Experimental and theoretical evaluation of new piperidine and oxaquinuclidine core containing derivatives as an efficient corrosion inhibitor for copper in nitric acid medium

Abstract

The inhibition efficiency of copper corrosion in 1 M HNO₃ by five piperidine and oxaquinuclidine core containing compounds namely 2,4,6,11-tetraphenyl-9-oxa-1,5-diazatricyclo [5.3.1.0^3.8] undecane (OX1), 2,4,6,11-tetraaryl (4-methoxyphenyl)-9-oxa-1,5-diazatricyclo [5.3.1.0^3.8] undecane (OX2), 2,4,6,11-tetraaryl (4-chlorophenyl)-9-oxa-1,5-diazatricyclo [5.3.1.0^3.8] undecane (OX3), 2,4,6,11-tetraaryl-p-tolyl-9-oxa-1,5-diazatricyclo [5.3.1.0^3.8] undecane (OX4), and 2,4,6,11-tetraaryl (4-fluorophenyl)-9-oxa-1,5-diazatricyclo [5.3.1.0^3.8] undecane (OX5) has been investigated using gravimetric method, electrochemical studies, FT-IR, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), DFT and Monte Carlo simulation techniques. Inhibitors are chosen based on electron donating and accepting ability to the metal surface. These compounds differentiated in phenyl ring containing electron withdrawing (Cl, F) and electron releasing (OCH₃, CH₃) substituents. Experimental and computational studies showed that methoxy (OCH₃) substituent exhibit more efficiency compared to other compounds and it is due to more electron donating nature of the OCH₃ group. The adsorption of the inhibitors on copper surface obeyed Langmuir adsorption isotherm. Polarization results show that OXs are acting as a mixed type of inhibitors. In the surface characterization studies, change in frequency (FT-IR), change in surface roughness (SEM) and appearance of additional element peaks (EDX) before and after film formation confirmed the protective layer formation. Quantum chemical parameters and Monte Carlo simulation studies further evidenced by the inhibitor adsorption of the copper surface.

Keywords:

• Copper corrosion inhibitors
• 1 M HNO₃
• DFT
• Fukui function
• Monte Carlo simulation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors thank the UGC, New Delhi for Major Research Project [grant No. 42-358/2013 (SR)]. G. V acknowledges Ministry of Tribal Affairs, Government of India for the award of NFST Scheme [Ref. No: 201718-NFST-TAM-00803].