Abstract: Many water desalination technologies have been
developed but in general they are energy intensive and have high cost
and adverse environmental impact. Recently, adsorption technology
for water desalination has been investigated showing the potential of
using low temperature waste heat (50-85oC) thus reducing energy
consumption and CO2 emissions. This work mathematically
compares the performance of an adsorption cycle that produces two
useful effects namely, fresh water and cooling using two different
adsorbents, silica-gel and an advanced zeolite material AQSOA-ZO2,
produced by Mitsubishi plastics. It was found that at low chilled
water temperatures, typically below 20oC, the AQSOA-Z02 is more
efficient than silica-gel as the cycle can produce 5.8 m3 of fresh water
per day and 50.1 Rton of cooling per tonne of AQSOA-ZO2. Above
20oC silica-gel is still better as the cycle production reaches 8.4 m3
per day and 62.4 Rton per tonne of silica-gel. These results show the
potential of using the AQSOA-Z02 at low chilled water temperature
for water desalination and cooling applications.
Abstract: There are several possibilities of reducing the required
amount of cement in concrete production. Natural zeolite is one of
the raw materials which can partly substitute Portland cement. The
effort to reduce the amount of Portland cement used in concrete
production is brings both economical as well as ecological benefits.
The paper presents the properties of concrete containing natural
zeolite as an active admixture in the concrete which partly substitutes
Portland cement. The properties discussed here bring information
about the basic mechanical properties and frost resistance of concrete
containing zeolite. The properties of concretes with the admixture of
zeolite are compared with a reference concrete with no content of
zeolite. The properties of the individual concretes are observed for
360 days.
Abstract: The development of Drugs Delivery System (DDS)
has been widely investigated in the last decades. In this paper, first a
general overview of traditional and modern wound dressing is
presented. This is followed by a review of what scientists have done
in the medical environment, focusing on the possibility to develop a
new alternative for DDS through transdermal pathway, aiming to
treat melanoma skin cancer.
Abstract: Catalytic cracking of butene to propylene was carried out in a continuous-flow fixed-bed reactor over HZSM-5 catalysts modified by nickel and phosphorus. The structure and acidity of catalysts were measured by N2 adsorption, NH3-TPD and XPS. The results revealed that surface area and strong acid sites both decreased with increasing phosphorus loadings. The increment of phosphorus loadings reduced the butene conversion but enhanced the propylene selectivity and catalyst stability.
Abstract: The adsorption efficiency of various adsorbents for the removal of Zn(II) ions from the waste printing developer was studied in laboratory batch mode. The maximum adsorption efficiency of 94.1% was achieved with unfired clay pellets size (d ≈ 15 mm). The obtained values of adsorption efficiency was subjected to the independent-samples t test in order to investigate the statistically significant differences of the investigated adsorbents for the effective removal of Zn(II) ions from the waste printing developer. The most statistically significant differences of adsorption efficiencies for Zn(II) ions removal were obtained between unfired clay pellets (size d ≈ 15 mm) and activated carbon (½t½=6.909), natural zeolite (½t½=10.380), mixture of activated carbon and natural zeolite (½t½=9.865), bentonite (½t½=6.159), fired clay (½t½=6.641), fired clay pellets (size d ≈ 5 mm) (½t½=6.678), fired clay pellets (size d ≈ 8 mm) (½t½=3.422), respectively.
Abstract: This work details the generation of thin films of
structured zeolite catalysts (ZSM–5 and Y) onto the surface of a
metal substrate (FeCrAlloy) using in-situ hydrothermal synthesis. In
addition, the zeolite Y is post-synthetically modified by acidified
ammonium ion exchange to generate US-Y. Finally the catalytic
activity of the structured ZSM-5 catalyst films (Si/Al = 11, thickness
146 0m) and structured US–Y catalyst film (Si/Al = 8, thickness
230m) were compared with the pelleted powder form of ZSM–5 and
USY catalysts of similar Si/Al ratios.
The structured catalyst films have been characterised using a range
of techniques, including X-ray diffraction (XRD), Electron
microscopy (SEM), Energy Dispersive X–ray analysis (EDX) and
Thermogravimetric Analysis (TGA). The transition from oxide-onalloy
wires to hydrothermally synthesised uniformly zeolite coated
surfaces was followed using SEM and XRD. In addition, the
robustness of the prepared coating was confirmed by subjecting these
to thermal cycling (ambient to 550oC).
