Rheological Properties of Clay-Polymer Composite Hydrogels

Contamination by heavy metals poses many threats, affecting food chain safety, food quality, and the agricultural production. However, highly contaminated environments are reservoirs of heavy metal tolerant microbes, such as Stenotrophomonas bentonitica that is found in natural bentonite. In this work, we describe the synthesis and rheological characterization of alginate-cellulose hydrogels at different polymeric proportions, with best results for 30/70 W/W alginate/cellulose proportion and final concentration of 1%wt. For this concentration, we added bentonite at 1%wt to encapsulate S. bentonitica cells. A hydrogel precursor was created by adding CaCO3 in combination with D-glucono-δ-lactone, which was additionally cross-linked with a CaCl2 solution. Alginate beads were used to assess their metal bioremediation potential. The rheological properties under shear of the hydrogels were analysed for the different conditions and the results were related with microstructural changes analysed by HRSEM.