In this work, cationic Gemini surfactants
with different alkyl
chain lengths (
n
= 8, 10, and 12) and a bipyridyl
spacer were synthesized and tested as corrosion inhibitors for carbon
steel in 1 M HCl solution. The corrosion inhibition efficiency was
determined by weight loss measurement, potentiodynamic polarization,
and electrochemical impedance spectroscopy. Results showed that such
three inhibitors could effectively inhibit the corrosion of carbon
steel in 1 M HCl solution, especially at their low concentrations,
while the carbon chain length of Geminis used played a negligible
role in the inhibition efficiency. Scanning electron microscopy/energy
dispersive X-ray analysis observations demonstrated the formation
of a protective inhibitor layer on the carbon steel surface. Additionally,
the adsorption of the inhibitor molecules on the carbon steel surface
was found to obey the Langmuir isotherm.
The corrosion inhibition performance of propanediyl-1,3-bis(N,Ndimethyl-N-dodecylammonium bromide) and propanediyl-1,3-bis(N,N-dihydroxyethyl-N-dodecylammonium bromide), abbreviated as PDDB and PDHDB, respectively, for carbon steel in 1.0 mol•L −1 hydrochloric acid solution was investigated using the gravimetric method and various electrochemical techniques, together with scanning electron microscopy and energy-dispersive spectrometry. Results show that PDHDB always has a better inhibition performance relative to PDDB, which can be attributed to the introduction of hydroxyl groups at the hydrophilic headgroups, thereby causing an extra interaction between inhibitors and the metal surface and favoring its adsorption. These findings highlight that the modification to the headgroups of Gemini-type inhibitors may be another effective approach to improving their inhibition performance.
In
this paper, a polypyrrole/graphene oxide (PPy/GO) composite
electrode, applied to the capacitive deionization process for removing
heavy metal ions, was prepared by one-step electrochemical codeposition.
The PPy/GO composite electrode has a dense sheet structure, and PPy
is spherical and uniformly distributed on the surface of GO sheets.
The experimental results show that the PPy/GO composite electrode
has a higher capacitance (186.67 F/g) and a lower charge transfer
resistance (1.626 Ω·cm2) than the PPy electrode.
The adsorption capacity of the PPy/GO composite electrode is 41.51
mg/g, which is about 2.67 times (15.52 mg/g) that of the PPy electrode.
After five adsorption/desorption treatments, the adsorption capacity
was maintained at about 98.0%, and the regeneration rate was 94.7%.
Therefore, the electrode has good cycle stability and regenerability.
In addition, the adsorption capacity of different metal ions follows
the order Ag+ < Cd2+ < Cu2+ < Pb2+ < Fe3+, indicating that the PPy/GO
composite electrode has stronger adsorption capacity for the added
state, and the adsorption capacity for ions with the same valence
state decreases with the increase in ion hydration radius. The PPy/GO
composite electrode has a good prospect for the removal of heavy metal
ions in industrial wastewater.
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