Search results

The purpose of this paper is to study the effect of synthesis conditions on properties of TiO₂ nanoparticles to be used for photocatalysis and also producing TiO₂ using a low temperature method.

TiO₂ nanoparticles were synthesised via a sol‐gel method at low temperature and the effect of parameters such as: synthesis temperature, HNO₃ concentration, calcination temperature and synthesis time on properties of TiO₂ were studied. The effects of the physico‐chemical properties of TiO₂, its concentration and light intensity on photocatalytic properties of TiO₂ nanoparticles were investigated also.

The results showed that TiO₂ with Anatase phase were formed at 80‐100°C by using proper HNO₃ concentration, synthesis time and calcinations temperature. Calcinations programme and temperature and also the synthesis time affect the formation of TiO₂ crystalline phase (i.e. Rutile and Brookite), their surface area and crystallite size. To evaluate the photocatalytic properties of TiO₂ nanoparticles, fluorescein was used as a model molecule. Results showed that degradation of fluorescein could be described by pseudo‐first order kinetics. The effect of TiO₂ concentration and light intensity on photocatalytic activity showed that increasing concentration of TiO₂ and the light intensity would increase the degradation of fluorescein.

The method used in this work to prepare TiO₂ nanoparticles is an economic method for low temperature synthesis of TiO₂ nanoparticles with high photocatalytic activity, which could find numerous applications in coating technology.

The purpose of this paper is to provide a critical and in‐depth review of the present status and recent developments in synthetic methodologies, reaction engineering, process design and quality control aspects associated with the manufacture of mono and multifunctional acrylate monomers.

This paper reviews commercially important UV cure mono and multifunctional acrylate monomers. It covers their synthesis, catalyst, and appropriate solvents for azeotropic removal of byproducts. The detail discussion on catalysis, basis of design of reactors and commercial plant and the process engineering associated with the manufacture has been supported through citation of synthesis of various acrylate monomers. The methodologies adopted for determination of physical, chemical and compositional characterisation of acrylate monomers have been presented. In addition, the guidelines regarding the bulk storage and commercial handling of acrylates have been reviewed.

The reaction engineering of esterification reaction between acrylic acid and polyol has been worked out to provide the basis for selection of reactors. The reaction has been modeled as a series – parallel complex reaction for providing explanation for generation of various byproducts/adducts and multiple esters.

The detailed discussion on formation, characterisation and treatment of Michael adducts and purification of acrylate monomers will be relevant for new researchers for further development. A review of guidelines on selection of homogenous and heterogeneous catalysts for synthesis of acrylate monomers has been presented.

Since the related literature on acrylate monomers is scarce, scattered and proprietary, the consolidated coverage in one paper will be useful.

This paper aims to focus on the basic principle of WO₃ gas sensors to achieve high gas-sensing performance with good stability and repeatability. Metal oxide-based gas sensors are widely used for monitoring toxic gas leakages in the environment, industries and households. For better livelihood and a healthy environment, it is extremely helpful to have sensors with higher accuracy and improved sensing features.

In the present review, the authors focus on recent synthesis methods of WO₃-based gas sensors to enhance sensing features towards toxic gases.

This work has proved that the synthesis method led to provide different morphologies of nanostructured WO₃-based material in turn to improve gas sensing performance along with its sensing mechanism.

In this work, the authors reviewed challenges and possibilities associated with the nanostructured WO₃-based gas sensors to trace toxic gases such as ammonia, H₂S and NO₂ for future research.

This study aims to the effect of NaF, Li₂CO₃ and H₃BO₃ minerals was investigated, and the best mineralizer was found to be H₃BO₃. Furthermore, the effect of temperature was investigated, and the synthesized samples were calcined at temperatures of 1100, 1200 and 1300 °C to select the optimum calcination temperature.

This study was aimed at thoroughly investigating the effects of mineralizer addition and temperature on the synthesis of malayaite pink pigment based on raw materials of SnCl₂-SiO₂-Ca(OH)₂-K₂Cr₂O₇. To this end, the optimization of the synthesis parameters such as mineralizer addition and temperature was completely perused.

The optimum temperature was 1300 °C, and the color efficiency of pigments was evaluated by colorimetric (CIE L*a*b* system) analysis, and these parameters were close to those of industrial pigments.

