The carbon nanotubes growth study under catalytic decomposition of ethylene over F 2 O 3 /Al 2 O 3 catalyst

In this study, F2O3/Al2O3 catalyst was prepared by using co-precipitation method. This catalyst was used to grow carbon nanotubes (CNTs) bundles by catalytic decomposition of ethylene in a floating catalytic chemical vapor deposition reactor. It was noticed that nanotubes yield increased with an increase in F2O3/Al2O3 weight. The carbon yield obtained with different weights of F2O3/Al2O3 was ranging from 68-93%. However, the surface defects in the grown tubes were also increased with an increase in the catalyst weight. High yield with the low surface defects and impurities was found for 0.3 g catalyst. The formation of CNTs bundles was attributed to the well-dispersed Fe particles at the catalyst surface. These Fe particles were acting as nuclei for the CNTs growth. The van der Waals forces were acting between the as-grown individual CNTs. These forces make them to grow in the same direction in the form of bundles

Statistical Prediction of Rate Constants for the Pyrolysis of High-Density Plastic Waste

Poster presented at MULTIPHYSICS 2022, a conference organised by The International Society of Multiphysics, in Oslo, Norway, 15-16 December 2022. https://www.multiphysics.org/home.The 400 million tons of waste plastic are disposed of around the world. A study reported by SINTEF estimates that the Norwegian fishing fleet dumps around 380 tons of plastic material in the ocean each year. This waste is increasing at an alarming rate, threatening aquatic life, polluting the environment, and causing serious diseases. Since this waste includes hydrocarbons and is a massive source for economically producing pyrolytic oil that can replace traditional fuels. To obtain Liquid fuels and gases from the thermal destruction of high-density plastic (HDP) pyrolysis using empirical rate constants is costly and time-consuming. A commercially sustainable quantity of liquid fuel is not achieved. As a result, predicting statistical rate constants (k) which are based on a suitable combination of activation energy (Ea) and frequency factor (Ao), and investigating their sensitivity is a need of time that has not been documented. This study can provide a better insight into the reaction mechanism of HDP and assess the suitable combination of Ea, Ao, and k that can play a significant role in the effectiveness of liquid fuels and gases at a commercial scale. In this study, H-abstraction, chain fission, polymerization, and β-scission reactions have been chosen from literature due to the majority of free radicals. The Arrhenius equation is implemented in R software to predict temperature-dependent rate constants at a fixed temperature (340°C to 370°C). In MATLAB (R2020a) the second-order differential equation solver has been employed to assess how changes in temperature, Ea, and Ao affected the efficiency of species such as oil, gas, and waxes

Statistical prediction and sensitivity analysis of kinetic rate constants for efficient thermal valorization of plastic waste into combustible oil and gases

Sensitivity analyses of rate constants for chemical kinetics of the pyrolysis reaction are essential for the efficient valorization of plastic waste into combustible liquids and gases. Finding the role of individual rate constants can provide important information on the process conditions, quality, and quantity of the pyrolysis products. The reaction temperature and time can also be reduced through these analyses. For sensitivity analysis, one possible approach is to estimate the kinetic parameters using a MLRM (multiple linear regression model) in SPSS. To date, no research reports on this research gap are documented in the published literature. In this study, MLRM is applied to kinetic rate constants, which slightly differ from experimental data. The experimental and statistically predicted rate constants varied up to 200% from their original values to perform sensitivity analysis using MATLAB software. The product yield was examined after 60 min of thermal pyrolysis at a fixed temperature of 420 °C. The predicted rate constant “k(8)” with a slight difference of 0.02 and 0.04 from the experiment revealed 85% oil yield and 40% light wax after 60 min of operation. The heavy wax was missing from the products under these conditions. This rate constant can be utilized to maximize the commercial-scale extraction of liquids and light waxes from thermal pyrolysis of plastics

Sensitivity Analysis of Thermal Degradation of Plastic Waste Using Statistically Assumed Exponential Factors and Activation Energies

