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.