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The improper management of waste motor oil (WMO) disturbs the ecology. However, WMO is a potential feedstock for alternate energy production employing the pyrolysis technique. The present study presents the feasibility of WMO pyrolysis in sustainable alternate energy generation. Five different models, namely Flynn-Wall-Ozawa (FWO) and Starink, Coats-Redfern, consecutive reaction model (CRM), and distributed activation energy model (DAEM), were applied for the assessment of the thermo-kinetic parameters of WMO pyrolysis using the thermogravimetric analysis at three discrete heating rates (5, 10, and 40 ºC min−1). The thermogravimetric experimental data of WMO pyrolysis is validated by the artificial neural network (ANN). The average activation energy of WMO for FWO (140.7 kJ mol−1), Starink (143.6 kJ mol−1), Coats-Redfern (116.08 kJ mol−1), CRM (123.22 kJ mol−1), and DAEM (110 kJ mol−1) are lower than conventional organic wastes and hence beneficial for the co-pyrolysis process. [ABSTRACT FROM AUTHOR]

The current study explores the co-pyrolysis of waste motor oil (WMO) and rice stubble in a designed lab-scale pyrolyzer to produce alternative energy fuels. The parameter screening was followed by optimization utilizing the Box-Behnken design (BBD). Reactor temperature (T R), mixing ratio (M), and holding time (t) affected the co-pyro-oil yield substantially. A maximum co-pyro-oil yield of 90.3% was achieved at a T R = 485 °C, t = 12.5 min, and M = 5% rice stubble to waste motor oil, which was further characterized and compared with the commercial diesel fuel properties. The highest research octane number of 76.15 was obtained for the co-pyro-oil (Co-PO), followed by the pyro-oil generated from only waste motor oil (PO WMO). Consequently, the paraffin content increased to 64.34 wt% from 27.66 wt % for PO RS. The carbon number varied from C 7 –C 17 for PO WMO and Co–Po, aligning with the diesel fuel requirements. Furthermore, a substantial enrichment in the physio-chemical properties of the produced Co-PO with reduced moisture content and enhancement in higher heating value (HHV) was also noticed. Hence, the generated Co-PO could be utilized as transport-grade fuel. [Display omitted] • Investigation of co-pyrolysis of waste motor oil and rice stubble. • Minimum run resolution V characterization design was utilized for screening of process parameters. • Yield optimization was performed using RSM-BBD and desirability function. • Maximum co-pyro-oil yield of 90.3% was achieved at a T R = 485 °C, t = 12.5 min, and M = 5%. • Co-pyro-oil met diesel fuel requirements. [ABSTRACT FROM AUTHOR]

[Display omitted] • RSM-BBD numerical optimization of WMO pyrolysis using with desirability function. • Maximum pyro-oil yield of 92.55 % with a desirability of 0.843. • Improved ignitability and oxidative stability of the pyro-oil. • Pyro-oil met diesel fuel requirements. Sustainable management of hazardous waste and alternate energy generation needs to occur concurrently. Therefore, the objective of the present study is to investigate the optimum operating conditions for the pyrolysis of waste motor oil in a semi-batch scale robust pyrolyzer to generate transport grade fuels. Process parameter optimization was done using the Box-Behnken design and the desirability criteria to maximize the pyro-oil yield. Reactor temperature, holding time, and heating rate affected the pyro-oil yield the most. A maximum pyro-oil yield of 92.55 % with a desirability of 0.843 was obtained for 477 °C, and 10 °C/min of reactor temperature, holding time, and heating rate, respectively, at a constant nitrogen flowrate of 0.6 LPM. The confirmation and validation of the optimized condition were also performed. The paraffinic groups were abundantly found in the optimized pyro-oil, methylene possessing the highest fraction, followed by methyl and methine paraffinic groups. Besides, the (H/C) eff ratio surged from 1.85 to 1.95, whereas the O/C ratio noticeably decreased from 0.69 to 0.02 after the pyrolysis indicating improvement in the igniting characteristics and oxidative stability of the pyro-oil. Further, the decline in kinematic viscosity and density was also observed. Furthermore, a considerable improvement in the physiochemical properties of the generated pyro-oil with reduced moisture and enrichment in higher heating value was also observed. Altogether, the generated pyro-oil could be used as transport-grade fuel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sustainable hazardous waste management and simultaneous bio-oil up-gradation. • HHV increased to 41.40 MJ kg−1 and 62.70% water content reduction after co-pyrolysis. • Iso-paraffin index of 0.285 for the in-situ mode of operation. • Oxygenated groups decreased by 56% indicating improved bio-oil stability. • In-situ mode produced a balanced composition of aromatic and aliphatic hydrocarbon. Simultaneous renewable energy generation is an imperative part of sustainable hazardous waste management. Therefore, the present work explicates the co-pyrolysis of rice stubble (RS) waste biomass and spent motor oil (SMO) to upgrade the obtained bio-oil. Moreover, two different modes, namely, in-situ and ex-situ, were implemented to analyze the effect of physical inhibition. Monothetic analysis approach was followed to determine optimum process conditions. A substantial increment of ∼ 85% was observed in bio-oil yield for RS: SMO (1:1) in-situ operation whilst the only RS biomass pyrolysis. Moreover, the HHV increased by ∼ 2.15 times after co-pyrolysis with a considerable reduction (62.70%) in water content. Consequently, the paraffin content increased to 79.14 vol% with an iso -paraffin index of 0.285. Subsequently, a possible reaction mechanism is also proposed to evaluate results comprehensively. Altogether, the co-pyrolysis of these feedstocks resulted in improved aliphatic content and reduced oxygenates, encouraging its adequacy as an alternate fuel. [ABSTRACT FROM AUTHOR]

