A gas-liquid mass transfer model based on an unsteady state film mechanism applied to a
single bubble is presented. The mathematical model was solved using Laplace transform to
obtain an analytical solution of concentration profile in terms of the radial position r
and time t. The dynamic mass transfer flux was deduced and the influence of the bubble size
was also determined. A mathematical method for deducing the average mass transfer flux
directly from the Laplace transformed concentration is presented. Its accuracy is verified
by comparing the numerical results with those from the indirect method. The influences of
the model parameters, namely, the bubble size R, liquid film thickness δ, and the surface
renewal constant s on the average mass trannsfer flux were investigated. The proposed model
is useful for a better understanding of the mass transfer mechanism and an optimum design
of gas-liquid contact equipment.

The flow field of gas and liquid in a φ150mm rotating-stream-tray (RST) scrubber is
simulated by using computational fluid dynamic (CFD) method. The simulation is based on the
two-equation RNG κ-ε turbulence model, Eulerian multiphase model, mad a real-shape 3D
model with a huge number of meshes. The simulation results include detailed information
about velocity, pressure, volume fraction and so on. Some features of the flow field are
obtained: liquid is atomized in a thin annular zone; a high velocity air zone prevents
water drops at the bottom from flying towards the wall;the pressure varies sharply at the
end of blades and so on. The results will be helpful for structure optimization and
engineering design.

Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8%
and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct
alkaline leaching followed by fusion of the resulting leaching residues with caustic soda.
The experimental results show that the extraction of zinc is heavily dependent on the
contents of iron in the dusts. The higher iron content, the lower extraction of zinc is
obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with
5mol·L^-1 NaOH solution for 42h. The remaining zinc left in the leaching residues, which
supposed to be present as zinc ferrites, can be further leached when the residues were
fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching
residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts wit
hvarious contents of iron is compared. The production flowsheet for zinc from the dusts
using the process proposed is discussed.

The recovery of contaminants and useful substances from liquid wastes, the purification of
production effluents and the separation of thermally instable mixtures are some of the
multivarious applications of thin-film distillors in many processes of the chemical and
allied industries and of the food industries. In a study carried out in pilot plants with
distillation test systems there was found a good agreement between the experimental
separation results and those obtained by computing with a theorectical model; the latter is
based on the assumption of phase equilibrium between the vapour formed on an infinitely
small element of area in a liquid film of any given concentric periphery of the vertically
arranged evaporator. These tests were perfomed under various phase loads.

Based on the membrane-based absorption experiment of CO2 into water, shell-side flow
distribution and mass transfer in a randomly packed hollow fiber module have been analyzed
using subchannel model and unsteady penetration mass transfer theory. The cross section of
module is subdivided into many small cells which contains only one hollow-fiber. The cross
sectional area distribution of these cells is presented by the normal probability density
distribution function. It has been obtained that there was a most serious non-ideal flow in
shell side at moderate mean packing density, and the large amount of fluid flowed and
transferred mass through a small number of large voids. Thus mass transfer process is
dominated by the fluid through the larger void area. The mass transfer process in each cell
is described by the unsteady penetration theory. The overall mass transfer coefficient
equals to the probability addition of the mean mass transfer coefficient in each cell. The
comparisons of the values calculated by the model established with the empirical
correlations and the experimental data of this work have been done.The predicted overall
mass transfer coefficients are in good agreement with experimental data.

The compound metal oxide LaxPbyMnzO used as support was prepared by the sol-gel method, and
the catalyst in which Pd was used as active component and Snas co-active component for
direct synthesis of diphenyl carbonate (DPC) with heterogeneous catalytic reaction was
obtained by co-calcination and precipitation respectively.The catalyst was characterized by
XRD, SEM and TEM respectively. The specific surface area of catalysts was measured by
ChemBET3000 instrument, and the activity of the catalysts was tested by the synthesis of
DPC in a pressured reactor. The results showed that when the co-active component Sn was
added by co-calcination method A, its loading content was equal to 14.43% and active
component Pd was loaded by precipitation, the yield and selectivity of DPC could reach
26.78% and 99% respectively.

