Abstract: The separation efficiency of a hydrocyclone has
extensively been considered on the rigid particle assumption. A
collection of experimental studies have demonstrated their
discrepancies from the modeling and simulation results. These
discrepancies caused by the actual particle elasticity have generally
led to a larger amount of energy consumption in the separation
process. In this paper, the influence of particle elasticity on the
separation efficiency of a hydrocyclone system was investigated
through the Finite Element (FE) simulations using crude oil droplets
as the elastic particles. A Reitema-s design hydrocyclone with a
diameter of 8 mm was employed to investigate the separation
mechanism of the crude oil droplets from water. The cut-size
diameter eter of the crude oil was 10 - Ðçm in order to fit with the
operating range of the adopted hydrocylone model. Typical
parameters influencing the performance of hydrocyclone were varied
with the feed pressure in the range of 0.3 - 0.6 MPa and feed
concentration between 0.05 – 0.1 w%. In the simulation, the Finite
Element scheme was applied to investigate the particle-flow
interaction occurred in the crude oil system during the process. The
interaction of a single oil droplet at the size of 10 - Ðçm to the flow
field was observed. The feed concentration fell in the dilute flow
regime so the particle-particle interaction was ignored in the study.
The results exhibited the higher power requirement for the separation
of the elastic particulate system when compared with the rigid
particulate system.
Abstract: This project aims to investigate the potential of
torrefaction to improve the properties of Malaysian palm kernel shell
(PKS) as a solid fuel. A study towards torrefaction of PKS was
performed under various temperature and residence time of 240, 260,
and 280oC and 30, 60, and 90 minutes respectively. The torrefied
PKS was characterized in terms of the mass yield, energy yield,
elemental composition analysis, calorific value analysis, moisture and
volatile matter contents, and ash and fixed carbon contents. The mass
and energy yield changes in the torrefied PKS were observed to
prove that the temperature has more effect compare to residence time
in the torrefaction process. The C content of PKS increases while H
and O contents decrease after torrefaction, which resulted in higher
heating value between 5 to 16%. Meanwhile, torrefaction caused the
ash and fixed carbon content of PKS to increase, and the moisture
and volatile matter to decrease.
Abstract: The paper aims at investigating influence of medium
capacity on linear adsorbed solute dispersion into chemically
heterogeneous fixed beds. A discrete chemical heterogeneity
distribution is considered in the one-dimensional advectivedispersive
equation. The partial differential equation is solved using
finite volumes method based on the Adam-Bashforth algorithm.
Increased dispersion is estimated by comparing breakthrough curves
second order moments and keeping identical hydrodynamic
properties. As a result, dispersion increase due to chemical
heterogeneity depends on the column size and surprisingly on the
solid capacity. The more intense capacity is, the more important
solute dispersion is. Medium length which is known to favour this
effect vanishing according to the linear adsorption in fixed bed seems
to create nonmonotonous variation of dispersion because of the
heterogeneity. This nonmonotonous behaviour is also favoured by
high capacities.
Abstract: A continuum model is presented to study vdW
interaction on buckling analysis of multi-walled walled carbon
nanotube. In previous studies, only the vdW interaction between
adjacent two layers was considered and the vdW interaction between
the other two layers was neglected. The results show that the vdW
interaction cofficients are dependent on the change of interlayer
spacing and the radii of tubes. With increase of radii the vdW
coefficients approach a constant value. The numerical results show
that the effect of vdW interaction on the critical strain for a doublewalled
CNT is negligible when the radius is large enough for the
both the cases of before and after buckling.
Abstract: Isobaric vapor-liquid equilibrium measurements are reported for the binary mixtures of n-Butylamine and Triethylamine with Cumene at 97.3 kPa. The measurements have been performed using a vapor recirculating type (modified Othmer's) equilibrium still. The binary mixture of n-Butylamine + Cumene shows positive deviation from ideality. Triethylamine + Cumene mixture shows negligible deviation from ideality. None of the systems form an azeotrope. The activity coefficients have been calculated taking into consideration the vapor phase nonideality. The data satisfy the thermodynamic consistency test of Herington. The activity coefficients have been satisfactorily correlated by means of the Margules, NRTL, and Black equations. The activity coefficient values obtained by the UNIFAC model are also reported.
