PhD Theses (Chemical Engineering)

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Development of Kaolin-based Microporous Membrane for Energy Efficient Microalgal Harvesting and Effluent Recycle Under Circular Bioeconomic Approach
(2024) Agarwalla, Ankit
Biodiesel as a renewable energy source can provide an alternative to the alarmingly depleting energy from fossil fuels. Microalgae is an encouraging third-generation feedstock for the production of biodiesel as it has the capability of oil production throughout the year. Besides several advantages, commercial production of microalgal biomass feedstock is not considered sustainable due to its high production cost. In this context, recycling the culture media carry significant potential to reduce the overall cost for the long-term growth of microalgal industry. In this work, indigenous low-cost disc and tubular membranes were fabricated using naturally available kaolin as the key precursor. Different composition of kaolin (80-92 wt.%) and binder (8-20 wt.%) was used to optimize the raw material and binder composition. The optimized binder concentration in disc membrane was used to further fabricate tubular membranes. With increase in binder percentage from 8% to 20% in disc membranes, the percentage porosity, average pore size and water permeability decreased from 34.52% to 21.5%, 2.28 μm to 0.195 μm and 6.12×10-9 to 1.69×10-9 m Pa-1 s-1 respectively while flexural strength increased slightly from 7.1 MPa to 9.4 MPa. Hence, binder percentage of 8% i.e., 2% boric acid, 2% sodium metasilicate and 4% sodium carbonate was found to be optimum. Thereafter, tubular membranes will be fabricated using this binder concentration. The fabricated tubular membranes had porosity of ~26% - 47%, a pore diameter of 0.123-0.182 μm, water permeability of 4.2×10-8 – 17.1×10-8 m3 m-2 s-1 kPa-1, along with good mechanical and chemical strength.
Numerical Study on Droplet Breakup Dynamics in Microchannels
(2023) Biswas, Saikat
Droplets can be used as mini-reactors. They provide precise control over any reagent amount, which improves reaction repeatability and uniformity. The small droplets decrease exposure to potentially hazardous chemicals. The food industry, diagnostic testing, cosmetics, supra-magnetic nanoparticle production, medication delivery, and drug discovery all use homogeneous droplets. Droplets are often formed by mechanical agitation. However, mechanical mixing produces droplets of varying sizes. This might jeopardize process controllability. Microfluidics, the study of fluid dynamics at the micro to the nanoscale, enables the control of droplet size and quantity. With hundreds to thousands of droplets formed each second, the throughput of droplet formation rises. Droplets can be formed using i) Active method ii) Passive method. The passive method includes various ways, such as T-junction, co-flow, flow-focusing, and some variants. On the other hand, additional energy such as alternating or direct current is applied in the case of active splitting. In this work, an interest was felt in doing the numerical study on droplet breakup dynamics in microchannels using the passive method with the help of CFD. The objectives of the present work are as follows:
Xylitol from low-cost substrate and process optimization
(2023) Vardhan, Harsh
Xylitol is a high-quality polyalcohol, mainly used in pharmaceuticals, hygiene products, and food due to its functional properties such as anticarcinogenic, antibacterial, low-calorie, and hypoglycemic properties. At present, xylitol is primarily produced through chemical hydrogenation of xylose at high temperatures (150 °C) and pressure (5.5 MPa) on the reaction with metal catalysts such as Pl, Ru, Pt and Raney nickel. Separation and purification of xylitol is very expensive through this process. However, compared to this method, xylitol production through bioconversion of hemicellulosic hydrolysate by micro-organisms is an environment friendly, less energy-intensive, renewable, and overall economical process. This process ensures high safety, low production cost and high product selectivity. The primary objective of this research is to utilize the agricultural bio-waste (such as areca nut husk) as a feedstock for the production of xylitol, preferably in a repetitive batch fermentation process, with C. tropicalis as the fermentative microorganism. Primary processes include, biomass characterization and pretreatment (Mainly dilute acid hydrolysis and lime treatment), Acidic and Enzymatic hydrolysis of biomass, detoxification of acidic hydrolysate by using activated charcoal and cation-anion exchange resins, detoxified hydrolysate was fermented by C. tropicalis for xylitol production and finally downstream process was performed for product purification. Lignocellulosic materials are inexpensive and readily available biomass in the form of either agricultural wastes or forest residues. These materials can be used as energy producer sources for solids (xylitol, etc.) liquids (ethanol, butanol, etc.) and gaseous (CO, H2, etc.) as energy to meet increasing energy demands. Biomass pretreatment is a predetermined step to fragment lignocellulosic biomass into its basic components such as lignin and carbohydrate molecules. The first objective of present study is the pretreatment and characterization of lignocellulosic biomass namely Areca nut husk (Arecan catechu), which is widely available in the region of North-Eastern part of India. The study includes several physical characterizations like ultimate and proximate analysis, thermogravimetric analysis, crystallinity and chemical characterization that embraced Raman spectroscopy and FTIR. This study revealed that the Areca husk fiber contained 29.17% hemicellulose. Combination of all these properties revealed that Areca nut husk can be explored as the impending potential for low-cost source of xylose.
