Faculty Publications
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Item Process engineering aspects in bioleaching of metals from electronic waste(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2020) Minimol, M.; Shetty K, V.; Saidutta, M.B.Obsolete electronic devices and their components majorly contributed by the computer and mobile phone printed circuit boards (PCBs) constitute the electronic waste (e-waste). The e-wastes pose an environmental threat due to their eco-toxicological characteristics, thus making its management a mandate through an ecologically sustainable process. Further, the high concentration of metals in the e-waste makes it a secondary ore for metal recovery. Bioleaching is a bio-hydrometallurgical process, which is microbe-mediated dissolution of metals. Different nutritional classes of microorganisms like autotrophs and heterotrophs are active bioleaching agents of e-wastes. The mode of action of microbes for bioleaching of metals is obscure and is believed to ensue through redox reactions, protonic attack, or chelation. The process of bioleaching is influenced by biotic factors like the group and class of microorganism, growth rate, metabolic activity, etc. However, there are several abiotic factors that strongly affect the bioleaching efficiency. Development of a bioleaching process would need the study of various biological, nutritional, and engineering factors that influence the process. This chapter presents the critical analysis of various process engineering aspects in the bioleaching of metals from e-waste. To engineer a bioleaching process, (1) various biological, nutritional, and physicochemical factors, such as media composition, pH, e-waste loading, particle size, oxygen requirement, inoculum size, etc., should be optimized and (2) suitable bioreactor choice considering the microbial type, phases to be contacted, and the pattern of contacting followed by optimization of bioreactor operational parameters. This paper brings out a critical review of these bioprocess engineering aspects in bioleaching of metals from e-waste, directing the reader to the future scope of research on bioleaching, a bioremediation strategy to save and conserve environment for sustainable development. © 2020, Springer Nature Switzerland AG.Item Biohydrometallurgical methods and the processes involved in the bioleaching of WEEE(Elsevier, 2021) Minimol, M.; Shetty K, K.; Saidutta, M.B.The obsession toward the latest electronics and electrical goods has led to the generation of undesirable quantities of Waste Electrical and Electronic Equipments termed as electronic wastes (e-wastes). E-wastes, especially the printed circuit boards, are rich in their metal concentration and are considered as secondary resources for urban mining. The management of the metallic portion of these wastes is achieved through established physical, chemical, and biological treatment technologies. Biohydrometallurgy is a significant technology to address the issue in an eco-friendly mode. The different processes of biohydrometallurgy include bioleaching, bioflocculation, bioprecipitation, biosorption, biooxidation, and bioreduction. Bioleaching plays a vital role in the dissolution of metals from the solid matrix into the leaching solution using microorganisms. The different methods of bioleaching to accomplish metal recovery from e-waste are one-step bioleaching, two-step bioleaching, and spent medium bioleaching. The method to be selected depends on several growth and process factors to be successfully implemented. This chapter focuses on the methods of bioleaching and the processes involved in each of these methods to opt the most appropriate one for efficient metal recovery. Studies on biohydrometallurgy would confront the glitches involved in e-waste disposal and recycling in a sustainable manner. © 2021 Elsevier Inc. All rights reserved.Item Benzene hydroxylation to phenol with iron impregnated activated carbon catalysts(Elsevier Inc., 2006) Choi, J.-S.; Kim, T.-H.; Choo, K.-Y.; Sung, J.-S.; Saidutta, M.B.; Badekai Ramachandra, B.R.; Rhee, Y.-W.Iron impregnated on activated carbon was used as catalyst for the direct synthesis of phenol from benzene. The effect of Sn addition to the catalyst was studied. The prepared catalysts were characterized by BET, SEM and XRD analysis. The catalyst 5.0Fe/AC showed good activity in the conversion of benzene and addition of Sn seemed to improve the selectivity of phenol in the reaction. © 2006 Elsevier B.V. All rights reserved.Item Modeling of phenol degradation in spouted bed contactor using artificial neural network (ANN)(Walter de Gruyter GmbH, 2008) Dabhade, M.A.; Saidutta, M.B.; Murthy, D.V.R.Presence of phenol and phenolic compounds in various wastewaters and its harmful effects has led to the use of different treatment methods. Work on biological methods shows the use of different microorganisms and different bioreactors so as to improve the removal efficiency economically. The present work deals with the use of N. hydrocarbonoxydans (NCIM 2386), an actinomycetes, for the degradation of phenol. N. hydrocarbonoxydans was immobilized on GAC and used in a spouted bed contactor for effective contact of microorganisms and the substrate. The contactor performance was studied by varying flow rates, influent concentrations and the solids loading in the contactor. The effect of these variables on phenol degradation was investigated and modeling study was carried out using the artificial neural network (ANN). A feed forward neural network with back propagation was used for the model development. The experiments were planned as per the face centered cube design (FCCD) and used for training of the model, whereas data from four other experimental runs were used for testing and validation of the model. The network was optimized for the number of neurons based on the mean square error. The ANN model with three layers with three input neurons, eight neurons in hidden layers and one output neuron was found to predict effectively the effluent concentration for the given operating conditions in the spouted bed contactor. The mean square error was found to be 9.318e-12 for this ANN model. Also the experimental data was used to develop second order nonlinear empirical model obtained using multiple regression (MR) and the results compared with