Variation in ClO₂/Cl₂ Ratio in the Chloride-Chlorate Process under Different Conditions

Deshwal, Bal Raj,Lee, Hyung-Keun 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.4

The chloride-chlorate process is a highly efficient, easy to operate, and cost effective tool for generating ClO₂, wherein the theoretical ClO₂/Cl₂(η) ratio is 2. The present study attempts to investigate the optimal conditions for the best reaction yield in terms of chlorine dioxide production and minimal contamination of chlorine. The effects of the molar concentration of sulfuric acid, the temperature, and the chlorate/chloride (φ) ratio on the ClO₂/Cl₂(η) ratio is examined. The experimental η-value ranged from 0.46 to as high as 3.4 under different conditions. A reaction mechanism compatible with the experimental observations is proposed, and the role that side reactions have on influencing the ClO₂/Cl₂ ratio is highlighted. A general equation is derived to express the ClO₂/Cl₂ ratio.

Manufacture of Chlorine Dioxide from Sodium Chlorite : Process Chemistry

Deshwal, Bal Raj,Lee, Hyung Keun 한국공업화학회 2005 Journal of Industrial and Engineering Chemistry Vol.11 No.1

Chlorine dioxide (ClO₂) has emerged as a highly efficient chemical agent for bleaching, oxidation, and disinfection. Various fundamental studies have been performed to investigate the reaction kinetics and the mechanism of ClO₂production. These studies have led to improvements in the manufacturing processes and to the optimization of reaction conditions to provide a better yield and the rational utilization of raw materials. In this comprehensive review, various aspects of process chemistry in the manufacture of ClO₂from sodium chlorite are reported. This knowledge will be useful for improving the current processes and for developing a more advanced process in the future.

Manufacture of Chlorine Dioxide from Sodium Chlorate : State of the Art

Deshwal, Bal Raj,Lee, Hyung Keun 한국공업화학회 2005 Journal of Industrial and Engineering Chemistry Vol.11 No.3

Chlorine dioxide (ClO₂) has achieved a remarkable degree of commercial attention not only because of environmental concerns but also because of its wide range of applications in the fields of bleaching, oxidation, and disinfection. There is a growing interest in the development of simpler, more easily operated, more efficient. and more cost effective techniques for the generation of chlorine dioxide. This present comprehensive review highlights the various methods used for the manufacture of chlorine dioxide using sodium chlorate as the raw material and discusses their process chemistries, including the reaction kinetics and the mechanisms of the various reactions responsible for ClO₂ generation. Efforts have been made to incorporate all the pertinent details, including the most recent developments in the manufacture of chlorine dioxide. This review not only provides a deep insight into the manufacturing processes but also it paves the ways for improvements to the existing traditional processes and the design of advanced processes in the future.

APPROXIMATION BY MODIFIED POST-WIDDER OPERATORS

( Sheetal Deshwal ),( Rupesh K. Srivastav ),( Gopi Prasad ) 한국수학교육학회 2023 純粹 및 應用數學 Vol.30 No.1

The current article manages with new generalization of Post-Widder operators preserving constant function and other test functions in Bohmann-Korovkin sense and studies the approximation properties via different estimation tools like modulus of continuity and approximation in weighted spaces. The viability of the recently modified operators as per classical Post-Widder operators is introduced in specific faculties also. Numerical examples are additionally introduced to verify our theortical results. In second last section we introduce Grüss-Voronovskaya results and in last section, we show the better approximation our new modified operators via graphical exmaples using Mathematica.

Manufacture of Chlorine Dioxide from Sodium Chlorate: State of the Art

Bal Raj Deshwal,Hyung Keun Lee 한국공업화학회 2005 Journal of Industrial and Engineering Chemistry Vol.11 No.3

Study of Molarity Concentration Variation Over Optical, Structural and Gas Sensing Response for ZnO Thin Film Based NOx Gas Sensor

Sukhvir Kaur,Manish Deshwal 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.4

Zinc oxide (ZnO) thin fi lms as sensing layer with diff erent molarity concentration are obtained by the sol–gel method using spin coating technique. Zinc acetate dihydrate (Zn(CH 3 COO)2·2H 2 O) was taken as starting material. For desired molarity weighed Zinc Acetated dihydrate is dissolved in particular amount of Ethanol. The solution is put on hot plate with Magnetic stirrer at a temperature of 60 °C while stirring 400 rpm to 600 rpm procedure continued for 45 min to 60 min. After that the solution was kept at room temperature for 24 h for ageing eff ect. By using spin coating method the prepared solution was coated on silicon substrate and then annealed for preparing highly crystalline ZnO thin fi lms. The optical surface morphological and structural studies were done for the synthesized ZnO thin fi lms. The important parameter considered for the gas sensing behavior are operating temperature and sensor response The reported study provides a signifi cant development towards ZnO thin fi lm thickness variations with a very high sensitivity, rapid response and recovery times. The UV–Vistransmittance spectra of ZnO thin fi lms has been studied over quartz substrate under similar deposition parameters. The single coated samples were prepared with diff erent molarities of 1 M, 0.7 M, 0.5 M, 0.33 M, 0.1 M, 0.05 M. Energy band gap of each sample is calculated by using Tauc plot and studied for the varying band gap & the gas sensitivity for the samples.