Applicability of Graphene Oxide-based Membranes in Separation Processes: A Molecular Dynamics Simulation Study
(2024) Reddy, Pilli Rajasekhar
In the past decade, multilayered graphene oxide (GO) membranes have emerged as promising candidates for desalination and wastewater treatment applications. Despite their potential, a comprehensive understanding of separation mechanisms remains elusive due to the intricate morphology and structural arrangement of interlayer galleries. This thesis addresses these challenges by constructing two distinct structural configurations, namely lamellar and non-lamellar, to investigate separation mechanisms at the atomistic level. Moreover, one major issue with layered GO membranes is their tendency to swell in an aqueous environment. Recognizing the tendency of layered GO membranes to swell in aqueous environments, this thesis explores cation intercalation within interlayer galleries as a promising solution to mitigate this problem. The applicability of lamellar, non-lamellar, and cation-intercalated GO membranes as forward osmosis (FO) and reverse osmosis (RO) membranes in separation and purification applications is studied using non-equilibrium molecular dynamics (MD) simulations. Real-life scenarios, including seawater, pharmaceutical industrial wastewater, shale gas wastewater, and human urine are considered to assess the performance of GO membranes. These GO membranes exhibit an improved trade-off between water permeance and selectivity compared to conventional polymeric membranes. This enhanced performance is attributed to the inherent structural characteristics of GO membranes, such as nanosized 2D channels and open edges, which enable the rapid movement of water molecules across membrane layers while efficiently retaining undesired species. Additionally, the nanosized GO nanosheets have abundant oxygen-containing functional groups (OFGs), enhancing their mechanical strength and chemical stability.
Preparation, characterization, and biodegradation studies of novel active poly (3-hydroxybutyrate) nanocomposite films and their application in packaging fresh produce
(2024) Kumari, Satti Venu Gopala
The rising environmental concerns associated with non-biodegradable petrochemical-based food packaging underscore the critical need for sustainable alternatives. Poly (3-hydroxybutyrate) (PHB), a natural polyester of microbial origin has excellent potential for food packaging applications owing to its renewability, high crystallinity, biocompatibility, biodegradability, and physical attributes comparable to conventional plastics. Nonetheless, PHB has certain shortcomings, including low elongation at break, moderate gas barrier properties, and negligible antimicrobial and antioxidant activities for its direct application in food packaging. Observing these facts, our work focused on overcoming the limitations of PHB by combinational loading of essential oil and nanofiller, evaluating the suitability of developed PHB-based nanocomposite films for storing fresh produce and assessing the biodegradability of these films in natural environmental conditions viz. soil and river water. Firstly, five different chemical synthesis routes (precipitation, sonication-precipitation, microwave combustion, conventional combustion, and solvothermal processes) were screened to customize the properties of MgO nanoparticles (NPs) for their reinforcement in PHB. Wherein, the microwave combustion route yielded MgO NPs with higher specific surface area (67.32 m2/g), smaller particle size (5-35 nm), and outstanding antimicrobial and antioxidant activities compared
(A) study on optimal sensor placement strategies for water quality monitoring in water distribution networks
(2024) Gautam, Dinesh Kumar
Ensuring universal access to clean water and sanitation, a key objective of the United Nations Sustainable Development Goal 6, necessitates effective water treatment and distribution. However, the degradation of water quality in common sources like rivers and groundwater has heightened the demand for water treatment, underscoring the significance of water distribution networks (WDNs) in delivering safe water to consumers. This thesis addresses the critical task of optimal sensor placement in WDNs for water quality monitoring, considering challenges such as contamination events, network vulnerabilities and data transmission modes.