ANN using correlation coefficient (R2), average absolute error (AAE) and root mean square error (RMSE). Results show that R2, AAE and RMSE values of MR model were 0.9363, 2.085 % and 2.338 % respectively, while in case of ANN model these values were 0.9995, 0.59 % and 1.263 % respectively. This shows that ANN model prediction is better than multiple regression model prediction. Copyright © 2008 The Berkeley Electronic Press. All rights reserved.Item Shrinkage Behavior, Thermal expansion Behavior, and Electrical Conductivity Study of Samarium Doped Ceria Electrolytes(IOP Publishing Ltd, 2021) Lakhanlal, u.; Prasad Dasari, H.P.; Saidutta, M.B.In the present study, sintering behavior and electrical conductivity of Sm doped Ceria (SDC) and multi-doped (Sm/Pr/Li) Ceria electrolytes synthesized by microwave-assisted co-precipitation method is studied. SDC green pellet displayed a unimodal shrinkage behavior with a linear shrinkage of 15.67% along with a slight dedensification above 1350?. An increase in electrical conductivity with an increase in sintering temperature from 1200 to 1300 ? was observed. Further increasing the sintering temperature (1400 and 1500 ?) electrical conductivity decreased, which could be due to dedensification (as observed in sintering behavior). At 600 ?, the electrical conductivity of SDC1200 is around 1.34 × 10- 2 S cm-1. The sintering temperature is drastically decreased to 850 ? from 1200 ? with the addition of Li, and the electrical conductivity is increased with the addition of Pr to SDC electrolytes. At 600 ?, the electrical conductivity of 3Li-SPDC850 sintered at 850 ? is 1.44 × 10-2 S cm-1. The thermal expansion coefficient (TEC) of the electrolytes studied were in the range of 12.7 × 10-6 to 17.6 × 10-6 K-1. © 2021 Electrochemical Society Inc.. All rights reserved.Item Stimulus response experiments are conducted in four different rectangular columns having two and three spout cells. A pink-coloured polymer material is used as bed material with ambient air as the spouting fluid. A pulse input of dark blue colour polymer material is used as the stimulus, when the column is operating under steady flow conditions, and the response measured. A mathematical model 'plug flow-mixed flow in series' is used to fit the experimental data and the model parameters are evaluated.(Can Soc for Chem Eng, Mixing behaviour of solids in multiple spouted beds) Saidutta, M.B.; Murthy, D.V.R.2000Item The direct conversion of benzene to phenol by hydroxylation with hydrogen peroxide was carried out over various transition metals impregnated on MCM-41 and activated carbon. Copper-, iron-, and vanadium-impregnated on activated carbon gave better yields of phenol when compared to the corresponding reactions using cobalt-, nickel-, manganese-, and titanium-impregnated catalysts. Comparison of the MCM-41 and activated carbon-supported catalysts showed that activated carbon-supported catalysts gave a higher yield of phenol than did the MCM-41-supported catalysts. The activity of the transition metals supported on activated carbon in the production of phenol was V > Fe > Cu; the corresponding activity of the transition metals supported on MCM-41 was Cu > Fe > V. In addition to the role of transition metals in catalyzing the hydroxylation reaction, the hydrophobic nature of the activated carbon surface seems to enhance the performance of these catalysts relative to the MCM-41-supported catalysts.(Benzene hydroxylation to phenol catalyzed by transition metals supported on MCM-41 and activated carbon) Choi, J.-S.; Kim, T.-H.; Saidutta, M.B.; Sung, J.-S.; Kim, K.-I.; Jasra, R.V.; Song, S.-D.; Rhee, Y.-W.2004Item Methanol selective oxidation to formaldehyde over a modified Fe-Mo catalyst with two different stoichiometric (Mo/Fe atomic ratio = 1.5 and 3.0) was studied experimentally in a fixed bed reactor over a wide range of reaction conditions. The physicochemical characterization of the prepared catalysts provides evidence that Fe2(MoO4)3 is in fact the active phase of the catalyst. The experimental results of conversion of methanol and selectivity towards formaldehyde for various residence times were studied. The results showed that as the residence time increases the yield of formaldehyde decreases. Selectivity of formaldehyde decreases with increase in residence time. This result is attributable to subsequent oxidation of formaldehyde to carbon monoxide due to longer residence time.(Selective oxidation of methanol to formaldehyde using modified iron-molybdate catalysts) Kim, T.-H.; Badekai Ramachandra, B.; Choi, J.-S.; Saidutta, M.B.; Choo, K.-Y.; Song, S.-D.; Rhee, Y.-W.2004Item The direct conversion of benzene to phenol by hydroxylation with hydrogen peroxide was carried out over catalyst containing various transition metals impregnated on activated carbon. Iron and vanadium impregnated catalysts gave better yields of phenol compared to copper impregnated catalysts. The activity of transition metals supported on activated carbon catalyst in the production of phenol was V > Fe > Cu. In addition to the role of transition metals in catalyzing the hydroxylation reaction, the hydrophobic nature of the activated carbon surface and also the surface acidity and basicity seems to have enhanced the performance of these catalysts. © 2005 Springer Science + Business Media, Inc.(Transition metals supported on activated carbon as benzene hydroxylation catalysts) Choi, J.-S.; Kim, T.-H.; Choo, K.-Y.; Sung, J.-S.; Saidutta, M.B.; Song, S.-D.; Rhee, Y.-W.2005Item The direct conversion of benzene to phenol by hydroxylation with hydrogen peroxide was carried out over catalysts containing iron impregnated on activated carbon. Iron was impregnated on various surface modified activated carbons. The catalyst that was made by treating activated carbon with nitric acid, that was treated thermally in the presence of nitrogen at 600 °C and impregnated with 5 wt.% iron, gave a phenol yield of 20%. It was found that the synergistic interactions of surface groups and the impregnated iron have enhanced the performance of these catalysts. © 2005 Elsevier B.V. All rights reserved.(Direct synthesis of phenol from benzene on iron-impregnated activated carbon catalysts) Choi, J.-S.; Kim, T.-H.; Choo, K.-Y.; Sung, J.-S.; Saidutta, M.B.; Ryu, S.-O.; Song, S.-D.; Badekai Ramachandra, B.; Rhee, Y.-W.2005