The cracking of n–heptane over the pellets and structured catalysts
for both ZSM–5 and Y zeolite showed very similar product
selectivities for similar amounts of catalyst with an apparent
activation energy of around 60 kJ mol-1. This paper demonstrates that
structured catalysts can be manufactured with excellent zeolite
adherence and when suitably activated/modified give comparable
cracking results to the pelleted powder forms. These structured
catalysts will improve temperature distribution in highly exothermic
and endothermic catalysed processes.
Abstract: Although properly made concrete is inherently a durable material, there are many physical and chemical forces in the environment which can contribute to its deterioration. This paper deals with two aspects of concrete durability in chemical aggressive environment: degradation effect of particular aggressive exposure and role of particular mineral additives. Results of the study of leaching and acid corrosion processes in samples prepared with specific dosage of microsilica and zeolite are given in the paper.
Corrosion progress after 60-day exposition is manifested by increasing rate of both Ca and Si release, what is identified by XRF method. Kind and dosage of additions used in experiment was found to be helpful for stabilization of concrete microstructure.The lowest concentration of mean elements in leachates was observed for mixture V1 (microsilica only) unlike the V2 (microsilica + zeolite). It is surprising in the terms of recommendations of zeolite application for acid exposure. Using microsilica only seems to be more effective.
Abstract: Concrete durability as an important engineering property of concrete, determining the service life of concrete structures very significantly, can be threatened and even lost due to the interactions of concrete with external environment. Bio-corrosion process caused by presence and activities of microorganisms producing sulphuric acid is a special type of sulphate deterioration of concrete materials. The effects of sulphur-oxidizing bacteria Acidithiobacillus thiooxidans on various concrete samples, based on silica fume and zeolite, were investigated in laboratory during 180 days. A laboratory study was conducted to compare the performance of concrete samples in terms of the concrete deterioration influenced by the leaching of calcium and silicon compounds from the cement matrix. The changes in the elemental concentrations of calcium and silicon in both solid samples and liquid leachates were measured by using X – ray fluorescence method. Experimental studies confirmed the silica fume based concrete samples were found out to have the best performance in terms of both silicon and calcium ions leaching.
Abstract: The coal utilization in thermal power plants in Malaysia has increased significantly which produces an enormous amount of coal combustion by-product (CCBP) or coal ash and poses severe disposal problem. As each coal ash is distinct, this study presents the geochemistry of the coal ash, in particular fly ash, produced from the combustion of local coal from Kuching Sarawak, Malaysia. The geochemical composition of the ash showed a high amount of silica, alumina, iron oxides and alkalies which was found to be a convenient starting material for the hydrothermal synthesis of zeolites with the higher Na2O percentage being a positive factor for its alkaline activation; while the mineral phases are mainly quartz, mullite, calcium oxide, silica, and iron oxide hydrate. The geochemical changes upon alkali activation that can be predicted in a similar type of ash have been described in this paper. The result shows that this particular ash has a good potential for a high value industrial product like zeolites upon alkali activation.
Abstract: This article is presented an experimental and modeling
study of a four-bed pressure swing adsorption process using
zeolite13X to provide oxygen-enriched air. The binary mixture N2/O2
(79/21 vol %) was used as a feed stream. The effects of purge/feed
ratio (P/F), adsorption pressure, cyclic time and product flow rate on
product purity and recovery under nonisothermal condition were
studied. The adsorption dynamics of process were determined using
a mathematical model incorporated mass and energy balances. A
Mathlab code using finite difference method was developed to solve
the set of coupled differential-algebraic equations, and the simulation
results are agreed well with experimental results.
Abstract: Structured catalysts formed from the growth of
zeolites on substrates is an area of increasing interest due to the
increased efficiency of the catalytic process, and the ability to
provide superior heat transfer and thermal conductivity for both
exothermic and endothermic processes.
However, the generation of structured catalysts represents a
significant challenge when balancing the relationship variables
between materials properties and catalytic performance, with the
Na2O, H2O and Al2O3 gel composition paying a significant role in
this dynamic, thereby affecting the both the type and range of
application.
The structured catalyst films generated as part of this
investigation have been characterised using a range of techniques,
including X-ray diffraction (XRD), Electron microscopy (SEM),
Energy Dispersive X-ray analysis (EDX) and Thermogravimetric
Analysis (TGA), with the transition from oxide-on-alloy wires to
hydrothermally synthesised uniformly zeolite coated surfaces being
demonstrated using both SEM and XRD. The robustness of the
coatings has been ascertained by subjecting these to thermal cycling
(ambient to 550oC), with the results indicating that the synthesis time
and gel compositions have a crucial effect on the quality of zeolite
growth on the FeCrAlloy wires.
