Abstract: A simple method for the simultaneous determination
of hippuric acid and benzoic acid in urine using reversed-phase high
performance liquid chromatography was described. Chromatography
was performed on a Nova-Pak C18 (3.9 x 150 mm) column with a
mobile phase of mixed solution methanol: water: acetic acid
(20:80:0.2) and UV detection at 254 nm. The calibration curve was
linear within concentration range at 0.125 to 6.0 mg/ml of hippuric
acid and benzoic acid. The recovery, accuracy and coefficient
variance of hippuric acid were 104.54%, 0.2% and 0.2% respectively
and for benzoic acid were 98.48%, 1.25% and 0.60% respectively.
The detection limit of this method was 0.01ng/l for hippuric acid and
0.06ng/l for benzoic acid. This method has been applied to the
analysis of urine samples from the suspected of toluene abuser or
glue sniffer among secondary school students at Johor Bahru.
Abstract: This work considered the thermodynamic feasibility
of scrubbing volatile organic compounds into biodiesel in view of
designing a gas treatment process with this absorbent. A detailed
vapour – liquid equilibrium investigation was performed using the
original UNIFAC group contribution method. The four biodiesels
studied in this work are methyl oleate, methyl palmitate, methyl
linolenate and ethyl stearate. The original UNIFAC procedure was
used to estimate the infinite dilution activity coefficients of 13
selected volatile organic compounds in the biodiesels. The
calculations were done at the VOC mole fraction of 9.213x10-8. Ethyl
stearate gave the most favourable phase equilibrium. A close
agreement was found between the infinite dilution activity coefficient
of toluene found in this work and those reported in literature.
Thermodynamic models can efficiently be used to calculate vast
amount of phase equilibrium behaviour using limited number of
experimental data.
Abstract: Abstract–Indoor air (VOCs) samples were collected
simultaneously from variety of indoors (e.g. living rooms, baby-s
rooms) and outdoor environments which were voluntarily selected
from the houses in which pregnant residents live throughout Ankara.
This is the first comprehensive study done in Turkey starting from
prenatal period and continued till the babies had one year old. VOCs
levels were measured over 76 homes. Air samples were collected in
Tenax TA sorbent filled tubes with active sampling method and
analyzed with Thermal Desorber and Gas Chromatography/Mass
spectrometry (TD-GC/MS). At the first sampling period in the baby-s
rooms maximum concentration of toluene was measured about
240.77μg.m-3 and in the living rooms maximum concentration of
naphthalene was 180.24μg.m-3. At the second sampling period in the
baby-s rooms maximum concentration of toluene was measured
about 144.97μg.m-3 and in the living rooms maximum concentration
of naphthalene was 247.89μg.m-3. Concentration of TVOCs in the
first period was generally higher than the second period.
Abstract: Modeling transfer phenomena in several chemical
engineering operations leads to the resolution of partial differential
equations systems. According to the complexity of the operations
mechanisms, the equations present a nonlinear form and analytical
solution became difficult, we have then to use numerical methods
which are based on approximations in order to transform a
differential system to an algebraic one.Finite element method is one
of numerical methods which can be used to obtain an accurate
solution in many complex cases of chemical engineering.The packed
columns find a large application like contactor for liquid-liquid
systems such solvent extraction. In the literature, the modeling of this
type of equipment received less attention in comparison with the
plate columns.A mathematical bidimensionnal model with radial and
axial dispersion, simulating packed tower extraction behavior was
developed and a partial differential equation was solved using the
finite element method by adopting the Galerkine model. We
developed a Mathcad program, which can be used for a similar
equations and concentration profiles are obtained along the column.
The influence of radial dispersion was prooved and it can-t be
neglected, the results were compared with experimental concentration
at the top of the column in the extraction system:
acetone/toluene/water.
Abstract: This work proposes an optical fiber system (OF) for
sensing various volatile organic compounds (VOCs) in human breath
for the diagnosis of some metabolic disorders as a non-invasive
methodology. The analyzed VOCs are alkanes (i.e., ethane, pentane,
heptane, octane, and decane), and aromatic compounds (i.e., benzene,
toluene, and styrene). The OF displays high analytical performance
since it provides near real-time responses, rapid analysis, and low
instrumentation costs, as well as it exhibits useful linear range and
detection limits; the developed OF sensor is also comparable to a
reference methodology (gas chromatography-mass spectrometry) for
the eight tested VOCs.
