Papers by Keyword: Aluminosilicate

Abstract: The effective recycling of industrial waste is a globally significant issue. In this study, a geopolymer binder was synthesized using an alkaline activator derived from brown coal gangue and blast furnace slag, along with silica fume as an industrial waste material. Also, the properties of these geopolymer binders are examined using them as a briquette binder. At temperatures above 700°C, roasted brown coal gangue is more active than the initial state. The optimum dosage of alkaline activator is 10M NaOH, silica fume/NaOH ratio of 3, specific gravity of 1.42, and the addition of binder of 6%. The main polymerization products of the alkali activated brown coal gangue geopolymer samples are N-A-S-H gel and amorphous aluminosilicate gel, while the main polymerization products of the alkali activated brown coal gangue -blast furnace slag geopolymer samples are N-A-S-H gel, C-(A)-S-H gel and amorphous aluminosilicate gel. Blast furnace slag is added during the preparation of briquette binder by brown coal gangue geopolymer, which increase the mechanical strength of the geopolymer binder and the optimum dosage is 30%. This study demonstrates a high-value and sustainable pathway for co-utilizing multiple industrial by-products.

Abstract: The article is devoted to determining the patterns of improving the performance of concrete using hydro-remote ash-slag mix and polypropylene fiber. For this, a four-step methodology was developed for producing purified aluminosilicates from ash-slag mix. A set of experimental studies included the study of both raw materials and developed composites. The compressive strength, flexural strength, and freeze-thaw resistance were chosen as the target characteristics. The mechanism of the effect of purified aluminosilicates on the compaction of the composite structure was determined. At the same time, polypropylene fiber effectively inhibits the formation of cracks and they growth. The optimal composition is the replacement of cement with an ash-slag mix in an amount of 50% and in the presence of fiber. In this case, the compressive strength was increased by 19%, and the flexural strength by 122% compared with the reference composition. Thus, it was proved that both hydro-remote ash-slag mix and polypropylene fiber, and especially from combined use, make it possible to create effective fiber-reinforced concrete with excellent mechanical and durability characteristics.

Abstract: Effect of content of synthetic aluminosilicates in medium-density polyethylene on the fire hazard characteristics and mechanical properties of compositions is investigated. It has been shown that during decomposition of the filler with the release of water, its effectiveness depends not only on the endothermic effect of decomposition and the content of dehydration products, but also on the correspondence of temperature of the dehydration of the filler and the temperature of intensive decomposition of the polymer. Regardless of the type of fillers, an increase in their content in polymer composite material helps to reduce combustibility. It has been shown that compositions based on epoxy oligomers or medium-density polyethylene and synthetic zeolite have properties of self-extinguish and fairly high physical and mechanical characteristics. It is shown that epoxy polymer composite material with the content of inorganic fillers 40-70 wt.% can be used for sealing building structures and other products operating at elevated temperatures, as well as in a mode where the fire resistance and heat resistance of the sealing compound are decisive. A number of efficiency of flame-suppressing of fillers is presented. Formulations of compositions based on epoxy oligomers or medium-density polyethylene whith synthetic zeolite having an optimal ratio of fire hazard and mechanical properties and not having toxic or carcinogenic effects when heated are recommended.

Abstract: The demand of highly effective aluminosilicates such as class F fly ash for use in geopolymer synthesis initiated a strong scientific interest for a design of the quality assessment methods. At the same time, the existing assessment methods apparently differ in key parameters which determine the quality of aluminosilicate. This research was focused on determination of relationship between the key parameters of different assessment methods for different types of low-calcium fly ash with high portion of vitreous phase. The insoluble aluminosilicate portion in fly ash that remained after treatment in aggressive acidic media followed by high-temperature treatment at 1000 °C (or the parameter α) was measured in this study. The experimental data showed a very low correlation (R²=0.34) between parameter α and compressive strength of the fly-ash based geopolymer paste. The correlation factors between such genetic parameters of fly ash as portion of vitreous phase (C), SiO₂-bonding degree in vitreous phase (f_Si) and parameter α demonstrated dramatically different values: R² _(С-α)=0.01; R²(f_Si-α)=0.71; R² _(С-f_Si)=0.0, respectively.

Abstract: This work reports evidence of the synthesis of zeolite A at two different temperatures (60 °C and 105 °C) from kaolin. XRD spectral analysis revealed percent crystallinity of 74 ± 2 and 71 ± 3 in LTA60 and LTA105 respectively. The average crystallize size of LTA60 and LTA105 was also estimated using Scherrer’s equation to be 57 nm. FTIR analysis showed signature peaks characteristics of zeolite A in the two materials, except the appearance of absorbance peak at 2380 cm^{− 1} in the LTA60 spectrum which was not observed in LTA105. Nitrogen porosity measurements of LTA60 and LTA105 gave the following parameters: average pore width of 2.45 and 1.01 nm respectively for LTA60 and LTA105, surface areas of 19.18 and 8.00 m²/g and pore volume of 0.012 and 0.002 cm³/g in that order. The influence of the materials on HeLa cancer cell growth was also investigated and the results showed differential inhibitory effects with LTA60 revealing pronounced inhibitory effects compared to LTA105 after 72 hours of cell incubation. This studies highlighted the importance of crystallization conditions that could influence the physicochemical parameters including structure, porosity, size, and morphology of zeolite materials on cell activity. The work also provided unique opportunities for utilizing natural deposits of kaolin globally to fabricate biomimetic materials for various biological applications.

