B. Muralidharan

INHIBITION OF CORROSION OF MILD STEEL IN ACIDIC SOLUTIONS BY QUARTERNARY SALTS OF PYRIDINIUM BASES

The influence of pyridinium chloride (PC) and n‐hexa decyl pyridinium chloride (HDPC) on the corrosion of mild steel in 5N HCl and 5N H2SO4 has been studied using techniques such as weight loss and gasometric measurements, potentiodynamic polarisation studies, linear polarisation studies and small amplitude cyclic voltametric studies. It is found that HDPC is more inhibitive than PC and both the compounds perform better in H2SO4. Polarisation studies reveal that PC behaves as an anodic inhibitor in H2SO4 and as a mixed inhibitor in HCl. Measurements of values of polarisation resistance (Rp) and double layer capacitance (Cdl) in the presence of these compounds also reveal the better performance of HDPC in both the acids. The adsorption of PC and HDPC on a mild steel surface from both the acids is found to obey Temkin’s adsorption isotherm.

Determination of three analgesics in pharmaceutical and urine sample on nano poly (3, 4-ethylenedioxythiophene) modified electrode

Three analgesics, acetaminophen, acetylsalicylic acid, and dipyrone were determined by stripping voltammetry using nanosized poly(3,4-ethylenedioxythiophene)-modified glassy carbon electrode . The cyclic voltammetric behavior of the three analgesics was studied in aqueous acid, neutral, and alkaline conditions. One well-defined oxidation peak each for acetaminophen and acetylsalicylic acid and three oxidation peaks for dipyrone were observed in the cyclic voltammograms. The influence of pH, scan rate, and concentration revealed irreversible diffusion controlled reaction. A systematic study of the experimental parameters that affect the differential pulse stripping voltammetric response was carried out. Calibration was made under maximum peak current conditions. The scanning electron microscope analysis confirmed good accumulation of the drugs on the electrode surface. The range of study for both acetaminophen, acetylsalicylic acid were 0.015–0.4 and dipyrone was 0.025–0.4xa0μg/ml. The lower limit of determination for both acetaminophen, acetylsalicylic acid was 0.01xa0μg/mL and for dipyrone was 0.02xa0μg/mL. The suitability of the method for the determination of the three analgesics in pharmaceutical preparations and urine samples was also ascertained.

Electrochemical behaviour of addition agents impregnated in cadmium hydroxide electrodes for alkaline batteries

Abstract The development of electrode additives for the cadmium electrode of the nickel/cadmium battery is aimed mainly at increasing the discharge capacity and minimizing self-discharge. The dissolution and passivation of porous cadmium electrodes containing hydroxide and the relative stability of oxides are of importance in understanding the reversible behaviour of the cadmium electrode. Under standard conditions, the equilibrium potential of Cd(OH)2/Cd lies above the hydrogen-evolution reaction when the cell is not in use, and the active material of the cadmium electrode undergoes self-reductive dissolution (i.e., loss of active material) accompanied by oxygen evolution. The triangular potential sweep voltammetric technique is used to determine the reversibility of the cadmium electrode in alkaline solution. The role of additives such as Ni(NO3)2 (0.25–0.1 M) and FeSO4 (0.1–0.4 M), TiO2 (0.01–0.03 M) and Na2S (0.01–0.03 M) in Cd(NO3)2 on the reversibility of the electrode are discussed. The effect of discharge rate on the cyclic efficiency is also investigated. Self-discharge currents are determined by potentiostatic polarization method.

Stripping Voltammetric Determination of Analgesics in Their Pharmaceuticals Using Nano-Riboflavin-Modified Glassy Carbon Electrode

Cyclic voltammetric behaviors of three analgesics, acetaminophen (AAP), acetylsalicylic acid (ASA), and dipyrone (DP), were studied using nano-riboflavin-modified glassy carbon electrode. One well-defined oxidation peak each for AAP and ASA and three oxidation peaks for DP were observed. The influence of pH, scan rate, and concentration reveals irreversible diffusion controlled reaction. The SEM analysis confirmed good accumulation of the drugs on the electrode surface. Calibration was made under the maximum peak current conditions. The concentration range studied for the determination of drugs was 0.02 to 0.4 μgmL −1 for AAP and ASA and 0.025 to 0.4 μgmL −1 for DP. The lower limit of detection observed for AAP, ASA, and DP was 0.016, 0.007 μgmL −1 , and 0.013 μgmL −1 , respectively. The suitability of the method for the determination of these analgesics in pharmaceutical preparations and urine samples was also ascertained.

Synergistic influence of iodide ions on inhibition of corrosion of mild steel in H2SO4 by N-phenyl thiourea

Abstract The synergistic action of iodide ions on the inhibition of corrosion of mild steel in 0·5M H2SO4 by N-phenyl thiourea (N-PTU) has been investigated using weight loss measurements, potentiodynamic polarisation studies, linear polarisation studies, and impedance measurements. Inhibition efficiency is found to increase with increase in the concentration of N-PTU. The inhibiting action of N-PTU is considerably enhanced by the addition of potassium iodide. The adsorption of this compound either alone or in combination with iodide ions on the metal surface is found to obey Langmuirs adsorption isotherm. The increase in surface coverage 0 in the presence of iodide ions indicates joint adsorption of N-PTU and iodide ions. The synergism parameter is defined and evaluated from the values of inhibition efficiency and surface coverage. This parameter is found to be greater than unity, which indicates that the enhanced inhibition efficiency caused by the addition of iodide ions is only due to synergism and t...

A New Approach to Dyeing of 80 : 20 Polyester/Cotton Blended Fabric Using Disperse and Reactive Dyes

Polyester/Cotton blended fabrics are normally dyed by two-bath or one-bath two-step dyeing method. This paper deals with a new approach involving azeotropic ternary mixture of organic solvents pretreatment to dye polyester/cotton blends using disperse and reactive dyes in one-bath method. The effect of solvent pretreatments on dyeability, fastness, and few physicochemical properties has been investigated involving SEM, FTIR, DSC, and XRD studies, and results are presented.