Cellulose Nanocrystals‐Based Polyacrylamide as Flocculating Agent of Mature Fine Tailings

This study compares the performance of neat polyacrylamide (PAM) and their nanocomposites produced with cellulose nanocrystals (CNCs) on the flocculation of mature fine tailings (MFT). The surface of CNCs is chemically modified using three different bifunctional organosilanes containing vinyl functional groups (7-octenyl trimethoxysilane, methacryloxypropyl trimethoxysilane, vinyl trimethoxysilane). Acrylamide is polymerized in the absence and presence of pristine and silylated CNCs (5 and 10%w/w) to in situ produce PAM-CNC nanocomposites. Concentrations of 1000 and 2000 ppm of the produced polymers are used to flocculate MFT. FTIR spectra showed that the CNCs are successfully modified, regardless of the silane used. The dynamics of floc size evolution is assessed by focused beam reflectance measurements (FBRMs), and the results demonstrated that smaller flocs are produced by increasing the CNCs content in the polymerization. Capillary suction times (CSTs) data showed that the use of CNC-based PAM nanocomposites enhances flocs dewaterability in comparison to neat PAM. Moreover, the type of silane used in the chemical modification of CNCs influenced the flocculation performance of PAM-CNC nanocomposites. The obtained results are promising and encourage the development of a more detailed investigation regarding the production and performance assessment of hybrid flocculating polymers composed by PAM and CNCs.