Soil structuring using interpolyelectrolyte complexes of water-soluble polysaccharides

Soil degradation is an important problem on a global scale. Suitable materials for its solution are interpolyelectrolyte complexes (IPEC) of biodegradable polymers. IPEC based on the oppositely charged pairs of biodegradable polymers-chitosan and sodium alginate (Ch-SA), chitosan and sodium carboxymethylcellulose (Ch-SC), and chitosan-gellan gum (Ch-GG) were prepared and studied using different physicochemical techniques (FTIR-spectroscopy, dynamic light scattering, conductometric and turbidimetric titration, and rheoviscometric measurements). Thin films of IPECs were prepared by pouring polymer solutions on a flat surface and subsequent evaporation of water. These films were tested using mechanical analysis. Young modulus of IPEC films increases in the following order: Ch-SC < Ch-GG < Ch-SA. Urban soil samples were sequentially treated with Ch solution and negatively charged polymer solution (SC, SA, GG). This technique of soil treatment leads to formation of IPEC within the soil surface layer. The soil structures and also soil treated with pure water and individual polymer solutions were also tested using mechanical analysis. It was found that the most durable structures are formed by IPEC based on Ch and SC. All the applied systems can be arranged in the following sequence in ascending order of the Young's modulus: GG < Ch < SA < Water < SC < Ch-GG < Ch-SA < Ch-SC. The IPEC based on biodegradable and biocompatible polymers of polysaccharide nature can be successfully used for soil structuring. These polymers significantly increase the mechanical strength of the soil without harmful effects to the environment. Among the studied systems, the Ch-SC system has the greatest structuring ability. These soil structuring agents can be applied for improving of the quality of urban and agricultural soils.