Abstract: The problem of soil stabilization has been one of the important issues in geotechnical engineering. Nowadays, nanomaterials have revolutionized many industries. In this research, improvement of the Kerman fine-grained soil by nanozeolite and nanobentonite additives separately has been investigated using Atterberg Limits and unconfined compression test. In unconfined compression test, the samples were prepared with 3, 5 and 7% nano additives, with 1, 7 and 28 days curing time with strain control method. Finally, the effect of different percentages of nanozeolite and nanobentonite on the geotechnical behavior and characteristics of Kerman fine-grained soil was investigated. The results showed that with increasing the amount of nanozeolite and also nanobentonite to fine-grained soil, the soil exhibits more compression strength. So that by adding 7% nanozeolite and nanobentonite with 1 day curing, the unconfined compression strength is 1.18 and 2.1 times higher than the unstabilized soil. In addition, the failure strain decreases in samples containing nanozeolite, whereas it increases in the presence of nanobentonite. Increasing the percentage of nanozeolite and nanobentonite also increased the elasticity modulus of soil.
Abstract: Heteropoly acid nanoparticles anchored on graphene oxide based on UiO-66 were synthesized via in-situ growth hydrothermal method and tested for photodegradation of a tetracycline as critical pollutant. Results showed that presence of graphene oxide and UiO-66 with high specific surface area, great electron mobility and various functional groups make an excellent support for heteropoly acid and improve photocatalytic efficiency up to 95% for tetracycline. Furthermore, total organic carbon (TOC) analysis verified 79% mineralization of this pollutant under optimum condition.
Abstract: In order to face current compelling environmental problems affecting the planet, the construction industry needs to adapt. It is widely acknowledged that there is a need for durable, high-performance, low-greenhouse gas emission binders that can be used as an alternative to Portland cement (PC) to lower the environmental impact of construction. Alkali activated materials (AAMs) are considered a more sustainable alternative to PC materials. The binders of AAMs result from the reaction of an alkali metal source and a silicate powder or precursor which can be a calcium silicate or an aluminosilicate-rich material. This paper evaluates the particle size, specific surface area, chemical and mineral composition and amorphousness of silicate materials (most industrial waste locally produced in Ireland and Saudi Arabia) to develop alkali-activated binders that can replace PC resources in specific applications. These include recycled ceramic brick, bauxite, illitic clay, fly ash and metallurgical slag. According to the results, the wastes are reactive and comply with building standards requirements. The study also evidenced that the reactivity of the Saudi bauxite (with significant kaolinite) can be enhanced on thermal activation; and high calcium in the slag will promote reaction; which should be possible with low alkalinity activators. The wastes evidenced variable water demands that will be taken into account for mixing with the activators. Finally, further research is proposed to further determine the reactive fraction of the clay-based precursors.
Abstract: In this study grinding experiments were performed in a laboratory ball mill using Polish ferronickel slag in order to study the effect of the particle size on alkali activation and the properties of the produced alkali activated materials (AAMs). In this regard, the particle size distribution and the specific surface area of the grinding products in relation to grinding time were assessed. The experimental results show that products with high compressive strength, e.g. higher than 60 MPa, can be produced when the slag median size decreased from 39.9 μm to 11.9 μm. Also, finer fractions are characterized by higher reactivity and result in the production of AAMs with lower porosity and better mechanical properties.
Abstract: Alkali-active sandstone aggregate was ground by vertical and ball mill into particles with residue over 45 μm less than 12%, and investigations have been launched on particles distribution and characterization of ground sandstone powder, fluidity, heat of hydration, strength as well as hydration products morphology of pastes with incorporation of ground sandstone powder. Results indicated that ground alkali-active sandstone powder with residue over 45 μm less than 8% was easily obtainable, and specific surface area was more sensitive to characterize its fineness with extension of grinding length. Incorporation of sandstone powder resulted in higher water demand and lower strength, advanced hydration of C3A and C2S within 3days and refined pore structure. Based on its manufacturing, characteristics and influence on properties of pastes, it was concluded that sandstone powder was a good selection for use in concrete as mineral admixture.