The carbonization of magnesium oxide particles by CO2 was investigated using a stirring
mill reactor.The effects of the system temperature, stirring rotation speed, influx rate of
CO2 and initial diameter of the magnesium oxide particles on the carbonization process were
determined. The results show that the system temperature and the stirring rotation speed
are the most significant influencing factors on the carbonization rate. The determination
of critical decomposition temperature (CDT) gives the maximum carbonization rate with other
conditions fixed. A theoretical model involving mass transfer and reaction kinetics was
presented for the carbonization process.The apparent activation energy was calculated to be
32.8kJ·mo1^-1. The carbonization process is co-controlled by diffusive mass transfer and
chemical reaction. The model fits well with the experimental results.

The leaching kinetics of niobium from a low-gr~te niobium-tantalum ore by concentrated KOH
solution under atmospheric pressure has been studied. Significant effects of reaction
temperature, KOH concentration,stirring speed, particle size and mass ratio of alkali-to-
ore on the dissolution rate of niobiumwere examined. The experimental data of the leaching
rates and the observed effects of the relevant operating variables were well interpreted
with a shrinking core model under diffusion control. By using the Arrhenius expression, the
apparent activation energy for the dissolution of niobium was evaluated. Finally, on the
base of the shrinking core model, the rate equation was established.

A kinetic model was developed to describe the atom transfer radical polymerization (ATRP)
of 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA). The model was based on a
polymerization mechanism,which included the atom transfer equilibrium for primary radical,
the propagation of growing polymer radical, and the atom transfer equilibrium for the
growing polymer radical. An experiment was carried out to measure the conversion of
monomer, the number-average molecular weight of polymer and molecular weight distribution
for the ATRP process of DMAEMA. The experimental data were used to correlate the kinetic
model and rate constants were obtained. The rate constants of activation and deactivation
in the atom transfer equilibrium for primary radical are 1.0×10^4L·mol^-1·s^-1 and 0.04L
·mol^-1·s^-1, respectively. The rate constant of the propagation of growing polymer
radical is 8.50L·mol^-1·s^-1, and the rate constants of activation and deactivation in
the atom transfer equilibrium for growing polymer radical are 0.045L·mol^-1·s^-1 and 1.2
×10^5L·mol^-1·s^-1, respectively. The values of the rate constants represent the
features of the ATRP process. The kinetic model was used to calculate the ATRP process of
DMAEMA. The results show that the calculations agree well with the measurements.

Evaporating bubble column reactor (EBCR) is a kind of aerated reactor in which the reaction
heat is removed by the evaporation of volatile reaction mixture. In this paper, a
mathematical model that accounts for the gas-liquid exothermic reaction and axial
dispersions of both gas and liquid phase is employed to study the performance of EBCR for
the process of p-xylene(PX) oxidation. The computational results show that there are
remarkable concentration and temperature gradients in EBCR for high ratio of height to
diameter (H/DT). The temperature is lower at the bottom of column and higher at the top,
due to rapid evaporation induced by the feed gas near the bottom. The concentration
profiles in the gas phase are more nonuniform than those (except PX) in the liquid phase,
which causes more solvent burning consumption at high H/DT ratio. For p-xylene oxidation,
theo ptimal H/DT is around 5.

Based on principal component analysis, this paper presents an application of faulty sensor
detection and reconstruction in a batch process, polyvinylchloride (PVC) making process. To
deal with inconsistency in process data, it is proposed to use the dynamic time warping
technique to make the historical data synchronized first,then build a consistent multi-way
principal component analysis model. Fault detection is carried out based on squared
prediction error statistical control plot. By defining principal component subspace,
residual subspace and sensor validity index, faulty sensor can be reconstructed and
identified along the fault direction. Finally, application results are illustrated in
detail by use of the real data of an industrial PVC making process.