Structural, Functional and Morphological Modifications of Graphene Oxide-based Nanocarriers for Anticancer Drug Delivery
(2024) Sonatakke, Ankush Dasharath
Chemotherapy has continued to be the most frequently utilized therapy for cancer treatment. Despite the abundance of chemical chemotherapeutic agents and anticancer medications, their unregulated administration and inability to distinguish between rapidly proliferating healthy cells and cancer cells lead to adverse impacts on cancer therapeutics. Moreover, due to the diversity of cancer cells, the emergence of drug resistance, and the undesirable effects induced by high and/or repetitive drug doses, the administration of a solitary chemotherapeutic agent frequently fails to accomplish a comprehensive cancer regression. The major challenges related to effective and sustainable consumption of chemotherapeutic agents can be subsided with targeted drug delivery systems (DDS) directed by the advanced nanomaterials (nanocarriers), natural chemotherapeutic agents such as gallic acid (GA), caffeic acid (CA), targeting ligands such as folic acid (FA) and employing co-delivery systems for chemotherapeutic agents. Previous studies related to anticancer DDS have demonstrated the therapeutic potential of graphene-based nanocarriers due to their distinct surface characteristics.
Solvothermal Liquefaction of Peel and Pulp of Citrus limetta Fruits and Analysis of Products
(2024) Acharya, Sneha
The contemporary need for clean and sustainable renewable energy demands a shift towards harnessing diverse biomass resources for thermochemical conversion. Citrus fruits, particularly sweet lime scientifically recognized as Citrus limetta (CL), generates substantial waste in the form of peel and pulp after juice extraction. This dissertation addresses the disposal challenge by focusing on the liquefaction of these fruit wastes under less severe conditions of temperature (240-280 °C) and pressure (90-130 bar). Methanol, a high-polarity hydrogen-donor solvent, was chosen for its efficacy in biomass hydrogenation, yielding biocrude and biochar with properties akin to traditional fossil fuels. Varied biomass-to-solvent ratios resulted in a 12.5 wt. % biocrude yield from Citrus limetta peel at 240 °C, showing an increase compared to similar citrus fruit wastes. The generated biocrude from Citrus limetta pulp achieved a notable energy density of 26.76 MJ kg-1 at a constant temperature of 260 °C and a 1:4 biomass-to-solvent ratio. GC-MS analysis revealed a higher area percentage of phenol derivatives in the biocrude, indicating the decomposition of the thermally stable lignin biopolymer during liquefaction. Co-liquefaction of Citrus limetta peel and pulp co-feed exhibited synergy, enhancing the biocrude yield to 13.47 wt. % at 240 °C and a 1:2 biomass-to-solvent ratio. The rise in temperature during co-liquefaction yielded a maximum higher heating value (HHV) of 27.6 MJ kg-1 at 280 °C, surpassing single-feed liquefaction. GC-MS and proton nuclear magnetic resonance (1H NMR) results confirmed a biocrude rich in aromatics, alkanes and aliphatics. Biochar energy densities in the range of 14.45 MJ kg-1 to 20.62 MJ kg-1 suggested its application as a source for thermochemical conversion. Additionally, Brunauer Emmett Teller (BET) results underscored the porous nature of solid biochar and its utility as low-cost adsorbents in soil remediation and catalysts for thermochemical conversion. Finally, in evaluating biocrude energy density, Citrus limetta pulp demonstrated higher efficiency than the peel under conditions of 280 °C and a biomass-to-solvent ratio of 1:4. In situations where separating pulp and peel would be impractical, co-liquefaction of Citrus limetta peel and pulp could possibly be recommended for optimal biofuel production.