Abstract: The fly ash of waste incineration processes is usually hazardous and the disposal or reuse of waste incineration fly ash is difficult. In this study, the waste incineration fly ash was converted to useful zeolites by the alkali fusion and hydrothermal synthesis method. The influence of different operating conditions (the ratio of Si/Al, the ratio of hydrolysis liquid to solid, and hydrothermal time) was investigated to seek the optimum operating conditions for the synthesis of zeolite from waste incineration fly ash. The results showed that concentrations of heavy metals in the leachate of Toxicity Characteristic Leaching Procedure (TCLP) were all lower than the regulatory limits except lead. The optimum operating conditions for the synthesis of zeolite from waste incineration fly ash by the alkali fusion and hydrothermal synthesis method were Si/Al=40, NaOH/ash=1.5, alkali fusion at 400 oC for 40 min, hydrolysis with Liquid to Solid ratio (L/S)= 200 at 105 oC for 24 h, and hydrothermal synthesis at 105 oC for 24 h. The specific surface area of fly ash could be significantly increased from 8.59 m2/g to 651.51 m2/g (synthesized zeolite). The influence of different operating conditions on the synthesis of zeolite from waste incineration fly ash followed the sequence of Si/Al ratio > hydrothermal time > hydrolysis L/S ratio. The synthesized zeolites can be reused as good adsorbents to control the air or wastewater pollutants. The purpose of fly ash detoxification, reduction and waste recycling/reuse is achieved successfully.
Abstract: The deployable descent technology is a lightweight entry method using an inflatable heat shield. The heatshield consists of a pressurized core which is covered by different layers of thermal insulation and flexible ablative materials in order to protect against the thermal loads. In this paper, both aluminum and silicon-aluminum aerogels were prepared by freeze-drying method. The latter material has bigger specific surface area and nano-scale pores. Mullite fibers are used as the reinforcing fibers to prepare the aerogel matrix to improve composite flexibility. The flexible composite materials were performed as an insulation layer to an underlying aramid fabric by a thermal shock test at a heat flux density of 120 kW/m2 and uniaxial tensile test. These results show that the aramid fabric with untreated mullite fibers as the thermal protective layer is completely carbonized at the heat of about 60 s. The aramid fabric as a thermal resistance layer of the composite material still has good mechanical properties at the same heat condition.
Abstract: Activated carbon DSAC36-24 iy is adsorbent materials, characterized by a specific surface area of 548.13 m²g⁻¹. Their manufacture uses the natural raw materials like the nucleus of dates. In this study the treatment is done in two stages: A chemical treatment by H3PO4 followed by a physical treatment under nitrogen for 1 hour then under stream of CO2 for 24 hours. A characterization of the various parameters was determined such as the measurement of the specific surface area, determination of pHPZC, bulk density, iodine value. The study of the adsorption of organic molecules (hydroquinone, paranitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol) indicates that the adsorption phenomena are essentially due to the van der Waals interaction. In the case of organic molecules carrying the polar substituents, the existence of hydrogen bonds is also proved by the donor-acceptor forces. The study of the pH effect was done with modeling by different models (Langmuir, Freundlich, Langmuir-Freundlich, Redlich-Peterson), a kinetic treatment is also followed by the application of Lagergren, Weber, Macky.
Abstract: The objective of this research is to study the physical and mechanical properties and durability of self-compacting mortars prepared by substituting a part of cement up to a percentage of 30% pozzolan according to different Blaine specific surface area (SSB1=7000 cm2/g and SSB=9000 cm2/g)). Order to evaluate durability, mortars were subjected to chemical attacks in various aggressive environments, a solution of a mixture of nitric acid and ammonium nitrate (HNO3 + NH4NO3) and a magnesium sulfate salt solution (MgSO4)) with a concentration of 10%, for a period of one month. This study is complemented by a comparative study of the durability of mortars elaborated with sulphate resistant cement (SRC). The results show that these mortars develop long-term, mechanical and chemical resistance better than mortars based Portland cement with 5% gypsum (CEM 1) and SRC. We found that the mass losses are lowest in mortars elaborated with pozzolanic cement (30% substitution with SSB2) in both of chemical attack solutions (3.28% in the solution acid and 1.16% in the salt solution) and the compressive strength gains of 14.68% and 8.5% respectively in the two media. This is due to the action of pozzolan which fixes portlandite to form hydrated calcium silicate (CSH) from the hydration of tricalcic silicate (C3S).
