Phosphorylated lignosulfonate enables force-regulated solid-solid separation by suppressing pyrite-serpentine hetero-aggregation

A sulfonate-phosphate lignosulfonate was designed for force-regulated solid–solid separation. • PSLS suppressed pyrite-serpentine hetero-aggregation through selective MgOH anchoring. • Pyrite recovery reached 85.30%, 12.88 percentage points higher than that with SLS. • P-O-Mg bonding and sulfonate electronegativity enabled selective serpentine modification. • PSLS converted pyrite-serpentine attraction into nanoscale repulsive stabilization. Hetero-aggregation between dissimilar particles limits selective separation in complex aqueous systems, as exemplified by attractive serpentine-pyrite interactions. However, conventional depressants often suffer from limited selectivity, high reagent consumption, and environmental concerns. Herein, phosphorylated sodium lignosulfonate (PSLS) was designed as a water-soluble sulfonate-phosphate interfacial regulator to suppress serpentine-sulfide hetero-aggregation. By integrating serpentine-affinitive phosphate groups with the highly electronegative sulfonate structure of sodium lignosulfonate (SLS), PSLS enables selective anchoring on serpentine and enhanced electrostatic repulsion between serpentine and pyrite. Compared with SLS, PSLS increased pyrite recovery in the mixed-mineral system to 85.30%, corresponding to an improvement of 12.88%. The surface coverage of PSLS on serpentine reached 93.72%, markedly higher than that of SLS (63.80%). Atomic force microscopy (AFM) colloidal probe measurements combined with Derjaguin-Landau-Verwey-Overbeek (DLVO) analysis further showed that the adhesion force between pyrite and the serpentine MgOH plane decreased from 6.99 mN m −1 to 2.02 mN m −1 after SLS treatment and further to 0.22 mN m −1 after PSLS treatment. These results demonstrate that PSLS suppresses pyrite-serpentine hetero-aggregation by simultaneously strengthening serpentine-specific adsorption and regulating nanoscale interparticle forces. This work provides a practical strategy for designing lignin-derived regulators for efficient solid–solid separation in complex aqueous particle systems. Download: Download high-res image (97KB) Download: Download full-size image