Abstract: This study investigates the effectiveness of halloysite nanotube as filler on improvement in thermal performance of epoxy based intumescent fire retardant coating. Several intumescent fire retardant formulations were developed with and without halloysite nanotube. The thermal performance and char morphology of Intumescent fire retardant formulations was studied. Bunsen burner (ASTM E-119) test revealed that incorporation of HNTs (1.5 wt. %) improved flame retardancy by reducing the temperature of steel substrate up to 99 °C when exposed to fire for 1 hour. This study also revealed the physical and chemical mechanisms of action of HNTs in the intumescent systems. Results showed that halloysite improved the growth of the intumescent shield and give better quality of char. HNT formed aluminosilicate network for the phosphocarbonaceous structure by chemical contacts with ammonium polyphosphate. These new chemical species enhanced thermal stabilization of the char at high temperature and offered good structural properties on micro and macro scale. This increased the mechanical strength of the shielding layer during burning and also enhanced the residual weight percentage after thermal degradation as shown in thermal gravimetrical curves.

Abstract: Kaolin, widely used aluminosilicate source material was added with alkaline activator solution, creating geopolymer coating paste.Optimum design for kaolin based coating using geopolymer technology was studied. The work was to analyses the effect of solid liquid ratio, sodium silicate and sodium chloride ratio and sodium chloride molarity on its adhesive performances on lumber wood substrate. Upon observation, coating with 0.9 solid/liquid ratio, 0.45 sodium silicate/sodium chloride ratio and sodium chloride solution with 6M molarity shows promising adhesive strength. These results were further evident with morphological studies.

Abstract: Commercially made kaolin is identified as one of the important materials for production of aluminosilicate for catalyst bed support. In this work, an attempt is made to study the potential of local clay for production of aluminosilicate. Three area were identified as kaolin sources in Perak state as they are Trong, Simpang Pulai and Bidor, and labelled as TC, SP and BC, respectively. For preparation of aluminosilicate, formulation using 30% clay and the rest used feldspar (40%) and silica sand (30%). Each batch were formed into ball shapes’ before fired at 1250°C at controlled firing rate of 3°C/min. From the investigation, it is found that only two local clays (CBTC and CBSP) highly potential to be used to produce ceramic ball for catalyst support. In addition, the crushing strength is 100% better than the commercial made product which also have less than 1% water absorption.

Abstract: Heap bioleaching of sulfide ores (geotechnology) simulates naturally occurring processes when sulfides convert to oxides. This process is environmentally-friendly. Gold-bearing sulfide ore from a Russian deposit was studied. The samples were composed of quartz (38-48%), feldspars (22-24%) and micaceous minerals (18-21%). Carbonates occurred as ankerite, calcite, dolomite and siderite. The host minerals were pyrite (2.2-2.3%) and arsenopyrite (1.2-1/7%). The grade of gold was 1.6-2.0 g/t. Russian software package Selector was used to develop the model. Thermodynamics of the reaction pathway for the conversion of the gold-bearing sulfide ore in H₂SO₄ environment with and without using bacteria was calculated. Phases and their components which are able to form in these given conditions were selected during modeling. Modeling of irreversible evolution of the rocks caused by bacteria was carried out in the three reservoir system. They are interconnected by the flows of three movable phases: gases, solid phase and liquid phase. In this case, the composition of the solutions which were obtained under steady state conditions without bacteria and metastable equilibrium using bacteria can be compared. Bacterial oxidation occurs under acidic conditions. Oxidation without using bacteria occurs under more alkaline conditions. Bacteria increase the rate of sulfides oxidation and retard the formation of mixed-layer aluminum silicates (illites, montmorillomonites) and carbonates (magnesian calcite). It was found that bacteria have the potential to achieve the required destruction of sulfides in favorable environment. Bacteria make the rate of sulfide oxidation higher. In the presence of bacteria, the rate of aluminosilicates oxidation is slower compared to the conditions without using bacteria. Mineralogical analyses of the leach products confirmed this. Results show that thermodynamic approach can be successfully used for the modeling of bacterial-oxidation circuits and geology of the rocks and ores.

Abstract: Kaolin, an aluminosilicate source materials was mixed with alkaline activator solution to create a geopolmer paste which was coated on teak wood subsrates. In this work, the effect of solid/liquid ratio (0.4, 0.6, 0.8 and 1.0) was analysed while other parameters were maintained constant. Coating teak wood substrates via geopolymer technology was focused to see the enhancement made to the mechanical properties of teak wood. Various test such as adhesive strength test, water absorption and morphology study was conducted after seventh day of sample preparation. Kaolin coated sample with 1.0 solid/liquid ratio showed the highest adhesive strength of 10.5 MPa and the lowest water absorption of 6.3%. Morphology studies also supported the trend of promising compatibility between kaolin coating and teak wood substrate at 1.0 solid/liquid ratio which further evident the accuracy of collected data.