Vaibhav Gaikwad

Nonequilibrium Plasma Polymerization of HFC-134a in a Dielectric Barrier Discharge Reactor: Polymer Characterization and a Proposed Mechanism for Polymer Formation

Nonequilibrium plasma polymerization of hydrofluorocarbon HFC-134a (CF3CH2F) in argon bath gas has been studied in a dielectric barrier discharge reactor at atmospheric pressure and in the absence of oxygen and nitrogen. The reaction resulted in the formation of a polymeric solid fraction and the noncrosslinked properties of this material assisted in its characterization by solution state 13C and 19F nuclear magnetic resonance spectroscopy. Gel permeation chromatography revealed that the polymers include low (number average molecular weight, Mn values between 900 and 3000 g mol-1) and high (Mn approximately 60000 g mol-1) molecular weight fractions. A detailed polymerization mechanism is proposed, based on the published literature and the findings of the current investigation.

Growth of NiO nanorods, SiC nanowires and monolayer graphene via a CVD method

Green approaches for producing high purity advanced materials have always been a challenging task. Conventional methods for converting waste materials into char by heat treatment can have limitations in making defect free and pure materials for practical applications. Herein, we report a Green-Chemical Vapor Deposition (G-CVD) method to transform waste into functional materials in various forms by condensation of gases generated from waste on a chosen substrate. The flow of gases, mainly CO2, CH4 and CO, can be controlled via a regulated flow of a carrier gas and by controlling the temperature, gases can react/recombine on the substrate forming a crystalline lattice of semiconducting materials. Such a versatile green method can be sustainable and at the same time help in reducing the burden of landfill waste. We present how an appropriate control of the gas mixture resulting from the heat-treatment of waste rubber tyres and plastics leads to the growth of various types of functional materials on substrates. The growth mechanism of materials on substrates in this method is similar to the conventional CVD method. However, the utilization of waste to generate these gases adds the green and sustainable feature to this method and its high degree of reproducibility offers practical applicability. Once established for NiO nanorods, we tested the versatility of this technique to grow SiC nanowires, SiC nanoparticles and monolayer graphene. This highly reproducible G-CVD method of making advanced materials solely involves waste materials as the solid carbon source at atmospheric pressure without any other synthetic reagents.

Reaction of carbon tetrachloride with methane in a non-equilibrium plasma at atmospheric pressure, and characterisation of the polymer thus formed

In this paper we focus on the development of a methodology for treatment of carbon tetrachloride utilising a non-equilibrium plasma operating at atmospheric pressure, which is not singularly aimed at destroying carbon tetrachloride but rather at converting it to a non-hazardous, potentially valuable commodity. This method encompasses the reaction of carbon tetrachloride and methane, with argon as a carrier gas, in a quartz dielectric barrier discharge reactor. The reaction is performed under non-oxidative conditions. Possible pathways for formation of major products based on experimental results and supported by quantum chemical calculations are outlined in the paper. We elucidate important parameters such as carbon tetrachloride conversion, product distribution, mass balance and characterise the chlorinated polymer formed in the process.

Reaction of chloroform in a non-oxidative atmosphere using dielectric barrier discharge

This paper investigates the reaction of chloroform under non oxidative conditions in a quartz dielectric barrier discharge reactor. A non thermal plasma is generated in the dielectric barrier discharge reactor at atmospheric pressure where argon functions as a carrier gas and is mixed with chloroform and fed into the plasma zone. Parameters such as chloroform conversion, product distribution, reactor temperature and polymer characterisation are studied in this paper. A reaction mechanism outlining the reaction steps leading to the formation of major products is presented.

Non-thermal plasma polymerization of HFC-134A in a dielectric barrier discharge reactor; Polymer characterization and a proposed mechanism for polymer formation

Non-thermal plasma polymerization of HFC-134a in argon bath gas has been studied in a dielectric barrier discharge reactor at atmospheric pressure and in the absence of oxygen and nitrogen. The reaction resulted in the formation of a polymeric solid fraction and the non-crosslinked properties of this material assisted in its characterization by solution state 13C and 19F NMR spectroscopy. Gel permeation chromatography (GPC) revealed that the polymers include low (number average molecular weight, Mn values between 900 g mol-1 and 3000 g mol-1) and high (Mn approximately 60 000 g mol-1) molecular weight fractions. A detailed polymerization mechanism is proposed, based on published literature and the findings of the current investigation.

