Assembly of aluminum oxide particles with lignin-acrylic acid polymer in saline systems

Abstract

The flocculation process is widely used for separating particles from suspension systems. To make this process more environmentally friendly, a biobased flocculant was proposed to be used in this work. This study involves the experimental evaluation of a flocculation system of aluminum oxide particles (with two different sizes) and a kraft lignin-acrylic acid (KL-AA) polymer, as a biobased-flocculant, with advanced tools, such as focused beam reflectance measurement, vertical scanning analyzer, and gravitational scanning analyzer. A statistical framework was adapted to model the experimental results based on the mixture distribution theory, which led to a more in-depth analysis of the shape and size of flocs in the heterogeneous suspension system. The results revealed that the flocculation process of aluminum oxide suspension was altered by the salinity of the medium as well as the size of aluminum oxide particles. It was found that the flocs formed with KL-AA at a higher NaCl concentration had smaller sizes and exhibited higher shear resistance than the flocs formed in the absence of salt. Furthermore, by increasing the concentration of NaCl, the particles tended to possess more spherical shapes. The results also showed that the fractal dimension for flocculated particles increased by concentrating NaCl in the suspensions. Under gravity and centrifugal forces, the impact of KL-AA in flocculating particles was insignificant in the presence of salt.