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In this paper, boron-doped diamond (BDD) electro-activated persulfate was studied to decompose malachite green (MG). The degradation results indicate that the decolorization performance of MG for the BDD electro-activated persulfate (BDD-EAP) system is 3.37 times that of BDD electrochemical oxidation (BDD-EO) system, and BDD-EAP system also exhibited an enhanced total organic content (TOC) removal (2.2 times) compared with BDD-EO system. Besides, the degradation parameters such as persulfate concentration, current density, and pH were studied in detail. In a wider range of pH (2–10), the MG can be efficiently removed (>95%) in 0.02 M persulfate solution with a low current density of 1.7 mA/cm2 after 30 min. The BDD-EAP technology decomposes organic compounds without the diffusion limitation and avoids pH adjustment, which makes the EO treatment of organic wastewater more efficient and more economical.

In order to solve the problems of high energy consumption and low current efficiency in electrochemical oxidation (EO) degradation under the traditional constant output process (COP), a gradient output process (GOP) of current density is proposed in this paper. That is, the current density is gradually reduced in a fixed degradation time, and the Reactive Blue 19 simulated dye wastewater was used as the degradation target. The general applicability of the process was further confirmed by studying the optimal gradient current density output parameters, the dye concentration, electrolyte concentration and other dye compounds with different molecular structures. The corresponding results show that the chemical oxygen demand (COD) removal (78%) and the color removal (100%) under the GOP are similar to those in the COP, and the overall energy consumption is reduced by about 50% compared with that in the traditional constant current mode. Moreover, the current efficiency in the middle and late stages of EO process has increased by 8.6 times compared with COP.

Boron-doped diamond (BDD) is commonly considered as an excellent electrode material toward electrochemical oxidation, and its specific surface area is an important factor in determining its electrocatalytic performance. In this work, we have prepared three-dimensional (3D) BDD film material on the foamed Cu/W surface, denoted by Cu/W/BDD. A cone-shaped structure formed during the thermal treatment due to the phenomenon of BDD thermal weight loss, and thereafter the intermingled macro-micro structure of BDD was obtained. This intermingled 3D-BDD structure (3D-BDD1) has a high electrochemically active surface area, which is 7.9 times higher than that of 2D planar BDD structure (2D-BDD). The tetracycline hydrochloride (TCH) was chosen as the research benchmark to compare the performance difference of 3D intermingled structure and 2D planar structure. The TCH removal and the total organic carbon (TOC) removal by 3D-BDD1 is 1.51 times and 5.31 times than those by 2D-BDD, respectively. The electric energy of 2D-BDD and 3D-BDD1 needed to reduce the TOC concentration by 1 order of magnitude is 28.76 and 3.43 kWh m−3 order-1. The 2D-BDD consumed 7.95 times more energy per unit of TOC removal than the 3D-BDD1. In combination with fluid dynamics simulation, the fluid turbulence form of 3D structure and its disturbance to fluid flow are considered as the major reason responsible for the enhancement of degradation performance.

The boron-doped diamond (BDD) electrode, having ultra-high oxygen evolution potential and anodic stability, is potentially considered the ideal candidate for the next-generation ozone generator despite the relatively low current efficiency. In this work, we first report using a microporous BDD electrode etched by oxygen plasma, denoted as p-BDD, to improve the performance of electrochemical ozone generation. Two parameters, including O2 plasma etching temperature and time, are experimentally optimized. We demonstrated that the electrochemically active surface area (ECSA) of the optimal p-BDD is 2.51 times that of the bare BDD, and this p-BDD shows about one-quarter lower charge transfer resistance than the latter. Under the same unit energy consumption, the p-BDD has 3.76 times the ozone generation capacity compared to the latter. The p-BDD shows excellent long-term stability, only having 4.2% of the decrease in the current density up to 40 h of consecutive water electrolysis under the steady-state period, and it also remains a 100% recovery rate in its capability of electrochemical performance after mild treatment by cycling at a diluted sulfuric acid solution for 200 s

