Aluminosilicate Research Articles

High Rate Response and Dynamic Failure of Aluminosilicate Glass under Compression Loading

The mechanical behavior of un-strengthened aluminosilicate (ALS) glass is studied experimentally by using modified Split Hopkinson pressure bar and electronic universal testing machine. The compression tests on glass specimens are performed at strain-rates in the range of 10− 4 to 102s−1. The compression tests data revealed that ALS glass is strain-rate sensitive vis-à-vis the compressive strength of the glass. In dynamic compression tests, failure process of glass is investigated using a high-speed camera and the failure process in ALS glass is explicated with the associated stress-time history. The initiation of crack, development, and glass debris are discussed to explain the failure process of glass specimens. Test results showed that the axial splitting lead to final rupture of the glass. From both static and dynamic compression tests, the compressive strength, failure strain and energy absorption results for ALS glass specimens are also compared.

Hybrid fuzzy model to predict strength and optimum compositions of natural Alumina-Silica-based geopolymers

This study introduces the supervised committee fuzzy model as a hybrid fuzzy model to predict compressive strength (CS) of geopolymers prepared from alumina-silica products. For this purpose, more than 50 experimental data that evaluated the effect of Al2O3/SiO2, Na2O/Al2O3, Na2O/H2O and Na/[Na+K] on (CS) of geopolymers were collected from the literature. Then, three different Fuzzy Logic (FL) models (Sugeno fuzzy logic (SFL), Mamdani fuzzy logic (MFL), and Larsen fuzzy logic (LFL)) were adopted to overcome the inherent uncertainty of geochemical parameters and to predict CS. After validating the model, it was found that the SFL model is superior to MFL and LFL models, but each of the FL models has advantages to predict CS. Therefore, to achieve the optimal performance, the supervised committee fuzzy logic (SCFL) model was developed as a hybrid method to combine the benefits of individual FL models. The SCFL employs an artificial neural network (ANN) model to re-predict the CS of three FL model predictions. The results also show significant fitting improvement in comparison with individual FL models.

A simple analytical method for the simultaneous determination of multiple organic pollutants in sediment samples

Due to the extensive application of synthetic organic chemicals, the resulting environmental contamination with such chemicals is of great concern. Herein, we describe the development of a simple analytical method to determine several groups of organic compounds in sediment samples. Samples were soxhlet-extracted with dichloromethane, separated, and cleaned-up by passage through a combined column of neutral alumina/silica gel, then identified and determined by GCMS analysis. Four sediment samples were analyzed to validate the efficiency, and acceptable recoveries and good repeatability were obtained.•Combined chromatographic columns of silica gel and alumina have been used for separation and clean-up.•Five groups of organic compounds have been simultaneously analyzed.•Acceptable recoveries with good reproducibility have been achieved.

Applying of hygroscopic materials to dry transformer insulation

The problems related to the effects of high moisture content in the transformer insulation system and the risk resulting from the need for its immediate drying can be avoided by using a non-invasive method of continuous drying of solid insulation by means of high hygroscopic sorbents. The article compared the hygroscopicity of selected sorbents: molecular sieves 3A, 5A and 13X, aluminum oxide and silica gel. It was found that the highest hygroscopicity, for a low value of relative air humidity, is characterized by a 13X molecular sieve. For this reason, this material was selected for further testing by checking its ability to dry mineral oil.

