Defluoridation of Water by Graphene Oxide Supported Needle-Like Complex Adsorbents

The dicarboxylic acids like oxalic acid, malonic acid and succinic acid mediated graphene oxide–zirconium needle like complexes were synthesized and used to remove fluoride from simulated fluoride contaminated water. The adsorption of fluoride by dicarboxylic acids mediated graphene oxide–zirconium complexes were by both electrostatic interaction at acidic pH and ion-exchange mechanism at neutral pH. The maximum defluoridation capacity observed was 9.70 mg/g at the minimum contact time of 18 min at room temperature. Various batch equilibrium parameters like pH studies, contact time, common ion interference and temperature studies were optimized. The synthesized graphene oxide and graphene oxide supported complexes were characterized using UV–vis, FTIR, XRD and SEM with EDAX analysis to establish the mechanism of fluoride adsorption. The removal of fluoride was described by the pseudo-second-order reaction kinetics, Freundlich isotherm model and thermodynamic studies which indicates the nature of adsorption was endothermic and spontaneous. Regeneration studies depict that the dicarboxylic acid mediated graphene oxide–zirconium complex can be used as an effective adsorbent for the removal of fluoride ions from wastewater. Also, the field applicability of the material has been verified with field samples collected from nearby fluoride endemic villages.     

Preparation and application of silver nanoparticles on silk for imparting antimicrobial properties

Silver nanoparticles were produced by a chemical reduction method that reduced silver nitrate with reducing agents such as hydrazine and glucose. The silver nanoparticles were characterized with transmission electron microscope, scanning electron microscope, and optical microscope. The effects of process parameters such as the stirring speed, temperature, type of reducing agent, and dispersing agent on the particle size were studied. The particle size decreased with an increase in the stirring speed and a decrease in the process temperature. Smaller particles were formed when the silver nitrate was reduced by glucose versus those that were formed by reduction with hydrazine. Silver nanoparticles with average sizes of 10 and 35 nm, produced by reduction with hydrazine at 5 and 40°C, were applied to silk by an exhaust method. Silk fabrics treated with 40 ppm silver hydrosol produced at 5°C and 60 ppm silver hydrosol produced at 40°C showed 100% antimicrobial activity against the gram‐positive bacterium Staphylococcus aureus. The durability of the antimicrobial property of the treated silk fabric to washing was also examined and is presented. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymerization of Diphenylcarbodiimide Catalysed by Fullerene-60

Abstract

In the presence of fullerene-60 as a catalyst, the formation of diphenylcarbodiimide (DPCD) from phenylisocyanate followed by its polymerization into a hexamer in xylene at refluxing temperature was carried out. The product was analysed by FAB-Mass spectrometry, FT-IR, UV-Vis and HPLC techniques.     

Hybrid supercapacitor based on poly(aniline-co-m-anilicacid) and activated carbon in non-aqueous electrolyte

A hybrid asymmetrical super capacitor has been fabricated based on p-doped poly(aniline-co-m-anilicacid) and activated carbon coated on SS electrodes. The characterization of material, electrode and performance of the super capacitor has been studied by FTIR, Cyclic Voltammetry, TGA/DTA, AC Impedance spectroscopy, and galvanostatic charge-discharge tests. The super capacitor showed a maximum specific capacitance of 102 F/g at a scan rate of 10 mV/s. The normalized active-reactive power behavior of the capacitor has been determined. The time constant calculated for the super capacitor is 6 milliseconds, indicating the suitability of the system for efficient use at low frequency range.     

Physicochemical Studies of 4-Substituted N-(2-Mercaptophenyl)-Salicylideneimines: Corrosion Inhibition of Mild Steel in an Acid Medium

A series of 4-substituted N-(2-mercaptophenyl)salicylideneimine Schiff bases were synthesized and investigated for corrosion inhibition of mild steel in hydrochloric acid medium. Inhibition through adsorption mechanism is proposed for these inhibitors, which is well supported by electrochemical impedance spectroscopy, the Langmuir adsorption isotherm and Scanning Electron Microscope morphologies of inhibited and uninhibited mild steel specimens. The negative ?G _ads indicates the spontaneous adsorption of the inhibitor on a mild steel surface. Among all the examined inhibitors, 5-bromo-N-(2-mercaptophenyl)salicylideneimine showed a higher inhibition efficiency. In order to reveal the usefulness of these Schiff bases as corrosion inhibitors under various circumstances, weight loss measurements were performed at various temperatures, acid concentrations and immersion times.     

Magnesium Alloy - SiCp Reinforced Infiltrated Cast Composites

This article relates to the fabrication of magnesium and magnesium alloy with SiC_p reinforced metal matrix composites (MMCs) by a relatively new infiltration route. The preform for the fabrication of MMC was prepared by a mixed particle method where the matrix metal particles are mixed with the required volume percent of reinforcement without the use of any binders. Characterizations of fabricated composites were done by microstructure, microhardness, and wear studies. The studies revealed that an increase in the volume percent of reinforcement had beneficial effect on the microhardness values and wear studies.     

Physico-chemical characterization and catalysis on SBA-15 supported molybdenum hydrotreating catalysts

SBA-15 supported Mo, CoMo, NiMo catalysts were prepared. The supports were characterized by surface area, pore size distribution, and X-ray diffraction. The finished catalysts in oxide state were characterized by surface area analysis and X-ray diffraction in the region where the molybdenum oxide lines are seen. The sulfided catalysts were examined by oxygen chemisorption at low temperatures. The catalytic functionalities of these catalysts viz hydrodesulfurization (HDS) and hydrogenation were evaluated on sulfided catalysts. The catalytic activities of these catalysts are compared with γ-Al₂O₃- and SiO₂-supported catalysts. An attempt is made to understand the relationship between oxygen chemisorption and catalytic activities with the help of other characterization results.