Identification, Quantification and Removal of Microplastics from Various Sources
(2023) Yaranal, Naveenkumar Ashok
Microplastics in the environment pose a significant threat to the entire ecosystem. The frequent utility of plastic in daily life, inadequate disposal, and improper waste management leads to a wide distribution of microplastic in atmospheric, terrestrial, and aquatic environments. Household, industrial, tyre wear and tear, construction, incineration, plastic litter, landfill, and agricultural activities are the major sources of microplastics in the environment. Microplastics are associated with various monomers and plastic additives. On the other hand, it becomes the carrier of toxic and hazardous chemicals from the surrounding environment. Microplastics enter the human body through the air, food, and drinking water (tap and bottled water). Taking all these issues into consideration, the main objectives of this work are divided into four sections. The first section deals with microplastics in Brahmaputra River water, tap water, and household purified water. The second section deals with the identification of microplastics in sea water and beach sediments. The third section deals with the identification of microplastics in Indian edible salts and the removal of microplastics to produce microplastic-free salt. The fourth section deals with the quantification of microplastics and removal from the laundry outlets using the electrocoagulation method.
Molecular Modeling and Experimental Insights in the Application of Hydrophobic Deep Eutectic Solvents for Remediation of Micropollutant from Aqueous Systems
(2023) Paul, Nabendu
Micropollutants have emerged as a new class of pollutants due to their harmful effects on humans and livestock, even at low concentrations. Even if present in low quantities, micropollutants have been associated with a range of detrimental impacts on humans and livestock, including poisoning, neurotoxicity, endocrine-disrupting effects, and microorganism antibiotic resistance. Green solvents, especially hydrophobic DESs (HDESs) through liquid-liquid extraction and microextraction (LLE/LLME) can have a revolutionary impact in achieving the efficient pharmaceutical removal pathway.
Investigation of Multiphase Flow in Porous Micromodels using Micro-PIV Experiments and Numerical Simulations
(2023) Sharma, Vikas Kumar
This study investigated pore-scale flow dynamics and displacement mechanisms in multiphase flow through porous media using experimental and numerical approaches. 2D porous micromodels of various geometries were fabricated to visualize the fluid flow using Micro-Particle Image Velocimetry. Parameters such as displacing phase flow rate, viscosity, heterogeneity of porous medium, interfacial tension, and wettability were found to significantly impact the trapping and mobilization of the non-wetting phase through the porous medium. Chemical slugs (including alkaline solution, polymer solution, and alkali polymer solution) and nanoparticles (silica) improved fluid-fluid and fluid-solid interactions. Silica nanoparticles in an alkaline solution enhanced oil mobilization by reducing the interfacial tension, altering the contact angle, and preparing a stable microemulsion. The parameters such as flow rate and viscosity affected the displacement, showing the shear-induced circulations, viscous instability, droplet breakage, and coalescence, resulting in unsteady flow behavior during immiscible two-phase flow in heterogeneous micromodels. Higher flow rates reduced trapped fluid saturation but intensified shear-induced circulations. Heterogeneous micromodels exhibited more trapping than homogeneous porous medium. Numerical simulations focused on the immiscible two-phase flow in complex pores (such as dead-ends and contraction-expansion pores), highlighting the impact of injection velocity, viscosity ratio, interfacial tension, wettability, trapped oil viscosity, and geometric parameters. Lower contact angles had minimal effect on residual oil saturation until reaching a critical contact angle. Complete displacement from the dead-end occurred when the oil-water interface reached the dead-end bottom before the rupture point. Higher injection velocities improved oil recovery from the dead-ends, while lower velocities enhanced recovery from the contraction-expansion pores. Microscopic studies used 2D micromodels to explore displacement and oil recovery during low-salinity water flooding and subsequent chemical floodings. The observed phenomena included fluctuating flow, flow direction reversal, viscous fingering, film formation, unsteady behavior, and velocity jumps during low salinity water flooding. Polymer flooding had a limited impact on the trapped oil, while the alkali-polymer solution injection enhanced oil recovery through emulsification, interfacial tension reduction, and increased water-wettability. The core flooding experiments demonstrated an overall heavy oil recovery of 75.37% with simultaneous chemical slug injection, whereas individual slug injections resulted in lower oil recovery, particularly for alkali-surfactant-polymer flooding. Porous micromodels elucidated suspension flow dynamics, revealing the influence of initial particle location, concentration, and shear-induced particle migration.
