Removal of Cu(II) from Water by a Novel Graphene Oxide/Hexadecyltrimethylammonium Composite Sponge and Its Regeneration for Reuse

Abstract

Graphene oxide has great potential for use as an adsorbent due to the high specific surface area, high negative charges, and abundant oxygen-containing functional groups. However, the difficulty of graphene oxide to separate from water renders it impractical for real water treatment. In the present study, a novel graphene oxide/hexadecyltrimethylammonium composite sponge (GO/HDTMA) was prepared and investigated for use as a filtration material for the removal of Cu(II) from water. The formed porous GO/HDTMA sponge was highly stable in water. The adsorption was spontaneous and exothermic, increasing with decreasing temperatures. The material showed good ability to remove Cu(II) with competing cations (K+, Na+, Ca2+, and Mg2+) present. Five cycles of adsorption-desorption-regeneration studies showed that, after adsorption, the material could be successfully regenerated for repeated use by using a 1-M HCl solution as the desorption reagent. At a sufficiently high dose, GO/HDTMA showed an excellent performance for Cu(II) removal from river water containing different coexisting solutes. Finally, our 30-day column study revealed that the GO/HDTMA sponge is a good filtering material for the removal of Cu(II) from river water. In conclusion, the GO/HDTMA sponge is an excellent adsorbent material for use in flow-through water treatment applications for Cu(II) removal.