Abstract: Preparation of size controlled nano-particles of silver catalyst on carbon substrate from e-waste has been investigated. Chemical route was developed by extraction of the metals available in nitric acid followed by treatment with hydrofluoric acid. Silver metal particles deposited with an average size 4-10 nm. A stabilizer concentration of 10- 40 g/l was used. The average size of the prepared silver decreased with increase of the anode current density. Size uniformity of the silver nano-particles was improved distinctly at higher current density no more than 20mA... Grain size increased with EK time whereby aggregation of particles was observed after 6 h of reaction.. The chemical method involves adsorption of silver nitrate on the carbon substrate. Adsorbed silver ions were directly reduced to metal particles using hydrazine hydrate. Another alternative method is by treatment with ammonia followed by heating the carbon loaded-silver hydroxide at 980°C. The product was characterized with the help of XRD, XRF, ICP, SEM and TEM techniques.
Abstract: Group contribution methods such as the UNIFAC are
very useful to researchers and engineers involved in synthesis,
feasibility studies, design and optimization of separation processes.
They can be applied successfully to predict phase equilibrium and
excess properties in the development of chemical and separation
processes. The main focus of this work was to investigate the
possibility of absorbing selected volatile organic compounds (VOCs)
into polydimethylsiloxane (PDMS) using three selected UNIFAC
group contribution methods. Absorption followed by subsequent
stripping is the predominant available abatement technology of
VOCs from flue gases prior to their release into the atmosphere. The
original, modified and effective UNIFAC models were used in this
work. The thirteen selected VOCs that have been considered in this
research are: pentane, hexane, heptanes, trimethylamine, toluene,
xylene, cyclohexane, butyl acetate, diethyl acetate, chloroform,
acetone, ethyl methyl ketone and isobutyl methyl ketone. The
computation was done for solute VOC concentration of 8.55x10-8
which is well in the infinite dilution region. The results obtained in
this study compare very well with those published in literature
obtained through both measurements and predictions. The phase
equilibrium obtained in this study show that PDMS is a good
absorbent for the removal of VOCs from contaminated air streams
through physical absorption.
Abstract: Freeze concentration freezes or crystallises the water
molecules out as ice crystals and leaves behind a highly concentrated
solution. In conventional suspension freeze concentration where ice
crystals formed as a suspension in the mother liquor, separation of
ice is difficult. The size of the ice crystals is still very limited which
will require usage of scraped surface heat exchangers, which is very
expensive and accounted for approximately 30% of the capital cost.
This research is conducted using a newer method of freeze
concentration, which is progressive freeze concentration. Ice crystals
were formed as a layer on the designed heat exchanger surface. In
this particular research, a helical structured copper crystallisation
chamber was designed and fabricated. The effect of two operating
conditions on the performance of the newly designed crystallisation
chamber was investigated, which are circulation flowrate and coolant
temperature. The performance of the design was evaluated by the
effective partition constant, K, calculated from the volume and
concentration of the solid and liquid phase. The system was also
monitored by a data acquisition tool in order to see the temperature
profile throughout the process. On completing the experimental
work, it was found that higher flowrate resulted in a lower K, which
translated into high efficiency. The efficiency is the highest at 1000
ml/min. It was also found that the process gives the highest
efficiency at a coolant temperature of -6 °C.
