Potential use of a novel modified seaweed polysaccharide as flocculating agent

► Cationized agaroses were synthesized and characterized. ► Their flocculation performance was evaluated for the first time. ► Flocculation performances were comparable to commercial polyacrylamides. ► The best performing sample would flocculate mainly through bridge formation. ► Cationized agaroses may constitute promising flocculants for water treatment.