Table of Content

20 February 2003, Volume 3 Issue 1

Previous Issue    Next Issue

1

Solid Circulating Rate in a Spouted–fluidized Bed with Draft Tube at Elevated Pressure

LIU Xiang-dong; ZHANG Ming-yao

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (268KB) ( )  

Related Articles | Metrics

The momentum equation with gravity considered was applied to describe the variable-mass flow in the vertical perforated channel for radial packed reactors. The profiles of pressure and the virtual pressure along the perforated channels were measured for upward and downward flows in the distributor or collector on large scale mock-up. Under the experimental conditions, the coefficients of momentum exchange for distribution and collection were calculated to be equal to 0.77 with the average relative error of 10% and 1.26 with the average relative error of 15% respectively. It is concluded that gravity can not be neglected as the mass velocity is relatively small.

Influence of KCl Concentration on Chitin Deacetylation in Microwave Field

YANG Zhen-qiu; SONG Bao-zhen; OUYANG Fan

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (139KB) ( )  

Related Articles | Metrics

This paper presents the effect of KCl concentration on chitin deacetylation in the microwave field. The experimental result shows that the reaction was enhanced when salts were introduced into the reaction system. The degree of deacetylation (DD) of chitosan increases with time, but the rate of increase slows down gradually, revealing the characteristics of first order reaction. The molecular weight (MW) of chitosan decreases with time. The DD of chitosan decreases with the increase of the concentration of KCl, but it is higher than that of the control in the concentration range of KCl investigated. When KCl concentration equals 0.05 mol/L, the DD is 79.3%, as compared with that of the control (69.6%). Along with the increase of KCl concentration, the MW of chitosan decreased, but it increased when the concentration was greater than 0.2 mol/L.

Harvesting Spirulina Cells by Foam Flotation Technique on a Laboratory Scale

ZENG Wen-lu; LI Hao-ran; LI Bao-hua; CONG Wei; CAI Zhao-ling; OUYANG Fan

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (172KB) ( )  

Related Articles | Metrics

Taking Spirulina cells as the model, experiments were carried out on a novel and effective slant-armed bubble column to investigate the feasibility of foam flotation of micro-algal cells. The effects of a number of operation parameters such as carrying-gas flow rate, solution pH value, concentrations of ethanol and Tween 20 on the enrichment ratio and recovery of cells were examined and some useful data were presented.

Characteristics and Active Energy for the Precursor of Lithium Manganese Oxides

ZHAO Ming-shu; SONG Xiao-ping; ZHAI Yu-chun; TIAN Yan-wen

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (280KB) ( )  

Related Articles | Metrics

The decomposition kinetics of lithium manganese oxides precursor in air atmosphere was investigated at different heating rates with differential temperature analyses. The apparent activation energy of each stage was calculated using the Doyle-Ozawa and Kissinger methods. X-ray diffraction, granularity analysis, scanning electron microscopy and transmission electron microscopy showed that the LiMn2O4 phase was pure, with regular appearance and a uniform granularity distribution.

Cathodic Reduction of Zn Complex Ion in the ZnCl2–NH4Cl Electrolyte

MA Chun; YU Zhong-xing

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (160KB) ( )  

Related Articles | Metrics

The effect of culture conditions on microbial flocculant production from Nocardia sp. CCTCC M201005, a newly isolated bioflocculant producing bacterium, was investigated. Sucrose was proved to be an optimum carbon source. Complexity of organic and inorganic nitrogen sources stimulated both bacterial growth and flocculant synthesis, among which corn steep complexed with urea was the most efficient. Proper corn steep concentration accelerated bacterial growth while relatively low corn steep concentration was more favorable for bioflocculant formation. The highest flocculation activity was obtained at C/N 20~30. The medium supplemented fermentation was designed and carried out. The results showed that the final flocculation activity and cell density were increased more than 10% and 35% respectively compared with those in the fermentation with no medium supplementation. Flocculation conditions of bioflocculant produced by Nocardia sp. CCTCC M201005 (named REA-11) were also discussed. The thermostability of REA-11 was high at pH 3.0 to 6.5 and its activity was markedly improved by the addition of CaCl2. As a co-flocculant, the optimum concentration of CaCl2 was 8 mmol/L in this flocculation system.