Abstract: Adsorption of CS2 vapors has been studied on
different types of activated carbons obtained from different source
raw materials. The activated carbons have different surface areas and
are associated with varying amounts of the carbon-oxygen surface
groups. The adsorption of CS2 vapors is not directly related to surface
area, but is considerably influenced by the presence of carbonoxygen
surface groups. The adsorption decreases on increasing the
amount of carbon-oxygen surface groups on oxidation and increases
when these surface groups are eliminated on degassing. The
adsorption is maximum in case of the 950°-degassed carbon sample
which is almost completely free of any associated oxygen. The
kinetic data as analysed by Empirical diffusion model and Linear
driving force mass transfer model indicate that the adsorption does
not involve Fickian diffusion but may be considered as a pseudo first
order mass transfer process. The activation energy of adsorption and
isosteric enthalpies of adsorption indicate that the adsorption does not
involve interaction between CS2 and carbon-oxygen surface groups,
but hydrophobic interactions between CS2 and C-C atoms in the
carbon lattice.
Abstract: Zirconium diamine and triamine complexes can possess biological activities. These complexes were synthesised via the reaction of equimolar quantities of 1,10-phenanthroline {NC3H3(C6H2)NC3H3} (L1) or 4-4-amino phenazone {ONC6H5(NH)CH(NH2} (L2) or diphenyl carbizon {HNNCO(NH)2(C6H5)} (L3) with a Zirconium Salt {ZrOCl2} in a 1:1 ratio to form complexes [{NC3H3(C6H2)NC3H3}ZrOCl2}] [ZrOCl2L1], [{(O2NC6H4(NH)(NH2)}ZrOCl2] [ZrOCl2L2] and [{HNNCO(NH)2(C6H5)ZrOCl2}] [ZrOCl2L3] respectively. They were characterised using Fourier Transform Infrared (FT-IR) and UV-Visible spectroscopy. Also a variable temperature study of these complexes was completed, using UV-Visible spectroscopy to observe electronic transitions under temperature control. Also a DFT study was done on these complexes via the information from FT-IR and UV-Visible spectroscopy.
These complexes were found to show different inhibition to the growth of bacterial strains of Bacillus spp. & Klebsiella spp. & E. coli & Proteus spp. & Pseudomona spp. at different concentrations (0.001, 0.2 and 1M). For better understanding these complexes were examined by using a Density Functional Theory (DFT) calculation.
Abstract: In this study the enthalpies of dissociation for pure
methane and pure carbon dioxide was calculated using a hydrate
equilibrium data obtained in this study. The enthalpy of dissociation
was determined using Clausius-Clapeyron equation. The results were
compared with the values reported in literature obtained using
various techniques.
Abstract: This paper reported an experimental research of
steady-state heat transfer behaviour of a gas flowing through a fixed
bed under the different operating conditions. Studies had been carried
out in a fixed-bed packed methanol synthesis catalyst percolated by air
at appropriate flow rate. Both radial and axial direction temperature
distribution had been investigated under the different operating
conditions. The effects of operating conditions including the reactor
inlet air temperature, the heating pipe temperature and the air flow rate
on temperature distribution was investigated and the experimental
results showed that a higher inlet air temperature was conducive to
uniform temperature distribution in the fixed bed. A large temperature
drop existed at the radial direction, and the temperature drop increased
with the heating pipe temperature increasing under the experimental
conditions; the temperature profile of the vicinity of the heating pipe
was strongly affected by the heating pipe temperature. A higher air
flow rate can improve the heat transfer in the fixed bed. Based on the
thermal distribution, heat transfer models of the fixed bed could be
established, and the characteristics of the temperature distribution in
the fixed bed could be finely described, that had an important practical
significance.
Abstract: Treatment of tar-containing wastewater is necessary
for the successful operation of biomass gasification plants (BGPs). In
the present study, tar-containing wastewater was treated using lime
and alum for the removal of in-organics, followed by adsorption on
powdered activated carbon (PAC) for the removal of organics. Limealum
experiments were performed in a jar apparatus and activated
carbon studies were performed in an orbital shaker. At optimum
concentrations, both lime and alum individually proved to be capable
of removing color, total suspended solids (TSS) and total dissolved
solids (TDS), but in both cases, pH adjustment had to be carried out
after treatment. The combination of lime and alum at the dose ratio
of 0.8:0.8 g/L was found to be optimum for the removal of inorganics.
