Kinetics and mechanism of thermal decomposition of nitric acid in sulfuric acid solutions

1987 ◽  
Vol 36 (10) ◽  
pp. 1999-2002 ◽  
Author(s):  
A. I. Kazakov ◽  
Yu. I. Rubtsov ◽  
L. P. Andrienko ◽  
G. B. Manelis
Keyword(s):  
Thermal Decomposition ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Kinetics And Mechanism ◽  
Acid Solutions ◽  
Mechanism Of Thermal Decomposition ◽  
Sulfuric Acid Solutions

Inhibition of corrosion of copper in acids by norfloxacin

2017 ◽  
Vol 64 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Thanapackiam P. ◽  
Kumaravel Mallaiya ◽  
Rameshkumar S. ◽  
Subramanian S.S.
Keyword(s):  
Free Energy ◽  
Sulfuric Acid ◽  
Nitric Acid ◽  
Metal Surface ◽  
Inhibition Efficiency ◽  
Acid Solutions ◽  
Free Energy Of Adsorption ◽  
Acid Media ◽  
Content Type ◽  
Sulfuric Acid Solutions

Purpose This paper aims to evaluate the inhibition efficiency of norfloxacin on the corrosion of copper in 1.0 M nitric acid and 0.5 M sulfuric acid solutions. Design/methodology/approach Evaluation was carried out by electrochemical techniques such as electrochemical impedance spectroscopy and potentiodynamic polarization studies. Scanning electron microscopy was used, and it finally confirmed the existence of the adsorbed film. Findings The electrochemical measurements showed that norfloxacin has good inhibition efficiency on the corrosion of copper in 1.0 M nitric acid and 0.5 M sulfuric acid solutions. The inhibition action of norfloxacin in both of the corrosive media was observed to be of mixed type but with more of cathodic nature. The temperature dependence of the corrosion rate was studied in the temperature range from 35 to 55°C and the activation energy (Ea) was calculated. The adsorption of norfloxacin molecules on copper surface obeyed Langmuir adsorption isotherm. Studies on the potential of zero charge have been carried out to establish the mechanism of adsorption of the inhibitor onto the metal surface. The thermodynamic parameters such as the adsorption equilibrium constant (Kads) and the free energy of adsorption (ΔGads) were calculated. The value of free energy of adsorption very close to −40 kJmol−1 indicates that the adsorption is through electrostatic coulombic attraction and chemisorption. The decrease in value of Ea with the addition of inhibitor also shows the chemisorption of the inhibitor on the metal surface. Originality/value This paper indicates that norfloxacin can act as a good inhibitor for the corrosion of copper in both the acid media.

scholarly journals Traitement Des Phosphates Naturels De Tahoua (Niger) Par Quelques Acides Conventionnels

2017 ◽  
Vol 13 (24) ◽  
pp. 176
Author(s):  
Ousmane Mahamane Sani ◽  
Zanguina Adamou ◽  
Natatou Ibrahim
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Acid Solutions ◽  
Inorganic Acid ◽  
Sudden Drop ◽  
Dissolved Phosphorus ◽  
Nitric Acid Solutions ◽  
Fast Dissolution ◽  
Sulfuric Acid Solutions ◽  
Better Than

Within the framework of upgrading natural phosphate of Tahoua, a study was carried out on the dissolution of ore by inorganic acid (sulfuric acid, nitric acid) and organic acid (citric acid) solutions according to pH and attack time. The obtained results show a sudden drop of dissolution rate at pH above 2 and a dissolution almost zero beyond pH 4. The kinetic study shows fast dissolution of ore one hour after the attack. However, this dissolution is slow beyond one hour with few dissolved phosphorus during a relatively high period of time. Furthermore, the sulfuric acid solutions dissolve the ore better than those of citric and nitric acid: 41.07%; 37.03% and 35.64% of dissolved phosphorus respectively for sulfuric, citric and nitric acid solutions at the concentration of 1mol/L.

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