Extraction of Iron values from Red mud

Red mud is an aluminum industry waste generated by Bayer’s process. It contains around 30-50% iron oxide depending upon the quality of bauxite ore used in Bayer’s process Due to its highly caustic-corrosive nature and fine particle size it is considered toxic to the surrounding. In this work, an attempt has been made to achieve a suitable concentrate for iron making. It was found that the carbonation step helps in alkali recovery from red-mud in the form of dissolved sodium aluminate which can be recycled in Bayer’s process. X-Ray diffraction of the carbonated residue of the red-mud system showed that the complex structure of the desilication products i.e., cancrinite and sodalite formed in Bayer’s process dissociates into sodium aluminate, sodium silicate and sodium alumino silicate which improves the iron recovery. Specific pretreatment process with an incorporation of a primary magnetic beneficiation prior to reduction roasting followed by secondary magnetic beneficiation manifest optimal conditions for iron recovery and proved economical in terms of specific consumption of reductant. Carbonated red mud concentrated with magnetic separation followed by muffle furnace roasting using suitable reductant produced a 50.5% iron-rich concentrate with 70% iron recovery. This technique of iron recovery from red-mud consumes two harmful industrial wastes and shows promising results.

Effect of Recycled Calcined Alumino Silicate Content on Properties of Controlled Low-Strength Materials

Effect of Recycled Calcined Alumino Silicate Content on Properties of Controlled Low-Strength Materials

Enhancement of the Fischer–Tropsch process for producing long-chain hydrocarbons on a cobalt–alumina–silica gel catalyst

The effects of the H2/CO ratio, pressure, temperature, and the reaction-gas recycle ratio on the selectivity for hydrocarbons (HCs), including long-chain C35+ HCs, in the Fischer–Tropsch synthesis over a supported industrial cobalt–silica gel catalyst have been studied. The synthesis parameters have been as follows: a pressure of 2.0 or 6.0 MPa, an H2/CO ratio of 1–5, a recycle ratio of 2–6, a temperature of 150–240°C, and a gas hourly space velocity of 1000 h−1. It has been shown that gas recycling provides thermal stability in the catalyst bed, significantly increases the yield of C35+ HCs, and makes it possible to control the group and fractional composition of the synthesis products.

Reversible room temperature ammonia gas absorption in pore water of microporous silica-alumina for sensing applications.

Microporous silica and silica-alumina powders exhibit a reversible uptake and release of ammonia gas from water vapor containing gas mixtures at ambient temperature, with capacities of 0.9 and 2.0 mmol g-1 in the presence of 100 ppm and 1000 ppm NH3, respectively. The ammonia trapping mechanism was revealed using a combination of direct excitation 1H MAS, 1H-1H EXSY and 1H DQ-SQ NMR spectroscopy, indicating that the major part of the captured ammonia is blended in the hydrogen bonded water network in the pores of the adsorbent. A small fraction is irreversibly bound as result of protonation and chemisorption. While common ammonia adsorbents need thermal regeneration, microporous silica-alumina can be regenerated by sweeping with dry gas at ambient temperature, desorbing the physisorbed fraction together with occluded water. As carbon dioxide does not interfere with the ammonia absorption process, this reversible absorption process of ammonia gas at ambient temperature is particularly attractive for sensor applications.

Mesoporous waste-extracted SiO2–Al2O3-supported Ni and Ni–H3PW12O40 nano-catalysts for photo-degradation of methyl orange dye under UV irradiation

Conversion of two type of solid waste to silica–alumina structure that was promoted to a novel photocatalyst for water treatment.

VARIABLE FACTORS CONTROLLING AMORPHOUS-ZEOLITE PHASE TRANSFORMATION IN METAKAOLIN BASED GEOPOLYMER

Metakaolin based geopolymer binder was synthesized using variable factors such as Na2O/SiO2, Na2O/Al2O3 and H2O/Na2O molar ratios as well as curing time. Metakaolin was used as an alumino silicate source incorporating with strong alkali activators; sodium hydroxide solution to undergo polycondenation and hence a formation of hardened geopolymeric binder. This work was aimed to investigate the effect of Na2O/SiO2, Na2O/Al2O3 and H2O/Na2O ratios, as well as curing time on phase transformation. The chemical composition, phase development and microstructure of reaction products were examined by X-ray fluorescence, X-ray diffraction analysis and scanning electron microscopy with respect to their final compressive strength. Increasing the molar ratios of Na2O/Al2O3 and H2O/Na2O tended to favour the transformation of amorphous gel to various types of crystalline zeolite. Sodalite (pseudo-phase zeolite) and zeolite belonging to the Faujasite group, as well as zeolite X and A were identified in these mixtures. Based on this study, systems that favoured the formation of zeolitic products tended to possess lower strengths.