The removal efficiency achieved at optimum
concentrations were 78.6, 62.0, 62.5 and 52.8% for color, alkalinity,
TSS and TDS, respectively. The major advantages of the lime-alum
combination were observed to be as follows: no requirement of pH
adjustment before and after treatment and good settleability of
sludge. Coagulation-precipitation followed by adsorption on PAC
resulted in 92.3% chemical oxygen demand (COD) removal and
100% phenol removal at equilibrium. Ammonia removal efficiency
was found to be 11.7% during coagulation-flocculation and 36.2%
during adsorption on PAC. Adsorption of organics on PAC in terms
of COD and phenol followed Freundlich isotherm with Kf = 0.55 &
18.47 mg/g and n = 1.01 & 1.45, respectively. This technology may
prove to be one of the fastest and most techno-economically feasible
methods for the treatment of tar-containing wastewater generated
from BGPs.
Abstract: Camptothecin (CPT) is a cytotoxic quinoline alkaloid,
which inhibits the DNA enzyme topoisomerase I (topo I). It was
discovered in 1966 by M. E. Wall and M. C. Wani in systematic
screening of natural products for anticancer drugs. It was isolated
from the bark and stem of Camptotheca acuminata (Camptotheca,
Happy tree), a tree native in China. CPT showed remarkable
anticancer activity in preliminary clinical trials but also low
solubility and (high) adverse drug reaction. Because of these
disadvantages synthetic and medicinal chemists have developed
numerous syntheses of Camptothecine [1][2][3] and various
derivatives to increase the benefits of the chemical, with good results.
In our method CPT analogues has be six steps starting from available
material DL Malic acid.
Abstract: This paper presents the prediction of air flow,
humidity and temperature patterns in a co-current pilot plant spray
dryer fitted with a pressure nozzle using a three dimensional model.
The modelling was done with a Computational Fluid Dynamic
package (Fluent 6.3), in which the gas phase is modelled as
continuum using the Euler approach and the droplet/ particle phase is
modelled by the Discrete Phase model (Lagrange approach).Good
agreement was obtained with published experimental data where the
CFD simulation correctly predicts a fast downward central flowing
core and slow recirculation zones near the walls. In this work, the
effects of the air flow pattern on droplets trajectories, residence time
distribution of droplets and deposition of the droplets on the wall also
were investigated where atomizing of maltodextrin solution was
used.
Abstract: Calcite aCalcite and aragonite are the two common
polymorphs of CaCO3 observed as biominerals. It is universal that
the sea water contents a high Mg2+ (50mM) relative to Ca2+ (10mM).
In vivo crystallization, Mg2+ inhibits calcite formation. For this
reason, stony corals skeleton may be formed only aragonite crystals
in the biocalcification. It is special in case of soft corals of which
formed only calcite crystal; however, this interesting phenomenon,
still uncharacterized in the marine environment, has been explored in
this study using newly purified cell-free proteins isolated from the
endoskeletal sclerites of soft coral. By recording the decline of pH in
vitro, the control of CaCO3 nucleation and crystal growth by the cellfree
proteins was revealed. Using Atomic Force Microscope, here we
find that these endoskeletal cell-free proteins significantly design the
morphological shape in the molecular-scale kinetics of crystal
formation and those proteins act as surfactants to promote ion
attachment at calcite steps.nd aragonite are the two common polymorphs of CaCO3 observed as biominerals. It is universal that the sea water contents a high Mg2+ (50mM) relative to Ca2+ (10mM). In vivo crystallization, Mg2+ inhibits calcite formation. For this reason, stony corals skeleton may be formed only aragonite crystals in the biocalcification. It is special in case of soft corals of which formed only calcite crystal; however, this interesting phenomenon, still uncharacterized in the marine environment, has been explored in this study using newly purified cell-free proteins isolated from the endoskeletal sclerites of soft coral. By recording the decline of pH in vitro, the control of CaCO3 nucleation and crystal growth by the cell-free proteins was revealed. Using Atomic Force Microscope, here we find that these endoskeletal cell-free proteins significantly design the morphological shape in the molecular-scale kinetics of crystal formation and those proteins act as surfactants to promote ion attachment at calcite steps. KeywordsBiomineralization, Calcite, Cell-free protein, Soft coral
