Cheng Deng

Pollutant and microorganism removal from water by hydrodynamic cavitation

Hydrodynamic cavitation can effectively remove organic pollutants and microorganisms from water. Organic compound degradation and water disinfection removal rate is related to reaction time and operating temperature. Removal rate can be improved by increasing the reaction time or raising the operating temperature. Under our experimental conditions, the removal rate of colority, COD and petroleum pollutants was 80.0%, 72.13% and 70.00%, respectively. In addition, Escherichia coli removal rate was higher than 99.99%. As a new water treatment process, hydrodynamic cavitation can be utilized alone or in combination with other water treatment processes, showing broad application prospects.

Evolution of Composition and Structure of Poly[(alkylamino)borazine] to Boron Nitride Ceramic during Pyrolysis Process

Boron nitride (BN) was prepared by polymer-derived method using precursor poly [(alkylamino) borazin (PABZ). The evolution of composition and structure of precursor PABZ into BN ceramic during curing and pyrolysis process was investigated by FTIR, TG, XRD techniques and chemical analysis. The results showed that PABZ could fulfill curing heated at 80°C for 2hrs in NH3 atmosphere. During the curing process the both transamination reaction and condensation reaction occurred, resulting in cross-link between monomer molecular. With the proceeding of curing process, the new B-N bonds were formed and continued to expand in three dimensions. After cured treatment the thermal pyrolysis of PABZ in ammonia atmosphere was took place, and inorganic degree and crystallinity of products were better, which was more suitable for preparation of high purity hexagonal BN (h-BN) ceramic.

Structure Evaluation and Microbial Biomass Determining of Biological Activated Carbon

To investigate the microorganisms growth process and biostability of biological activated carbon by manual preparation, the microorganisms growth process were observed by the photos of optics and electronic microscope, and the microbial biomass was determined by phospholipids (Lipid-P) analysis. The bell bug, rotifer and eelworm were observed by the photos of optics and electronic microscope. The zoogloea size of the foster biological active carbon was big, the configuration was tight. The quantity of zoogloea on the top of BAC column was more than that on the below. The Lipid-P biomass of BAC on the top and below were 16nmolP/cm3 and 6.2nmolP/cm3 respectively, as same as that was the number of E. Coli cells were 1.6×109cfu/cm3 and 6.2×108cfu/cm3 respectively in 60-days. The Lipid-P biomass decreased to 90 days. The biological activated carbon was obtained by manual culture.

The Design of Dissolved Oxygen Detection System Based on C8051F020

A design of detection system about dissolved oxygen is proposed based on C8051F020 which is an integrated mixed-signal system-on-chip MCU. It can quickly and accurately detect Dissolved Oxygen (DO) in the water. The software adopts Multi-sensor data fusion and temperature compensation to eLiminate the effects of temperature and the sensor itself, enhance the measurement precision. And serial communication of RS232 is used in this system which can sent data to upper PC. The system is of high practicabiLity.

Numerical Simulation of Ozone Oxidation on Oily Wastewater

A simulation method was presented based on the theory analysis and ozone reaction equation. The preliminary mathematical models of ozonation correlative to oily pollutant removal were set up by numerical simulation. The ozonation models implied removal ratio of oil related to reaction time, ozone dosage and initial oil content. The simulation results were consistent with the experimental data.

Study on Antibacterial Efficacy and Catalytic Capability of Nanocrystalline Magnesia

Abstract: Objective: To study the antibacterial efficacy and the catalytic capability of nanocrystalline magnesia powder(nano-MgO). Methods: The antibacterial efficacy was evaluated in Bacteriostatic circle and the shake flask test and the catalytic capability was evaluated by paraoxon. Results: The nano-MgO had good antibacterial efficacy and highly catalytic capability. The catalytic capability was not influenced by light. When 50mL 20μg/L paraoxon solution was catalyzed by 0.5g nano-MgO for 5min, the disappearance of paraoxon was about 77.9%, and for 60min, the disappearances of them was 99.6％. Conclusion：The nano-MgO had good antibacterial efficacy and highly catalytic capability. Key words: nanocrystalline magnesia , antibacterial efficacy, paraoxon, catalytic degradation

Preparation and Characterisation of Polyborazine as Novel Precursor to Boron Nitride Ceramic

A processable polyborazine precursor was synthesized via substitution reaction and deamine condensation reaction by using methylamine, propylamine and B-trichloroborazine (TCB) as the starting materials. The chemical composition, structure and properties of the obtained polymer were investigated using element analysis, FT-IR, NMR, XPS and TG. The results indicated that the backbone of the polymer was approximate linear arrangement of boron-nitride ring molecules with B-N(CH3)-B structure as bridge bond, meanwhile minor amount of methylamino and propylamino remained in polyborazine as the pendant or end group. The melting point, number average molecular weight and polydispersity index of polyborazine was 90°С , 1002 and 1.355, respectively. The polyborazine showed good processability and polyborazine precursor fibers with diameter of 10~15 µm could be obtained by melt-spinning in N2 atmosphere. The ceramic yield of the polyborazine at 1000°С in nitrogen atmosphere was 53.2 wt%, which suggested that the as-achieved polymer can be used as a precursor to boron nitride ceramic fibers and membranes.

Effects of Synthesis Parameters on Hydrothermal Synthesis of NaA Zeolite

In this research, NaA zeolite samples were synthesized from aluminosilicate solution through hydrothermal method. The effects of different parameters such as the SiO2/Al2O3, OH-/Si and H2O/Na2O molar ratios of the initial gel solution, crystallization time and temperature on the crystallinity and morphology of the synthesized zeolites were investigated. The final products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experiment results indicated that the SiO2/Al2O3 molar ratio had influence on morphology and size of the synthesized zeolites, the optimum range of SiO2/Al2O3 molar ratio for synthesizing NaA zeolite was 1.5-2. Alkalinity (OH-/Si and H2O/Na2O molar ratio) had a significant effect on particle sizes of the synthesized zeolites, the higher the alkalinity, the smaller the crystal particle size. In addition, it was found that crystallization temperature during hydrothermal treatment played an important role in reducing the over all reaction time. The crystallization time had effect on the crystallinity of the synthesized zeolites. Finally, the optimum synthesis parameters can be proposed in order to synthesize NaA zeolite with desirable particle size, crystallinity and morphology.