Preparation of Surface-modified Nanosized Al(OH)3 Powders

LIU You-zhi; LI Yu; LIU Lai-shuan

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (363KB) ( )  

Related Articles | Metrics

Nanosized Al(OH)3 powder was prepared by the carbonation method from sodium aluminates solution and carbon dioxide. The influence of concentration of reactant, rotating speed of rotating packed bed and ratio of gas-liquid flow rate on Al(OH)3 particle size in the preparation process was investigated. The optimal operating optimum conditions were determined as follows: sodium aluminates 120 g/L, ratio of gas-liquid flow rate 1.5~4.0, rotating speed 1200 r/min. Adding surface modifier TEBAC/PO43- is helpful to the control of agglomeration of Al(OH)3 particles. The product was characterized by TEM and XRD. The prepared particles are monoclinic and well-dispersed with a mean size of 20 nm .

Photoelectrochemical Degradation of PCP on TiO2 Film Electrode

XU Wen-lin;WANG Ya-qiong

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (58KB) ( )  

Related Articles | Metrics

An investigation of photoelectrochemical degradation of pentachlorophenol (PCP) on a TiO2 film electrode was presented. The TiO2 film electrode was prepared by anodisation of titanium metal in sulfuric acid solution and its photoelectrocatalystic performance was studied. The destruction of PCP follows approximately the first-order kinetics. The reaction constant decreases slightly from 2.6×10–5 s–1 to 2.0×10–5 s–1 as the initial PCP concentration is increased from 0.1 mmol/L to 1.0 mmol/L under the experimental condition.

Physical Modeling of the Vortex Phenomenon in Continuous Casting Mould

LEI Hong; ZHU Miao-yong; HE Ji-cheng

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (238KB) ( )  

Related Articles | Metrics

Two different types of 1-[2-(hydroxyethoxy)methyl]-6-naphthylmethylthymines have been designed, synthesized and evaluated for their anti-HIV-1 activities in different cells lines. The binding free energy (DG) including steric and electrostatic between the two different ligands and reverse transcriptase Non-Nucleoside Binding Pocket (NNBP) have been docked and calculated to evaluate their accommodation circumstance on a SGI work station. The DG and anti-HIV-1 activity has been correlated in order to guide further drug design, which showed that the steric binding effect dominated in the whole binding action between the compounds and reverse transcriptase (RT). The results showed that more negative DG led to higher activity of compounds.

Alkylation Reaction of Thiophene with Olefins over Acid Catalyst of AlCl3 Supported Resins

LUO Guo-hua; XU Xin; YANG Chun-yu TONG Ze-min; PENG Shao-yi

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (176KB) ( )  

Related Articles | Metrics

A gold leaching process for an acid leached residue from an arsenic refractory gold concentrate in lime slurry under pressurized oxygen is investigated. The residue contains 17.4% of elemental sulfur. The experimental results show that the optimum quantity of lime added to the leaching solution should ensure the mole ratio of elemental sulfur to OH– in the range of 0.8 to 1.1. In 3 to 5 h, 90% of gold is leached at 85°C under 0.1 to 0.3 MPa oxygen pressure with the optimum lime addition in the solution. The thiosulphate produced from elemental sulfur in lime solution during oxygen leaching might be the major complexing agency for gold leaching.

