Influence of molecular mass of lignosulfonates on the resulting surface charges of solid particles

Different lignosulfonate (LS) samples were prepared via a three-step method and were characterized by FT-IR, UV, GPC and functional groups measurement. FT-IR and UV spectra confirmed the prepared samples had typical characteristics of lignin materials. GPC and functional groups measurement results indicated the samples had different molecular mass (Mw), but same quantities of sulfonic groups (S). The influence of Mw of LS on the resulting surface charges of dimethomorph particles via adsorption was further investigated. The results indicated that the adsorption isotherms of LS on dimethomorph surfaces belonged to L-type and the adsorption capacity (qm) increased with increasing Mw. However, the non-linear correlation between zeta potentials with the products of S and adsorption amount (SA) indicated SA did not positively improve the surface charges expectedly. Based on the analysis, an adsorption confirmation was proposed allowing prediction of the relation between Mw and surface charge efficiency of LS for solid particles.