Facile synthesis of MIL-100(Fe) adsorbents for boosting organic dye removal

Highly effective MIL-100(Fe) adsorbent material was successfully synthesized from (NH4)2Fe(SO4)2·6H2O and H3BTC precursors under mild conditions. Characteristics regarding crystal structure, functional groups, elemental composition, surface morphology, specific surface area, and surface charges revealed the formation of pure and microporous MIL-100(Fe) adsorbent with a super surface area (1916.26 m2/g). The results showed that the adsorption of tartrazine organic dye was affected by adsorption time, solution pH, adsorbent dosage, pollutant concentration, and temperature. The adsorption kinetics was best described by a pseudo-second-order model with a coefficient of determination R2 = 0.999. The Toth and Langmuir models best fitted to the experimental data, showing a maximum adsorption uptake of 104.913 mg/g, which is much better than many other adsorbents. The thermodynamic parameters revealed the adsorption process of tartrazine on MIL-100(Fe) material was exothermic, spontaneous, and mainly controlled by chemical adsorption. The desorption and reuse ability of the material was effectively performed by using ethanol (98%), which showed an adsorption efficiency still remained at 88% after five adsorption cycles. This work provides an environmentally friendly synthesis of MIL-100(Fe) material with high adsorption efficiency and opens up opportunities to develop new materials for organic dye treatment in water.