Study on Hydrodesulfurization of L/W Coexistence Zeolite Modified by Magnesium for FCC Gasoline

L/W coexistence zeolite was synthesized with low-cost silica–alumina microspheres via an in situ hydrothermal method and modified by Mg as catalyst additive for FCC gasoline hydro-upgrading. The physicochemical properties of the supports and corresponding catalysts were characterized by means of XRD, SEM, N2 adsorption–desorption, NH3-TPD, Py-IR, H2-TPR, HRTEM, and Raman spectroscopy. The characterization results demonstrated that the L/W composite possessed the typical characteristics of L and W zeolites and that the morphology of L/W coexistence zeolite was completely different from that of the mechanical mixed zeolite. NH3-TPD and Py-IR results showed that the amount of acid sites decreased with an increase in Mg incorporation. Moreover, H2-TPR profiles indicated that Mg regulated the metal–support interaction, which was conducive to the formation of type-II CoMoS phase. With the promoting effects of Mg, Cat-2Mg catalyst exhibited a good balance between hydrodesulfurization (HDS) efficiency (91.4%) and...

Immobilization of toxic inorganic anions (Cr2O72-, MnO4- and Fe(CN)63-) in metakaolin based geopolymers: A preliminary study

Geopolymer (GP) consists of polymeric Al and Si tetrahedral network, with alkali metal cation (Na+ or K+) balancing the negative charge of Al tetrahedra. Although immobilization of heavy metal cations, that could balance the negatively charged Al tetrahedra in GP, was extensively studied, this is the first study that deals with immobilization of metal anions (dichromate, permanganate and hexacyanoferrate). GP samples were prepared from metakaolin (MK) as an aluminosilicate material and sodium silicate activator (Si/Al molar ratio 2) in the presence of the three anions. The efficiency of immobilization was studied in terms of % leaching of metal anions using atomic absorption spectrophotometry and in terms of leaching of total metal anions by conductivity measurements. The % leaching was less than 10% when 0.2% (w/w) of metal anion salts were incorporated in the GP. However, the % leaching increased from 10% to 20% with increasing loading of dichromate salt from 0.2% to 1.5% (w/w) which indicates that GP has limited capacity (limited number of pores) for immobilization of metal anions. When silica gel and alumina were employed as additives to MK (changing Si/Al ratio), the leaching of dichromate and total ions increased substantially and the surface of GP becomes more crystalline as indicated by SEM and EDS studies. The present work suggests that the mechanism of heavy metals immobilization by balancing the negatively charged Al tetrahedra of GP is not true.

Phase, Microstructure and Beneficiation of Manganese Ore by Acid Leaching

In this research work, sawdust was used as a reducing agent for sulphuric acid leaching of manganese ore from Prang Ghar, Lower Mohmand Agency, Pakistan. X-ray diffraction of the powdered sample indicated the presence of Hausmannite (Mn3O4), Calcium Aluminum Silicate Hydrate, Silica (SiO2) and Hematite (Fe2O3). X-ray diffraction and the energy dispersive spectroscopic analysis show that the manganese ore sample was siliceous in nature. In the present study, six process parameters were investigated i.e. the particle size of the ore, leaching temperature, time duration, Mn ore amount, sulphuric acid concentration and amount of sawdust. Manganese extraction of 88.93 (wt%) was achieved for a leaching time of 60 minutes at 120°C using 5% (v/v) H2SO4 concentration for 10 g Mn ore and 5 g sawdust. The results demonstrate that sawdust is a low cost, renewable and non-hazardous reducing agent in comparison to other available reagents.

