Faculty Publications
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Item Evaluation, ranking, and selection of pretreatment methods for the conversion of biomass to biogas using multi-criteria decision-making approach(Springer, 2020) Vannarath, A.; Thalla, A.K.Lignocellulosic biomass resources include agri-waste and agri-biomass which are utilized as a suitable feedstock for bioenergy production. The recalcitrant nature of these biomass can be reduced by the application of various pretreatment methods to access the cellulosic content. This study depicts the evaluation and ranking of different pretreatment methods, and selecting the rank 1 as the best pretreatment method using multiple attribute decision-making approach to facilitate the increased biogas yield. The evaluation was done using technique for order preference by similarity to ideal solution (TOPSIS) and integrated design of experiments (DoE)–TOPSIS. Seven alternatives with five relevant attributes were adopted for this study. Based on the above decision-making framework, alkaline pretreatment (Ca(OH)2 (8%)) option was ranked first for both the techniques. The second and third options were NaOH and NH3.H2O (10%) pretreatment, respectively. The integrated DoE–TOPSIS method has reduced the uncertainty in results by considering different weight sets and replications. The model results and experimental results were in good agreement and portray the best pretreatment method to be employed in the anaerobic digestion, thus, minimizing the series of digestion test during the downstream process of pretreatment aided anaerobic digestion. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Item Synthesis and characterisation of an ultra-light, hydrophobic and flame-retardant robust lignin-carbon foam for oil-water separation(Elsevier Ltd, 2021) Vannarath, A.; Thalla, A.K.The lignin extracted from Arecanut husk (Areca catechu) was used as an additive in lignin-carbon foam synthesis to enhance oil uptake in oil-water separation. The lignin yield from the arecanut husk increased as the husk fibre size reduced. The extracted lignin and lignin-carbon foam were characterised for morphology, structural, compositional and thermal degradation properties. The synthesised lignin-carbon foam appears to be ultralight (density = 0.0294 g/cm3), excellent hydrophobic (water contact angle was 124°), mesoporous (3D cell-like structure), fire-retardant and thermally stable. The foam showed an excellent sorption capacity for different oils, and the highest sorption was observed for diesel oil (7842.71 mg/g). The optimisation of contact time (30 min), lignin-carbon foam dosage (0.5 g), and initial oil concentration (30 g/L) were done for the diesel oil sorption. The isotherm study and kinetic model evaluation were done for the diesel adsorption on the lignin-carbon foam. The Temkin model was found the best fit for the adsorption isotherm. The adsorption kinetics of the lignin-carbon foam for diesel oil was best described by pseudo-second-order kinetics. The thermodynamic parameters showed that the adsorption was endothermic and spontaneous (standard enthalpy change, ?H° = +4926.46 J/mol and standard entropy change, ?S° = 25.249 J/mol/K). The proposed mechanism depicts that the adsorption primarily influenced hydrogen bonding (H-bonding) and n-? interactions. The enduring adsorption of oil into the lignin-carbon foam within few seconds shows the material oleophilicity and confirms their application prospect in oil spill cleanup. © 2021Item Effects of chemical pretreatments on material solubilization of Areca catechu L. husk: Digestion, biodegradability, and kinetic studies for biogas yield(Academic Press, 2022) Vannarath, A.; Thalla, A.K.This study aimed to understand the pretreatment-aided anaerobic digestion of lignocellulosic residues and to assess the substrate solubilization capacity of pretreatment processes. We evaluated the feasibility of biogas production using chemically pretreated Areca catechu L. (Arecanut husk, AH). AH was pretreated for 24h at two different temperatures—25 °C and 90 °C with four different chemicals viz. H2SO4 (acidic), NaOH (alkaline), H2O2 (oxidative), and ethanol in 1% H2SO4 (organosolv) under each temperature. AH solubilization assessment included analyses of parameters such as volatile solids to total solids (VS:TS) ratio, soluble chemical oxygen demand, total phenolic content, and biomass composition. Alkaline pretreatment of AH at 90 °C resulted in the maximum biogas yield of 683.89mL/gVS, which was 2.3 times more than that obtained using raw AH without pretreatment. Methane content of biogas produced using AH pretreated with 2–10% of NaOH was found to be between 71.53% and 75.06%; methane content of biogas using raw AH was 62.31%. In order to describe the AH degradation patterns, biogas production potential from pretreated AH was evaluated using bacterial kinetic growth models (First-order exponential, logistic, transference, and modified Gompertz models). The modified Gompertz and logistic models (correlation coefficient >0.99) were found to have the best fit of all kinetic models for the cumulative experimental biogas curve. We formulated a multiple linear regression equation depicting the biodegradability index (BI) as a technical tool to determine biomethane production; BI is represented as a function of biomass composition (cellulose, hemicellulose, and lignin), with a high correlation (>0.95). Based on our analyses of AH pretreatment and substrate utilization for biogas production, we propose that the biochemical composition of lignocellulosic residues should be carefully considered to ensure their biodegradability when subjected to anaerobic digestion. © 2022 Elsevier Ltd