Papers by Keyword: Zeta Potential

Abstract: This study examined the influence of pH (4, 7, 10), temperature (20 °C, 30 °C, 40 °C), nanoparticle concentration (13 ppm, 26 ppm), and Pb²⁺ addition (0 , 7 ppm) on the dispersion behavior of bentonite nanoclays in water. Using light scattering techniques, the hydrodynamic radius, zeta potential, and diffusion coefficient were measured. Results showed pH as the primary control, with aggregation highest at neutral pH and stability greatest under basic conditions. Concentration changes modestly influenced dispersion, while Pb²⁺ reduced stability through electric double layer compression and induced precipitation at high pH. Temperature effects were minimal. The results highlight the importance of pH and ionic environment in regulating nanoclay behavior and stability, with implications for its use in water treatment and remediation systems.

Abstract: Gold nanoparticles (AuNPs) have garnered significant interest in the field of biomaterials and biomedical engineering due to their wide-ranging applications, excellent biocompatibility, low toxicity, and customizable stability. This study focuses on synthesizing AuNPs through an environmentally friendly approach, specifically by utilizing the aqueous leaf extract of Allium tuberosum as both a reducing and capping agent. The synthesized AuNPs were characterized using UV-Vis Spectroscopy, revealing an absorption peak at 548 nm within the surface plasmon resonance (SPR) of AuNPs. Morphological analysis conducted via SEM showed a mixture of rod-shaped and spherical-shaped AuNPs, with dimensions of 41.0 nm (width) and 181.6 nm (length) confirmed through DLS measurements. EDX analysis confirmed the high abundance of gold in the synthesized AuNPs. Furthermore, a zeta potential value of -26.2 mV indicates that the AuNPs have decent stability. Phytochemical analyses and FT-IR results implicated that the Saponin present in the Allium tuberosum leaf extract played a crucial role in reducing metal ions and stabilizing the AuNPs. The potential of Allium tuberosum leaf extract for synthesizing diverse metal nanoparticles highlights its promise for biomaterials and biomedical engineering. The synthesized AuNPs show versatility for applications like targeted drug delivery, non-invasive imaging, and emerging biomedical uses.

Abstract: This study investigates Halloysite Nanotube (HNT) dispersibility in ethanol-water mixtures – 0% and 10% ethanol at 100, 300, and 500 ppm HNT concentrations. Overall, the study finds that changes in HNT concentration linearly affect the response variables and showed that the 10% ethanol solvent has a higher zeta potential, smaller particle size, higher viscosity, and settling velocity. The enlargement of HNT particles at 10% ethanol while keeping better stability than water solvent is unexpected and can open novel studies about the dispersion of HNT in this solvent system.

Abstract: Abstract. Advanced semiconductor technology features complicated three-dimensional nanostructures and nanoconfined spaces such as nanosheets, supervias, deep contact holes and nanocavities. Uniform wet etching of such nanoconfined spaces across different feature sizes or critical dimensions (CD) is extremely challenging. Typically, etch rate decreases with decrease in CD size. In this paper we report methods to achieve uniform wet etch rate (ER) of SiO₂ across different CD sizes by mixing organic solvents in the etching solution. We also report a reversal of etch rate trend where SiO₂ structure of smaller CD etches faster than a larger CD, by tuning the ratio of organic to water solvents in the etching solution. We also investigate the impact of parameters such as solvent type, wall material, surface tension and ionic strength on ER. Our data suggests, while surface tension and ionic strength show no impact, the type of wall material, surface potential and organic solvent amount in the etching solution show a strong influence on SiO₂ ER. Also, zeta potential could explain most of our results but not all, suggesting that surface potential is not the only factor impacting CD dependent ER in a nanoconfined spaces.

