2. Thesis and Dissertations
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Item Nickel Ferrite Nanocomposite for the Removal of Nsaids, Antibiotics and Caffeine(National Institute of Technology Karnataka, Surathkal, 2024) Indumathi, I.; B, Raj MohanThe earth's surface is made up of 97% salty seawater and the rest is freshwater, which is the only resource for drinking, domestic and industrial use. These water sources are constantly contaminated with organic and inorganic wastes, pathogens, and pharmaceutical and personal care products (PPCP) (PPCP). The release of PPCP products, particularly as nonsteroidal anti-inflammatory drugs (NSAIDs), caffeine and antibiotics is present in municipal sewage influent and effluent at low concentrations ranging from a few ng/L to mg/L. It is also transported to surface water via either a direct or indirect pathway, which is extremely harmful to aquatic habitats and has an impact on the population of naturally occurring bacteria. On the nanotechnological adsorbent basis, adsorption is now growing among wastewater remediation techniques, which can effectively remove existing PPCP in water bodies even at low concentrations. Nickel ferrite NiFe2O4 (NFO) has been extensively used because of its vast surface-active sites, specific surface area, exceptional magnetic and chemical characteristics and alterable shape and size with which they can be modified or functionalized. In recent years, the functionalization of NFO nanoparticles with biomolecules such as β-cyclodextrin (β-CD) and amino acid has improved the possibility of adsorption of targeted pollutants. β-cyclodextrin (β-CD) with six glucose subunits has a significant feature of forming solid inclusion complexes with a wide variety of guest molecules within the hydrophobic cavity of the host cyclodextrin. The functionalization of amino acids with at least one amino group (-NH2) and one carboxyl group (-COOH) could improve the stability of nickel ferrite as well as its ability to absorb the targeted contaminants by providing strong chelating sites. Thus, a laboratory scale experiment was conducted to study the physical, chemical, thermal and magnetic properties of NFO@SiO2@β-CD, L-Leucine functionalized NFO nanocomposite (NFO@L) as an adsorbent and NFO as a catalyst was used in the activation of PMS for the degradation process. The NFO@SiO2@β-CD was used to study the feasibility of the removal of Ketoprofen (KF) and Diclofenac (DCF). The co-precipitation approach was utilised to synthesize nickel ferrite (NFO) nanoparticles, which were then functionalized with TEOS to form NFO@SiO2; β-cyclodextrin was then functionalized using 3-Glycidoxypropyltrimethoxysilane (GPTMS) as an interface to form NFO@SiO2@β-CD. FTIR, XRD, FE-SEM, EDX, TGA/DTG, VSM, BET, zeta potential and particle size analysis were then used to characterise the nanocomposites. The average diameter of NFO@SiO2@β-CD was determined to be 109.1 nm, with superparamagnetic behaviour, a mesoporous surface and a specific surface of 20.78 m2/g. The functionalized NFO@SiO2@β-CD nanocomposite removed 94% of diclofenac in 5 min and 80% of ketoprofen in 360 min with the adsorption capacities of 8.46 and 0.54 mg/g, respectively. The obtained experimental datum for both the pollutants was fitted in kinetic and isotherm models, with the pseudo-second-order kinetic model and Freundlich adsorption isotherm showing the best fit with the highest regression of R2 = 0.99. The nanocomposite was regenerated using 0.1 M NaOH and recycled for about four consecutive cycles in which the reduction in the removal efficiency of ketoprofen and diclofenac was observed to be 51.36% and 64%, respectively. The removal of ciprofloxacin (CIP) and lomefloxacin hydrochloride (LFH) in the aqueous phase was investigated using a hydrothermally synthesized L-Leucine functionalized nickel ferrite nanocomposite (NFO@L). Various analytical techniques were used to analyze L-Leucine functionalized nickel ferrite, and the nanocomposite’s average particle diameter was determined to be between 11 and 15 nm. The maximal measured zeta potential was - 21.5 mV. Fourier transform infrared spectroscopy (FTIR), ninhydrin assay and X-ray diffraction (XRD) analysis confirmed the attachment of L-Leucine onto nickel ferrite. The nanocomposite’s surface-to-volume ratio was calculated to be 92.916 m2/g. The S-shaped curve from the vibrating sample magnetometer analysis reflected the superparamagnetic behaviour of the nanocomposite with a saturation magnetization of 0.665 emu/g. Various parametric experiments were conducted, in which 93.549% ciprofloxacin was removed in 120 min at 303 K, pH 8 and with a NFO@L dosage of 100 mg in 100 mL whereas 75.192% lomefloxacin hydrochloride was removed in 140 min at 333 K, pH 9 and with a NFO@L dosage of 70 mg in 100 mL. The plot of experimental datum in kinetic and isotherm studies fitted well with the Pseudo second order kinetic model and Langmuir isotherm. The ICP – OES analysis revealed that the leaching of iron ions was within the permissible limits in the final