Achieved MG adsorption capacity and yield on ARM-Fe₃O₄, ROS-Fe₃O₄, MAT-Fe₃O₄ and JUN-Fe₃O₄ NPs in the first process of MG adsorption in ambient dark conditions.

Adsorbent	q eI (mg g−1)	MG RI%
ARM-Fe3O4	15.81	53,42
ROS-Fe3O4	15.37	51.90
MAT-Fe3O4	10.83	35.91
JUN-Fe3O4	05.70	19.25