Chemical inhibitors are widely used
to protect metallic alloys
from corrosion in aqueous environments. This Letter investigates the
possible synergistic behavior of a quaternary ammonium carboxylate
compound toward the development of a new system taking advantage of
the surface activity of a known antimicrobial surfactant molecule,
hexadecyl trimethylammonium cation, combined with a known organic
corrosion inhibitor, the trans-4-hydroxy-cinnamate
anion. Short-term potentiodynamic polarization (PP) studies combined
with immersion in aqueous chloride solutions demonstrated the high
inhibition efficiency of the combination of ions, and NMR pfg-diffusion
measurements revealed micellar formation that was concentration- and
pH-dependent. The NMR data suggest that speciation changes occur in
the solution that correlate with enhanced corrosion inhibition efficiency
at higher pH and at concentrations above the CMC of the compound.
This new contribution may provide a rational molecular design toward
delivering corrosion inhibitors to a metal surface through controlled
speciation in solution.
Chemical biocides remain the most effective mitigation strategy against microbiologically influenced corrosion (MIC), one of the costliest and most pervasive forms of corrosion in industry. However, toxicity and environmental concerns associated with these compounds are encouraging the development of more environmentally friendly MIC inhibitors. In this study, we evaluated the antimicrobial effect of a novel, multi-functional organic corrosion inhibitor (OCI) compound, cetrimonium trans-4-hydroxy-cinnamate (CTA-4OHcinn). Attachment of three bacterial strains, Shewanella chilikensis, Pseudomonas balearica and Klebsiella pneumoniae was evaluated on wet-ground (120 grit finish) and pre-oxidised carbon steel surfaces (AISI 1030), in the presence and absence of the new OCI compound. Our study revealed that all strains preferentially attached to pre-oxidised surfaces as indicated by confocal laser scanning microscopy, scanning electron microscopy and standard colony forming unit (CFU) quantification assays. The inhibitor compound at 10 mM demonstrated 100% reduction in S. chilikensis attachment independent of initial surface condition, while the other two strains were reduced by at least 99.7% of the original viable cell number. Our results demonstrate that CTA-4OHcinn is biocidal active and has promise as a multifunctional, environmentally sound MIC inhibitor for industrial applications.
A novel Brønsted acidic ionic liquid 2-ethyl imidazolium hydrogen sulfate, [2-Eim] HSO4, was synthesized. Its structure was investigated using FT-IR, 1 H NMR, 13 C NMR, UV, TGA and DTA spectra. This ionic liquid is utilized as a highly efficient and homogeneous catalyst for the promotion of hexahydroquinolines via one-pot multi-component condensation of aromatic aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate at room temperature and neat conditions. Also, optimization of the reaction conditions was investigated using the response surface method {Central Composite Design (CCD)}. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst could be reused and recovered at least four times without appreciable loss of activity.
Ionic
liquids (ILs) have advantageous physical properties, which
resulted in a rapid growth of research in this area in the past 15
years. One of the biggest challenges preventing the widespread use
of ILs is the cost of production due to complex synthetic routes and/or
expensive starting materials. Keeping in mind these industrial needs
for scale-up and the desirable properties for applications in the
lubrification area, here, we report the design and synthesis of four
novel series of hydrophobic room-temperature ILs (RTILs) achieved
from cheap and commercially available starting materials, namely,
silicon-based, imidazolium-based, phosphonium-based, and monomer imidazolium-based.
These syntheses were developed as expedited chemistry protocols and
possess a greener synthetic profile compared to previously reported
ILs of similar structures. All the RTILs were characterized by 1D
NMR (1H NMR, 13C NMR, 31P NMR, 19F NMR, and 11B NMR) and 2D NMR (COSY, HSQC, and
HMBC) analyses, high-resolution mass spectrometry, and chemical tests
(primarily the silver nitrate test). Preliminary thermal analysis
tests by thermogravimetric analysis show all novel RTILs display remarkably
high thermal stabilities (386–474 °C). Differential scanning
calorimetry data show low glass transitions ranging from −36
to −72 °C, which suggests good free volume and ion mobility.
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