Direct Transformation of Metallized Paper into Al-Si Nano-Rod and Al Nano-Particles Using Thermal Micronizing Technique

The abundant application of metallized paper and the quick growth of their wastes lead to the removal of a huge amount of valuable resources from economic cycle. In this work, for the first-time, the thermal micronizing technique has been used to directly transform the metallized paper wastes to Al-Si nano-rod and Al nano-particles for use as the input in different manufacturing sectors such as additive manufacturing or composite fabrication. Structure of metallized paper has been investigated using FT-IR analysis and first-principle plane-wave calculation. Then, based on the structure of metallized paper, thermal micronizing technique has been modified to directly transform this waste into nano materials. Structure of nano-particles and nano-rods has been investigated using SEM, TEM, and XPS analysis. Results showed two main Al-Si nano-rod and Al nano-particle morphologies created as a result of the different surface tensions, which facilitate their separation by Eddy current separation technique. These quick transformation and facile separation together make this technique a unique process to deal with this complex waste and producing value-added products which can re-capture these high value materials from waste and make the reforming economically viable.

Application of High-Resolution NMR and GC–MS to Study Hydrocarbon Oils Derived from Noncatalytic Thermal Transformation of e-Waste Plastics

The increases in the volumes of electronic waste have become an aggravating environmental, economic, and social health issue in recent times. This study investigates the conversion of e-waste plastics into hydrocarbon oils via noncatalytic thermal transformation followed by an in-depth characterization of these oils using diverse analytical techniques such as gas chromatography–mass spectrometry (GC–MS), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. In particular, NMR spectroscopy is a key analytical tool utilized in this study to gain a comprehensive insight into the chemical nature of the resultant oils along with a semiquantitative investigation of the changes in their composition over a temperature range of 800–1200 °C. The one-dimensional (1D) 1H and two-dimensional (2D) heteronuclear single-quantum correlation spectra were acquired for the oils, wherein the 2D NMR spectrum provided improved resolution of peaks to address the overlaps encountered in the 1D spectrum. The experimental results obtained from GC–MS, FTIR spectroscopy, and NMR spectroscopy were found to align well with each other. The oils produced in this study have a high calorific value of 38.27 MJ/kg and thus may find use in several applications. A detailed mechanism for the thermal degradation of styrene acrylonitrile plastics and the formation of major products is elucidated in this study.

Reaction of CCl 3 F (CFC-11) with CH 4 in a dielectric barrier discharge reactor

The reaction of CCl 3 F (CFC-11) with CH 4 in a non-equilibrium plasma has been examined. CFC-11 has the highest ozone depleting potential (ODP) among all refrigerants used commercially (ODP value of 1) and also has very high global warming potential (GWP) of 4680 and an atmospheric lifetime of 45 years.1 The manufacture of CFC-11 was banned by the Montreal Protocol in 1996 due to its deleterious effects on Earths ozone layer. It is widely recognized that significant quantities of CFC-11 remain in polyurethane foams in discarded refrigerators or refrigerators awaiting disposal. While there are several methods developed to recover CFC-11 from polyurethane foams, a suitable process is required for its disposal. In this study, a dielectric barrier discharge reactor, employing alumina dielectrics (the detail description can be founds in2, 3), has been applied for the conversion of CFC-11 with the aim of synthesizing value-added materials. It has been found that polymers of non-crosslinked architecture can be synthesized from the reaction of CFC-11 and CH 4 . This work is focused on structural analyses of the polymers as well as discussions on conversion of CFC-11 under various conditions and characterization of the electrical discharge.

Non-thermal plasma polymerization of HFC-134a in a dielectric barrier discharge reactor; Polymer characterization and understanding the mechanism of polymer formation

Summary form only given. The plasma polymerization of HFC-134a (CF3CH2F) has been investigated in a non-thermal plasma dielectric barrier discharge reactor. HFC-134a is a green house gas and it has a global warming potential of 1410 with respect to CO2 and 100-year time horizon. Its release is regulated in many countries and its manufacture is likely to be controlled in the near future. A dielectric barrier discharge reactor, constructed from concentric alumina tubes was used for the investigation. The polymer generated from reaction was soluble in tetrahydrofuran solvent which suggests that it is non-crosslinked. The polymer was characterized using various NMR spectroscopic techniques (e.g., 13C, 19F) which reveal that the functional groups in the polymer include CHF, CF2 and CF3 groups. Based on these data, a detailed reaction mechanism has been developed which is similar but not identical to those available in the open literature. We previously reported the conversion of HFC-143a, the characterization of plasma discharge and the molecular weight of the polymers. This work is focused on a detailed structural analysis of the polymers and a proposed mechanism for their formation.