Studies on Utilization of Algal Biomass for Food Packaging
(2023) Mondal, Kona
The increasing demands for safe and healthier food products have led to the development of novel packaging technologies that protect the globe from hazards arising from fossil-based non-biodegradable food packaging material. In this regard, renewable bio-based and biodegradable plastics produced by economically viable industrial processes can be considered and utilized as sustainable plastic food packaging material. Besides, the whole world is combating the crucial problem of post-harvest losses of fresh produces, wherein India is facing a 30-40% loss due to post-harvest. In this context, novel packaging technologies in the form of edible film and coating as a preservation technique can provide an alternative solution to protect post-harvest fresh produce. In the present work, the development of sustainable primary food packaging material in the form of edible films and coating is studied and characterized for various physicochemical, biochemical, and microbial properties. Also, the developed edible coating formulation is applied to food systems (green chili, tomato, onion, and potato) to check the effectiveness of the coating. The storage study of the coated fresh produce has been conducted at room temperature to determine the effectiveness of coating on the quality and shelf-life extension of the produce and to draw a comparison against the uncoated. Among the variety of edible biopolymers, chitosan, and guar gum have been utilized in this work. Further, targeting to develop active edible packaging and tuning the inherent properties of these edible biopolymers for obtaining better effectiveness, natural food additives such as green algae extract, and essential oil is added. Algae is an emerging biomaterial, predominantly used for biodiesel production by utilizing its oil. It is used in the pharmaceuticals and food industry. However, the residue of algae biomass after oil extraction is treated as waste either used as cattle and aqua feed or dumped as waste. Interestingly, this industrial bio-based waste can be utilized as a whole or by extracting its bioactive compounds and can be incorporated into the biopolymer to obtain effective properties. The green algae biomass residue has been utilized and the extract is added to the edible packaging formulation for enhancement of barrier, physicochemical, antioxidant, antimicrobial, and other characteristics properties which are necessary for food packaging. Besides, sustainable bio-composites have been fabricated with the incorporation of cellulose nanocrystal biomaterials extracted from algae biomass residue for the development of secondary packaging material. In this context, Poly(lactic acid) (PLA), and Poly(ε-caprolactone) (PCL) have been utilized in order to develop secondary packaging, which is one of the most widely studied sustainable polymers that possess several properties that are comparable to conventional polymers. The developed biodegradable bio-composites are studied in detail for crystalline behavior and migration properties. Active agent curcumin is deliberately added to the bio-composites to study the effect of nanostructured material on the migration behavior of active compounds. The active secondary food packaging material is further applied to food systems to understand the effect of packaging material. Further, a cytotoxicity test has been performed on all the developed packaging materials for understanding the non-toxicity and biocompatible nature. Overall, in this thesis, an alternative pathway for extending the shelf-life of perishables using edible coating technology has been reported and it has also demonstrated the capability of utilizing algae biomass waste for the fabrication of primary and secondary food packaging material. Also, this thesis work provides the first step in the utilization of algae biomass for the development of primary active packaging material.
Solvation and Extraction Mechanism of Aromatic Solutes and Asphaltene utilizing Deep Eutectic Solvents: Experimental and Atomistic Simulation Studies
(2023) Kumar, Nikhil
Deep eutectic solvents (DES) have emerged over the last two decades as a novel class of ionic liquids (ILs). In their broadest sense, DESs are usually formed by mixing a quaternary ammonium salt (typically choline chloride and derivatives) with hydrogen bond donor molecules such as amines, amides, alcohols, carboxylic acids, sugars, or polyols. The mixing of these two components upon gentle heating and in a specific molar ratio leads to a depression of the melting point, resulting in most of the cases in a liquid at room temperature, where no waste is produced, and no further purification steps are needed. Furthermore, DES's components are often biodegradable and non-toxic.
Bioinspired Synthesis of Metal Oxides and Sulphide Electrocatalysts for CO2 and N2 Conversion to Formate and Ammonia
(2023) Chowdhury, Anirban
This doctoral work focuses on the development of environmentally friendly processes for the synthesis of metal oxides and metal sulphide (nano)electrocatalysts. These catalysts are then utilized for the electrochemical reduction of CO2 and N2 to produce value-added chemicals in a semi-batch laboratory electrolyzer.
