RES³T - Rossendorf Expert System for Surface and Sorption Thermodynamics

Interfacial properties of pyrite–water suspensions were examined by potentiometric titrations. Initial experiments show that the dissolution of pyrite occurs even under anaerobic conditions. The role played by H⁺, OH⁻, Fe²⁺ and S²⁻ as potential determining ions (PDI) on surface charge development was also assessed. The pH_zpc of pyrite was experimentally determined at 1.7. When pH = pH_zpc, the pFe_zpc of pyrite was 2.97. A 1-pK diffuse-layer model (1-pK DLM) quantified proton titration data using following reaction stoichiometries:

>FeSS^−⅓ + H⁺ → FeSSH^+⅔   log K = 0.93±8.34E−02
>FeSS^−⅓ + 2H⁺ → HHSS^−⅓ + Fe²⁺   log K = −2.87±0.77
>FeSS^−⅓ → Fe²⁺ + >SS^−5/₃   log K = −2.90±0.12