Papers by Keyword: Hydroxyl Radical

Abstract: Indium gallium arsenide (InGaAs) is one of the candidate materials to overcome the physical limitation of Si due to its excellent electrical properties. The effect of surface oxidation on the etching characteristics of InGaAs surface in acidic solutions were investigated. InGaAs surfaces was etched in HCl/H₂O₂/H₂O (CPM) and HNO₃/H₂O₂/H₂O (NPM), while there was no thickness change in diluted HCl or HNO₃. The CPM-treated InGaAs surface had a lower etching rate than the NPM-treated one, while etching rate of oxidized layer was higher in diluted HCl than in HNO₃. NaCl added in the NPM acts as an etching inhibitor for InGaAs and the etching rate was significantly suppressed. It is thought that Cl⁻ anion inhibits the formation of hydroxyl radical (OH∙) or consumes OH∙ in acidic solution, inhibiting surface oxidation of InGaAs and suppressing its material loss.

Abstract: MnO_x/wasted rock dust catalyst (WZ01) and modified wasted rock dust catalyst (WZ02) were prepared by impregnation method and hydrothermal method as the wasted rock dust (WRD) generated in stone processing plants was used as carriers. The structure of the two catalysts were characterized by energy dispersive spectrometer (EDS), X-ray diffraction (XRD), N₂ adsorption-desorption, scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). Their removal efficiencies and reaction mechanisms of oxalic acid were compared and analyzed, which could provide an innovative perspective for catalytic efficiency improvement and cost reduction. The results showed that the WRD contained O, Si, Al, K, Mg, Fe, Ca and Na elements. Mn was amorphous in WZ01 and loaded on the surface of WRD, and Mn was in the form of orthorhombic Mn₂O₃ in WZ02. WZ02's surface morphology showed obvious changes and was wrinkled with many microchannels. The specific surface area, total pore volume and average pore size of WZ02 had been improved. After 30 minutes of reaction at room temperature, the removal efficiencies of oxalic acid with an initial concentration of 500 mg·L^-1 were 40.6% and 54.6% by using WZ01 and WZ02 as catalysts with catalyst dosages of 2 g·L^-1 and O₃ concentration of 4.92 mg·L^-1, respectively. The removal efficiency of oxalic acid decreased greatly after WZ01 recycling and Mn, which acted as active components, was massively washed out. The removal efficiency of oxalic acid was stable after WZ02 was triply recycled as only a small amount of Mn was washed out. The removal efficiency of oxalic acid reduced after tert butanol was introduced into the two reaction systems, and a large amount of •OH was detected by using coumarin fluorescence technology. The removal of oxalic acid by WZ01 and WZ02 catalyzed ozonation were achieved by the combination of adsorption and hydroxyl radical reaction.

Abstract: In this study, template method was applied to synthesize CdS hollow nanospheres via sonochemical method. The morphology, size of the nanospheres and crystal structure of the synthesized hollow CdS were characterized. The results showed that the hollow CdS nanospheres formed have pure cubic sphalerite structure and exhibit good monodispersity and size uniformity. The photocatalytic activity of the samples was evaluated by the decoloration of Rhodamine B (RhB), Methylene Blue (MB) and Methyl Orange (MO) aqueous solution under UV-vis light irradiation. The results indicated the hollow CdS had a good photocatalytic activity and show little selectivity of attack and are able to oxidize various organic pollutants. Moreover, the results of hydroxyl radical (^•OH) detection using fluorescent probe method was in accordance with the RhB decolorization efficiency, which the ^•OH is likely to be the main active species responsible for dye degradation.

Abstract: The 1.5t/h algae and bacteria wastewater with high concentration was treated by hydroxyl radical (OH) produced by a strong ionization discharge. In this paper, the feasibility of kill bacteria and alga by OH was investigated, and effects of OH concentration, treatment time and pollution initial concentration on degrading microorganisms by OH were investigated in detail. The results indicated that the treatment process was effective in the degradation of the bacteria and alga at the initial pH value of 7.1, OH dosage of 2.33mg/L, the initial microcystis aeruginosa concentration of 10⁶/mL and the initial bacterial dosage of 10⁶cfu/mL, the bacteria and alga degradation rate reached 99.99% at 303K after 15min treatment. The results provided a theoretical basis for the OH treatment of microbial contamination in drinking water in large-scale.

