Composite hydrogels based on calcium alginate and polyethyleneimine for wastewater treatment

Abstract

Water shortage has risen severely in recent years, confronting mankind with a worldwide challenge, especially as the accessible water resources are further limited by diverse contamination. The most widespread industrial process for water treatment is the activated sludge process, in which, however, excessive sludge production has become an enormous environmental problem worldwide. To overcome this problem, hydrogels possess outstanding potential in view of adsorptive removal of contaminants like heavy metal ions, fertilizers, and dyes. In this paper, we report about the synthesis of biobased alginate hydrogel beads along with polyethyleneimine-modified composite hydrogels for water treatment. The adsorption of methylene blue as a positively charged and of congo red as a negatively charged model dye is quantitatively investigated, both separately and in combination. In addition, the pH-dependent adsorption of the dyes is determined. The use of alginate-based hydrogel systems combines several prospects: they are bio-based, inexpensive, easily available to a sufficient extent, sustainable, and are applicable in a broad range of wastewater treatment by its charged groups.