Faculty Publications
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Item Synthesis of renewable carbon biorefinery products from susceptor enhanced microwave-assisted pyrolysis of agro-residual waste: A review(Institution of Chemical Engineers, 2022) Rajasekhar Reddy, B.R.; Sridevi, V.; Kumar, T.H.; Sankar Rao, C.S.; Palla, V.C.S.; Suriapparao, D.V.; Undi, G.S.Valuable renewable carbon biorefinery products can be obtained by using agro-residual biomass as a feedstock. Bio-oil, gas, and char products can be obtained from Microwave-assisted pyrolysis (MAP) by converting agro-residual waste. In MAP, the process variables like microwave power, temperature, heating rate, raw materials, susceptors, and catalysts play an important role to alter the product spectrum. The temperature, heating rate, and pyrolysis time can be tuned to obtain the desired products during biomass decomposition. The obtained carbonaceous products can be used as intermediated feedstocks to synthesize a variety of end products. Hence, in this review, the application of MAP for the conversion of agro-residual waste is discussed. Special focus is given to the interaction of microwaves with susceptors. This manuscript provides background, current status, progress, and future scope of MAP technology for waste valorization. The objectives of the review are to address (i) The necessity of environmental protection, (ii) The role of biorefinery in the biomass conversion, (iii) The advancements in the MAP for the resource recovery, (iv) The mechanism of heat generation from microwaves, (v) The effects of process parameters, susceptors, and catalysts in MAP, (vi) The interactions of biomass and susceptors during the pyrolysis, (vii) The formation of valuable renewable carbon products and (viii) The future scope and challenges for the integration of MAP in solid waste management. © 2022 The Institution of Chemical EngineersItem Role of ZSM5 catalyst and char susceptor on the synthesis of chemicals and hydrocarbons from microwave-assisted in-situ catalytic co-pyrolysis of algae and plastic wastes(Elsevier Ltd, 2022) Suriapparao, D.V.; Tanneru, T.; Rajasekhar Reddy, B.R.; Yerrayya, A.; Bhasuru, B.A.; Pandian, P.; Prakash, S.R.; Sankar Rao, C.; Sridevi, V.; Desinghu, J.The synergetic effect between algae biomass in co-pyrolysis with synthetic plastics (polypropylene (PP), polyethylene (PE), and expanded polystyrene (EPS)) was investigated in this work. Individual feedstock pyrolysis and co-pyrolysis of algae with PP, PE, and EPS were conducted at a constant supply of microwave energy (420 J/s). Pyrolysis char was used as a susceptor in all the experiments. The average heating rate was varied in the range of ∼50–60 °C/min for achieving the final pyrolysis temperature of 600 °C. In catalytic co-pyrolysis, the ZSM-5 catalyst was used for upgrading the physicochemical properties of pyrolysis oil. The use of catalyst promoted the excessive cracking of biomass in co-pyrolysis, leading to higher gas and coke residue comparatively. The viscosity, density, and flash point of oil obtained in catalytic co-pyrolysis were significantly reduced. While the oil obtained from individual pyrolysis of algae is rich in phenolic derivatives, and that of PP, PE has aliphatic hydrocarbons, and EPS has monoaromatic hydrocarbons as major compounds. The synergistic role of plastic and biomass in co-pyrolysis was observed in the formation of products and oil composition. The bio-oil from catalytic co-pyrolysis is composed of aliphatic oxygenates, aliphatic hydrocarbons, cyclic aliphatic hydrocarbons, and phenolics. The chemicals and hydrocarbons present in the oil have a carbon number in the range of C6 to C30. An increase in carbon and hydrogen elemental composition was observed in bio-oil obtained from co-pyrolysis. © 2021 Elsevier LtdItem A review on analysis of biochar produced from microwave-assisted pyrolysis of agricultural waste biomass(Elsevier B.V., 2023) Ramesh, R.; Surya, D.V.; Sankar Rao, C.S.; Yadav, A.; Sridevi, V.; Remya, N.Every year the agricultural product processing industries produce large quantities of agricultural waste biomass (AWB). Whose disposal has become a serious issue concerning solid waste management due to environmental and health issues. Microwave-assisted pyrolysis (MAP) is an intriguing technology for producing valuable products from waste feedstocks. AWB is converted into a valuable product like biochar by using MAP. The conversion of AWB into biochar by MAP is influenced by several factors such as type of feedstock, pyrolysis temperature, residence time, pressure, heating