Protein-Surface and Protein-Ligand Interactions: Insights from Atomistic Simulations
(2024) Tiwari, Shivam
Proteins are one of the most abundant and essential class of organic molecules present in the living systems. Their role in the sustenance and growth of life is unique. However, proteins can turn toxic and unfavourable if they are displaced from their native form or present in an undesirable environment. In this thesis, we perform a computational investigation of protein's interaction with various surfaces and chemical entities in varying environments. Various roles of protein are explored in this thesis, ranging from, as a foulant in a desalination membrane, as a cell invader to toxic β plaques causing cell damage. Specifically, in the first part (first two chapters) of the thesis, the protein plays a role of a membrane foulant. We investigated the reason for differences found in fouling of reverse osmosis (RO and a forward osmosis (FO) membrane with lysozyme protein. We explained the role of hydration repulsion and electrostatic interactions in the differences found in FO and RO fouling. we studied the interaction of SARSCoV2' s spike protein (which plays a crucial role in cell entry of the CoV2 virus) with the montmorillonite surface, a clay mineral. Substantial damage to the secondary structure of spike protein is observed in the presence of a mineral surface. In the last two chapters, protein is in the form of toxic β sheets, responsible for a range of age-related dementia. Mechanism of binding and disaggregation of Aβ fibrils with a novel peptidomimetic compound was investigated. The compound showed a strong binding on Aβ fibril via hydrophobic interactions and significant destruction of the fibril's β sheet content. Finally, the interaction between A β fibrils and lipid bilayer was studied using a prodrug peptide β-Aspartyl. The study showed that β-Aspartyl inhibits the interaction between A β fibrils and lipid bilayer. The study also showed the role of π- π stacking and cation-π interactions in binding β-Aspartyl on fibrils.
Treatment of Steel Industry Wastewater by an Integrated Ozonation and Electrocoagulation Process
(2024) Das, Pranjal Pratim
The steel industry plays a crucial role in global economic growth, yet its expansion has led to increased wastewater discharge, which varies based on the unit operations used, such as blast furnaces, coke ovens, and rolling mills among others. Such wastewater often contains toxic pollutants like cyanide, phenol, oil & grease, ammonia-N, and colored compounds. Conventional treatment methods, including chemical coagulation and biological processes, sometimes fail to fully remove these contaminants, thus prompting the need for more effective solutions.
Valorization of Rice-Husk for Optimal Production of Bio-Oil, Bio-Char, And Silica Nanoparticles
(2022) Das, Sutapa
Rice husk is an agricultural waste-product whose management has yet not been standardized on a commercial-scale following sustainable norms. Ineffective waste management of this abundant biomass often leads to large amounts of rice husk being decomposed via means such as open-pit incineration. This severely impacts the environment and is one of the leading causes of air pollution, notable mostly in the region of North India. Over the decades, different processes have been adapted to tackle this issue. One of the thermochemical techniques, pyrolysis, offers immense potential towards converting this biomass to several value-added products. This thesis employs the usage of slow pyrolysis to achieve the conversion of rice husk to bio-oil, bio-char and silica nanoparticles. In order to optimize the overall process towards maximizing the product yield, an optimization scheme, namely, Response Surface Methodology (RSM) has been employed which helps determine the ranges for the different process variables - temperature, gas holding time and gas flow rate. Extensive characterization of the process and the products have been carried out. Slow pyrolysis has been performed under inert (N2) and reactive environments (CO2) to understand the effect of ambient conditions of the product profile. For instance, bio-char, displayed adsorbent features such as high porosity, surface area, and hydrophilicity when generated under CO2 environment, while under N2 environment, it possessed a high carbon content, thus highlighting its usage as a soil conditioner for improving soil fertility. Bio-oil, on the other hand, was also obtained and its physico-chemical characterization revealed potential for usage as a fuel. It was subjected to different upgradation techniques such as solvent-exchange and catalytic-upgradation in presence of bio-char. Thus, the latter technique also presented itself as another route towards utilization of organic modifiers for improving bio-oil properties. Silica nanoparticles (SI NP), were also generated using the rice husk as a feedstock. These particles were obtained as a result of calcination process involving bio-char. SI NP could themselves be modified and applied as a membrane, using natural cotton substrate, for effectively separating oil from an oil-water mixture. Thus, in a nutshell, this thesis aims to highlight the effectiveness of the slow pyrolysis process by utilizing the abundant biomass for obtaining the diverse collection of valuable products.