Abstract: Polylactic acid-g-polyvinyl acetate (PLLA-g-PVAc)
was used as a compatibilizer for 50/50 starch/PLLA blend. PLLA-g-
PVAc with different mol% of PVAc contents were prepared by
grafting PVAc onto PLLA backbone via free radical polymerization
in solution process. Various conditions such as type and the amount
of initiator, monomer concentration, polymerization time and
temperature were studied. Results showed that the highest mol% of
PVAc grafting (16 mol%) was achieved by conducting graft
copolymerization in toluene at 110°C for 10 h using DCP as an
initiator. Chemical structure of the PVAc grafted PLLA was
confirmed by 1H NMR. Blending of modified starch and PLLA in the
presence compatibilizer with different amounts and mol% PVAc was
acquired using internal mixer at 160°C for 15 min. Effects of PVAc
content and the amount of compatibilizer on mechanical properties of
polymer blend were studied. Results revealed that tensile strength and
tensile modulus of polymer blend with higher PVAc grafting content
compatibilizer showed better properties than that of lower PVAc
grafting content compatibilizer. The amount of compatibilizer was
found optimized in the range of 0.5-1.0 Wt% depending on the mol%
PVAc.
Abstract: A Rotary Disc Contactor with inner diameter of
9.1cm and maximum operating height of 40cm has been used to
investigate break up phenomenon. Water-Toluene, Water as
continuous phase and Toluene as dispersed phase, was selected as
chemical system in the experiments. The mentioned chemical system
has high interfacial tension so it was possible to form big drops
which permit accurate investigation on break up phenomenon as well
as the first and second critical rotor speeds.
In this study, Break up phenomenon has been studied as a function
of mother drop size, rotor speed and continuous phase height. Further
more; the effects of mother drop size and continuous phase height on
the first and second critical rotor speeds were investigated. Finally,
two modified correlations were proposed to estimate the first and
second critical speeds.
Abstract: Distillation column is one of the most common
operations in process industries and is while the most expensive unit
of the amount of energy consumption. Many ideas have been
presented in the related literature for optimizing energy consumption
in distillation columns. This paper studies the different heat
integration methods in a distillation column which separate Benzene,
Toluene, Xylene, and C9+. Three schemes of heat integration
including, indirect sequence (IQ), indirect sequence with forward
energy integration (IQF), and indirect sequence with backward
energy integration (IQB) has been studied in this paper. Using
shortcut method these heat integration schemes were simulated with
Aspen HYSYS software and compared with each other with
regarding economic considerations. The result shows that the energy
consumption has been reduced 33% in IQF and 28% in IQB in
comparison with IQ scheme. Also the economic result shows that the
total annual cost has been reduced 12% in IQF and 8% in IQB
regarding with IQ scheme. Therefore, the IQF scheme is most
economic than IQB and IQ scheme.
Abstract: Experimental liquid-liquid equilibra of butan-2-ol -
ethanol -water; pentan-1-ol - ethanol - water and toluene - acetone -
water ternary systems were investigated at (25oC). The reliability of
the experimental tie-line data was ascertained by using Othmer-Tobias
and Hand plots. The distribution coefficients (D) and separation
factors (S) of the immiscibility region were evaluated for the three
systems.
Abstract: The present work presents the extraction of copper(II)
from sulphuric acid solutions with Sodium diethyldithiocarbamate
(SDDT), and six different organic diluents: Dichloromethane,
Chloroform, Carbon tetrachloride, Toluene, xylene and Cyclohexane,
were tested. The pair SDDT/Chloroform showed to be the most
selective in removing the copper cations, and hence was considered
throughout the experimental study.
The effects of operating parameters such as the initial concentration
of the extracting agent, the agitation time, the agitation speed and the
acid concentration were considered.
For an initial concentration of Cu (II) of 63 ppm in a 0.5 M sulphuric
acid solution, both with a mass of the extracting agent of 20 mg, an
extraction percentage of about 97.8 % and a distribution coefficient
of 44.42 were obtained, respectively, confirming the performance
of the SDDT-Chloroform pair.
Abstract: The paper considers the effect of feed plate location
on the interactions in a seven plate binary distillation column. The
mathematical model of the distillation column is deduced based on
the equations of mass and energy balances for each stage, detailed
model for both reboiler and condenser, and heat transfer equations.
The Dynamic Relative Magnitude Criterion, DRMC is used to assess
the interactions in different feed plate locations for a seven plate
(Benzene-Toluene) binary distillation column ( the feed plate is
originally at stage 4). The results show that whenever we go far from
the optimum feed plate position, the level of interaction augments.
Abstract: Regenerative Thermal Oxidizer (RTO) is one of the
best solutions for removal of Volatile Organic Compounds (VOC)
from industrial processes. In the RTO, VOC in a raw gas are usually
decomposed at 950-1300 K and the combustion heat of VOC is
recovered by regenerative heat exchangers charged with ceramic
honeycombs. The optimization of the treatment of VOC leads to the
reduction of fuel addition to VOC decomposition, the minimization of
CO2 emission and operating cost as well.