NO_x removal from the flue gas of oil-fired boiler using a multistage plasma-catalyst hybrid system

Park, S.Y.,Deshwal, B.R.,Moon, S.H. Elsevier Scientific Pub. Co 2008 Fuel processing technology Vol.89 No.5

The study on removal of NO<SUB>x</SUB> from the flue gas of oil-fired boiler has been carried out using non-thermal plasma cum catalyst hybrid reactor at 150 <SUP>o</SUP>C. Propylene (C<SUB>3</SUB>H<SUB>6</SUB>) was used as a reducing agent. A multistage plasma-catalyst hybrid reactor was newly designed and successfully operated to clean up the flue gas stream having a flow rate of 30 Nm<SUP>3</SUP>/h. TiO<SUB>2</SUB> and Pd/ZrO<SUB>2</SUB> wash-coated on cordierite honeycomb were used as catalysts in the present study. Though the plasma-catalyst hybrid reactor with TiO<SUB>2</SUB> showed good activity on the removal of NO yet it removed only 50-60% of NO<SUB>x</SUB> because a significant portion of NO oxidized to NO<SUB>2</SUB>. On the contrary, the plasma-catalyst hybrid reactor with Pd/ZrO<SUB>2</SUB> removed about 50% of inlet NO with a negligible amount of NO oxidation into NO<SUB>2</SUB>. The plasma/dual-catalysts hybrid system (front two units of plasma-Pd/ZrO<SUB>2</SUB>+rear two units of plasma/TiO<SUB>2</SUB>) proved to be very promising in NO<SUB>x</SUB> removal in the presence of C<SUB>3</SUB>H<SUB>6</SUB>. DeNO<SUB>x</SUB> efficiency of about 74% has been achieved at a space velocity of 3300/h at 150 <SUP>o</SUP>C.

Selectivity and Sensitivity Property of Metal Oxide Semiconductor Based Gas Sensor with Dopants Variation: A Review

Payal Patial,Manish Deshwal 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.1

This review paper exhaustively explores metal oxide semiconductor (MOS) gas sensors with prime focus to explore the ways for performance enhancement of a gas sensor. The paper discusses various aspects for a sensor and encompasses with several other gas sensors extensively. The fabricated sensors that are reported in the literature are compared and analyzed for a better understanding to the eff ects of diff erent dopants with diff erent MOS thin films. The present study is confined to the gases that are either highly toxic or inflammable in nature. The performance attributes like sensitivity, selectivity, as well as the stability of MOS gas sensors are influenced by a number of factors, that are discussed. The dopant-induced changes in MOS materials used in the gas sensing are also elaborated in the paper. The present study reveals the eff ect of dopant atoms to the structural and optical properties as well as the selectivity and sensitivity for particular metal oxides semiconductor and few semiconductor thin films. Dopants alter the microstructure and morphology of MOS, as well as their activation energy, optical absorption, and band gap, enhancing their characteristics for gas detection. Dopants may cause defects in MOS by creating oxygen vacancies. These defects improve the gas sensing capabilities. This study also looked at a variety of nanostructures. Finally, examples of MOS are provided to show how different MOS materials can be used for gas sensing. The review recognizes various aspects that can be utilized for enhancements of selectivity and sensitivity towards a particular gas for a sensor.

Systematic Review on Design and Development of Efficient Semiconductor Based Surface Acoustic Wave Gas Sensor

Payal Patial,Manish Deshwal 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.4

In today’s digital world, the industries have adopted the automized machines that are remotely controlled. So in such environment various types of monitoring have become an essential part. One of them is gas sensing mechanisms that are implemented to monitor various types of harmful /toxic/fl ammable gases. As available in the literature, there are various methods available for the detection of such gases. In the present review, the authors are considering the Surface Acoustic Waves based gas sensors only. The present review paper discusses about various parameters that can be enhanced for an optimized sensitivity and the selectivity for a particular sensor. The present study also compares the bulk material sensing properties with sensing properties of thin fi lms. The thin films are generally distinguished from bulk material due to their thicknesses that are in the range of several nanometers but much less than 700 nm after which a material attains bulk properties.

Variation in ClO2/Cl2 Ratio in the Chloride-Chlorate Process under Different Conditions

Hyung-Keun Lee,Bal Raj Deshwal 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.4