Abstract: Thermal insulating composites help to reduce the total power consumption in a building by creating a barrier between external and internal environment. Such composites can be used in the roofing tiles or wall panels for exterior surfaces. This study purposes to develop lightweight cement-based composites for thermal insulating applications. Waste materials like silica fume (an industrial by-product) and fly ash cenosphere (FAC) (hollow micro-spherical shells obtained as a waste residue from coal fired power plants) were used as partial replacement of cement and lightweight filler, respectively. Moreover, aerogel, a nano-porous material made of silica, was also used in different dosages for improved thermal insulating behavior, while poly vinyl alcohol (PVA) fibers were added for enhanced toughness. The raw materials including binders and fillers were characterized by X-Ray Diffraction (XRD), X-Ray Fluorescence spectroscopy (XRF), and Brunauer–Emmett–Teller (BET) analysis techniques in which various physical and chemical properties of the raw materials were evaluated like specific surface area, chemical composition (oxide form), and pore size distribution (if any). Ultra-lightweight cementitious composites were developed by varying the amounts of FAC and aerogel with 28-day unit weight ranging from 1551.28 kg/m3 to 1027.85 kg/m3. Excellent mechanical and thermal insulating properties of the resulting composites were obtained ranging from 53.62 MPa to 8.66 MPa compressive strength, 9.77 MPa to 3.98 MPa flexural strength, and 0.3025 W/m-K to 0.2009 W/m-K as thermal conductivity coefficient (QTM-500). The composites were also tested for peak temperature difference between outer and inner surfaces when subjected to heating (in a specially designed experimental set-up) by a 275W infrared lamp. The temperature difference up to 16.78 oC was achieved, which indicated outstanding properties of the developed composites to act as a thermal barrier for building envelopes. Microstructural studies were carried out by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) for characterizing the inner structure of the composite specimen. Also, the hydration products were quantified using the surface area mapping and line scale technique in EDS. The microstructural analyses indicated excellent bonding of FAC and aerogel in the cementitious system. Also, selective reactivity of FAC was ascertained from the SEM imagery where the partially consumed FAC shells were observed. All in all, the lightweight fillers, FAC, and aerogel helped to produce the lightweight composites due to their physical characteristics, while exceptional mechanical properties, owing to FAC partial reactivity, were achieved.
Abstract: Recently, copper and manganese-containing systems are recognized as active and selective catalysts in many oxidation reactions. The main idea of this study is to obtain more information about γ-Al2O3 supported Cu-La catalysts and to evaluate their activity to simultaneous oxidation of CO, CH3OH and dimethyl ether (DME). The catalysts were synthesized by impregnation of support with a mixed aqueous solution of nitrates of copper, manganese and lanthanum under different conditions. XRD, HRTEM/EDS, TPR and thermal analysis were performed to investigate catalysts’ bulk and surface properties. The texture characteristics were determined by Quantachrome Instruments NOVA 1200e specific surface area and pore analyzer. The catalytic measurements of single compounds oxidation were carried out on continuous flow equipment with a four-channel isothermal stainless steel reactor in a wide temperature range. On the basis of XRD analysis and HRTEM/EDS, it was concluded that the active component of the mixed Cu-Mn-La/γ–alumina catalysts strongly depends on the Cu/Mn molar ratio and consisted of at least four compounds – CuO, La2O3, MnO2 and Cu1.5Mn1.5O4. A homogeneous distribution of the active component on the carrier surface was found. The chemical composition strongly influenced catalytic properties. This influence was quite variable with regards to the different processes.
Abstract: Recovering resources from water purification sludge
(WPS) have been gradually stipulated in environmental protection
laws and regulations in many nations. Hence, reusing the WPS is
becoming an important topic, and recovering alum from WPS is one of
the many practical alternatives. Most previous research efforts have
been conducted on studying the amphoteric characteristic of aluminum
hydroxide for investigating the optimum pH range to dissolve the
Al(III) species from WPS, but it has been lack of reaction kinetics or
mechanisms related discussion. Therefore, in this investigation, water
purification sludge (WPS) solution was broken by ultrasound to make
particle size of reactants smaller, specific surface area larger.