Abstract: In this work, we consider transient electroosmotic flow of fractional Maxwell fluids model derived for both velocity and temperature in a micro-channel. We use the Poisson-Boltzmann equation to describe the potential electric field applied along the length of the micro-channel. Exact solutions of both velocity and temperature were obtained using Laplace transform combined with finite Fourier sine transform. Due to the complexity of the equations for velocity and temperature, the inverse Laplace transform was obtained using the numerical inversion formula based on Gaver Stehfest’s algorithms. The numerical solutions were simulated with the help of Mathcard software and the graphical results showing the effects of time, relaxation time, electrokinetic width and fractional parameters on the velocity of the fluid flow and the effects of time and fractional parameter on the temperature distribution in the microchannel were presented and discussed. The results show that the applied electric field, the electroosmotic force, electrokinetic width, and relaxation time play vital role on the velocity profile in the micro-channel and the fractional parameter can be used to regulate both the velocity and temperature in the micro-channel. The effects of the various influential parameters on both fluid velocity and temperature distribution were found to be useful for the design of microfluidic devices. These devices could be useful for biomedical diagnosis and analysis, for clinical detection of viruses and bacteria in biological processes. Keywords: Caputo fractional derivative, Electro kinetic width, Electroosmotic flow, Heat transfer, Zeta potential,

Abstract: Gallium arsenide (GaAs) nanoparticles' optical and emission properties can be tuned bychanging their size across the visible spectrum. GaAs nanoparticles' optical characteristics aredegraded by oxidation on their surface. This work investigated the optical constants and the opticalband gap for a GaAs nanoparticle immersed in acetone using the laser ablation into liquids (LAL)technique after being exposed to a Nd: YAG pulsed laser operating at the wavelength (1064nm)10Hz frequency, and 7ns pulse width for a fixed flounce of 1.32 J/cm2, and the time of ablationwas 5 minutes. In order to calculate the optical conductivity (σ), refractive index (n), extinctioncoefficient (k), dielectric constant, absorption coefficient (α), and optical band gap, an opticalinvestigation was carried out utilizing a UV-Visible Spectrophotometer region in the wavelengthrange 300-1200 nm. The band gap energy was determined to be 3.8 eV, which is greater than thebulk Ga energy. The band gap energy of nanoparticles increases with increasing laser pulse energyand decreases with increasing pulse repetition rate. Transmission spectra increased as wavelengthsincreased, while optical absorption coefficients, extinction coefficients, and refractive coefficientsdecreased. The difference in optical constants is explained by defect states and the average bandenergy of the system. The acetone stability test reveals a peak at -0.69 mV, indicating low stabilityin nanoparticles.

Abstract: The Catharanthus roseus plant was extracted and converted to nanoparticles in this work. The Soxhlet method extracted alkaloid compounds from the plant Catharanthus roseus and converted them to the nanoscale. Chitosan polymer was used as a linking material and converted to Chitosan nanoparticles using Sodium TriPolyPhosphate (STPP). The extracted alkaloids were linked with Chitosan nanoparticles CSNPs by maleic anhydride to get the final product (CSNPs- Linker- alkaloids). The synthesized (CSNPs- Linker- alkaloids) was characterized using SEM spectroscopy UV–Vis., Zeta Potential, and HPLC High-Performance Liquid Chromatography. Scanning electron microscope (SEM) analysis shows that the Chitosan nanoparticles (CSNPs) have small dimensions with regular spherical and nanotube shapes of a diameter range of (49 - 70) nm. The final product (CSNPs- Linker- alkaloids) has two shapes (spherical particles and tubes) in nano dimensions and is close to each other compared to normal Chitosan. The absorption peaks for Chitosan (CS), Chitosan nanoparticles (CSNPs), Chitosan nanoparticles (CSNPs), and maleic anhydride revealed that converting Chitosan to Chitosan nanoparticles and mixing it with the plant extract, led to an increase in the absorption value and wavelength range. Also, the appearance of two peaks at 222 nm and 402 nm nano instead of the peak of Chitosan at 289.9 nm. Zeta Potential results of CSNPs- Linker- alkaloids showed that the extract of the nano-alkaloids bound to chitosan nanoparticles carries a positive charge of 54.4 mV. This surface charge is essential in maintaining the colloidal solution's stability in its natural form without changing. High-Performance Liquid Chromatography (HPLC) was used to estimate qualitative and quantitative plants extracted from Catharanthus roseus. Quantitative HPLC results show that Catharanthus roseus contains a good and acceptable concentration of Vinblastine, Vincristine, Vinorelbine, Vincamine, and Vintafolide (66.75, 242.91, 0.7, 83.77, 42.34) ppm respectively. The qualitative results show a good match for the influential groups of pure standard vincristine and alcoholic extract and dry powder of the Catharanthus roseus plant. The successful synthesis of nanoparticles from the Catharanthus roseus plant can be used in biosensors and biomedical applications.

