الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Organically modified clay minerals (organoclays)
are smectites in which the interlayer inorganic cations,
balancing the negative layer charge, have been replaced
by cationic organic surfactants. The most suitable clay
mineral for modification is the montmorillonite, while the
surfactant is a quaternary ammonium halide with a long
alkyl side chain.
The first step of this work was concerned with raw
clay characterization throughout many techniques. The
chemical composition of the clay powder sample has
been estimated through the quantitative determination of
its constitution oxides using X-ray fluorescence (XRF)
technique. It is observed that the major constituents in the
raw clay were SiO2, Al2O3 and Fe2O3 in a descending
order. The higher SiO2 and lower Al2O3 content are
mainly due to the predominance of montmorillonite clay
mineral as well as the presence of considerable amounts
of quartz (SiO2) and feldspar (alkali alumino- silicates) as
non clay minerals. X-ray diffraction patterns of the bulk
and clay fraction (oriented sample) were observed. The
essential clay minerals were montmorillonite that is
characterized by its strongest d-line (d=12.6 Å,4.50 Å and
3.02 Å and others); Kaolinite mineral, characterized by its
strongest d-line (d=7.14 Å, 4.22 Å and 3.57 Å and
others ); and quartz , characterized by its strongest d-lines
(d=3.34 Å and 4.25 Å and others). In general as shown in
DTA, when this clay mineral is heated at constant rate, the first stage involves the endothermic release of water
adsorbed on the outer and inner surfaces. In the second
stage, i.e. at about 600oC, further endothermic effect
occured, which is related to the release of OH groups
from the octahedral layer of the three-layered structure.
The first endothermic effect is usually attributed to
dehydration and the second to dehydroxylation. The third
stage in the thermal events was characterized by an
endothermic effect followed by an exothermic one
corresponding to the formation of an X-ray-amorphous
product. The obtained particle size distribution of raw
clay sample was 0.86 % sand, 14.44 % silt and 84.70 %
clay. The obtained results were also plotted on Folk’s
clay-silt-sand ternary diagram. It is evident that the raw
clay sample lies in the clay region due to the
predominance of its fine fraction content (99.14%) with
low amount of sand particles (0.86%). The cation
exchange capacity (CEC) for clay determined by
replacement of sodium was found to be 101 mEq/100 g
(according to the specification of its producer). Since the
mEq equal to mg*valence of surfactant divided by its
molecular weight, the amount of CEC is changeable
according to the molecular weight of each surfactant. The
FTIR spectrum spectrum of raw clay exhibited the
characteristic peaks of montmorillonite clay mineral and
didn’t show any intense peaks corresponding to organic
matter.
The second step of this work was concerned with
preparation and characterization of organo-moidifed nanoclays. In this study, a series of organo-modified
nanoclays was synthesized using three different
surfactants having different alkyl chain lengths and
concentrations [0.5–5.0 cation exchange capacity (CEC)].
These surfactants were Ethanolamine (EA), Cetyltrimethylammoniumbromide
(CTAB) and Tetraoctadecylammoniumbromide
(TO). The obtained modified nanoclays
were characterized by X-ray diffraction (XRD),
Fourier Transform Infrared spectroscopy (FTIR) and
Scanning electron microscopy (SEM) and compared with
unmodified nanoclay.
The results of XRD analysis indicated that the
basal d-spacing has increased with increasing alkyl chain
length and surfactant concentration. the infrared spectra
of organo modified nanoclays exhibits the characteristic
peaks of untreated clay with two additional peaks in
range 2920 and 2850 cm-1, which are attributed to the
υCH2 antisymmetric stretching vibration and symmetric
stretching vibration (υCH2) of intercalated surfactants
with clay layer. It is also observed that the changes in
both wave number and intensity of the bands occur as the
CEC increases. In general, the intensity of characteristic
bands at 2920 and 2850 cm-1 is significantly enhanced as
the chain length and concentration of surfactant increased.
from the obtained microstructures of these organomodified
nanoclays, the mechanism of surfactant
adsorption was proposed. At relatively low loading of
surfactant, most of surfactant entered the spacing by an
ion-exchange mechanism and was adsorbed onto the interlayer cation sites. When the concentration of the
surfactant exceeds the CEC of clay, the surfactant
molecules then adhere to the surface adsorbed surfactant.
Some surfactants entered the interlayers, whereas the
others were attached to the clay surface. When the
concentration of surfactant increased further beyond 2.0
CEC, the surfactants might occupy the inter-particle
space within the house-of-cards aggregate structure.
The third step of this work was concerned with the
application of organo-moidifed nanoclays as adsorbent
material for hydrocarbon (gasoline, diesel, and lubricating
oil) from water. In this study, organo-modified nanoclay
(OMNC) was prepared and subjected to removal of
hydrocarbons. Results from this work provided valuable
information on using organoclay as a sorbent for purifying
contaminated water by petroleum hydrocarbon. The
following tests were conducted; 1) the Foster Swelling
Test, this technique was employed to carry out studies on
the compatibility of specific organo-modified nanoclay
(OMNC) that was obtained after the modification with
ammonium quaternary salt (CTAB) with some different
organic liquids. The gasoline, diesel, and lubricating oil
sorption capacity was measured following a method
based on the hydrocarbon-water separation test “Standard
Methods of Testing Sorbent Performance of Adsorbents”
(ASTM F716-82 and ASTM F726-99). The concentration
of hydrocarbon (gasoline, diesel, and lubricating oil)
present in the aqueous phase was determined by chemical
oxygen demand (COD). The best result was for assay 1, the contaminated water with gasoline, reaching the total
hydrocarbon removal percentage as high as 97.32 %.
from the results, organo-moidified nanoclay (OMNC) had
a large capacity to bind organic compounds, including
petroleum hydrocarbons. This mechanism would cause
the retention of oil spill (Hydrocarbons) in the OMNC
structure in a relatively ordered fusion.