Abstract: The ability of agricultural and decorative plants to
absorb and detoxify TNT and RDX has been studied. All tested 8
plants, grown hydroponically, were able to absorb these explosives
from water solutions: Alfalfa > Soybean > Chickpea> Chikling vetch
>Ryegrass > Mung bean> China bean > Maize. Differently from
TNT, RDX did not exhibit negative influence on seed germination
and plant growth. Moreover, some plants, exposed to RDX
containing solution were increased in their biomass by 20%. Study of
the fate of absorbed [1-14ðí]-TNT revealed the label distribution in
low and high-molecular mass compounds, both in roots and above
ground parts of plants, prevailing in the later. Content of 14ðí in lowmolecular
compounds in plant roots are much higher than in above
ground parts. On the contrary, high-molecular compounds are more
intensively labeled in aboveground parts of soybean. Most part (up to
70%) of metabolites of TNT, formed either by enzymatic reduction
or oxidation, is found in high molecular insoluble conjugates.
Activation of enzymes, responsible for reduction, oxidation and
conjugation of TNT, such as nitroreductase, peroxidase,
phenoloxidase and glutathione S-transferase has been demonstrated.
Among these enzymes, only nitroreductase was shown to be induced
in alfalfa, exposed to RDX. The increase in malate dehydrogenase
activities in plants, exposed to both explosives, indicates
intensification of Tricarboxylic Acid Cycle, that generates reduced
equivalents of NAD(P)H, necessary for functioning of the
nitroreductase. The hypothetic scheme of TNT metabolism in plants
is proposed.
Abstract: A homologous series of aromatic esters, 4-nalkanoyloxybenzylidene-
4--bromoanilines, nABBA,
consisting of two 1,4-disubstituted phenyl cores and a Schiff
base central linkage was synthesized. All the members can be
differed by the number of carbon atoms at terminal
alkanoyloxy chain (CnH2n-1COO-, n = 2, 6, 18). The molecular
structure of nABBA was confirmed with infrared
spectroscopy, nuclear magnetic resonance (NMR)
spectroscopy and electron-ionization mass (EI-MS)
spectrometry. Mesomorphic properties were studied using
differential scanning calorimetry and polarizing optical
microscopy.
Abstract: ZnO nanostructure were synthesized via microwave
method using zinc acetate as starting material, guanidinium as
structure directing agents, and water as solvent.. This work
investigates the photodegradation of azo dyes using the ZnO Flowerlike
in aqueous solutions. As synthesized ZnO samples were
characterized using X-Ray powder diffraction (XRD), scanning
electron microscopy (SEM), and FTIR spectroscopy.In this work
photodecolorization of congored azo dye under UV irradiation by
nano ZnO was studied.
Abstract: The persistent nature of perfluorochemicals (PFCs) has attracted global concern in recent years. Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are the most commonly found PFC compounds, and thus their fate and transport play key roles in PFC distribution in the natural environment. The kinetic behavior of PFOS or PFOA on boehmite consists of a fast adsorption process followed by a slow adsorption process which may be attributed to the slow transport of PFOS or PFOA into the boehmite pore surface. The adsorption isotherms estimated the maximum adsorption capacities of PFOS and PFOA on boehmite as 0.877 μg/m2 and 0.633 μg/m2, with the difference primarily due to their different functional groups. The increase of solution pH led to a moderate decrease of PFOS and PFOA adsorption, owing to the increase of ligand exchange reactions and the decrease of electrostatic interactions. The presence of NaCl in solution demonstrated negative effects for PFOS and PFOA adsorption on boehmite surfaces, with potential mechanisms being electrical double layer compression, competitive adsorption of chloride.