R. Tamilarasan

Optimization of methylene blue using Ca2+ and Zn2+ bio-polymer hydrogel beads: A comparative study

Recently noted that the methylene blue cause severe central nervous system toxicity. It is essential to optimize the methylene blue from aqueous environment. In this study, a comparison of an optimization of methylene blue was investigated by using modified Ca(2+) and Zn(2+) bio-polymer hydrogel beads. A batch mode study was conducted using various parameters like time, dye concentration, bio-polymer dose, pH and process temperature. The isotherms, kinetics, diffusion and thermodynamic studies were performed for feasibility of the optimization process. Freundlich and Langmuir isotherm equations were used for the prediction of isotherm parameters and correlated with dimensionless separation factor (RL). Pseudo-first order and pseudo-second order Lagegrens kinetic equations were used for the correlation of kinetic parameters. Intraparticle diffusion model was employed for diffusion of the optimization process. The Fourier Transform Infrared Spectroscopy (FTIR) shows different absorbent peaks of Ca(2+) and Zn(2+) beads and the morphology of the bio-polymer material analyzed with Scanning Electron Microscope (SEM). The TG & DTA studies show that good thermal stability with less humidity without production of any non-degraded products.

Synthesis, investigation on structural and electrical properties of cobalt doped Mn–Zn ferrite nanocrystalline powders

Abstract Synthesis of CoxMnyZnyFe2O4 (x = 0.1, 0.5, 0.9 and y = 0.45, 0.25, 0.05) nanocrystalline powders was done by chemical co-precipitation method. The crystal structure was determined by using X-ray diffraction (XRD) studies. The crystallite size and lattice parameters were calculated from the XRD data. The XRD results revealed that the crystallite size of the nanocrystalline powder was found to decrease from 37 nm to 28 nm with the substitution of cobalt. The effect of cobalt ions on the crystallization process, the lattice parameters and electrical properties of Mn–Zn ferrites has been also investigated. The AC conductivity increased with an increase in frequency but it decreased with an increase in cobalt content. The complex impedance analysis of the data showed that the resistive and capacitive properties of the Co–Mn–Zn ferrite are predominant due to the fact that the processes are associated with the grains and grain boundaries. The dielectric constant and dielectric loss dependence on doping level and frequency at room temperature were also studied.

A study on leakage current and electrical properties of oleic acid-coated cobalt-doped Mn-Zn ferrite nanocrystalline powders

BackgroundMn-Zn ferrites have drawn a continuously an increasing interest because of their potential applications as multifunctional devices. These materials simultaneously exhibit ferroelectricity and ferromagnetism. The dielectric and leakage current properties of Cobalt substituted Mn-Zn ferrites coated with oleic acid were not reported.MethodsThis paper presents the synthesis, electrical, and leakage properties of nanoparticles of cobalt-doped Mn-Zn ferrite [CoxMnyZnyFe2O4 (x = 0.1, 0.5, and 0.9 and y = 0.45, 0.25, and 0.05)] coated with oleic acid and prepared by chemical co-precipitation method. The crystal structure was determined by X-ray diffraction (XRD), the effect of strain on the electronic structure was analyzed using Williamson-Hall plot. Complex impedance spectroscopic analysis was carried out, and the impedance plots show the resistive and reactive parts of the impedance. Frequency dependence on AC conductivity was investigated for all the compositions, and leakage current properties were also studied.ResultsThe nanoparticles were found to have an average size of 13.62 nm. The average crystallite size (DaveXR) of the precipitated particles found to decrease from 15.22 to 12.65 nm with increasing cobalt substitution. The presence of two semicircular arcs at the lower and higher frequency regions indicates the grain boundary conduction and grain conduction at room temperature. Leakage current density of the order of 10-4 A/cm2 (at field strength of 0.02 kV/cm) was observed for all compositions.ConclusionThe variation of the strain values from negative to positive indicates that the strain changes from compression to tensile. The dielectric permittivity was found to decrease from 104to 103 with increase in frequency. The semicircle in the higher frequency region is attributed to the grain conduction of the materials, and the semicircle in the lower frequency region is due to the grain boundary conduction. Both the grain and grain boundary are found to be active at room temperature. AC conductivity is found to be compositional dependent.

Extraction of bio-oil from nonedible urban waste source using Bauhinia variegata seeds

ABSTRACT This paper presents the production of biodiesel from Bauhinia variegata seeds using the solvent extraction technique. This process has attracted considerable attention recently in the renewable energy sector because it can reduce greenhouse gas emissions and subsidize energy security. The solvent extraction technique has a low production cost and low oil residue compared with the other methods. Six different solvents were employed for the separation process; among them, hexane proves to be the best solvent for bio-oil extraction (yield −28.43%) at the temperature of 68°C. The caloric value of B. variegata seeds is 4800 kcal/kg, which makes it a better choice of fuel. Its physicochemical properties such as acid value, calorific value, flash point, saponification value, iodine number, specific gravity, fire point, and kinematic viscosity were determined for bio-oil and compared with diesel. This result supports the production of biodiesel from B. variegata seeds oil as a viable alternative fuel to diesel in an eco-friendly manner.