http://dspace.dtu.ac.in:8080/jspui/handle/123456789/3 2026-04-28T03:58:01Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22674 Title: APPLICATIONS OF MEMBRANE-BASED OPERATIONS IN SEPARATION OF NATURAL PHENOLIC COMPOUNDS Authors: TIWARI, ASHWANI KUMAR Abstract: With the growing global population, there is an increasing need to develop sustainable and green separation processes for high-value bioactive compounds. Naturally occurring phenolic compounds such as betanin and rutin have gained considerable importance in the food and pharmaceutical industries; however, existing separation methods often rely on solvent-intensive, energy-demanding, or non-scalable techniques that compromise product purity and biological activity. Although membrane-based processes have been explored for polyphenol recovery, there remains a lack of systematic, model-integrated, and scale-up-oriented studies that bridge laboratory experimentation with industrial feasibility, particularly for real feed streams. In this context, the present thesis makes a distinct contribution by establishing nanofiltration (NF) as a quantitatively optimised and industrially translatable platform for the selective concentration of two structurally different phenolic compounds, namely betanin and rutin. A self-assembled NF setup using HFT-NF 150 membranes is employed to generate a comprehensive experimental dataset, wherein the individual and interactive effects of pressure, feed concentration, and feed flow rate on permeate flux and solute rejection are rigorously evaluated. Unlike prior studies that report only empirical trends, this work integrates a three-parameter Spiegler-Kedem transport model to extract membrane reflection coefficients, solute permeability, and hydraulic permeability, thereby providing mechanistic insight into solute-membrane interactions and enabling predictive validation of experimental performance. A further aspect of this research is the application of variance-based global sensitivity analysis to membrane separations, allowing the quantitative ranking of operating and transport parameters by their influence on flux and rejection for phenolic solutes. This approach moves beyond conventional one-factor-at-a-time analyses and establishes a robust framework for rational process optimisation. Crucially, the thesis extends beyond model solute systems to address the separation of betanin from its natural matrix, beetroot juice, an area scarcely examined in existing literature. Comprehensive fouling studies using multiple theoretical fouling models are performed to elucidate viii dominant fouling mechanisms, quantify flux decline behaviour, and assess long-term operational stability under realistic feed conditions. These results provide actionable design insights to mitigate fouling and extend membrane longevity. Finally, scale-up simulations grounded in experimentally derived transport and sensitivity parameters demonstrate the technical feasibility of translating laboratory findings into an industrial-scale NF unit. Collectively, this thesis offers a unified experimental-modelling-scaling framework for phenolic compound recovery, delivering original contributions in mechanistic understanding, optimisation strategy, real-feed validation, and process design that advance the state of the art in sustainable membrane-based separations. 2026-01-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22648 Title: HARNESSING ALKALI ASSISTED CALOTROPIS GIGANTEA LEAF AS PHYTOSORBENT FOR REMOVAL OF CRYSTAL VIOLET FROM WATER Authors: RACHANA Abstract: This study investigates using activated Calotropis gigantea (CG) leaves as a natural, cost-effective phytosorbent for the sequestration of crystal violet (CV). The various techniques, including FTIR, XRD, FESEM, DLS, BET, and UV-Vis spectrophotometer, were used to illustrate the efficiency of the phytosorbent. The adsorption behavior of the biosorbent was examined by varying several parameters, such as pH, dye concentration, adsorbent amount, thermodynamics, and equilibrium time. Adsorption isotherms and kinetic models were also fitted. The maximum adsorption capacity of CV on ACG was found to be 111.11 mg/g achieved at 35°C or 308.15 K. The calculated thermodynamic parameters, such as ΔH and ΔS for CV uptake on the adsorbent surface, come out to be 22.397 kJ/mol and -100.25 J/mol/K, respectively. The positive enthalpy change, confirms the endothermic nature of the adsorption process. The negative values of ΔG confirmed the spontaneous nature of the adsorption process. The recyclability of the adsorbent is also good after 4 cycles of regeneration, and the adsorbent has ~80% removal with the real waste water sample. Overall, phytosorbents based on dried Calotropis gigantea leaves demonstrate strong potential as an effective biosorbent for the adsorption of crystal violet via contaminated water. 2025-12-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22631 Title: ELECTROCHEMICAL BIO-SENSING OF CAFFEIC ACID IN REAL SAMPLES USING Ag@g-C₃N₄ COMPOSITE MATERIAL FOR HIGHLY SELECTIVE AND SENSITIVE APPLICATIONS Authors: AKHTER, MD SHOAIB Abstract: Caffeic acid (CA) is recognized as a phenolic antioxidant with anti-inflammatory, antibacterial, anticarcinogenic and immunomodulatory effects, positioning it as a key representative of hydroxycinnamic acids found in wine. Caffeic acid is detectable in various products including fruits, vegetables, wine, olive oil and coffee. Numerous studies suggest that eating foods rich in CA may provide protection against cancer by inhibiting the production of nitro compounds (including nitrosamines and nitroamides) that are primary contributors to this disease. The goal of this research is to create an enzyme-based biosensor for the detection of caffeic acid utilising silver nanoparticles on a graphitic carbon nitride (Ag@g-C3N4) nanocomposite. The Ag@g-C3N4 nanocomposite was synthesised through chemical methods and applied to an indium tin oxide-coated glass substrate via electrophoretic deposition. The resulting biosensor demonstrates a favourable linear range from 1.0 pM to 1.0 μM with a detection limit of 0.75 pM and displays no significant interference from glucose, ascorbic acid, urea and mixtures. Additional efforts were made to validate the biosensor using real samples from coffee, green tea and black tea. The electrochemical findings indicated that the proposed biosensor is a dependable analytical tool for assessing the quality of caffeic acid in food samples. 2025-06-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22620 Title: STUDY OF NATURAL COLOURS Authors: MANN, MANSI Abstract: NOT AVAILABLE 2024-06-01T00:00:00Z