Finally, the activity of the structured catalyst was verified by a
series of comparison experiments with standard zeolite Y catalysts in
powdered pelleted forms.
Abstract: Silver-exchanged zeolites and clays are used in
polymer composites to confer broad-spectrum antimicrobial
properties on a range of functional materials. Tobermorite is a layer
lattice mineral whose potential as a carrier for Ag+ ions in
antibacterial composites has not yet been investigated. Accordingly,
in this study, synthetic tobermorite was ion-exchanged with 10 wt%
silver ions and the resulting material was incorporated into a
composite film with chitosan. Chitosan is a biocompatible,
biodegradable derivative of chitin, a polysaccharide obtained from
the shells of crustaceans. The solvent-cast Ag+-exchanged
tobermorite-chitosan films were found to exhibit antimicrobial action
against Staphylococcus aureus, Escherichia coli and Pseudomonas
aeruginosa.
Abstract: Oilsands bitumen is an extremely important source of
energy for North America. However, due to the presence of large
molecules such as asphaltenes, the density and viscosity of the
bitumen recovered from these sands are much higher than those of
conventional crude oil. As a result the extracted bitumen has to be
diluted with expensive solvents, or thermochemically upgraded in
large, capital-intensive conventional upgrading facilities prior to
pipeline transport. This study demonstrates that globally abundant
natural zeolites such as clinoptilolite from Saint Clouds, New Mexico
and Ca-chabazite from Bowie, Arizona can be used as very effective
reagents for cracking and visbreaking of oilsands bitumen. Natural
zeolite cracked oilsands bitumen products are highly recoverable (up
to ~ 83%) using light hydrocarbons such as pentane, which indicates
substantial conversion of heavier fractions to lighter components.
The resultant liquid products are much less viscous, and have lighter
product distribution compared to those produced from pure thermal
treatment. These natural minerals impart similar effect on industrially
extracted Athabasca bitumen.
Abstract: Mechanical and water transport properties of high
performance concrete (HPC) containing natural zeolite as partial
replacement of Portland cement are studied. Experimental results
show that in the investigated mixes the use of natural zeolite leads to
an increase of porosity, decrease of compressive strength and
increase of moisture diffusivity and water vapor diffusion coefficient,
as compared with the reference HPC. However, for the replacement
level up to 20% of the mass of Portland cement the concretes still
maintain their high performance character and exhibit acceptable
water transport properties. Therefore, natural zeolite can be
considered an environmental friendly binder with a potential to
replace a part of Portland cement in concrete in building industry.
Abstract: Ammonia nitrogen is one of the most hazardous
water pollutants, discharging into water receptors through industrial
effluents. Negative environmental impacts of such chemical species
in hydrosphere include accelerated eutrophication, water toxicity and
harming the aquatics. Natural zeolite clinoptilolite has very high
selectivity & capacity for ammonium cation sorption. It occurs in
high abundances and rich mines of this zeolite exist in different parts
of Iran and thus are available more cheaply and with different sizing.
The aim of this study is to investigate ammonia nitrogen removal
over this natural sorbent from real samples of high polluted
wastewater discharging from a fertilizer producing plant. The
experimental results showed that this natural sorbent without even
any pre treatment system & with the same particle size available in
Iranian markets has still high capability & selectivity in ammonia
nitrogen removal both in batch and continuous tests.
Abstract: Nitrogen loss from irrigated cropland, particularly
sandy soils, significantly contributes to nitrate (NO3
-) levels in
surface and groundwaters. Thus, it is of great interest to use
inexpensive natural products that can increase the fertilizer efficiency
and decrease nitrate leaching. In this study, the ability of natural
Iranian zeolite clinoptilolite (Cp) and surfactant modified zeolite
clinoptilolite (SMZ) to remove NH4
+ and NO3
-, respectively, from
aqueous solutions was determined. The feasibility of using Cp and
SMZ as soil amendment to reduce nitrate leaching from soil using
lysimeters was also investigated. Zeolite showed 10.23% to 88.42%
NH4
+ removal efficiency over a wide range of initial NH4
+
concentrations. Nitrate removal efficiency by SMZ was 32.26% to
82.26%. Field study results showed that Cp and SMZ significantly (p
< 0.05) reduced leachate NO3-N concentration compared to control.
There was no significant difference between maximum and mean
leachate NO3-N concentration of SMZ lysimeters and those of Cp
lysimeters.
Abstract: Pyrolysis of waste tire is one of alternative technique
to produce petrochemicals, such as light olefins, mixed C4, and monoaromatics.
