Hazardous dyes were removed using a nano γ-Fe2O3 based magnetic cationic hydrogel.
Equilibrium was established within 5 min exhibiting fast sorption kinetics.
Sorption capacity was high outcompeting other sorbents in the literature.
Sorbent was highly reusable over 30 consecutive sorption–desorption cycles.
Sorbent is superparamagnetic which allows its convenient magnetic separation.