LAUSR

Abstract In this work, we report, for the first time, that cationic (Rhodamine B, RhB) and anionic dyes (Methyl orange, MO) were removed efficiently by hierarchical organic three-dimensional MgAl-LDH, which was successfully synthesized via a one-step hydrothermal strategy using sodium dodecyl sulfate (SDS) as a soft template agent. The removal mechanisms of RhB and MO were extensively investigated and determined to be surface adsorption and anion exchange, respectively. In addition, the influence of reaction parameters affecting dyes removal including dosage, contact time, initial dye concentrations and temperature were investigated. The maximum adsorption capacity of MO (377.89 mg·g−1) was far beyond that of RhB (48.29 mg·g−1) as well as other adsorbents. Multilayer adsorption occurred in RhB or MO at a low concentration, while monolayer adsorption was the dominant process in MO at high concentration (>200 mg·L−1). The thermodynamic calculations demonstrated that the adsorption process for both RhB and MO was spontaneous and endothermic. This work significantly broadens the application prospects of 3D-LDHs by modifying their surface properties and exploring O3D-LDHs as excellent adsorbents for organic pollutants in environmental remediation.