Noble metals supported on acid zeolite catalysts were
reported as potential catalysts to produce the high valuable products
from waste tire pyrolysis. Especially, Pd supported on HBeta gave a
high yield of olefins, mixed C4, and mono-aromatics. Due to the high
prices of noble metals, the objective of this work was to investigate
whether or not a non-noble Ni metal can be used as a substitute of a
noble metal, Pd, supported on HBeta as a catalyst for waste tire pyrolysis.
Ni metal was selected in this work because Ni has high activity
in cracking, isomerization, hydrogenation and the ring opening of
hydrocarbons Moreover, Ni is an element in the same group as Pd
noble metal, which is VIIIB group, aiming to produce high valuable
products similarly obtained from Pd. The amount of Ni was varied as
5, 10, and 20% by weight, for comparison with a fixed 1 wt% Pd,
using incipient wetness impregnation. The results showed that as a
petrochemical-producing catalyst, 10%Ni/HBeta performed better
than 1%Pd/HBeta because it did not only produce the highest yield of
olefins and cooking gases, but the yields were also higher than
1%Pd/HBeta. 5%Ni/HBeta can be used as a substitute of
1%Pd/HBeta for similar crude production because its crude contains
the similar amounts of naphtha and saturated HCs, although it gave
no concentration of light mono-aromatics (C6-C11) in the oil. Additionally,
10%Ni/HBeta that gave high olefins and cooking gases was
found to give a fairly high concentration of the light mono-aromatics
in the oil.
Abstract: The acidity of different raw Jordanian clays
containing zeolite, bentonite, red and white kaolinite and diatomite
was characterized by means of temperature programmed desorption
(TPD) of ammonia, conversion of 2-methyl-3-butyn-2-ol (MBOH),
FTIR and BET-measurements. FTIR spectra proved presence of
silanol and bridged hydroxyls on the clay surface. The number of
acidic sites was calculated from experimental TPD-profiles. We
observed the decrease of surface acidity correlates with the decrease
of Si/Al ratio except for diatomite. On the TPD-plot for zeolite two
maxima were registered due to different strength of surface acidic
sites. Values of MBOH conversion, product yields and selectivity
were calculated for the catalysis on Jordanian clays. We obtained that
all clay samples are able to convert MBOH into a major product
which is 3-methyl-3-buten-1-yne (MBYNE) catalyzed by acid
surface sites with the selectivity close to 70%. There was found a
correlation between MBOH conversion and acidity of clays
determined by TPD-NH3, i.e. the higher the acidity the higher the
conversion of MBOH. However, diatomite provided the lowest
conversion of MBOH as result of poor polarization of silanol groups.
Comparison of surface areas and conversions revealed the highest
density of active sites for red kaolinite and the lowest for zeolite and
diatomite.
Abstract: Global temperature had increased by about 0.5oC over
the past century, increasing temperature leads to a loss or a decrease
of soil organic matter (SOM). Whereas soil organic matter in many
tropical soils is less stable than that of temperate soils, and it will be
easily affected by climate change. Therefore, conservation of soil
organic matter is urgent issue nowadays. This paper presents the
effect of different doses (5%, 15%) of Ca-type zeolite in conjunction
with organic manure, applied to soil samples from Philippines,
Paraguay and Japan, on the decomposition resistance of soil organic
matter under high temperature. Results showed that a remain or
slightly increase the C/N ratio of soil. There are an increase in
percent of humic acid (PQ) that extracted with Na4P2O7. A decrease
of percent of free humus (fH) after incubation was determined. A
larger the relative color intensity (RF) value and a lower the color
coefficient (6logK) value following increasing zeolite rates leading
to a higher degrees of humification. The increase in the aromatic
condensation of humic acid (HA) after incubation, as indicates by the
decrease of H/C and O/C ratios of HA. This finding indicates that the
use of zeolite could be beneficial with respect to SOM conservation
under global warming condition.
Abstract: The purpose of this study is to investigate the capacity
of natural Turkish zeolite for NH4-N removal from landfill leachate.
The effects of modification and initial concentration on the removal
of NH4-N from leachate were also investigated. The kinetics of
adsorption of NH4-N has been discussed using three kinetic models,
i.e., the pseudo-second order model, the Elovich equation, the
intraparticle diffuion model. Kinetic parameters and correlation
coefficients were determined. Equilibrium isotherms for the
adsorption of NH4-N were analyzed by Langmuir, Freundlich and
Tempkin isotherm models. Langmuir isotherm model was found to
best represent the data for NH4-N.