Novel process to prepare magnetic metal-ceramic nanocomposites from zeolite precursor and their use as adsorbent of agrochemicals from water

In this work the preparation of two samples of magnetic adsorbent from a zeolite precursor was described. This process implied NH4+ and Fe2+ exchange of zeolite A and its subsequent thermal treatment at temperature 600–800 °C, under a reducing atmosphere. These two magnetic adsorbents, composed of Fe/Fe3O4 nanoparticles embedded in an amorphous silica-alumina ceramic phase, were fully characterized by determining their chemical composition, quantitative phase analysis, surface area, SEM and TEM analysis, pH of zero potential and magnetic properties. In particular, their Fe content was 0.2 or 4.8%, Fe3O4content 5.4 or 7.1% and the average dimension of nanoparticles was 1.82 or 11.13 nm. Then, the removal of the agrochemical simazine from water was performed by using these two magnetic adsorbents. The investigated parameters were pH, time, solid/liquid ratio and initial simazine concentration. The pH of maximum simazine adsorption was 6.5 and 3.0 for the two adsorbents. At these pH values, simazine adsorption occurred rapidly and massively even from very dilute simazine solutions (simazine concentration of about 0.25 μmole/L).Finally, a process of simazine removal from waters based on repeated cycles of adsorbent addition to simazine bearing water, followed by its easy magnetic separation, is proposed. This process allows bringing the final agrochemical concentration well below 0.05 mg/L, the maximum agrochemical concentration allowed by Italian laws in wastewaters. Simazine bearing exhausted adsorbents are regenerated by a (no more than) 5 min thermal treatment at 300 °C, which results in the decomposition of simazine without damage of the adsorbent.

A Novel Approach to Preparing Highly Porous and Dispersed Supported Nickel Catalyst

AbstractThis article proposes a new synthesis of amorphous silica‐alumina (ASA) supported Ni catalyst using hydrothermal synthesis method by the assistant of cis‐9‐octadecenylamine. Cis‐9‐octadecenylamine, as a coordination agent and surfactant, could form Ni‐cis‐9‐octadecenylamine complex with nickel salt under hydrothermal condition, which boosts the metal dispersion. Characterization results by N2 adsorption‐desorption shows that the as‐prepared catalyst is provided with enhanced porosity, especially mesoporous and by XRD, TEM and H2‐TPR display that the resulting Ni particles are very small and uniform. The ASA supported Ni catalyst proves to be highly efficient and stable in naphthalene hydrogenation, and gives 100% conversion and more than 99% selectivity to decalin with an extremely wide activity window at 180∼280 °C, which is superior to its counterparts prepared via traditional impregnation method.

Determination of Pore Network Accessibility in Hierarchical Porous Solids

This paper validates the hypothesis that the supposedly nonspecific adsorbates nitrogen and argon wet heavy metals differently and shows how this unexpected effect can be actively utilized to deliver information on pore interconnectivity. To explore surface chemistry influences on differential adsorbate wetting, new findings for a mixed silica–alumina material were compared with data for pure silica and alumina materials. The new structural characterization described can determine the distribution of the particular subset of meso- and micropores that connect directly to macropores that entrap mercury following porosimetry, as mapped by computerized X-ray tomography. Hence, it elucidates the spatial organization of the network and measures the improved accessibility to smaller pores provided by larger pores. It was shown that the silica–alumina pellets have a hierarchical pore-size arrangement, similar to the optimal blood vessel network architecture in animals. The network architecture derived from the ne...

Impact of Alumina Trihydrate and Silica on Mechanical, Thermal and Electrical Properties of Silicone Rubber Composites for High Voltage Insulations

Research & Development in Material Science Impact of Alumina Trihydrate and Silica on Mechanical, Thermal and Electrical Properties of Silicone Rubber Composites for High Voltage Insulations Hidayatullah Khan1*, Muhammad Amin2, Ayaz Ahmad1 and Muhammad Yasin3 1Department of Electrical Engineering, COMSATS Institute of Information Technology, Pakistan 2Department of Electrical Engineering, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Pakistan 3Department of Electrical Engineering, National University of Sciences and Technology, Pakistan *Corresponding author: Hidayatullah Khan, Department of Electrical Engineering, COMSATS Institute of Information Technology, Wah Cantt, Punjab 47040, Pakistan Submission: November 07, 2017; Published: December 01, 2017 DOI: 10.31031/RDMS.2017.02.000540 ISSN : 2576-8840Volume2 Issue3