To the best of the authors’ knowledge, for the first time, the effect of mineralizer addition and temperature on the synthesis of malayaite pink pigment was investigated through the sol-gel method. Herein, different parameters were optimized to propose a novel pigment with a much better performance.

The purpose of this study was to the low-temperature synthesis of cobalt-containing diopside pigments based on granulated blast furnace slag and to study the characteristics of the mineral formation processes, changes in the structure and colour indices.

Synthesis of cobalt-containing diopside pigments based was carried out by the directional formation of the mineralogical composition with the introduction of part of the components using granulated blast-furnace slag.

It has been established that the formation of the diopside phase in pigments containing blast-furnace slag as the main component proceeds at low temperatures (1,100°C–1,150 °C). The colour of diopside pigments is formed because of the isomorphic substitution of Si4+ ions for Al3+ ions and Mg2+ ions for Co2+ ions. It is expedient to add CoO in an amount of 0.9 mol (18 Wt.%) into the composition of diopside pigments based on blast-furnace slag to obtain defect-free violet glazes.

The developed diopside pigments enable obtaining of high-quality violet glazes for ceramics. The application of the obtained results can significantly reduce the consumption of traditional raw materials in the composition of silicate ceramic pigments, as well as reduce their firing temperature.

Calcium, magnesium and silicon oxides are the main components of blast-furnace slag. In addition, granulated blast furnace slag is mainly represented by the glassy phase, which determines its high activity during the firing process. These factors are prerequisites for using the blast-furnace slag as a valuable substitute for chemically pure or natural raw materials in silicate pigments and reducing their firing temperature.

The spectrally selective solar absorption paint is prepared from spinel-based mixed metal oxides with inorganic binder as a key component. Inorganic binder (furnace cement) is blended with mixed metal oxide pigment during synthesis. High temperature stability upto 1,100ºC is achieved by the use of this modified coating system. The purpose of this paper is to work on solar selective coating synthesis, and application of a coating as a water-borne paint is the additive key feature that helps in reduction of solvent use.

The paint was formulated using water-based system, and the main component of colorant was made by mixed metal oxide–based spinel pigment and highly temperature stable inorganic binder.

The paint formed shows excellent absorptive power with low emittance even at high temperature. Optical and thermal properties were determined along with adhesion, abrasion and other properties. The solar absorptance for these samples were as = 0.93–0.95 with corresponding thermal emittance of eT = 0.096 (at room temperature) and 0.2–0.22 (at elevated temperature 100°C).

The paint formed shows excellent absorptive power with low emittance even at high temperature. The paint can be applied in solar absorptive tower system. The obtained results indicated excellent thermal stability of prepared paint coatings. As inorganic binder was used, the paint has reduction in solvent use, and being water as a base, it is environment friendly, easy to apply and durable at high temperatures, as the binder itself is stable up to 1,500ºC.

It is essentially valuable to use simpler methods for making the protected pigment by inclusion of hematite in a transparent zirconium silicate crystal. The purpose of this paper is to compare solution combustion and co‐precipitation methods as two different routes for synthesis of zircon‐based coral pigment.

X‐ray diffraction, scanning electron microscopy and simultaneous thermal analysis were used to characterise and evaluate the precipitated zircon and Fe₂O₃ phases. The synthesised samples were incorporated into a suitable ceramic glaze and then their L*, a* and b* colour parameters were measured via Commission Internationale de I'Eclairage colorimetric method.

The results revealed that partial reduction of hematite (α‐Fe₂O₃) to maghemite (γ‐Fe₂O₃) destroyed the quality of the pigment obtained from the combustion processing method. Nevertheless, it is found that co‐precipitation would be an appropriate method for synthesis coral pigment.

It is found that the solution combustion method is not able to directly synthesise a zircon‐based coral pigment during combustion reaction. Furthermore, the presence of carbon has led to partial reduction of hematite resulting in unwanted crystalline maghemite phase. This reveals that solution combustion method is not suitable to obtain zircon‐based coral pigment.

