-G|Foam-Ni cathodes, the degradation efficiency of phenol by MnO 2 /Nano-G|Foam-Ni/Pd cathode was significantly improved. The removal efficiencies of phenol and total organic carbon (TOC) by MnO 2 /Nano-G|Foam-Ni/Pd cathode reached 98.7% and 85.3% after 120 min electrolysis under oxygen aeration condition, respectively. The optimal reaction parameters were current density of 39 mA cm −2 , electrolyte (Na 2 SO 4 ) concentration of 0.1 mol L −1 , electrode distance of 4 cm and initial pH of 7. By determining the variations of H 2 O 2 and OH content in the cathode chamber, it was found that Pd metal crystals improved the reduction of O 2 to H 2 O 2 and MnO 2 nanorods accelerated the dissociation of H 2 O 2 to OH, producing more H 2 O 2 and OH to oxidize phenol and eliminate TOC in wastewater. The results in this study provide useful information for the control of refractory organic pollutants with electrochemical advanced oxidation in wastewater treatment .
Phenol is an important chemical that is widely used as a raw material in various industries. However, its high toxicity necessitates effective treatment of phenol-containing wastewater. In this study, membrane-based separation of a phenol/water solution was investigated. A simple and feasible method for tuning the solvent evaporation was developed to fabricate poly(ether-block-amide) copolymer (PEBA) membranes with enhanced separation performance. The solvent evaporation rates and temperatures of three different PEBAs were systematically regulated. PEBA1074, as a promising candidate, was studied using different characterization techniques, such as differential scanning calorimetry and scanning electron microscopy, to reveal changes in crystallinity and membrane structure under different solvent evaporation conditions. The results showed that a low solvent evaporation rate and high temperature favored the formation of a uniform membrane with an increased number of amorphous domains. A separation factor of 78 and a flux of 1.5 kg/(m2⸱h) were obtained at 80 °C for the separation of 1.5 wt% phenol/water solution. This separation performance is superior to those of previously reported PEBA membranes. This work provides a new and easy method to fabricate PEBA membranes with enhanced separation performance, which can promote the industrial application of pervaporative separation of phenol from wastewater.
Na Zhang,Jiaqi Bu,Yong Meng,Jia Wan,Lu Yuan,Xin Peng
In this study, Ti-Si-Sn-Sb/GAC particle electrodes were prepared by sol–gel method. The particle electrodes were characterized by SEM, XRD, EDX, and BET then used to carry out three-dimensional (3D) electrocatalytic oxidation degradation on simulated refractory p-aminophenol (PAP) wastewater. The effects of initial pH, cell voltage, aeration flow rate and initial PAP concentration on degradation experiments were investigated. Under the optimal conditions, the PAP and COD removal rates were 89.45% and 75.17% respectively. In addition, the possible degradation mechanism of PAP was further investigated by UV–Vis and HPLC. Finally, it was found that the Ti-Si-Sn-Sb/GAC particle electrodes with high catalytic activity and excellent stability could significantly improve the PAP wastewater removal efficiency.
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