Advanced Materials Research Vols. 455-456

Abstract: A novel photo-electro-chemical catalytic reactor with single/double-tank was designed. TiO₂/Ti thin film electrode was used as photo-anodes, graphite as cathode and a saturated calomel electrode (SCE) as the reference electrode in the reactor. The efficiency of photo-electro-chemical catalysis was enhanced because the target pollutant was degraded not only titanium dioxide electrode in anodic tank, but also hydrogen peroxide through reducing dissolved oxygen with graphite electrode in catholyte. Malachite green (MG) and crystal violet (CV) were degradated effectively in these two reactors. The degradation efficiency of the double-tank reactor is superior to that of single-tank reactor and its apparent reaction rate constant is twice or more of than that of the single-tank reactor, which was result from the higher concentration of H₂O₂ in the double-tank reactor. In the single-tank reactor, H₂O₂ generated during cathodal reaction diffused to the anode and was consumed, while it could be prevented in the double-tank reactor. Under the conditions of cathodic potential E_c at-0.6V, initial solution pH at 3.0 and initial solution concentration 30 mg·L^-1, the catalytic degradation of MG and CV were both pseudo-first order reactions.

Abstract: The purpose of this paper is to investigate the effects of ionic liquids (ILs) oil-in-water emulsion on CO₂ absorption. 1-octyl-3-methylimidazolium hexafluorophosphate as ILs was dispersed into water forming oil-in-water emulsion to absorb carbon dioxide. Effects of dispersed phase volume fraction, droplet size, and the regeneration of dispersion were studied. Experimental results indicate that ILs oil-in-water emulsion can enhance the CO₂ absorption rate under lower dispersion phase volume fraction, and the CO₂ mass transfer rate increases with dispersion phase volume fraction. The smaller droplet size can help droplet go into the boundary layer to load CO₂ so as to increase the CO₂ mass transfer rate. ILs emulsion can be regenerated, but their enhancement effect becomes weaken with the increase of regeneration times.

Abstract: In this work, a new desulfurization process of high sulfur coal was designed and examined. The novel process involved pyrolysis of high sulfur coal at low temperature and then a dry magnetic separation. For testing the cleaning coal process, a Chinese high sulfur coal, Baisu coal was pyrolyzed in a fixed bed reactor from 400 to 700°C for 30min, and then separated by a dry magnetic separator. The results showed that under optimum conditions, a remarkable reduction of sulfur content in coal was achieved, and more importantly, almost all pyrite sulfur in coal was removed.

Abstract: Numerical simulation is used for researching the transient characteristic and internal characteristic of the reactor coolant pump under station blackout accident. The simulation method has been presented by analyzing difference scheme for governing equations. The analytical model of reactor coolant pump flow field has been established by analyzing adequately the influence of varying rotation speed to the pump external characteristic. Finally, the pump internal flow characteristic is exposed.

Abstract: Heap bioleaching is regarded as an environmental-friendly technology to extract valuable metals, such as gold, silver, copper, etc., from low grade or waste ores. The chemical reactions accelerated by microorganisms are usually complex. Microbial activity is ascribed to the physiochemical factors such as temperature. Due to the variety of ore components, the thermal effect is difficult to elaborate. In this study, typical ores used for heap bioleaching of chalcopyrite are theoretically analyzed to explore the mechanism involving the thermal effect of chemical reactions. The thermal distribution is compared between different proportional combinations. The results show that biotite is the dominant contributor and should be verified carefully in the heap bioleaching of chalcopyrite.

Abstract: The impact of different baffles on liquid homogenization in crystallization process were described. Compared with the flow field and velocity vectors of straight and curved baffles, it was found that the crystallizer with curved baffles can provide a more powerful driving force in the axial direction. And combined with the radial driving force provided by the disc turbine, dead zones at the bottom of blades were also eliminated. Due to its certain degree of twist, curved baffles can not only provide axial driving force, but it has broken the double circulation. Therefore, it made the flow field in crystallization reactor eventually distributed very well, eliminated the adhesion effect, and also made the axial flow in the crystallizer very significantly.

Abstract: A sequencing batch reactors (SBR) was adopted to investigate the denitrifying phosphorus removal efficiency employing nitrite as electron acceptor under anaerobic/anoxic condition. The experimental results showed that high nitrogen and phosphorus removal efficiency could be obtained under the following conditions: nitrite concentration of 30~40 mg/L, COD concentration of 400 mg/L, pH 8.0±0.2 in anaerobic stage and pH 7.2±0.2 in anoxic stage, sludge retention time (SRT) of 22 days. When the reactor performed steadily, a dominant functional strain was screened from the activated sludge, which has high nitrite and phosphorus removal efficiency. Batch tests results showed that the removal degree of nitrite and phosphorus could reach 99.18% and 84.94% respectively when their concentrations were 20mg/L and 10mg/L. according to the morphology and physio-biochemical characteristics, and the results of 16S rDNA sequencing, it is determined that the strain belongs to the Genus of Sphingobacterium. The experimental results achieved in this study might offer guidance to the development of shortcut denitrifying phosphorus removal process.

Abstract: This paper gives an experimental research on slightly contaminated raw water by utilizing the combined technology of electro-flotation and suspending TiO₂ photochemical catalysis. During the static experiment of degrading humic acid by electro-flotation—suspended TiO₂ photochemical catalysis, the ratio of COD_Mn removal reaches 87.8% in such conditions as two ultraviolet germicidal lamps of 10W, the voltage of 20V, the current of 0.4A, 0.5cm intervals of two groups of plates, the TiO₂ dosage of 1g/L and the reaction time of 150 minutes. The preferable synergistic effect can be achieved when combining electro-flotation and photocatalytic oxidation together.

Abstract: This paper studied on the treatment of urban domestic wastewater with Anaerobic MBBR in the tropical and subtropical areas in the South of China. The emphasis focused on the effects of the Hydraulic Retention Time (HRT) and pH value to the COD_Cr concentration and the NH3-N concentration of the outflow of the reactor. Moreover, the mechanism of denitrification was also explored. The results showed that the mechanism of denitrification of the reactor was found. When HRT was equal to or more than 8h, NH3-N was reduced mainly in the way of short-cut nitrification and denitrification. When HRT was less than 8h, the reactions of short-cut nitrification and denitrification & anaerobic ammonia oxidation both existed in the reactor.

Abstract: the effect of the interference between the diffuser vanes with the volute tongue was studied in this paper, based on the 3-d model of the residual heat removal pump and the numerical flow analysis platform developed with the commercial CFD software NUMECA. Results indicate that poor matching of the diffuser vanes and the volute may cause serious flow losses. The relative position between the diffuser vanes and the volute was optimized by numerical experiments. Final modifications indicate that the efficiency is increased by 6.4%.