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Bakelite, a thermosetting plastic, is harder to recycle as compared to than thermoplastic polymers through thermal method due to its inherent property to harden on application of heat. This study co-pyrolyzes waste bakelite with polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), and polymethyl methacrylate (PMMA) in a conventional semi-batch pyrolysis reactor and microwave pyrolysis reactor to determine how the reactor type and thermoplastic blending affect product distribution, yield, and composition of condensable fraction. The blending of thermoplastics and pyrolysis reactor types greatly affects product distribution. Bakelite, on pyrolysis, produces 39.12 wt% condensable product, which increased to 45.42 wt%, 58.76 wt%, 61.53 wt%, and 66.76 wt% in conventional pyrolysis and 49.87 wt%, 61.26 wt%, 66.51 wt%, and 72.88 wt% in microwave pyrolysis by blending HDPE, PP, PMMA, and PS respectively. The composition analysis through Gas chromatography-mass spectrometry and Fourier-transformed infrared spectroscopy confirms the formation of alkanes, cycloalkanes, alkenes, cycloalkenes, aromatics, and oxygenated compounds, from both pyrolysis processes. However, their percentage differ significantly in both processes. Microwave-assisted pyrolysis with activated carbon yields superior oil in both quantity and composition compared to conventional pyrolysis, effectively transforming waste plastics into valuable products.

Plastic is widely used, leading to an increase in plastic waste in the environment and resulting in pollution. Plastic waste can currently be managed differently and reduced by converting it into useful products via different methods. The extensive use of thermosetting polymers such as bakelite, which are nonrecyclable, has led to an increase in bakelite scrap and pollution. Therefore, minimizing pollution due to such waste requires sustainable, modern, eco-friendly, and economical recycling technology and the upgrading of existing recycling technology. This work reports the recycling of discarded bakelite through pyrolysis and a kinetic study of the isothermal pyrolysis of bakelite via model fitting methods as well as product analyses. Therefore, isothermal degradation experiments for discarded bakelite were carried out at different temperatures (300, 350, 400, 450, and 500 °C) for 2 h. The isothermal degradation of bakelite follows the D1-diffusion model fitting method, with an activation energy (Ea) of 17.178 kJ/mol and an Arrhenius constant (A) of 0.095 min−1. The kinetic information provided throughout the research will aid in the development of an appropriate reactor for the valorization of discarded bakelite. Batch pyrolysis of bakelite gives the highest yield of 39.12% pyrolytic waxy oil at 450 °C. The presence of components such as alkanes, cycloalkenes, alkenes, alcohols, ethers, and aromatic compounds in the pyrolytic waxy oil and residue was confirmed by FTIR and GC‒MS analysis.

This study explores the co-pyrolysis recycling of the Polypropylene-Bakelite blend to improve the kinetics, thermodynamics, and conversion of thermal degradation of bakelite into useful products. The thermogravimetry analysis of the blend was conducted from ambient to 1000 °C at various heating rates in an N2 atmosphere. Thermogravimetric-Differential thermogravimetry curves revealed four steps of pyrolytic degradation, including two major weight loss steps (220–420 °C and 420–550 °C). The blending of polypropylene with Bakelite caused a shift in the pyrolytic degradation temperature zone and a synergetic effect. The pyrolytic degradation of the blended sample followed the F3 order-based mechanism with an average activation energy of 151 kJ/mol at 220–420 °C and the P3/2 nucleation mechanism with an average activation energy of 306 kJ/mol at 420–550 °C. The blend produced 47.66 % oil, 11.1 % wax, 15.1 % residue, and 26.14 % non-condensable gas during batch pyrolysis at 450 °C. The Gas Chromatography-Mass Spectrometry and Fourier Transform Infrared Spectroscopy analyses revealed that the oil contained 18.86 % saturated hydrocarbons (C8-54), 20.33 % unsaturated hydrocarbons (C7-19), and 60.81 % oxygenated compounds (C9-41) that could be used as transportation fuel.