According to the reaction kinetics, these phenomena let the dissolved
aluminum salt quantity increased and the reaction rate go faster.
Abstract: In recent research copper and manganese systems
were found to be the most active in CO and organic compounds
oxidation among the base catalysts. The mixed copper manganese
oxide has been widely studied in oxidation reactions because of their
higher activity at low temperatures in comparison with single oxide
catalysts. The results showed that the formation of spinel
CuxMn3−xO4 in the oxidized catalyst is responsible for the activity
even at room temperature. That is why the most of the investigations
are focused on the hopcalite catalyst (CuMn2O4) as the best coppermanganese
catalyst. Now it’s known that this is true only for CO
oxidation, but not for mixture of CO and VOCs. The purpose of this
study is to investigate the alumina supported copper-manganese
catalysts with different Cu/Mn molar ratio in terms of oxidation of
CO, methanol and dimethyl ether. The catalysts were prepared by impregnation of γ-Al2O3 with
copper and manganese nitrates and the catalytic activity
measurements were carried out in two stage continuous flow
equipment with an adiabatic reactor for simultaneous oxidation of all
compounds under the conditions closest possible to the industrial. Gas
mixtures on the input and output of the reactor were analyzed with a
gas chromatograph, equipped with FID and TCD detectors. The
texture characteristics were determined by low-temperature (- 196oС)
nitrogen adsorption in a Quantachrome Instruments NOVA 1200e
(USA) specific surface area & pore analyzer. Thermal, XRD and
TPR analyses were performed. It was established that the active component of the mixed Cu-
Mn/γ–alumina catalysts strongly depends on the Cu/Mn molar ratio.
Highly active alumina supported Cu-Mn catalysts for CO, methanol
and DME oxidation were synthesized. While the hopcalite is the best
catalyst for CO oxidation, the best compromise for simultaneous
oxidation of all components is the catalyst with Cu/Mn molar ratio
1:5.
Abstract: Silica was extracted from agriculture waste rice husk
ash (RHA) and was used as the silica source for synthesis of
RMCM-48 and RSBA-16. An alkali fusion process was utilized to
separate silicate supernatant and the sediment effectively. The
CTAB/Si and F127/Si molar ratio was employed to control the
structure properties of the obtained RMCM-48 and RSBA-16
materials. The N2 adsorption-desorption results showed the
micro-mesoporous RSBA-16 possessed high specific surface areas
(662-1001 m2/g). All the obtained RSBA-16 materials were applied as
the adsorbents for acetone adsorption. And the breakthrough tests
clearly revealed that the RSBA-16(0.004) materials could achieve the
highest acetone adsorption capacity of 181 mg/g under 1000 ppmv
acetone vapor concentration at 25oC, which was also superior to
ZSM-5 (71mg/g) and MCM-41 (157mg/g) under same test conditions.
This can help to reduce the solid waste and the high adsorption
performance of the obtained materials could consider as potential
adsorbents for acetone adsorption.
Abstract: In this article a comparison was made between Cu and
TiO2 supported catalysts on activated carbon for ozone
decomposition reaction. The activated carbon support in the case of
TiO2/AC sample was prepared by physicochemical pyrolysis and for
Cu/AC samples the supports are chemically modified carbons. The
prepared catalysts were synthesized by impregnation method. The
samples were annealed in two different regimes- in air and under
vacuum. To examine adsorption efficiency of the samples BET
method was used. All investigated catalysts supported on chemically
modified carbons have higher specific surface area compared to the
specific surface area of TiO2 supported catalysts, varying in the range
590÷620 m2/g. The method of synthesis of the precursors had
influenced catalytic activity.
