Sustainable composite super absorbents made from polysaccharides

Compared to traditional super absorbent polymers using raw materials from petrochemical industry, natural polymer absorbents are more favorable because they are sustainable and biodegradable. In this study, composite absorbents were developed by crosslinking carrageenan with sodium alginate using calcium chloride. Effect of composition on absorption was tested. Absorption was improved by increasing carrageenan content. The super absorbent exhibited the maximal swelling ratio of 13.1 g/g in 0.9% saline water in just 5 min. The maximal tensile strength was reached with a value of 12.8 MPa. Water contact angle revealed that carrageenan is more hydrophobic than sodium alginate. Presence of sulfate groups might be a key factor promoting absorption. The scanning electron microscopic images showed that the composite material had a structure with alginate arranged at the outside surface. These results demonstrate that a sustainable and biodegradable absorbent was successfully developed with a matrix of properties for potential application in diapers.