Enhanced corrosion protection mechanism of BTA-loaded MIL-53-NH2 (Al)@diatomite composites for carbon steel rock bolts in simulated mine leach liquor

MNA@DE composites were fabricated via in situ growth with high BTA loading capacity. MNA@DE composites were fabricated via in situ growth with high BTA loading capacity. • BTA-MNA@DE-M showed excellent corrosion-inhibition performance in simulated mine leach liquor. • MNA@DE exhibited pH-responsive BTA release for sustained inhibition of carbon steel corrosion. To address the susceptibility of carbon steel rock bolts to corrosion in complex mine environments and the limited long-term protection provided by conventional corrosion inhibitors, MIL-53-NH 2 (Al)@diatomite composites were prepared via in situ hydrothermal growth. The corrosion-inhibition performance of the benzotriazole (BTA)-loaded composites for carbon steel rock bolts in simulated mine leach liquor was systematically investigated. MNA@DE exhibited a considerably higher BTA adsorption capacity than pristine diatomite, with MNA@DE–H showing the highest value (134.48 mg g −1 ) at pH 5.0. Electrochemical measurements indicated that 0.10 wt% BTA-MNA@DE-M exhibited the best corrosion-inhibition performance, with a corrosion current density of 1.76 μA cm −2 and a polarization-based inhibition efficiency of 82.94%. The R ct -based inhibition efficiency increased from 20.77% to 87.56% over 168 h, indicating that the corrosion-inhibition performance of the material steadily improved with increasing of immersion time. Mechanistic analysis revealed that under weakly acidic conditions, hydrogen bonding and cation–π interactions between the surface - NH 3 + groups in the composites and BTA facilitated the efficient loading and immobilization of BTA. In a weakly alkaline simulated mine leach liquor, BTA molecules were slowly released because of weaker interactions between the carrier and BTA. The released BTA was subsequently adsorbed on the carbon steel surface, suppressing interfacial charge transfer and thereby progressively enhancing the corrosion-inhibition performance with the extension of immersion time. Therefore, this study provides a new strategy for the design and development of long-lasting corrosion-inhibiting materials for carbon steel rock bolts in complex mine environments. Slow release of BTA in weakly alkaline mine leach liquor enables sustained adsorption on carbon steel, suppresses charge transfer, and provides long-term corrosion protection. Download: Download high-res image (260KB) Download: Download full-size image