Simultaneous Removal of Cu(II) and Dyes from Aqueous Solution Using LDH@GO-SH as an Adsorbent

Abstract

The simultaneous adsorption of Cu(II) and dyes (MB and MO) on LDH@GO-SH was investigated in single, MB–Cu, and MO–Cu binary systems. The coexistence of dye enhanced the adsorption of Cu(II) by LDH@GO-SH, while the presence of Cu(II) differently affected the adsorption of MB and MO. The adsorption capacity of MO remarkably increased due to the presence of Cu(II). The presence of Cu(II) had a negative effect on MB adsorption for lower MB initial concentration systems (2–10 mg·L−1), while it had a positive effect for higher MB concentration systems (25 mg·L−1 and 50 mg·L−1). The adsorption of Cu(II) in binary systems was satisfactorily fitted by a Langmuir model and pseudo-first-order kinetic model. Surface complex interaction was supposed to be a potential mechanism for the enhancement of Cu(II) adsorption in both MB–Cu and MO–Cu binary systems. The electrostatic interactions between MO and Cu(II) were another reason for the enhancement of Cu(II) adsorption in the MO–Cu binary system. LDH@GO-SH maintained a high adsorption capacity after three adsorption–desorption cycles, indicating that it can be repeatedly used for the treatment of heavy-metal-ion-containing wastewater.