The fourth step of this work was concerned with
investigate the effect of thermal activated nanoclay (NC)
with limestone (LS) addition on mechanical properties
and microstructure of composite cements. In this study,
six different mixes compositions were prepared from
starting materials, The benefits of limestone filler (LS)
and natural pozzolana (thermal NC activated at 750 oC) as
partial replacement of Portland cement are well
established. However, both supplementary materials have
certain shortfalls. LS addition to Portland cement causes
an increase of hydration at early ages inducing a high
early strength, but it can reduce the later strength due to
the dilution effect.
On the other hand, Nanoclay (NC) contributes to
hydration after 28 days improving the strength at medium
and later ages. Hence, ternary composite cement (OPC–
LS–NC) with better performance could be produced. In
this study, the effect of nanoclay addition with fixed
addition percent of limestone (5%) on the mechanical
properties and microstructure of composite cement mortar
was investigated. The OPC was partially substituted by
nanoclay (NC) of 0, 2, 4, 6 and 8% by weight of cement.
The fresh composite cement pastes were first cured at
100% relative humidity for 24 hours and then cured in tap
water for 28 days then moved to cured in sea water for 9
months to study the durability of composite cement
samples. The results revealed that the use of ternary
composite cement improves the early age and the longterm
compressive and flexural strengths. Durability was
also enhanced as better sulfate ions penetration resistances
was proved.
Accordingly, the following conclusions could be drawn:-
· The alkyl ammonium cation exchange enables the
conversion of the hydrophilic interior clay surface
into hydrophobic surface and consequently increase
the layer distance as well.
· The basal d-spacing of the organo-modified nanoclay
was proportional to the surfactant concentration and
the alkyl chain length.
· At relatively low loadings of the surfactant (e.g.,
below1.0 CEC), most of the surfactants were
adsorbed into the interlayer spacing. While at
higher loading level, the surfactant molecules may
not only enter the clay interlayers but also may
occupy the inter-particle space within the house-ofcards
aggregate structure. The arrangement of the
intercalated surfactants in the interlayer varies from
lateral-monolayer, to lateral-bilayer, then to paraffintype
monolayer and finally to paraffin-type bilayer.
· The maximum basal d-spacing of the organomodified
nanoclay synthesized with TO (5 CEC)
was 33.6 Å, which was almost two and half the
value of that obtained by EA surfactant.
· Changes in both the wave number and the intensity
of bands in FTIR occur as the CEC increases. In
general, as the chain length of surfactant increased
due to increasing in surfactant concentration from
0.5 to 5 CEC, the intensity of characteristic bands
at 2920 and 2850 cm−1 enhanced significantly with
increasing in surfactant concentration.
· Photomicrographs of unmodified clay are exhibit
massive, aggregated morphology, and in some
instances, some bulky flakes and curved plates
were appeared. On the other hand, organo-modified
nanoclays exhibited that the physical appearance of
the clay particles changed significantly. Gathered
agglomerations with severely curled or crumpled
structures are formed much more easer. With the
increase of surfactant packing density, curved
plates of clay transformed to flat ones.
· Organo-moidified nanoclays (OMNC) exhibited a
high swelling capacity (with agitation) and
intermediate swelling (without agitation) when tested
in gasoline and lub. oil. On the other hand, when
inserted in diesel both without and with agitation, the
treated samples exhibited high swelling capacity.
· Organo-moidified nanoclays (OMNC) adsorbed
more hydrocarbon solvents (Gasoline, Diesel and
Lub.oil) than raw clay. Also, the organo-moidified nanoclay (OMNC) adsorbed more gasoline and
diesel than lub. Oil.
· It is indicated also that the organo-moidified
nanoclay (OMNC) adsorbed hydrocarbons (gasoline
and diesel ) more than 3 times of its weight and more
than 2 times for lub. Oil.
· Organo-moidified nanoclay (OMNC) have a large
capacity to bind organic compounds, including
petroleum hydrocarbons due to clay modification
from hydrophilic to hydrophobic.
· The water of consistency of nanoclay-limestone
cement mixes increased linearly with the increase
of nanoclay (NC) content in pastes.
· The reduction of final setting time of nanoclaylimestone
composite cement pastes may due to the
reaction of hydration product Ca(OH)2 with pozzolanic
material nanoclay (NC) to give more calcium silicate
hydrate (C-S-H).
· The bulk density of the cement composite decreased
with the increase of nanoclay (NC) content. However,
the bulk density for all composites cement pastes are
lower than that of the OPC pastes at all immersing
time. On the other hand, the addition of nanoclay
(NC) with limestone (LS) led to decreasing the total
porosity in comparison with that of OPC paste.
· The results indicated that the compressive strength
for all cement pastes increased with the immersing
time. Generally, the compressive strength of cement
pastes content nanoclay (NC) was higher than that of
OPC at all immersing ages of hydration. This is mainly attributed to the pozzolanic reaction of
nanoclay (NC) with the liberated lime Ca(OH)2
forming more hydration products CSH. The paste
containing 4 % nanoclay (NC) with 5 % limestone
(LS) gave the highest strength at later ages as
compared with the control sample OPC and other
batches pastes.