Bakelite, a thermosetting plastic, can't be recycled suitably by pyrolysis as it is charred upon heating with low conversion to useful products. So, it is required to improve the conversion before charring in order to recycle it into valuable products through pyrolysis. Co-pyrolyzing bakelite with high-density polyethylene (HDPE) should improve its conversion before charring and obtaining more useful products. The design of a co-pyrolysis process requires kinetics and thermodynamic parameters. In this context, co-pyrolysis synergy, kinetics, and thermodynamics of HDPE blended Bakelite (1:1 by wt.) are studied by a variety of kinetics models to calculate kinetics triplets and predict a suitable mechanism. The thermal degradation experimental data are taken from ambient to 1000 °C at 5, 10, 20, 30, and 50 °C/min heating rates in an inert atmosphere. The co-pyrolysis synergy is ascertained from the alteration of temperature zone and weight loss pattern in thermal degradation. HDPE blended Bakelite degraded thermally in two stages (215–420 °C and 425–550 °C). The thermal degradation of HDPE blend Bakelite for the first stage (i.e., 215–420 °C) follows the third order (F3)- based model with activation energy 154 kJ/mol while that for the second stage (i.e., 425–550 °C) follows the 1-D diffusion (D1) model with activation energy 355 kJ/mol. The order of the reaction for the first stage is in the range of 0.035–0.352 and that in the second stage is in the range of 0.110–1.048 for different temperatures. The values of change in free energy, change in enthalpy, and change in entropy for the thermal degradation of HDPE blended Bakelite in the first and the second stage is 590.303 kJ/mol, 66.745 kJ/mol, −939.958 × 10-3JK-1mol-1 and 813.062 kJ/mol, 148.574 kJ/mol, - 876.864 × 10-3 JK-1mol-1 respectively. These kinetic and thermodynamic parameters definitely contribute to the optimization of pyrolysis reactor design.

This work reports the thermo-catalytic conversion of medical plastic wastes to fuel oil using the detergent grade Zeolite A as the catalyst. The effect of catalyst on the pyrolysis is ascertained from the kinetic data obtained from thermogravimetric analysis assuming it to be a first-order reaction. A significant reduction in activation energy of the thermal degradation reaction is found in presence of the Zeolite A catalyst. The pyrolysis runs were performed at different temperatures from 400–550 °C in a stainless-steel batch reactor system to obtain an optimum condition for suitable waste to energy process. The highest oil yield of 79% was obtained at 500 °C with 10% catalyst concentration. The thermogravimetric analysis and the batch pyrolysis experimental result indicated a promising effect of the catalyst in terms of the enhanced rate of reaction and conversion. The oil fraction obtained in the optimum condition of catalytic pyrolysis was analysed for its composition and fuel properties. It confirmed the presence of branched alkane and alkene with composition C10–C18. Again, the fuel properties of the oil such as specific gravity (0.793), viscosity (3.75Cst@ 30 °C), and flash point (

In this paper, the kinetic parameters of discarded computer keyboard plastic waste are estimated using thermogravimetric analysis (TGA) with four different non-isothermal kinetic models at a wide range of heating rates 5, 10, 15, 20, 40, 60 and 100 °C/min. The gross calorific value of waste computer keyboard plastic is 38.96 MJ/Kg. FT-IR analysis confirms the presence of alcohol, phenol, ether, ester, carboxylic acid, aromatic, and alkene compounds in keyboard plastic waste. The average values of activation energy are calculated as 158.1668, 198.883, 193.612, and 197.765 kJmol−1 from Kissinger, Friedman, FWO, and Coats-Redfern methods, respectively. The kinetic data obtained in this work would be useful for accurate prediction of reaction behaviour and in the design of efficient commercial process for the conversion of such plastic wastes to energy.

Kaolin was refluxed with HNO3, HCl, H3PO4, CH3COOH, and NaOH of 3M concentration at 110 °C for 4 hours followed by calcination at 550 °C for 2 hours. The physico-chemical characteristics of resulted leached kaolinite clay were studied by XRF, XRD, FTIR, TGA, DTA, SEM and N2 adsorption techniques. XRF and FTIR study indicate that acid treatment under reflux conditions lead to the removal of the octahedral Al3+ cations along with other impurities. XRD of acid treated clay shows that, the peak intensity was found to decrease. Extent of leaching of Al3+ ions is different for different acid/base treatment. The acid treatment increased the Si/Al ratio, surface area and pore volume of the clay. Thus, the treated kaolin clay can be used as promising adsorbent and catalyst supports. © 2013 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)