Faculty Publications

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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
Phenolic profile of unripe areca nuts cultivated in various districts of Karnataka, India
(John Wiley and Sons Ltd, 2024) Hugar, P.; Dutta, A.; Srilakshmi, S.; Belur, P.D.; Raval, K.; Iyyaswami, R.
Background: Annual production of areca nut in Karnataka state exceeds 1.08 million tonnes, contributing 80% and 49% to Indian and global production, respectively. Areca nut (pericarp of Areca catechu L.) is found to be a rich source of valuable phenolic compounds. Total phenolic content (TPC) and total flavonoid content (TFC) were estimated in 21 unripe areca nut samples collected from the major areca nut growing regions of Karnataka state. Arecoline, a prominent alkaloid present in areca nut was estimated and phenolic profile of one areca nut sample was generated using UHPLC–MS/MS studies. Results: A significant variability was found in TPC, TFC and arecoline content among the samples, belongs to different agroclimatic zones. Flavonoids were found to be the major phenolic compounds present in these unripe areca nut samples. The median values of TPC, TFC and arecoline were found to be 99.609 ± 0.002 mg gallic acid equivalent, 78.86 ± 0.007 mg catechin equivalent and 2.17 ± 0.13 mg/g of the sample on fresh weight basis. A positive correlation was found to exist between TPC and arecoline content in the green unripe areca nuts of 6–7 months' maturity. Through UHPLC–MS/MS studies, 61 prominent compounds have been identified. Conclusion: The TPC and TFC of areca nuts collected from different districts of Karnataka falling in various agroclimatic zones varied significantly. In general, the arecoline content found in all these samples was less than that reported elsewhere, and the variability among the samples was also found to be minimal. A positive correlation was observed between TPC and arecoline. UHPLC–MS/MS studies showed the presence of about 52 unique phenolic compounds. © 2023 The Authors. JSFA Reports published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Fabrication of CuxO/TiO2 hybrid nanocomposite by the synergetic effect of mixed phytoextract of agro-waste materials for enhanced visible-light-induced photocatalytic activity in degradation of ciprofloxacin
(Elsevier Ltd, 2025) Shetty, P.; Shetty Kodialbail, V.
The current study presents the environmentally friendly method for the synthesis of visible light active CuxO/TiO2 nanocomposite using the mixed plant extracts of areca nut exocarp (peel) and soapnut pericarp (shell) for photocatalytic degradation of ciprofloxacin, an antibiotic which is an emerging water contaminant. CuxO/TiO2 nanocomposite was synthesised by one pot method by simultaneous addition of precursors using the mixed aqueous extract. It consisted of CuO, Cu2O and TiO2 in all the crystalline phases with a band gap energy of 1.7 eV. The nanocomposite exhibited mixed morphology consisting of needle-like and particulate structures. The CuxO/ TiO2 nanocomposite facilitated 94 % degradation of 10 ppm ciprofloxacin within a span of 120 min under visible light irradiation. The CuxO/ TiO2 nanocomposite synthesized using the mixed extract exhibited superior photocatalytic activity than that synthesized solely with either areca nut peel extract or soap nut shell extract. The phyto-fabricated CuxO/ TiO2 nanocomposite showed better visible light-mediated photocatalytic activity than the phyto-fabricated CuxO, phyto- fabricated TiO2 and Degussa P-25. The kinetics of degradation followed pseudo-first order kinetic model with the rate constant of 0.0218 min?1. Thus, the phyto-fabricated CuxO/ TiO2 demonstrated a good potential as a photocatalyst to harness solar light in the treatment of wastewater contaminated with pollutants of emerging concern. © 2025 Elsevier B.V.

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