Crystallization, Separation, Extraction, and Quantification on a Microfluidic Platform
(2022) Singh, Sunil Kumar
The primary focus of the thesis is to explore, design and develop a microfluidic platform for the efficient resolution of enantiomers, surfactant separation, dye extraction, and Hemoglobin quantification. A flexible μ-reactor and a μ-crystallizer are fabricated for the continuous production of diastereomer salt crystals from racemic α-phenylethylamine (I) where optically active L-(+)-tartaric acid (II) is used as a resolving agent. Moreover, a Y-shape microchannel was fabricated and thin copper sheet electrodes were placed across the channel to separate both anionic and cationic surfactant simultaneously from its mixture under the influence of ultra-low electric voltage. It was found that separation efficiency solely depends on the residence time of the fluid. Furthermore, liquid-liquid extraction was investigated to transfer a component transfer from one liquid phase to another liquid phase under the presence of an applied external electric field in a microchannel. With this, we explored interfacial instability in the presence of an external electric field inside the microchannel for the extraction of methylene blue dye from the aqueous phase using N-amyl alcohol. Additionally, we attempt to develop a simple, low-cost, easy to use point of care (PoC) device based on the spectrophotometric principle for the quantification of Hemoglobin (Hb) on a microfluidic platform. The specific interactions of Methylene Blue (MB) with Hb in the presence of CDs show a unique characteristic optical feature, and the same is exploited for the quantitative estimation of Hb.
Studies on Energy and Environmental Applications of Ravenna Grass (Saccharum ravennae) Biomass
(2024) Dhara, Simons
The Ph.D. thesis focuses on the utilization of Saccharum ravennae grass as a biofuel source and for environmental applications. Bioethanol production involved optimizing sugar yields using enzymatic hydrolysis with various pretreatment methods, including CCD RSM for alkaline lignin extraction , which were targeted as the first two objectives of the thesis . Thereafter, the last two objectives of the thesis affirmed the utilization of the extracted lignin with the PSf membranes for Cr(VI), Pb 2+2+, and dye removal from
Studies on Development of Bio-based Biodegradable Polymers and Their Efficacy as Biomaterials
(2023) Chethana, M
Exhaustion of non-renewable resources and increasing concern towards the non-biodegradability of conventional polymers demands research for alternative, bio-based and biodegradable polymers having comparable properties. Recently, research in the field of sustainable polymers is highly focused on the use of renewable wastes generated from agriculture, food, and the meat industry for the development of biodegradable biomaterials. The biomaterials prepared from these renewable wastes find their applications in the field of medicine and help to restore biological functions. Polyhydroxybutyrate (PHB) is a biodegradable biomaterial of bacterial origin produced intracellularly as an energy reserve in a stress-induced condition which has a potential application in drug delivery. Poly(latic acid) (PLA) is another class of bio-based polymer produced by the polymerization of lactide predominantly used in biomedical applications and packaging. Prodigiosin is a bacterial pigment used as a remedy for cancer treatment, and nanocellulose is a bionanomaterial suitable for high-performance applications. In this perspective, the current study extensively deals with the utilization of waste sorghum stalks consisting of fermentable sugars, cellulose, and hemicellulose for the production of biomaterials such as PHB and nanocellulose. Prodigiosin is produced from Serratia nematodiphila isolated from river water, and metal-free PLA is synthesized using prodigiosin as a metal-free catalyst. Over the assessment, the juice from agricultural waste sorghum stalks consisting of ~60 g/L of fermentable sugar is used as an inexpensive carbon source for the production of PHB. The minimal media supplemented with sorghum juice is used for the optimization and production of PHB. The optimized conditions yielded the maximum productivity of ~8.2 g/L of PHB within 24 h of cultivation. The fed-batch operation with dO2 controlled strategy maximized the productivity four-folds in comparison to the batch operation. It was able to obtain PHB with a molecular weight of ~400 KDa and recovery of ~94% using solvent extraction. The characterization of the produced

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