Abstract: Alginite has been evaluated as an efficient pollution control material. In this paper, alginite from maar Pinciná (SR) for removal of Cd2+ ions from aqueous solution was studied. The potential sorbent was characterized by X-ray fluorescence analysis (RFA) analysis, Fourier transform infrared spectral analysis (FT-IR) and specific surface area (SSA) was also determined. The sorption process was optimized from the point of initial cadmium concentration effect and effect of pH value. The Freundlich and Langmuir models were used to interpret the sorption behavior of Cd2+ ions, and the results showed that experimental data were well fitted by the Langmuir equation. Alginite maximal sorption capacity (Qmax) for Cd2+ ions calculated from Langmuir isotherm was 34 mg/g. Sorption process was significantly affected by initial pH value in the range from 4.0-7.0. Alginite is a comparable sorbent with other materials for toxic metals removal.
Abstract: In this study, the phase transition characteristics of flame-synthesized γ-Al2O3 nanoparticles to α-Al2O3 have been investigated. The nanoparticles were synthesized by using a coflow hydrogen diffusion flame. The phase transition and particle characteristics of the Al2O3 nanoparticles were determined by examining the crystalline structure and the shape of the collected nanoparticles before and after the heat treatment. The morphology and crystal structure of the Al2O3 nanoparticles were determined from SEM images and XRD analyses, respectively. The measured specific surface area and averaged particle size were 63.44m2/g and 23.94nm, respectively. Based on the scanning electron microscope images and x-ray diffraction patterns, it is believed that the onset temperature of the phase transition to α-Al2O3 was existed near 1200oC. The averaged diameters of the sintered particles heat treated at 1,260oC were approximately 80nm.
Abstract: The objective of this work was to examine the
changes in the microstructure and macro physical properties caused
by the carbonation of normalised CEM II mortar. Samples were
prepared and subjected to accelerated carbonation at 20°C, 65%
relative humidity and 20% CO2 concentration. On the microstructure
scale, the evolutions of the cumulative pore volume, pore size
distribution, and specific surface area during carbonation were
calculated from the adsorption desorption isotherms of nitrogen. We
also examined the evolution of macro physical properties such as the
porosity accessible to water, the gas permeability, and thermal
conductivity. The conflict between the results of nitrogen porosity
and water porosity indicated that the porous domains explored using
these two techniques are different and help to complementarily
evaluate the effects of carbonation. This is a multi-scale study where
results on microstructural changes can help to explain the evolution
of macro physical properties.
Abstract: Aluminum salt that is generally presents as a solid
phase in the water purification sludge (WPS) can be dissolved,
recovering a liquid phase, by adding strong acid to the sludge solution.
According to the reaction kinetics, when reactant is in the form of
small particles with a large specific surface area, or when the reaction
temperature is high, the quantity of dissolved aluminum salt or
reaction rate, respectively are high. Therefore, in this investigation,
water purification sludge (WPS) solution was treated with ultrasonic
waves to break down the sludge, and different acids (1 N HCl and 1 N
H2SO4) were used to acidify it. Acid dosages that yielded the solution
pH of less than two were used. The results thus obtained indicate that
the quantity of dissolved aluminum in H2SO4-acidified solution
exceeded that in HCl-acidified solution. Additionally, ultrasonic
treatment increased the rate of dissolution of aluminum and the
amount dissolved. The quantity of aluminum dissolved at 60℃ was 1.5
to 2.0 times higher than that at 25℃.
Abstract: In our recent study, we have used ZnO nanoparticles assisted with UV light irradiation to investigate the photocatalytic degradation of Phenol Red (PR). The ZnO photocatalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area analysis (BET) and UVvisible spectroscopy. X-ray diffractometry result for the ZnO nanoparticles exhibit normal crystalline phase features. All observed peaks can be indexed to the pure hexagonal wurtzite crystal structures, with the space group of P63mc. There are no other impurities in the diffraction peak. In addition, TEM measurement shows that most of the nanoparticles are rod-like and spherical in shape and fairly monodispersed. A significant degradation of the PR was observed when the catalyst was added into the solution even without the UV light exposure. In addition, the photodegradation increases with the photocatalyst loading. The surface area of the ZnO nanomaterials from the BET measurement was 11.9 m2/g. Besides the photocatalyst loading, the effect of some parameters on the photodegradation efficiency such as initial PR concentration and pH were also studied.