Selective adsorption and separation of dyes from aqueous solution by core-shell structured NH2-functionalized UiO-66 magnetic composites.

Core-shell structured NH2-functionalized UiO-66 magnetic composites (γ-Fe2O3@C@UiO-66-NH2) were fabricated via a simple, facile and green approach to investigate their adsorption behaviors towards different organic dyes (methylene blue, malachite green, acid fuchsin and acid orange II). Different characterization methods containing XRD, TEM, EDXA, FTIR, BET and XPS were used to indicate that the as-prepared γ-Fe2O3@C@UiO-66-NH2 material exhibited core-shell structure and excellent surface performance. Adsorption experiments showed that γ-Fe2O3@C@UiO-66-NH2 could selectively adsorb anionic dyes and effectively separate the mixture, which might be mainly ascribed to the negatively-charged anionic dyes as opposite to the positively-charged Zr metal sites in γ-Fe2O3@C@UiO-66-NH2. The kinetics and adsorption isotherm of acid orange II and acid fuchsin adsorption in γ-Fe2O3@C@UiO-66-NH2 were also investigated. For acid orange II and acid fuchsin, the maximum adsorption capacity obtained from the Langmuir isotherm model was 48.12 mg/g and 31.54 mg/g, respectively. Moreover, γ-Fe2O3@C@UiO-66-NH2 exhibited good structural stability and reusability, which suggesting that γ-Fe2O3@C@ UiO-66-NH2 as an easy-prepared adsorbent material exhibited great application potential in the selective removal of dyes from water systems.