Separation and Purification of Stigmasterol and b-Sitosterol from Phytosterol by the Crystallization Method

XU Wen-lin; HUANG Yi-bo; QIAN Jun-hong; SHA Ou

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (224KB) ( )  

Related Articles | Metrics

Influences of HNO3, H2O2 and BTA concentrations on filming of copper surface and CMP process were studied by electrochemical methods. Cu EIS in various media were examined. Relations of corrosion current density to polishing pressures and rotative rates were investigated. Changes of corrosion potential and polarization curves were explored. Electrochemical mechanisms of CMP were explained by changes of electrochemical variables such as corrosion potential and corrosion current density. The formula of 1% HNO3+1% BTA+0.2% H2O2+5% g-Al2O3 was confirmed to be feasible and reasonable.

Research Advances in Biodesulfurization Technology of Coal and Oil

JIANG Cheng-ying;WANG Rong; LIU Hui-zhou; CHEN Jia-yong

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (205KB) ( )  

Related Articles | Metrics

Thermal plasma pyrolysis of waste tyres for recovering energy was performed in a nitrogen plasma reactor. The main gaseous products were identified by chromatography as H2, CO, CH4, C2H2 and so on. From a series of experiments, the effects of the process parameters of thermal plasma pyrolysis were investigated. Under our experimental conditions with steam injection, the total contents of H2 and CO reached up to 38.3% in the gas product, C2H2 up to 4%, and the maximum calorific value of the pyrolysis gas was 8.96 MJ/m3. The results indicate that plasma-assisted thermal decomposition of waste tyre particles may be a useful way for recovering energy and useful chemicals.

Catalytic Cracking of Bio-oil from Biomass Pyrolysis

GUO Xiao-ya; YAN Yong-jie; LI Ting-chen; REN Zheng-wei; YUAN Chuan-min

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (238KB) ( )  

Related Articles | Metrics

In preparation of motor fuel, bio-oil from pyrolysis of biomass must be further upgraded so as to improve its quality. Upgrading operation via catalytic cracking was carried out in a tubular fixed-bed reactor with HZSM-5 as catalyst, under atmospheric pressure, in the temperature range of 340~420oC, and at weight space velocity (WHSV) of 2.9~5.6 h-1. The effects of process parameters such as temperature, WHSV, solvent and size of catalyst pellets on product yield were studied. The results show that 44.68% (w) of organic distillate was yielded at temperature 380oC and WHSV=3.7 h-1. In addition, the analysis of upgraded oil shows that the amount of oxygenated compounds in the bio-oil, such as organic acid, aldehyde, ester, alcohol, ketone were greatly reduced meanwhile aromatic and polyaromatic hydrocarbons were formed.

Preparation of Super-fine Spherical CaCO3 by the Carbonation Method

XIANG Lan; XIANG Ying; YUAN Hong-xia; WANG Ting-jie

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (101KB) ( )  

Related Articles | Metrics

The effects of temperature, time, and agitation speed on the acidic precipitation of ammonium polyvanadate from the plant of vanadate-leaching solution were investigated on a laboratory scale. The results show that for the vanadate-leaching solution containing 30 g/L of vanadium, keeping pH about 2.2 at the beginning of precipitation reaction, temperature at about 95oC, agitation speed at 300 r/min, and reaction time being 120 min, could result in the following results: precipitation rate is more than 99%, H2O content in red cake is less than 20%, Na content in dried red cake is between 0.70% and 1.08%, and sulphur content in dried red cake is between 0.78% and 1.02%.

Experiments on Reducing Potassium Chromate and Potassium Dichromate to Chromic Oxide Hydrate under Hydrothermal Conditions

YAO Zhi-mao; LI Zuo-hu; ZHANG Yi

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (302KB) ( )  

Related Articles | Metrics

Reduction of potassium chromate and potassium dichromate to chromic oxide hydrate under hydrothermal conditions using sucrose as the reducing agent was investigated. The effects of the stoichiometric mole ratio of sucrose to chromate or dichromate salts (Rm), the isothermal temperature (Tiso) and time (tiso) on the conversion of Cr6+ to Cr3+ were also studied in detail. By using the orthogonal experiment L9(34), the order of the above affecting factors was obtained: tiso

