Suppression of pyrite oxidation by co-depositing bio-inspiredPropS-SH-tannic acid coatings for the source control acid mine drainage br

In previous works, both tannic acid (TA) and organosilane-based passivators have been proven to possess good inhibi-tion effects on pyrite oxidation, which could effectively prevent acid mine drainage (AMD) generation at the source.However, the hydrophilicity of TA passivationfilm and the complex coating process of organosilane-based passivators(high temperature conditions were required during the process carried out) may limit their further practicaluse. Therefore, to achieve the purpose of better coating treatment of pyrite under mild conditions, TA and gamma-mercaptopropyltrimethoxysilane (PropS-SH) were introduced to synergistically passivate pyrite in this work. Electro-chemistry tests and chemical leaching experiments both confirmed that PropS-SH-TA coated pyrite had better oxida-tion resistance than raw pyrite and single PropS-SH or TA coated pyrite. Additionally, the analysesof scanning electronmicroscopy (SEM) measurements and static water contact angle tests demonstrated that a scaly coating was formed onPropS-SH-TA coated pyrite surface, which may be the reason for the significant improvement of its surface hydropho-bicity. Finally, the study on thefilm-forming mechanism of PropS-SH-TA composite passivator displayed that thebenzoquinone derivatives formed by TA could copolymerize with PropS-SH through Michael addition or Schiff basereaction, which constructed a dense hydrophobicfilm on pyrite surface. The newly formed compositefilm couldprovide a better oxidation barrier for pyrite based on TA passivationfilm