The inhibitory impact
of low-cost synthesized pyrazoline derivatives
named
Pz
series (
Pz1
and
Pz2
) on the corrosion of API 5L X60 carbon steel in 5 M HCl was inspected
to serve as corrosion inhibitors against such a solution for its usage
in the oilfield well acidization process. Also, the same compounds
were unitized as biocides for sulfate-reducing bacteria (SRBs) to
inhibit the microbial-induced corrosion effect. This study was conducted
via several electrochemical techniques, namely, electrochemical potentiodynamic
polarization (EP) and electrochemical impedance spectroscopy (EIS),
in addition to computational density functional theory (DFT). The
inhibition efficiency (IE) of
Pz
series on the corrosion
of 5L X60 carbon steel in 5 M HCl was found to increase whenever the
Pz
series molecule concentration was increased. EP measurements
revealed that
Pz1
and
Pz2
have both cathodic
and anodic features (mixed inhibitor) and their corrosion IEs were
around 90%. The physicochemical properties of the
Pz1
and
Pz2
compounds were studied using Langmuir adsorption
isotherms, where the equilibrium adsorption data were found to follow
it accurately. EIS outputs were found to comply with the values obtained
from EP. Scanning electron microscopy was used to examine the topographic
anisotropy between the inhibited and uninhibited 5L X60 carbon steel
samples to double-check the electrochemical findings. DFT calculations
and Monte Carlo simulations were utilized to predict the behavior
of inhibitors and to rationalize the experimental results. The serial
dilution bioassay technique was used to assess the
Pz
series as potential biocides to counter the effect of SRBs in compliance
with the TM0194-2014-SG standard test method, and the results showed
the potency of
Pz
series in inhibiting such bacterial
growth.
Increasing levels of carbon dioxide (CO 2 ) from human activities is affecting the ecosystem and civilization as we know it. CO 2 removal from the atmosphere and emission reduction by heavy industries through carbon capture, utilization, and storage (CCUS) technologies to store or convert CO 2 to useful products or fuels is a popular approach to meet net zero targets by 2050. One promising process of CO 2 removal and conversion is CO 2 electrochemical reduction (CO 2 ER) using metal and metal oxide catalysts, particularly copperbased materials. However, the current limitations of CO 2 ER stem from the low product selectivity of copper electrocatalysts due to existing knowledge gaps of the reaction mechanisms using surfaces that normally have native oxide layers. Here, we report systematic control studies of the surface interactions of major intermediates in CO 2 ER, formate, bicarbonate, and acetate, with CuO nanoparticles in situ and in real time using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). Spectra were collected as a function of concentration, pH, and time in the dark and the in absence of added electrolytes. Isotopic exchange experiments were also performed to elucidate the type of surface complexes from H/D exchange. Our results show that the organics and bicarbonate form mostly outer-sphere complexes mediated by hydrogen bonding with CuO nanoparticles with Gibbs free energy of adsorption of about −25 kJ mol −1 . The desorption kinetics of the surface species indicated relatively fast and slow regions reflective of the heterogeneity of sites that affect the strength of hydrogen bonding. These results suggest that hydrogen bonding, whether intermolecular or with surface sites on CuO nanoparticles, might be playing a more important role in the CO 2 ER reaction mechanism than previously thought, contributing to the lack of product selectivity.
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