Magnetic Fe3O4@UiO-66 nanocomposite for rapid adsorption of organic dyes from aqueous solution

Human society is becoming more intransigent on removing organic dyes from polluted water before discharging to the environment. To fulfill this goal, a magnetic metal-organic framework adsorbent based on functionalized magnetic Fe3O4 nanoparticles and highly water stable UiO-66 with high porosity and sensitivity to the external magnetic field was designed and synthesized via an easy step-by-step self-assembly technique. The synthesized adsorbent magnetic nanoparticles (Fe3O4@UiO-66) were applied to remove organic dyes, i.e., methyl orange (MO) and methylene blue (MB), from a contaminated aqueous solution. The experiments displayed that magnetic Fe3O4@UiO-66 has good adsorption uptake for MO (244 mg/g) and MB (205 mg/g). The influence of several factors, including contact time, dye concentration, initial solution pH, the temperature of adsorption, and salt concentration, on the adsorption capacities of these dyes was assessed. The adsorption kinetic investigation demonstrated that the experimental adsorption data for both dyes well fitted the pseudo-second-order model. The thermodynamic research illustrated that the adsorption of both cationic and anionic organic dyes onto Fe3O4@UiO-66 was a thermodynamically spontaneous and endothermic process, and thermodynamically derived by entropy change rather than an enthalpy impact. Accordingly, the maximum adsorption capacities of Fe3O4@UiO-66 for MO increased from 243.9 to 303.0 mg/g with increasing the adsorption temperature from 25 to 45 °C. The excellent adsorption capacity, good water stability, excellent adsorption selectivity, proper regeneration, as well as good behavior in magnetic separation endorsed that the magnetic Fe3O4@UiO-66 could be a suitable adsorbent for dye elimination from aqueous solutions.