A fuzzy neural network (FNN) model is developed to predict the 4-CBA concentration of the
oxidation unit in purified terephthalic acid process. Several technologies are used to deal
with the process data before modeling.First,a set of preliminary input variables is
selected according to prior knowledge and experience. Secondly,a method based on the
maximum correlation coefficient is proposed to detect the dead time between the process
variables and response variables. Finally, the fuzzy curve method is used to reduce the
unimportant input variables.The simulation results based on industrial data show that the
relative error range of the FNN model is narrower than that of the American Oil Company
(AMOCO) model. Furthermore, the FNN model can predict the trend of the 4-CBA concentration
more accurately.

A new superstructure model of heat exchanger networks (HEN) with stream splits based on
rangers of streams supply temperatures and heat capacity flow rates is presented. The
simultaneous optimal mathematical model of flexible HEN synthesis is established too.
Firstly, the streams with rangers of supply temperatures and/or the streams with the
rangers of heat capacity flow rates are pretreated; Secondly, several rules are proposed to
establish the superstructure model of HEN with splits and the simultaneous optimal
mathematical model of flexible HEN; Thirdly, the improving genetic algorithm is applied to
solve the mathematical model established at the second step effectively, and the original
optimal structure of HEN based on the maximum operation limiting condition can be obtained
easily; Finally, the rules of heat exchange unit merged and the heat load of heat exchanger
relaxed are presented, the flexible configuration of HEN satisfied the operation condition
between the upper and down bounds of supply temperature and heat capacity flow rates can be
obtained based on the original optimal structure of HEN by means of these rules. A case
study demonstrates the method presented in this paper is effective

Effective utilization of water and energy is the key factor of sustainable development in
process industries, and also an important science and technology problem to be solved in
systems engineering. In this paper,two new methods of optimal design of water utilization
network with energy integration in process industries are presented, that is, stepwise and
simultaneous optimization methods. They are suitable for both single contaminant and multi
-contaminant systems, and the integration of energy can be carried out in the whole process
system, not only limited in water network, so that energy can be utilized effectively. The
two methods are illustrated by case study.

The density functional theory, simplified by the local density approximation and mean-field
approximation, is applied to study the surface properties of pure non-polar fluids. A
reasonable long rang correction is adopted to avoid the truncation of the potential. The
perturbation theory is applied to establish the equation for the phase equilibrium, in
which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used
as the perturbation term. Three parameters, elk, d and ms, are regressed from the vapor-
liquid equilibria, and the surface properties, including density profile, surface tension
and local surface tension profile are predicted with these parameters.

A surface equation of state, applicable to liquid-expanded (LE) monolayers, was derived by
analyzing the Helmholtz free energy of the LE monolayers. Based on this equation, a general
equation was obtained to describe all states of single-component phospholipid monolayers
during comprassion. To verify the applicability of the equation, π-A isotherms of 1,2-
dipalmitoylphosphatidylcholine (DPPC), 1,2-dipalmitoylphosphatidylglycerol (DPPG), and 1,2
-dimyristoyphosphatildylcholine (DMPC) were measured. The comparison between model and
experimental values indicates that the equation can describe the behavior of pure
phospholipid monolayers.

The diffusion coefficients of aqueous L-threonine solutions were determined from 298.15K to
328.15K by the metallic diaphragm cell method with accuracy, promptness and convenience.
Meanwhile, the densities and viscosities of the solutions were also determined and
correlated. Based on a seml-empirical model for correlating the diffusion coefficients of
some amino acids in their aqueous solutions, a new semi-empirical model for correlating the
diffusion coefficients involving temperature was provided, which is more comprehensive and
less experiment dependent compared to the previous model. The fitting results are
satisfactory. Compared to a former model for correlating the diffusion coefficients of
solid organic salts in their aqueous solutions, this model provides significant improvement
in correlation of diffusion coefficients with different temperatures avoiding arduous work.

