In-situ synthesis of 3D multifunctional graphene-based layered double oxide composite for the removal of nickel and acid orange

Abstract

Graphene-like materials as a prevalent two-dimensional (2D) material have attracted tremendous attention in the water remediation field, yet the inherent nature of aggregation limits its macroscopic practical applications. To address the dilemma, a novel in-situ synthesis strategy, i.e., integrated “self-template” and “structure designing”, was proposed in this study. Specifically, the organic layered double hydroxide (3D-LDH) was employed as self-template and carbon source to construct the functional three-dimensional (3D) graphene loading with layered double oxide (G@LDO). In virtue of the special 3D structure and components, G@LDO exhibited preeminent and ultrafast remediation ability toward acid orange (AO7, 1870.15 mg/g) and nickel (II) (Ni2+, 110.10 mg/g). Moreover, G@LDO maintained the exceptional removal of AO7 and Ni2+ in a wide pH range and even in the authentic water matrices. The removal mechanisms were systematically investigated, unveiling that AO7 removal was strongly associated with metal-complexation, memory effect, and π-π electron donor–acceptor (EDA). While for Ni2+ removal, besides ion-exchange interaction with Mg2+ associated with LDO, the other S component induced the vacancy defect provided additional active sites for Ni2+ capture. In addition, the recycle experiments demonstrated that G@LDO kept above 85% after five runs. Overall, this work not only opens a new avenue for the preparation of graphene-like material, but also provided a theoritical guidance for the authentic application on the removal of dyes and heavy metals.