Enhancing Remazol Yellow FG Decolorination by Adsorption and Photoelectrocatalytic Degradation

The combination of adsorption and photoelectrocatalytic degradation system for Remazol Yellow FG decolorization has been studied. The adsorption of Remazol Yellow FG was carried out using alumina and silica, which was activated using H2SO4 1 M and NaOH 1 M. The adsorption results at optimum pH were then used for photoelectrocatalytic process. Photoelectrocatalytic degradation cell was built by electrode Ti/TiO2 as a cathode and Ti/TiO2-PbO as an anode. Material characterizations were performed by UV-Vis Spectrophotometers, X-Ray Diffraction (XRD), and Fourier Transform Infra-Red (FTIR). Activation of the adsorbent can increase Remazol Yellow FG adsorption on alumina base and silica acid that were reached 99.500% and 81.631%, respectively. The optimum condition of Remazol Yellow FG 6 adsorption by alumina acid was at pH 3, alumina base were at pH 4 and pH 5, and silica base were at pH 6 and pH 10. Degradation of Remazol Yellow FG using TiO2-PbO electrode was 72.756% at potential cells of 7.5 Volts for 10 minutes. The combination of adsorption and photoelectrocatalytic degradation can decrease the concentration of Remazol Yellow FG achieved 99.705%

Strength of brittle materials in moderately corrosive environments

AbstractThe strengths of four brittle materials―cordierite glass ceramic, fused silica, silicon, and polycrystalline alumina were measured after exposure to weakly corrosive water and moderately corrosive buffered HF (BHF) solution. Exposure to water did not alter the strengths in subsequent inert strength tests and decreased the strengths in reactive strength tests. Exposure to BHF increased the strengths in both tests, but only after an incubation exposure time. Prior to the incubation time, the BHF had the same effect as water, suggesting that the bond rupture kinetics were unaffected. Examination of strength‐controlling indentation flaws after the incubation time showed clear corrosive effects on the flaw geometry indicative of reductions in the indentation residual stress fields. The implication is that moderately corrosive environments increase the strength or lifetime of a brittle component by reducing the crack driving force via flaw alteration and do not, as perhaps expected, decrease the strength or lifetime through enhanced chemical reactivity.

Synthesis of zeolite from rice husk ash waste of brick industries as hydrophobic adsorbent for fuel grade ethanol purification

A lot of researchers have devoted on ethanol utilization as renewable energy to substitute petroleum based gasoline. When ethanol is being used as a new fuel candidate, it should have at least of 99.5% purity. Usually produced via sugar fermentation process, further purification of ethanol from other components in fermentation broth to obtain its fuel grade is a crucial step. The purpose of this research is to produce synthetic zeolite as hydrophobic adsorbent from rice husk ash for ethanol-water separation and to investigate the influence of weight, adsorption time and initial ethanol concentration on zeolite adsorption capacity. This research consisted of rice husk silica extraction, preparation of hydrophobic zeolite adsorbent, physical characterization using SEM, EDX and adsorption test for an ethanol-water solution. Zeolite with highest adsorption capacity was obtained with 15: 1 alumina silica composition. The best adsorption condition was achieved when 4-gram hydrophobic zeolite applied for adsorption of 100 mL of 10% (v/v) ethanol-water solution for 120 minutes, which resulted in ethanol with 98.93% (v/v) purity. The hydrophobic zeolite from rice husk ash is a potential candidate as an efficient adsorbent to purify raw ethanol into fuel grade ethanol. Implementation of this new adsorbent for ethanol production in commercial scale may reduce the energy consumption of that usually used for the distillation processes.