Graphene oxide–starch composite as an efficient adsorbent for removing Cu(II): removal performance and adsorption mechanism

Water pollution caused by heavy metals is a severe environmental issue. In this work, a graphene oxide–starch composite (GO/WS) was facilely prepared via hydrothermal process. The as-prepared GO/WS was characterized and employed as adsorbent to remove Cu(II). The removal performance was evaluated, and the adsorption mechanism was analyzed. Result shows that GO/WS outperforms either single graphene oxide (GO) or water soluble starch (WS) in terms of adsorption capacity. Specifically, GO/WS (D = 500 mg L−1) adsorbs 542.01 mg g−1 of Cu(II) (C0 = 300 mg L−1) in 24 min, exhibiting some advantages as higher capacity and shorter equilibrium time over other similar adsorbents. Adsorption complies with the Freundlich model and PSO model and is controlled by surface reaction, exhibiting favorable and chemical feature. Moreover, adsorption is thermodynamically spontaneous and exothermic. The chemical bonding of C=O, C–O-related groups in both GO and starch with Cu(II) serves as the main adsorption mechanism. Owing to its high adsorption efficiency, GO/WS may be a promising adsorbent for heavy metal scavenging.