Luteolin adsorption-oxidative desorption dual-effect regulation: an innovative strategy for inhibition and re-activation of copper-activated pyrite

Luteolin effectively depresses copper-activated pyrite for selective Zn–S separation. • H2O2 reactivates LUT-depressed pyrite by inducing LUT desorption. • H2O2-induced LUT desorption occurs via direct molecular oxidation and indirect Fe2+/Fe3 + modulation. Organic depressants have been extensively investigated for pyrite depression under low-alkali conditions due to their abundance and environmental compatibility. However, studies on the de-depression and reactivation of depressed pyrite remain limited. This research proposes a solution wherein luteolin (LUT) depresses pyrite in a copper potassium butyl xanthate (PBX) system, and oxidative treatment with H 2 O 2 enables its desorption and reactivation. Flotation tests demonstrated a dramatic recovery of depressed pyrite from 1.05% to 96.95% post-H 2 O 2 treatment, with successful application in recovering pyrite from tailings during zinc separation in artificial mixed ore tests. Mechanistic investigations via contact angle measurements, Zeta potential analysis, UV–Vis, FTIR spectroscopy, ToF-SIMS and AFM revealed that H 2 O 2 induces LUT desorption from pyrite surface at natural pH, facilitating PBX adsorption to form a hydrophobic layer. Raman spectroscopy suggested oxidative modifications to LUT’s molecular structure. Additionally, XPS analysis confirmed increased Fe 3+ content on H 2 O 2 -treated pyrite, while LUT exhibits weaker interactions with Fe 3+ than with Fe 2+ revealed by microcalorimetry analysis. Consequently, H 2 O 2 reduces LUT adsorption, triggering its desorption and restoring pyrite’s flotation response. This work offers a practical strategy for reactivating pyrite inhibited by organic depressants, which is of great significance for promoting the efficient flotation separation of sulfide ore. Download: Download high-res image (171KB) Download: Download full-size image