Abstract: The stability of dispersed nanoparticles in the base fluid has always been one of the most important challenges in using nanofluids as a coolant in heat transfer applications in different industries such as modern electronic equipment, heat exchangers, solar technologies, etc. In the present study, the dynamic light scattering (DLS) method is used to obtain the particle size distribution of Al₂O₃-ZnO dispersed in DI water. After adjusting the optical arrangement and designing the DLS setup, the correlation curves are plotted by analyzing the detected signals of the experiments. Then, a decay rate is derived by fitting an exponential function to the correlation curve to get the particle size distribution by using the Stoke-Einstein equation. In order to investigate the stability of Al₂O₃-ZnO water-based nanofluid, the particle size distribution profiles are studied several times. In addition, the stability of Al₂O₃-ZnO-CNT hybrid nanofluid is followed by absorbance measurements using a UV-Vis spectrophotometer. Moreover, the thermal conductivity coefficient and electrical conductivity of the Al₂O₃-ZnO hybrid nanofluid with and without CNT particles are determined by utilizing KD2 Pro and PCT-407 devices, respectively. The results showed that the peak in the particle size distribution curve for Al₂O₃-ZnO hybrid nanofluid shifted from 476 nm to 128 nm after 5 days. Furthermore, the inclusion of carbon nanotubes increased the stability of zinc oxide particles in the nanofluid. In addition, by adding carbon nanotubes in a ratio of 1:1:0.5 to Al₂O₃-ZnO nanofluid and forming 0.05 wt.% hybrid nanofluid, the thermal conductivity coefficient was enhanced by 30% in comparison with deionized water, while a 0.05 wt.% hybrid nanofluid without CNT particles improved the thermal conductivity by 19%. Although the electrical conductivity increased by adding nanoparticles to the base fluid, it didn’t change significantly for nanofluids containing CNTs compared to nanofluids without CNT particles.

Abstract: Silver nano-colloids have been generated via Laser Ablation Synthesis in Solution (LASiS) system. Nanoparticle formation with particle size below 50 nm in DI water was confirmed using UV-VIS spectroscopy, Dynamic Light Scattering (DLS) technique, and transmission electron microscopy (TEM). Supercapacitor structure, having dimension 11 mm x 10 mm, was successfully Aerosol Jet printed on an untreated polymer substrate using as produced LASiS silver nano-colloid.

Abstract: Nanotechnology is receiving an intense attention these days due to its potential application in various fields including cosmeceutical and pharmaceutical. Nanoparticles encapsulating natural extract are usually characterised for their particle size and polydispersity index but zeta potential is hardly discussed. The zeta potential is the measurement that shows the aggregation behaviour, reactivity and toxicology. In this study, nanoparticle encapsulating Cymbopogon sp. have been formulated to develop a cosmeceutical product. The antioxidant properties from aqueous extract of Cymbopogon sp. was encapsulated with chitosan/alginate biopolymeric nanoparticles. Central Composite Design (CCD) of Response Surface Methodology (RSM) was employed to investigate and optimise the effects of independent variables such as pH of SA, concentration of non-ionic surfactant concentration of CaCl₂ and pH of chitosan on zeta potential and encapsulation efficiency (EE). Following the model, the optimum condition for zeta potential was selected as 6.2 of sodium alginate pH, 0.12% of non-ionic surfactant concentration, 0.05 concentration of CaCl₂ and 5.6 of chitosan pH with negative zeta potential of 18.3mV. The zeta potential obtained experimentally was close to its predicted value which is-18.09mV. The model provides a basis on the optimisation of the zeta potential on chitosan/alginate nanoparticle encapsulating Cymbopogon sp. extracts.