Cyanide-containing organic wastewater is discharged in large quantities by coking, electroplating and pharmaceutical industries, which seriously endangers environmental safety and human health. In this paper, Electrochemical Oxidation-Persulfate (EO-PS) Advanced Oxidation Process (AOP) was firstly used to treat high concentration cyanide-containing organic wastewater obtained from a chemical enterprise. The potential application of this process in the treatment of high concentration cyanide-containing organic wastewater was explored for the first time, and the effects of current density, initial pH, temperature and initial concentration on chemical oxygen demand (COD), total organic carbon (TOC) and total cyanide (CN−) removal in wastewater were systematically investigated. The results shown that the EO-PS process had an excellent removal effect on organics and cyanide in high concentration cyanide-containing organic wastewater which contained 11,290 mg L−1 COD, 4456 mg L−1 TOC and 1280.15 mg L−1 CN−. The COD, TOC and CN− removal at optimized operating parameters for 24 h were 95.8%, 87.8% and 98.4%, respectively. The corresponding electrical energy per order was only 41.6 kWh m−3 order−1. In addition, the pollutants removal can be accelerated under conditions of high current density, acidic solution, appropriate temperature and low pollutant concentration, among which low current density, low pH, appropriate temperature and low pollutant concentration can effectively diminish energy consumption. Cyanide, COD and TOC degradation in all reaction conditions followed the pseudo-first-order kinetic model.

The microstructure of boron doped diamond (BDD) is the main factor affecting its degradation performance, and the type of wastewater is also a major factor. In this paper, niobium based BDD electrodes were prepared by hot filament chemical vapor deposition (HFCVD) technology at 650 °C, 750 °C, 850 °C substrate temperatures. For the three BDD electrodes with different substrate temperatures, the comparison of electrochemical performance and degradation efficiency was conducted. The results showed that with the increase of deposition temperature, the microstructure of BDD electrodes surface changed, the grain size and boron content increased, and the sp3/sp2 phase ratio also increased, which caused the electrochemical oxidation performance of the BDD electrodes improved, the color removal rate of the electrodes increased, and the energy consumption reduced. The decolorization rates of the 850 °C-BDD electrode for Reactive orange X-GN and Reactive blue 19 at 180 min were 99.79 % and 93.38 %, respectively. In addition, the degradation performance of 8 dyes by 850 °C-BDD electrode was systematically studied. Affected by the molecular structure of dye, the degradation degree of each type of dye from easy to difficult was: Fuchsin acid, Reactive red 2, Acid orange G, Alizarin red, Acid blue 92, Reactive orange X-GN, Orange II, Reactive blue 19.

In this study, boron-doped diamond film (BDD) electrode with high sp3/sp2 ratio was prepared by hot filament chemical vapor deposition (HFCVD). A systemic electrochemical advanced oxidation processes (EAOPs) study was carried out by using BDD anode and three different supporting electrolyte (Na2SO4, NaCl, and Na2S2O8) to degrade the high volume and high concentration (0.5 L, 100 mg L-1) simulated anthraquinone Reactive Blue 19 (RB-19) dye wastewater. BDD-PS (persulfate) system was used to study the effects of current density, initial pH and solution temperature on decolorization degree and mineralization rate (TOC removal rate) by comparing with other two electrolytes (NaCl and Na2SO4). BDD activated PS could effectively degrade RB-19 in a large pH range (1.5-12), and higher degradation efficiency and lower energy consumption under strong acid and alkali conditions than traditional BDD-EO based on Na2SO4 and NaCl electrolytes. More interestingly, at the temperature of 70 ℃, the TOC removal reached 90% in 30 min and 100% in 60 min, which is apparently higher than that under NaCl and Na2SO4 as electrolytes. Our work indicates BDD-PS technology can effectively degrade organic wastewater, which has the characteristics of efficiently and better pH applicability, and more importantly which can decompose RB-19 with the aid of increase of temperature.

Boron-doped diamond (BDD) has been receiving growing attention in the field of electrochemical oxidation, but it faces the challenges of limited active area and low mass transfer. In this paper, we based on the principle of BDD thermal weight loss, to prepared an Si/BDD electrode with an irregular cone structure using a simple process. After heat treatment, the content of sp2 phase on the surface of BDD decreased, and the purity of sp3 phase increased. According to CV, the electrochemically active surface area of the electrode was increased by 3.9 times. In this paper, Tetracycline hydrochloride (TCH) was used as the target organic pollutant for degradation experiments. The TCH removal using BDD1 electrode was increased by 1.57 times compared with BDD0, and the TOC removal was increased by 1.74 times. The turbulence intensity distribution on the electrode surface was by calculated fluid dynamics (CFD) simulation. The working life of the electrode was measured by the accelerated life test (ALT). This paper provide a new and tunable route for preparing high degradation efficiency BDD electrode, and explored electrode life and turbulence intensity distribution of fluids on the electrode surface, which could potentially support the application of novel BDD anode.