Generation of sulfonated kraft lignin acrylic acid polymer and its use as a flocculant

The main purpose of this work was to generate sulfonated lignin-acrylic acid polymer and to study its flocculation performance for aluminum oxide suspension. The sulfonation pretreatment enhanced the charge density and solubility of kraft lignin facilitating its subsequent polymerization with acrylic acid. The maximum anionic charge densities of 3.3 and 2.5 meq/g and maximum molecular weights of 898 and 330 kg/mol were obtained for purified sulfonated lignin – acrylic acid and purified kraft lignin–acrylic acid polymers, respectively. The elimination of polyacrylic acid (i.e., homopolymer) from the lignin derivatives improved the efficiency of lignin products as flocculants for aluminum oxide particles.