The petroleum industry has developed rapidly since its inception and evolved into an irreplaceable society component, especially in the urban areas. Besides being a limited resource, lubricating oil generates waste oil, posing a threat to both human health and the environment. The sustainable management of waste lubricating oil (WLO) could be done by applying the pyrolysis technique to avoid its antagonistic impact on the ecology. Finding a robust design for WLO pyrolysis with a reliable range of operating paraments is challenging. Hence, the main objective of the review is to study the different parameters and reactor configurations affecting the sustainability of the pyrolysis of WLO to high-value fuels. For this study, many research articles from top-rated journals in scientific indexes, including recent publications, are reviewed. This article represents an extensive review of WLO pyrolysis, including (i) the reactor configuration, (ii) co-pyrolysis studies with other wastes, (iii) advantages of catalytic pyrolysis and (iv) the factors affecting the yield and productivity of pyro oil. The valuable byproduct produced can compensate for the energy obligation and increase the overall process's productivity. The microwave pyrolysis oil was efficient in terms of the exergy analysis. However, the electric pyrolysis oil was more superior in terms of performance combustion and emission characteristics. It would be interesting to study the co-pyrolysis of the WLO process for a multi-component waste mixture rather than a binary blend. Yet more research is required to study the performance, combustion, and emission characteristics of pyro oil generated in both catalytic and non-catalytic pyrolysis processes to have a comparative analysis of the oil quality on the diesel engine. [Display omitted] • A comprehensive insight into waste lubricating oil pyrolysis. • Elucidating sustainable approaches towards waste-to-energy technology. • Detailed overview of the effect of process parameters of WLO pyrolysis. • Advantages and effect of co-pyrolysis and catalytic up-gradation studies were ascertained. • Pyrolysis oil can be used as transportation fuels with upgradation and blending. [ABSTRACT FROM AUTHOR]

• Conversion and utilization of waste motor oil as an alternate energy source. • Applicability of four different iso-conversional model-free methods. • The reaction model followed the autocatalytic (sigmoidal) mechanism. • Reaction model is d α dt = 3.21 x 10 10 β e (- 139863 RT) (1 - α) 3.049 α - 6.994 [ - ln 1 - α ] 5.626 . • Thermodynamic parameters suggests a spontaneous endothermic reaction. The pyrolytic kinetics of waste motor oil (WMO) based on various differential and integral based model-free methods is studied utilizing the data obtained from TGA. For the different heating rates, i.e., 5 °C/min, 10 °C/min, and 40 °C/min the overall volatile conversion was found to be > 90%. The calculation of activation energy is performed using four different models (a) Friedman (b) Kissinger-Akahira-Sunnose (c) Flynn-Wall-Ozawa and (d) Starink methods. The mean activation energy was found to be 139.863 kJ/mol, which has been later used for the determination of z(α) master plots. Moreover, the prediction of the reaction model has been made by analyzing the different theoretical and experimental z(α) master plots. Further, the unknown parameters of the Sestak & Berggrens's model are obtained using the model fitting methods in MATLAB. The obtained reaction model is f α = d α dt = 3.21 x 10 10 β e - 139863 RT (1 - α) 3.049 α - 6.994 - ln 1 - α 5.626 which followed the autocatalytic (sigmoidal) mechanism. Furthermore, the thermodynamic stability of the system had been determined by calculating the change in entropy, enthalpy and Gibbs free energy. The kinetic parameters along with the thermodynamic results recommend a highly reactive system feasible for waste to energy generation using pyrolysis. [ABSTRACT FROM AUTHOR]