The rise in the production of plastic waste has prompted the exploration of various recovery options instead of landfilling, burning, and other unethical ways of decomposing. The experimentally generated rate constants for the thermal processing of plastic waste do not yield enough liquid fuels and gases for commercial-scale usage. It is imperative to predict kinetic rate constants statistically using an appropriate combination of activation energies (Ea) and frequency factors (Ao) for the optimized thermal valorization of plastic waste. This approach also assists in controlling the selectivity and quantity of the pyrolysis products. A statistical kinetic model was tested to find the best combination of rate constants from different combinations of Ea and Ao to pyrolyze the high-density polyethylene. Two series of Ea and Ao were first assumed using R software. These series were then used to predict kinetic rate constants and analyze their sensitivity independently using MATLAB. The rate constants were varied from their originally predicted values during the sensitivity analysis. It was found that the rate constant k(7) dominated the other predicted rate constants where high oil and gas yields were concerned. The gas yield increased from lower to higher extreme positions in the range of 60%–74% with the first series and from 65% to 81% with the second series. The maximum oil content was found around 74% and 65% with the first series and second series, respectively

Response Surface Methodology Analysis of Pyrolysis Reaction Rate Constants for Predicting Efficient Conversion of Bulk Plastic Waste into Oil and Gaseous Fuels

The growing production of plastic waste and improper dumping after use has become a worldwide challenge. This waste is a substantial source of petroleum and can be effectively converted into pyrolytic oil and other useful products. A statistical prediction of the rate constants is essential for optimizing pyrolysis process parameters, such as activation energy (Ea), frequency factor (Ao), temperature (T), and kinetic rate constants (k). In this research, we utilized Box–Behnken using RSM with Design Expert software to predict statistical rate constants at 500 °C and 550 °C. The efficiency of the predicted rate constants was investigated and compared to the findings of experimental rate constants extracted from the literature. At 500 °C, the estimated rate constants did not reveal a significant rise in the oil output since these constants promoted high gas yield. Compared to the experimental rate constants, statistically predicted rate constants at 550 °C demonstrated substantially high-oil output with only 1% byproducts. The experimental rate constants yielded 32% oil at 550 °C, whereas the predicted rate constants yielded 85% oil. The statistically predicted rate constants at 550 °C could be used to estimate commercial-scale extraction of liquid fuels from the pyrolysis of high-density plastics. It was also concluded that Ea, Ao, and T must be analyzed and optimized according to the reactor type to increase the efficiency of the expected rate constants

Construction of 0D/2D Schottky heterojunctions of ZnO and Ti3C2 nanosheets with the enriched transfer of interfacial charges for photocatalytic hydrogen evolution

The development of cost-effective co-catalysts of high photocatalytic activity and recyclability is still a challenge in the energy transformation domain. In this study, 0D/2D Schottky heterojunctions, consisting of 0D ZnO and 2D Ti3C2, were successfully synthesized by the electrostatic self-assembling of ZnO nanoparticles on Ti3C2 nanosheets. In constructing these heterojunctions, Ti3C2 nanosheets acted as a co-catalyst for enhancing the transfer of excitons and their separation to support the photocatalytic response of ZnO. The as-prepared ZnO/Ti3C2 composites demonstrate an abbreviated charge transit channel, a huge interfacial contact area and the interfacial electrons' transport potential. The extended optical response and large reactive area of the ZnO/Ti3C2 composite promoted the formation of excitons and reactive sites on the photocatalyst's surface. The ZnO/Ti3C2 Schottky heterojunction showed significantly high photocatalytic activity for hydrogen production from a water-ethanol solution under the light illumination in the visible region. The hydrogen evolution overoptimized the ZnO/Ti3C2 composition with 30 wt.% of Ti3C2, which was eight times higher than the pristine ZnO. These findings can be helpful in developing 0D/2D heterojunction systems for photocatalytic applications by utilizing Ti3C2 as a low-cost co-catalyst.Web of Science1513art. no. 455

Investigating the impact of Cu2+ doping on the morphological, structural, optical, and electrical properties of CoFe2O4 nanoparticles for use in electrical devices