A three dimension of dynamic mathematical model of the molten carbonate fuel cell is
established,in which the heat generation, mass transfer and electrochemical characteristics
are described. The performance of the fuel cell including the distributions of the
temperature and the velocity is predicted numerically. Then the experimental data including
the output performance of the fuel cell generation system and the temperature distributions
are compared. The numerical results are in agreement with the experiment results.

Biodegradation of waste in landfill is a slow process requiring decades for completion.
Accelerated degradation of municipal refuse in modulated landfill environments may
alleviate or eliminate pollution to the land, water and air. In this work, nineteen
effective microorganisms (EMs) were isolated fromold landfill refuse by enrichment
culturing techniques and used for the inoculum of municipal refuse. The preliminary
experiments demonstrate that a combination of EMs inoculation in landfill with leachate
recycle resulted in increased rates of decomposition and faster process stability. The
concentrations of COD, VFA and SO4^2- in digester with EMs inoculation and leachate recycle
decreased more rapidly than others. Gas production from digester with EMs inoculation and
leachate recycle commenced around 32 days, which is a week shorter than with leachate
recycle only. And peak cumulative gas production was obtained much earlier in digester with
EMs inoculation and leachate recycle (150 days) compared to 180 days with leachate recycle
only. Moreover, in the first two months, the rate of settlement in digester with EMs
inoculation and leachate recycle was more rapid than others.

Nanostructured γ-Fe2O3/SiO2 complex oxide was prepared by sol-gel method with
tetraethoxysilane and iron nitrate as precursors. The particle size distribution, thermal
and phase stabilities and gas sensing properties were systematically characterized by TEM,
granularity distribution, TG-DTA, XRD and gas sensitivity measurements. The particle size
is about 10 nm and size distribution is very narrow. The sensitivity of the sensing element
to CO, H2, C2H4, C6H6 and the effects of calcination temperature on the sensitivity and
conductance of gases were examined. The combination of excellent thermal stability and
tunable gas sensing properties through careful control of the preparation and judicious
selection of material compositions gives rise to novel nanocomposites, which is attractive
for the sensitive and selective detection of reducing gases and some hydrocarbon gases.

This paper presents a method of separation of fine particles, of the order of a few microns
or less, from aqueous media by flotation using colloidal gasaphrons (CGAs) generated in
aqueous solutions. More than 150 experiments were conducted to study the effects of
surfactant type, surfactant concentration, CGAs flow rate, and particle concentration on
the removal efficiency (fine particles of polystyrene were used as a target compound). The
results indicate that CGAs, generated from cationic surfactant of hexdecyltrimethyl
ammonicum bromide (HTAB) and anionic surfactant of sodium dodecylbenzne sulfonate (SDBS),
are an effective method for the separation off ine particles of polystyrene from
wastewater. The flotation yields are higher than 97%.

First and Second Law analyses were conducted to evaluate the performance of a closed latent
heat thermal energy storage (LHTES) system employing calciumchloride hexahydrate (CaCl2-
6H2O).The First and the Second Laws of thermodynamics were applied to the system from
viewpoint of energy and exergy analyses,respectively. The energy storage tank in the system
is neither fully mixed nor fully stratified. It may be considered as semithermal
stratified. Experiments that include both charging and discharging periods were performed
on sunny winter days in 1996. The energy and exergy variations and the overallenergy and
exergy efficiencies of the closed LHTES system were calculated for the complete charging
and discharging cycle of the selected fifteen clear-sky winter days. Mean energy and exergy
efficiencies were found to be 55.20% and 34.83%, respectively.

