Self-healing coatings based on PropS-SH and pH-responsive HNT-BTA nanoparticles for inhibition of pyrite oxidation to control acid mine drainage

Aiming at the prevention and control of acid mine drainage (AMD) at the source for a long-term period, herein, we report for the first time an active passivation coating with self-healing function to protect metal sulfide minerals from oxidation. Benzotriazole (BTA) inhibitor was loaded into halloysite nanotube (HNT) under vacuum condition and encapsulated by Cu-BTA complexes stoppers, and then the PropS-SH/HNT-BTA (PSHB) coating was prepared by mixing HNT-BTA nanoparticles with gamma-mercaptopropyltrimethoxysilane (PropS-SH) to inhibit pyrite oxidation. The morphology and composition of HNT nanocontainers were characterized by SEM, TEM, EDS and FTIR methods. The loading capacity of BTA in HNT-BTA lumen was determined by TGA measurements. The releasing behavior of BTA under different pH conditions was investigated by UV-vis spectrophotometer and the release mechanism of BTA from HNT-BTA lumen was validated using Ritger-Peppas model. It was found that HNT-BTA could achieve stimulus-responsive release of BTA under acidic conditions. The passivation and self-healing properties of PSHB coating were studied by electrochemical measurements, chemical leaching tests and scratch tests. The experimental results showed that the novel PSHB coating had long-term oxidation resistance and active self-repair function after damage. Meanwhile, the passivation and self-healing mechanism of the PSHB coating is also introduced. It is thought that this study is helpful to bring new ideas in the field of metal sulfide mineral passivation.

Automated summary

In this study, an active passivation coating with self-healing function was developed to protect metal sulfide minerals from oxidation, showing stimulus-responsive release of BTA under acidic conditions. The coating exhibited long-term oxidation resistance and active self-repair function, providing new ideas for metal sulfide mineral passivation.