Pressure Drop Characteristics of Vertical Dilute-phase Gas Conveying

JING Shan; JIANG Pan-liang; HU Qing-yuan; WANG Jin-fu; JIN Yong

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (132KB) ( )  

Related Articles | Metrics

The chelate resins of dicarboxylic acid dihydrazides-formaldehyde were synthesized by polycondensation of dicarboxylic acid dihydrazides with formaldehyde. The collecting ability for Zn2+ was investigated by batch tests. The collecting efficiency of these three resins decreased in the order of succinic acid dihydrazides-formaldehyde resin>malonic acid dihydrazides-formaldehyde resin>oxalic acid dihydrazides-formaldehyde resin. The influences of pH value, capturing time and temperature were investigated. It is found that the collecting efficiency is dependent on pH value, and high temperature is unfavorable to collecting Zn2+. The resins reach the highest capacity of Zn2+ capture after 3 h of adsorption.

New Technology for Pd Recovery from Selectively Leached Residue of Waste Palladium Catalyst

YANG Jian-wen;ZHONG Hai-yun;ZHAO Xuan;ZHONG Hui;LI Jian;DAI Yan-yang;MIAO Jian-li

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (145KB) ( )  

Related Articles | Metrics

There is still 10~100 g/t Pd in the selectively leached residue of waste catalyst, and five factors are considered to probably cause the result: reabsorption, diffusion resistance in pores, hydrolysis, partial substitution, inclusion etc. Using weak alkaline leaching agent CN– as an alternative was proposed and testified to be effective. By this technique, Pd content in –150 mesh milled residue was dropped from 51.6 g/t to 1.2 g/t. In a 100 t scale vat leaching test with granular materials, Pd was dropped to 3.0 g/t. The leaching recovery is respectively 97.7% and 94.2%. Pd in leaching solution was directly adsorbed with AC (active carbon) with high absorption rate and good selectivity. Pd loaded AC was burned in oxygen-rich fire, and above 99.95% purity of Pd powder was made by the amino-complexing method. This technology has the features of simple process, less facilities required, high metal recovery and high product purity etc.

Asymmetric Conversion of 1-Phenyl-1,2-ethanediol by Candida parapsilosis SYB-1

NIE Yao; XU Yan

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (148KB) ( )  

Related Articles | Metrics

Thermal cycle resistance of Al2O3/Ni-Ti/Kovar joints was studied, which were prepared by active brazing technique. The experimental results show that the joint shear strength increases after 200~600~200oC thermal cycles. The phenomenon is analyzed in view of the materials thermal expansion, solder microstructure and cycle temperature. The reason of strength increase is that the annealing effect in thermal cycles reduces the joining residual stress.

Prediction of Solids Holdup Time Series of a Gas–Solid Circulating Fluidized Bed

LI Xiao-xiang; SHI Yan-fu; HUANG Wei-xing; YU Hua-rui; ZHU Jing-xu

. 2003, 3(1):  0-0. 

Asbtract ( )   PDF (259KB) ( )  

Related Articles | Metrics

A prediction model based on combination of phase space reconstruction with artificial neural network was proposed. In this model, the Takens phase space reconstruction method is used to reconstruct the attractors, which represent the system hydrodynamics from the single variable time series, and the radial based function artificial neural network is used to fit the attractors in phase spaces. Firstly, the model was verified by the Lorenz chaotic system. Then the model was used to predict the local solids holdup fluctuation in a circulating fluidized bed riser with 16 m height and 0.10 m ID. The experiments were conducted with FCC particles and superficial gas velocity ranging from 3.5~8.2 m/s and the solids circulating fluxes ranging from 50~202 kg/(m2.s). The local solids holdup time series signals were measured at 900 Hz using an optical fiber probe. The results showed that (1) the proposed model based on phase space reconstruction and the artificial neural network is a useful method in predicting local solids holdup fluctuation in gas-solid circulating fluidized beds; (2) the predictability of solids holdup in the CFB is possible only in a short-time, in accordance with that the circulating fluidized bed is a chaotic system.