The solid-liquid equilibria of musk ketone + musk xylene, musk xylene+1,3-dimethyl-2,4-
dinitro-5-tert-butyl benzene are measured by differential scanning calorimeter (DSC), these
systems are proved to be simple eutectics. Moreover the melting points and the fusion
enthalpies of musk ketone, musk xylene and 1,3-dimethyl-2,4-dinitro-5-tert-butyl benzene
are also measured by the DSC. These solid-liquid equilibrium data and the heats of fusion
are reportedfor the first time. Then UNIFAC model is used to correlate the solid-liquid
equilibrium data.It is shown that the solid-liquid equilibria of musk systems can be
predicted bv the UNIFAC model.

Three adsorption rate models are derived for multicomponent adsorption systems under either
pore diffusion or surface diffusion control. The linear driving force (LDF) model is
obtained by assuming a parabolic intraparticle concentration profile. Models I and Ⅱ are
obtained from the parabolic concentration layer approximation. Examples are presented to
demonstrate the usage and accuracy of these models. It is shown that Model I is suitable
for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed
adsorption processes while the LDF model should not be used in batch adsorption and may be
considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.

Thermal dehydration of gypsum and borogypsum was investigated under nonisothermal
conditions in air by using simultaneous thermogravimetric-differentialthermal analyzer.
Nonisothermal experiments were carried out at various linear heating rates. Kinetics of
dehydration in the temperature range of 373-503 K were evaluated from the DTA (differential
thermal analysis)-TGA (thermogravimetric analysis) data by means of Coats-Redfern,Kissinger
and Doyle Equations. Values of the activation energy and the pre-exponential factor of the
dehydration were calculated. The results of thermal experiments and kinetic parameters
indicated that borogypsum is similar to gypsum from dehydration mechanism point of view
although it consists of boron and small amount of alkali metal oxides.

A solid state H2S/air electrochemical cell having the configuration of H2S,
(MoS2+NiS+Ag)/YSZ/Pt,air has been examined with different H2S flow rates and concentrations
at atmospheric pressure and 750-850℃.Performance of the fuel cell was dependent on anode
compartment H2S flow rate and concentration. The cell open-circuit voltage increased with
increasing H2S flow rate. It was found that increasing both H2S flow rate and H2S
concentration improved current-voltage and power density performance. This is resulted from
improved gas diffusion in anode and increased concentration of anodic electroactive
species. Operation at elevated H2S concentration improved the cell performance at a given
gas flow rate. However, as low as 5% H2S in gas mixture can also be utilized as fuel feed
to cells. Highest current and power densities, 1750mA·cm^-2 and 200mW·cm^-2,are obtained
with pure H2S flow rate of 50 ml·min^-1 and air flow rate of 100ml·min^-1 at 850℃.

Two dense pellicular agarose-glass matrices of different sizes and densities, i.e., AG-S
and AG-L, have been characterized for their bed expansion behavior, flow hydrodynamics and
particle classifications in an expanded bed system. A 26 mm ID column with side ports was
used for sampling the liquid-solidsuspension during expanded bed operations. Measurements
of the collected solid phase at different column positions yielded the particle size and
density distribution data. It was found that the composite matrices showed particle size as
well as density classifications along the column axis, i.e., both the size and density of
each matrix decreased with increasing the axial bed height. Their axial classifications
were expressed by a correlation related to both the particle size and density as a function
of the dimensionless axial bed height. The correlation was found to fairly describe the
solid phase classifications in the expanded bed system. Moreover, it can also be applied to
other two commercial solid matrices designed for expanded bed applications.

Fe nanowire arrays are prepared by electrodeposition in porous anodic aluminum oxide
template from a composite electrolyte solution. These nanowires have an uniform diameter of
approximate 25 nm and a length in excess of 2.5μm.The micrographs and crystal structures
of Fe nanowlres are studied by transmission electron microscopy (TEM), selected-area
electron diffraction (SAED), and X-ray diffraction(XRD). It is found that each nanowire is
essentially a single crystal and has a different orientation in each array. Hysteresis
loops of Fe nanowire array show that its easy magnetization direction is perpendicular to
the sample plane.