The conventional method to synthesise ceramic pigments is a solid‐state reaction that requires high temperature and long processing time. The products are usually coarse and inhomogeneous so this method requires further processing like wet or dry milling in order to produce fine powders. Diffusion barrier in solid‐state processing prevents the control of the microstructure and the reactivity of the system. Soft‐chemical routes such as solution combustion and co‐precipitation methods are better choices to get finer powders and to achieve the desired phases at lower temperatures in shorter time as well.

Co‐precipitation synthesis of iron‐zircon coral pigment using sodium silicate (water glass) as Si source and its comparison with solution combustion method is valuable and has not been reported until now.

The widespread usage of magnetic nanoparticles (MNPs) requires their efficient synthesis during combustion process. This study aims to present a mathematical model for the oxidation of MNPs in a counter-flow non-premixed combustion system to produce MNPs, where the key sub-processes during the oxidation reaction are involved.

To accurately describe structure of flame and determine distributions of temperature and mass fractions of both reactants and products, equations of energy and mass conservations were solved based on the prevailing assumptions that three regions, i.e. preheating, reaction and oxidizer zones exist.

The numerical simulation was first validated against experimental data and characteristics of the combustion process are discussed. Eventually, the influences of crucial parameters such as reactant Lewis numbers, strain rate ratio, particle size, inert gas and thermophoretic force on structure of flame and combustion behavior were examined. The results show that maximum flame temperature can achieve 2,205 K. Replacing nitrogen with argon and helium as carrier gases can increase flame temperature by about 27% and 34%, respectively. Additionally, maximum absolute thermophoretic force was found at approximately 9.6 × 10–8 N.

To the best of authors’ knowledge, this is the first time to numerically model the preparation of MNPs in a counter-flow non-premixed combustion configuration, which can guide large-scale experimental work in a more effective way.

This paper aims to study the various developments taking place in the field of gas sensors made from polyaniline (PANI) nanocomposites, which leads to the development of high-performance electrical and gas sensing materials operating at room temperature.

PANI/ferrite nanocomposites exhibit good electrical properties with lower dielectric losses. There are numerous reports on PANI and ferrite nanomaterial-based gas sensors which have good sensing response, feasible to operate at room temperature, requires less power and cost-effective.

This paper provides an overview of electrical and gas sensing properties of PANI/ferrite nanocomposites having improved selectivity, long-term stability and other sensing performance of sensors at room temperature.

The main purpose of this review paper is to focus on PANI/ferrite nanocomposite-based gas sensors operating at room temperature.

The main purpose of this study was to prepare the cotton fibers and cellulose powder by a layer of nano-crystalline-titanium dioxide (TiO₂) using the sol-gel sono-synthesis method to clean the wastewater containing reactive dye. Moreover, TiO₂ nano-materials are remarkable due to their photoactive properties and valuable applications in wastewater treatment.

In this research, TiO₂ was synthesized and deposited effectively on cotton fibers and cellulose powder using ultrasound-assisted coating. Further, tetra butyl titanate was used as a precursor to the synthesis of TiO₂ nanoparticles. Reactive dye (red 195) was used in this study. X-ray Diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy were performed to prove the aptitude for the formation of crystal TiO2 on the cotton fibers and cellulose powder along with TiO₂ nanoparticles as well as to analyze the chemical structure. Decoloration of the wastewater was investigated through ultraviolet (UV-Visible) light at 30 min.

The experimental results revealed that the decolorization was completed at 2.0 min with the cellulose nano TiO₂ treatment whereas cotton nano TiO₂ treated solution contained reactive dyestuffs even after the treatment of 2 min. This was the fastest method up to now than all reported methods for sustainable decolorization of wastewater by absorption. Furthermore, this study explored that the cellulose TiO₂ nano-composite was more effective than the cotton TiO₂ nano-composite of decoloration wastewater for the eco-friendly remedy.

Cotton fibers and cellulose powder with nano-TiO₂, and only reactive dye (red 195) were tested.

With reactive dye-containing wastewater, it seems to be easier to get rid of the dye than to retain it, especially from dyeing of yarn, fabric, apparel, and as well as other sectors where dyestuffs are used.

This research would help to reduce pollution in the environment as well as save energy and cost.

Decoloration of wastewater treatment is an essential new track with nano-crystalline TiO2 to fast and efficient cleaning of reactive dyes containing wastewater used as a raw material.