analyte. The recycle and regeneration studies showed good stability with a small reduction after four cycle runs. A laboratory batch study on the degradation of Lomefloxacin hydrochloride (LFH), Caffeine (CAF) and LC (CAF and LFH mixed solution) was carried out by stimulating potassium peroxymonosulfate (PMS) using NFO. The NFO nanoparticles were synthesized through a co-precipitation method and characterized using FTIR, XRD, FESEM/EDX, TGA/DTA/DTG, BET, AFM, VSM, Zeta potential, and particle size distribution from FESEM (using ImageJ software). The NFO nanoparticles' specific surface area was estimated to be 112.02 m2/g, and the magnetic properties of the NFO nanoparticles were investigated using VSM analysis. The parametric study included the study on the effect of bare NFO, PMS without catalyst, pH, catalyst dosage, PMS variation with optimized catalyst, initial concentration of LFH and CAF, and reaction time, with nearly 98.61 % LFH was degraded in 220 min, 100 % CAF was degraded in 80 min, 78.07 % LC was degraded in 40 min. The degraded compounds m/z of LFH, CAF and LC were identified using LC-MS. The regeneration and recycling of NFO nanoparticles were investigated to determine the stability of the NFO nanoparticles in the degradation of LFH and CAF in which the degradation efficiency decreased to 90.68 % and 64.1 % respectively upon the third wash with distilled water. As a result, the NiFe2O4/PMS system showed improved degradation even after two recycle runs. Based on these findings, the results suggested that the NFO@SiO2@β-CD nanocomposite, Leucine functionalized nickel ferrite nanocomposite and Nickel ferrite (NFO) could be a potent adsorbent and catalyst to target specific low-concentrated pharmaceutical pollutants, making it an efficient and economical system even for multi-pharmaceutical pollutants.Item Development of Novel Photocatalytic Reactor for Dye Wastewater Treatment(National Institute of Technology Karnataka, Surathkal, 2020) Das, Suman; Mahalingam, HariOver the years, industrial development has increased, causing a rapid increase in all form of pollution. A large amount of organic waste released into the freshwater bodies have increased water pollution several folds. In this regard, an effective environmentally friendly process for wastewater treatment is urgently needed, because sometimes it is difficult to degrade different toxic pollutants efficiently by conventional methods. Photocatalytic nanoparticles are an excellent choice for the mineralization of organic pollutants present in wastewater. The use of the photocatalyst nanoparticle into a reactor is also challenging since a light source is compulsory to activate the catalysts. In this work, TiO2, rGO, g-C3N4 and TiO2/rGO/g-C3N4 mixture in two forms: an admixture and chemically synthesized composite photocatalysts were immobilized in polystyrene films and employed as a photocatalytic film. The characterizations were done using SEMEDX, FTIR, XPS, XRD, ICP-OES, BET-Surface area analyzer, particle size analyzer, band-gap analyzer, etc. Initially, the photocatalytic performance of the prepared TiO2 polystyrene film was checked followed by (TiO2, rGO, and g-C3N4)-admixture and then TiO2/rGO/g-C3N4-chemical composite. The photocatalytic oxidation of synthetic dye wastewater (Remazol Turquoise Blue) under ultra-violet and sunlight irradiation was carried out in different types of photocatalytic reactors (batch, scaled-up a batch with recirculation, and multiphase reactors). The reactor volume was varied from 200 to 2900 mL, and the degradation of Remazol Turquoise Blue was confirmed by TOC and HPLC analysis. The optimization of photocatalytic reaction parameters (effect of catalyst loadings, pH, initial dye concentration, light source, polystyrene photocatalytic film thickness, recyclability the film, oxidizing agents, etc), as well as the reactor parameters (recirculation rate, air flow rate, diameter ratio, etc), were investigated in detail systematically. The synergistic effect of the photocatalysts was also analyzed by using the admixture of the photocatalysts, which showed a great significance in this work. The photocatalytic treatment of RTB dye under optimized conditions shows that there was more than 90% decolorization in most of the reactors after 90 min of irradiation. Amongii various reactors used in this study, the multiphase photocatalytic reactor has unique way to utilize the photocatalyst, which makes it novel and efficient. Also, the multiphase reactor showed the best performance since the observed decolourization and degradation were almost same. To make this study cost-efficient and suitable for large scale application, waste polystyrene was used as a substrate material instead of pristine polystyrene. This work presents a simple, easy, economical, and eco-friendly way to deal with the toxic organic pollutants. The photocatalytic reactors used in this work are highly efficient and can be easily scaled up for the industrial-scale application and employed for any other organic pollutant present in the water.