Sodium Lignosulfonate-Loaded Halloysite Nanotubes/Epoxy Composites for Corrosion Resistance Coating

Corrosion resistancecoating applied on Q235 carbon steel in achloride-rich environment was explored in our research. The coatingas a barrier inhibits the penetration of the corrosion medium andprovides active corrosion protection for Q235 carbon steel. Halloysitenanotubes (HNTs) were loaded with sodium lignosulfonate (SLS) undervacuum conditions. 4.53% of loading efficiency was validated by thermogravimetricanalysis (TGA). The deposition of polyelectrolyte layers includingpoly-(dimethyl diallyl ammonium chloride) (PDDA) and poly-(styrenesulfonate)(PSS) not only resulted in controlling the release rate of SLS butalso enabled the HNTs to possess pH-responsive release property. Themodified HNTs were defined as PSS/PDDA/SLS/HNTs, whichwere characterized by SEM, TEM, FTIR, and zeta potential analyses.TGA elucidates that PSS/PDDA/SLS/HNTs exhibit superior thermal stability.The results of UV-vis spectroscopic analysis confirm that HNTsexhibit a higher release amount in an alkaline medium than in neutraland acidic conditions. Afterward, PSS/PDDA/SLS/HNTs were mixed withthe epoxy coating, which was applied on Q235 carbon steel immersedin 3.5 wt % NaCl solution. Electrochemical measurements illustratethe excellent corrosion resistance of the epoxy coating with the additionof PSS/PDDA/SLS/HNTs. Also, water contact angle analysis demonstratesthe modification of the epoxy coating with decent hydrophobicity.

Automated summary

The corrosion resistance of a coating applied on Q235 carbon steel in a chloride-rich environment was studied. The coating acts as a barrier, preventing the penetration of the corrosion medium and providing active corrosion protection. Halloysite nanotubes (HNTs) loaded with sodium lignosulfonate (SLS) under vacuum conditions showed high loading efficiency. The modified HNTs, characterized by SEM, TEM, FTIR, and zeta potential analyses, exhibited pH-responsive release and superior thermal stability. The epoxy coating modified with PSS/PDDA/SLS/HNTs demonstrated excellent corrosion resistance and hydrophobicity.