Synthesis and characterisation of a novel pH-sensitive flocculant and its flocculation performance

In this study, a novel pH-sensitive flocculant, poly(AM-DEA-DPL) (PADD), was synthesised using acrylamide (AM), diethylaminoethyl methacrylate (DEA), and dodecyl glucoside (DPL) as monomers through solution copolymerisation. The synthesis conditions were optimised, and the intrinsic viscosity and conversion rate of the polymer were improved. The molecular structure of the flocculant was determined through Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance (1H NMR) spectroscopy analysis. The isoelectric points of PADD were found to be pH 4 through zeta potential measurements, indicating that PADD is an amphoteric flocculant. The change in turbidity with pH reflected the pH sensitivity and the change in the hydrophilicity and hydrophobicity of the polymer. Gel permeation chromatography (GPC) measurements showed that the average molecular weight of the polymer was 89,310. PADD had great turbidity removal and flocculation effects on both hydrophilic kaolin and hydrophobic molybdenite. At pH 2–8, a small amount of flocculant had excellent flocculation effects on kaolin and molybdenite suspensions. According to FTIR characterisation and zeta potential measurements of the flocs, and to previous reports, this was mainly the result of electrostatic attraction, adsorption bridging, hydrophobic association, and synergy. The PADD flocculant has promising industrial applications.