Abstract-The double and triple Langmuir probe diagnostic systems with their necessary driving circuits are developed successfully for the characterization of laboratory built low pressure inductively coupled nitrogen plasma, generated by 13.56 MHz radio frequency (RF) power supply along with an automatic impedance matching network. Using the DC properties of these two probes, the discharge plasma parameters like ion saturation current (I io ), electron temperature (kT e ) and electron number density (n e ) are measured at the input RF power ranging from 250 to 400 W and filling gas pressures ranging from 0.3 to 0.6 mbar. An increasing trend is observed in kT e and n e with the increase of input RF power at a fixed filling gas pressure of 0.3 mbar, while a decreasing trend is observed in kT e and n e with the increase of filling gas pressure at a fixed input RF power of 250 W.
The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea. The characterization of physical properties of the synthesized adhesives was carried out by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension. In later stage, phenomenological analyses of spray jet breakup of heated complexes were performed in still air. Using a high speed digital camera, the jet breakup dynamics were visualized as a function of the system input parameters. The further analysis of the grabbed images confirmed the strong influence of the input processing parameters on full cone spray patternation. It was also predicted that the heated starch adhesive solutions generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium. Below 40°C of heating temperature, the radial spray cone width and angle did not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The discharge coefficient, mean flow rate, and mean flow velocity were significantly influenced by the load pressure but less affected by the temperature.
An argon plasma jet was sustained in open air and characterized for its chemical composition. The optically characterized plasma jet was used to treat industrial wastewater containing mixed textile dyes and heavy metals. Since plasma jet produces UV-radiations, the photocatalytic TiO2 was used to enhance plasma treatment efficiency especially for degradation of dyes. Mixed anatase and rutile phases of TiO2 (5.2–8.5 nm) were produced through surfactant assisted sol–gel approach. The emission spectrum confirmed the presence of excited argon, OH, excited nitrogen, excited oxygen, ozone and nitric oxide in the plasma jet. The spectral lines of excited Ar, NO, O3, OH−, N2, $${\mathrm{N}}_{2}^{+}$$
N
2
+
, O, $${\mathrm{O}}_{2}^{+}$$
O
2
+
and O+ species were observed at wavelength of 695–740 nm, 254.3 nm, 307.9 nm, 302–310 nm, 330–380 nm, 390–415 nm, 715.6 nm, 500–600 nm and 400–500 nm. These reactive species decompose the organic pollutants and separate the heavy metals from the water samples. The conductivity of plasma exposed water samples increased while pH and hardness decreased. The atomic absorption spectrophotometry analysis confirmed the presence of heavy metals in the samples, which were effectively removed through plasma treatment. Finally, the effect of plasma treatment on Staphylococcus aureus strains was more pronounced than Escherichia coli strains.
Melamine formaldehyde (MF) resins have been synthesized at different reaction temperature and pH values. Different molar ratios of melamine and formaldehyde were used to synthesize the corresponding resins. The prepared resin samples were characterized by using molecular weight determination viscometry and thermogravimetric analysis (TGA). The maximum percentage of solid content (69.7%) was obtained at pH 8.5 and 75°C temperature. The molecular weight of MF resin was increased with an increase of melamine monomer concentration. The highest residual weight 14.125 wt.% was obtained with sample 10.
The world does not have too much time to ensure that the fast-growing population has enough land, food, water and energy. The rising food demand has brought a positive surge in fertilizers' demand and agriculture-based economy. The world is using 170 million tons of fertilizer every year for food, fuel, fiber, and feed. The nitrogenous fertilizers are being used to meet 48% of the total food demand of the world. High fertilizer inputs augment the reactive nitrogen levels in soil, air, and water. The unassimilated reactive nitrogen changes into a pollutant and harms the natural resources. the use of controlled-release fertilizers for slowing down the nutrients' leaching has recently been practiced by farmers. However, to date, monitoring of the complete discharge time and discharge rate of controlled released fertilizers is not completely understood by the researchers. In this work, corn starch was thermally processed into a week gel-like coating material by reacting with urea and borate. the granular urea was coated with native and processed starch in a fluidized bed reactor having bottom-up fluid delivery system. the processed starch exhibited better thermal and mechanical stability as compared to the native starch. Unlike the pure starch, the storage modulus of the processed starch dominated the loss modulus. The release time of urea, coated with processed starch, remained remarkably larger than the uncoated urea.
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