Flocculation and adsorption-desorption mechanism of polymers on albite

For several decades, inorganic electrolytes, natural polymers and synthetic, high molecular weight polymers have been used as coagulants or flocculants for clarification of effluents, acid mine drainage and treatment of paper, textile, sugar and other industrial waste water processing applications. Research has shown that interactions between the functional groups on particulate surfaces and those on polymers are responsible for adsorption and subsequent flocculation, and can be appropriately controlled by tailoring polymers with specific functional groups suitable for particular applications. The effectiveness of a polymer for a given flocculation system depends on several parameters, e.g. the polymer dosage, amount adsorbed on the solid surfaces, molecular weight of the polymer, particle size, shape, porosity, ionic strength of the system, electrokinetic properties and more importantly, conformation of the polymer at the solid-liquid interface. Electrokinetic studies on pure albite show that it is negatively charged throughout the entire pH, and the isoelectric point of the mineral is below pH = 2. Adsorption of the non-ionic polymer (N-300) is found to increase with increasing the pH and concentration of the polymer. A hydrogen-bonding mechanism between the polymer carbonyl (-C=O) or the amide (-NH₂) groups and the surface oxygen species is proposed to be responsible for the adsorbtion of non-ionic polymer onto albite. According to desorption tests, no significant change was observed for the albite-non-ionic polymer system.