Polyacrylamide Soil Conditioners: The Impact on Nanostructured Clay Minerals’ Aggregation and Heavy Metals’ Circulation in the Soil Environment

Polyacrylamide is a water-soluble synthetic polyelectrolyte which consists of repeating units (forming a chain structure and containing hydrophilic groups). Due to the different nature of the groups present in the macromolecules, polyacrylamides can be divided into nonionic, anionic, and cationic ones. They are used in many industries, including mineral processing; wastewater treatment; production of paints, inks, varnishes, plastics, paper, cosmetics, and ceramics; pharmacy, food industry, or in agriculture as polymeric additives controlling soil erosion process. The addition of high molecular compounds affects the rheological properties and stability of colloidal suspensions. Their presence in the system can increase or decrease its stability. Stabilization or flocculation may result from the adsorption of high molecular compounds in various conformations on the surface of the solid particles dispersed in liquid phase or from the presence of nonadsorbed polymer chains in the dispersion phase. This paper aims to review polyacrylamides structure, synthesis methods, and their adsorption on the surface of clay minerals. The literature studies on the impacts of PAM adsorption on clay particles’ aggregation and heavy metal ions’ accumulation in soil environments have been also presented.