In the present work, the thermal efficiency of the RTO was
investigated experimentally in a pilot-scale RTO unit using toluene as
a typical representative of VOC. As a result, it was recognized that the
radiative heat transfer was dominant in the preheating process of a raw
gas when the gas flow rate was relatively low. Further, it was found
that a minimum heat exchanger volume to achieve self combustion of
toluene without additional heating of the RTO by fuel combustion was
dependent on both the flow rate of a raw gas and the concentration of
toluene. The thermal efficiency calculated from fuel consumption and
the decomposed toluene ratio, was found to have a maximum value of
0.95 at a raw gas mass flow rate of 1810 kg·h-1 and honeycombs height
of 1.5m.
Abstract: Using plug flow model in conjunction with
experimental solute concentration profiles, overall volumetric mass
transfer coefficient based on continuous phase (Koca), in a packed
liquid-liquid extraction column has been optimized. Number of 12
experiments has been done using standard system of water/acid
acetic/toluene in a 6 cm diameter, 120 cm height column. Thorough
consideration of influencing parameters we intended to correlate
dimensionless parameters in term of overall Sherwood number which
has an acceptable average error of about 15.8%.
Abstract: REY area has been located in Tehran Province and several archaeological ruins of this area indicate that the settlement in this area has been started since several thousand years ago. In this paper, the main investigation items consist of analysis of oil components and groundwater quality inside the wells. By finding the contents of oil in the well, it is possible to find out the pollution source by comparing the oil contents of well with other oil products that are used inside and outside of the oil farm. Investigation items consist of analysis of BTEX (Benzene, Toluene, Ethyl-benzene, Xylene), Gas chromatographic distillation characteristics, Water content, Density, Sulfur content, Lead content, Atmospheric distillation, MTBE(Methyl tertiary butyl ether). Analysis of polluting oil components showed that except MW(Monitoring Well)10 and MW 15 that oil with slightly heavy components was detected in them; with a high possibility the polluting oil is light oil.
Abstract: Polymeric microreactors have emerged as a new
generation of carriers that hold tremendous promise in the areas of
cancer therapy, controlled delivery of drugs, for removal of
pollutants etc. Present work reports a simple and convenient
methodology for synthesis of polystyrene and poly caprolactone
microreactors. An aqueous suspension of carboxylated (1μm)
polystyrene latex particles was mixed with toluene solution followed
by freezing with liquid nitrogen. Freezed particles were incubated at
-20°C and characterized for formation of voids on the surface of
polymer microspheres by Field Emission Scanning Electron
Microscope. The hollow particles were then overnight incubated at
40ºC with unfunctionalized quantum dots (QDs) in 5:1 ratio. QDs
Encapsulated polystyrene microcapsules were characterized by
fluorescence microscopy.
Likewise Poly ε-caprolactone microreactors were prepared by
micro-volcanic rupture of freeze dried microspheres synthesized
using emulsification of polymer with aqueous Poly vinyl alcohol and
freezed with liquid nitrogen. Microreactors were examined with Field
Emission Scanning Electron Microscope for size and morphology.
Current study is an attempt to create hollow polymer particles which
can be employed for microencapsulation of nanoparticles and drug
molecules.
Abstract: Contamination of aromatic compounds in water can
cause severe long-lasting effects not only for biotic organism but also
on human health. Several alternative technologies for remediation of
polluted water have been attempted. One of these is adsorption
process of aromatic compounds by using organic modified clay
mineral. Porous structure of clay is potential properties for molecular
adsorptivity and it can be increased by immobilizing hydrophobic
structure to attract organic compounds. In this work natural
montmorillonite were modified with cetyltrimethylammonium
(CTMA+) and was evaluated for use as adsorbents of aromatic
compounds: benzene, toluene, and 2-chloro phenol in its single and
multicomponent solution by ethanol:water solvent. Preparation of
CTMA-montmorillonite was conducted by simple ion exchange
procedure and characterization was conducted by using x-day
diffraction (XRD), Fourier-transform infra red (FTIR) and gas
sorption analysis. The influence of structural modification of
montmorillonite on its adsorption capacity and adsorption affinity of
organic compound were studied. It was shown that adsorptivity of
montmorillonite was increased by modification associated with
arrangements of CTMA+ in the structure even the specific surface
area of modified montmorillonite was lower than raw
montmorillonite. Adsorption rate indicated that material has affinity
to adsorb compound by following order: benzene> toluene > 2-chloro
phenol. The adsorption isotherms of benzene and toluene showed 1st
order adsorption kinetic indicating a partition phenomenon of
compounds between the aqueous and organophilic CTMAmontmorillonite.
Abstract: Polyurethane foam (PUF) were prepared by
reacting polyols synthesized from soy-oil into mixture of 2,4-
Toluene diisocyanate (TDI) with 4,4--Methylene Diamine
Isocyanate (MDI) with ratio of 70:30. The polyols obtained
via esterification reaction were categorize into different
temperature of reaction and by used of varied concentration
of phosphoric acid catalyst. The purpose of catalysts is to
shifting selectivity to a desired and value added of product.
The effect of stoichiometric balance (molar ratio of
epoxide/ethylene glycol) to the concentration of the catalyst
on the final properties was evaluated.