rate, susceptor, particle size, and microwave power. However, no review article is available to understand the role of MAP on biochar production from AWB. The current review focused on understanding the fundamentals of biochar production. It also reviews the challenges in producing biochar process by compatible, acceptable, and sustainable and its future directions to gain economic benefits even at small-scale applications. The generation of biochar from MAP and its uses in agriculture are discussed. The current review would address the knowledge gap and highlight the critical implications in biochar production and applications. © 2023 Elsevier B.V.Item Recent advancements of CFD and heat transfer studies in pyrolysis: A review(Elsevier B.V., 2023) Dadi, V.S.; Sridevi, V.; Tanneru, H.K.; Busigari, R.R.; Ramesh, P.; Kulkarni, A.; Mishra, G.; Basak, T.There is a pressing need to process the solid waste by using pyrolysis technology due to its uniqueness to produce various solid, liquid and gaseous products. However, further understanding of pyrolysis process is needed. Most importantly, the role of computational fluid dynamics (CFD) in pyrolysis is to be thoroughly investigated. In recent times, there has been significant progress in the research works aligned with evaluating the role of CFD in biomass pyrolysis. Hence, the current review manuscript focusses the current state of the art in the application of CFD tools to multi-scale biomass pyrolysis systems. Modeling of fluid and heat transport in conventional pyrolysis reactors, microwave-assisted pyrolysis reactors, and solar-assisted pyrolysis reactors for the conversion of biomass have been critically analyzed. The theoretical basis and the practical applicability of the CFD models to efficiently emulate and predict the overall complexity of pyrolysis process for the multi-scale and multi-phase nature of biomass have been discussed. However, the validity and accuracy of the CFD models needs to be enhanced. In the future directions, the steps for expanding the applicability of these theoretical and computational models have been outlined. This review would provide detailed understanding of CFD role in pyrolysis process conducted in various reactor systems. © 2023 Elsevier B.V.Item Effect of solvent pre-treatment on microwave assisted pyrolysis of Spirulina (Algal Biomass) and Ficus benghalensis (Lignocellulosic Biomass) for production of biofuels: comparative experimental studies(Springer Science and Business Media Deutschland GmbH, 2025) Varma, J.V.; Sridevi, V.; Musalaiah, M.; King, P.; Hamzah, H.T.; Tanneru, H.K.; Ramesh, R.; Malleswari, G.B.The study focuses on the comparison of microwave-assisted pyrolysis (MAP) of Spirulina, (algal biomass), and aerial roots of Ficus benghalensis (lignocellulosic biomass) as feedstocks for biofuel production. Solvent ethanol was used to pretreat feedstocks. The experiments were carried out using a microwave power of 450 W, considering both fresh and solvent-pretreated feedstocks. Solvent-pretreated Spirulina demonstrated a high bio-oil yield of 56.1 wt. % and a biochar yield of 13.5 wt. %, whereas for solvent-pretreated Ficus benghalensis, the corresponding yields were 35.4 wt. % and 12.3 wt.%. Both solvent-treated and fresh algal biomass feedstocks showed higher yields than lignocellulose biomass. Pre-treatment of feedstocks showed positive results on microwave energy consumption and pyrolysis index. The average heating values were 27.3 0C/min for pretreated Spirulina and 46.2 0C/min for pretreated Ficus benghalensis. Fourier Transform Infrared (FTIR) characterized the obtained bio-oils and biochar. The FTIR results indicated the presence of distinctive functional groups such as N=C=O, O=C=O, N-O, and S=O in MAP of Spirulina bio-oil, and C=C and C-I stretching in MAP of Ficus benghalensis bio-oil. The FTIR results for biochar were consistent across both feedstocks, showing common functional groups such as C-Cl, C=C, C-H, O-H, C-F, and S=O. However, in the case of Spirulina, an extra functional group, C=N, was also detected. Pre-treatment of microalgal biomass is essential for the maximal recovery of biofuel precursors packed inside the complex microalgal cell wall. It was concluded that pre-treatment is an efficient way to improve the yield and composition of bio-oil with low microwave power and short microwave irradiation time. Efforts are still required to develop an economical and environmentally benign pre-treatment approach to facilitate 100% biomass conversion to added-value products. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.