This study investigated the production of Cu2+-doped CoFe2O4 nanoparticles (CFO NPs) using a facile sol-gel technique. The impact of Cu2+ doping on the lattice parameters, morphology, optical properties, and electrical properties of CFO NPs was investigated for applications in electrical devices. The XRD analysis revealed the formation of spinel-phased crystalline structures of the specimens with no impurity phases. The average grain size, lattice constant, cell volume, and porosity were measured in the range of 4.55-7.07 nm, 8.1770-8.1097 angstrom, 546.7414-533.3525 angstrom(3), and 8.77-6.93%, respectively. The SEM analysis revealed a change in morphology of the specimens with a rise in Cu2+ content. The particles started gaining a defined shape and size with a rise in Cu2+ doping. The Cu0.12Co0.88Fe2O4 NPs revealed clear grain boundaries with the least agglomeration. The energy band gap declined from 3.98 eV to 3.21 eV with a shift in Cu2+ concentration from 0.4 to 0.12. The electrical studies showed that doping a trace amount of Cu2+ improved the electrical properties of the CFO NPs without producing any structural distortions. The conductivity of the Cu2+-doped CFO NPs increased from 6.66 x 10(-10) to 5.26 x 10(-6) (sic) cm(-1) with a rise in Cu2+ concentration. The improved structural and electrical characteristics of the prepared Cu2+-doped CFO NPs made them a suitable candidate for electrical devices, diodes, and sensor technology applications.Web of Science1510art. no. 350

Evaluation of ultrasonically ZnO loading effect on photocatalytic self-cleaning, UV protection and antibacterial activity of plasma/citric acid-activated cotton fabric

Zinc oxide (ZnO) nanoparticles were loaded over non-thermal plasma (P1) and citric acid (P2)-functionalized cotton fabrics using a room temperature sonification process. The cotton samples were pretreated with dielectric barrier discharge (DBD) plasma and citric acid to introduce some reactive moieties on the fabric to enhance the adhesion power of ZnO nanoparticles with an average particle size of 41 nm. The nanoparticles were dispersed homogeneously on the surface of the P1 sample, which enhanced the antibacterial, UV protection and photocatalytic self-cleaning characteristics of ZnO-loaded fabric. The self-cleaning efficiency of P1 and P2 samples was measured to be about 77% and 63%, respectively. The inhibition zones of 5.5 mm and 5.4 mm were produced by sample P1 against E. coli and S. aureus bacteria, respectively, which were slightly higher than the inhibition zones produced by sample P2. The inhibition zone of the samples roughly decreased by 17% after performing 10 wash cycles. The unloaded cotton fabric had a UPF value of 70.02 units and blocking percentage of 70.92% and 76.54% for UVA and UVB radiations, respectively. The UVA-blocking capacity of samples P1 and P2 was 95.27% and 91.22, respectively. Similarly, the UVB blocking capacity was 94.11% and 92.65%, respectively. The pre-coating plasma treatment was found to be helpful in improving the UV-blocking ability of ZnO-loaded cotton fabric.Web of Science1212art. no. 212

Enhancement of magnetic and dielectric properties of Ni0.25Cu0.25Zn0.50Fe2O4 magnetic nanoparticles through non-thermal microwave plasma treatment for high-frequency and energy storage applications

Spinel ferrites are widely investigated for their widespread applications in high-frequency and energy storage devices. This work focuses on enhancing the magnetic and dielectric properties of Ni0.25Cu0.25Zn0.50 ferrite series through non-thermal microwave plasma exposure under low-pressure conditions. A series of Ni0.25Cu0.25Zn0.50 ferrites was produced using a facile sol-gel auto-ignition approach. The post-synthesis plasma treatment was given in a low-pressure chamber by sustaining oxygen plasma with a microwave source. The structural formation of control and plasma-modified ferrites was investigated through X-ray diffraction analysis, which confirmed the formation of the fcc cubical structure of all samples. The plasma treatment did not affect crystallize size but significantly altered the surface porosity. The surface porosity increased after plasma treatment and average crystallite size was measured as about similar to 49.13 nm. Morphological studies confirmed changes in surface morphology and reduction in particle size on plasma exposure. The saturation magnetization of plasma-exposed ferrites was roughly 65% higher than the control. The saturation magnetization, remnant magnetization, and coercivity of plasma-exposed ferrites were calculated as 74.46 emu/g, 26.35 emu/g, and 1040 Oe, respectively. Dielectric characteristics revealed a better response of plasma-exposed ferrites to electromagnetic waves than control. These findings suggest that the plasma-exposed ferrites are good candidates for constructing high-frequency devices.Web of Science1519art. no. 689