Abstract: In this article,Cordyceps militaris,that from Hubei and Yunnan,were used as the research objects, to extract seleno-polysaccharide ,then the antioxidant activity of seleno-polysaccharide were determined by reducing power,the scavenging capacity on superoxide anion radical and hydroxyl radical.The results indicated that,the content of selenium in Hubei and Yunnan Cordyceps militaris samples were 210.0μg/g and 57.5μg/g,respectively;the share of Se-polysaccharide in total selenium were 11.086% and 26.713%,respectively,lower degree to turn the selenium organic in Hubei Cordyceps militaris.The reducing power of seleno-polysaccharide from Hubei and Yunnan Cordyceps militaris were 0.0253,0.0297,respectively;two kinds of Cordyceps militaris have certain ability to remove superoxide anion radical and different between them,the seleno-polysaccharide of Yunnan Cordyceps militaris has a better effect to remove superoxide anion radical under different sample amount.About hydroxyl radical,there were no ability to remove it.

Abstract: Oxidative degradation of ethylenediaminetetraacetic acid in aqueous solution at normal temperature and pressure by the bimetallic Fe-Cu, which was verified by ESR spectroscopy, was investigated. The results showed that the removal efficiency of EDTA, TOC and TN could be about 99%, 60% and 39% respectively after 3h reaction. The degradation products were iminodiacetate, formate and acetate. The effects of initial pH, concentration of EDTA, Cu content and Fe-Cu loading were also investigated. Significantly, the bimetallic Fe-Cu process exhibited higher reactivity than monometallic Fe⁰ process for the degradation of EDTA and it would not cause new heavy metal pollution in effluent.

Abstract: Chemical Oxygen Demand (COD) is an much important key water quality parameter . In view of the technical defects of existing detection methods and monitoring instruments for measuring COD, a new detection method based on ultrasonic assisted sample digestion and spectrum analysis was put forward in this paper, and the automatic monitoring system prototype based on such detection method had been developped. Aiming at environmental water samples, the spot experiment had been carried out to contrast prototype with Chinas national standard analysis method for measuring COD, and the results showed that the automatic monitoring instrument prototype had good repeatability (10%) and high accuracy (±10%), which met the technical qualifications of Chinas envirormental protection industry standards.

Abstract: The chemical oxygen demand was over standard seriously due to residual organic additives in sulfonated drilling wastewater, especially sulfonated phenolic resin with hardly degradable chemical structure. The novel solar-assisted catalytic oxidation process was developed to remove the organic pollutants in sulfonated drilling wastewater. The factors including irradiation light source, oxidant, Fe²⁺, were investigated. The results showed that, solar has more catalytic effects than UV on H₂O₂-K₂S₂O₈/Fe²⁺ system, H₂O₂- K₂S₂O₈/Fe²⁺ system was more effective in degrading organic pollutants than H₂O₂/Fe²⁺ and K₂S₂O₈/Fe²⁺, in which the synergies occurred between H₂O₂ and K₂S₂O₈ in the solar-assisted catalytic oxidation process. The removal amount of organic pollutants was increased with the dosage of Fe²⁺ additon. With the catalytic oxidation process developed, the COD was reduced to 114.4 mg·L^-1. Meanwhile, the sulfonated phenolic resin was completely destroyed, and heavy metal was decreased significantly.

Abstract: Advanced treatment of biochemical treated coking wastewater was studied experimentally with ozonation process. The effects of initial pH value, ozone concentration, reaction temperature, and reaction time on the COD and color removal rate were investigated. The results showed that ozonation was an effective method for advanced treatment of biochemical treated coking wastewater. The increasing of initial pH value, ozone concentration, reaction temperature, and reaction time has enhanced the removal rate of COD and color. Meanwhile, the results also revealed that the maximal COD and color removal rate of 69.65% and 92.27% could be reached under the optimal conditions of the initial pH value is 10.5, ozone concentration is 150 mg/L, reaction temperature is 298 K, and reaction time is 30 min.

Abstract: Oxidative degradation of ethylenediaminetetraacetic acid(EDTA) in aqueous solution at normal temperature and pressure by the novel bimetallic Al-Fe was investigated. The results showed that the removal efficiency of EDTA, TOC and TN could be about 98%, 75% and 47% respectively after 3h reaction. The effects of initial pH, concentration of EDTA, mass ratio of Al⁰ and Fe⁰ and Al-Fe loading were also investigated. Significantly, the bimetallic Al-Fe process exhibited higher reactivity than monometallic Fe⁰/Al⁰ process for the degradation of EDTA.