Post-modified NH2-MIL-101(Cr) as a high-efficiency adsorbent for 1 simultaneous removal of cationic and anionic dyes from textile wastewater

Abstract

Adsorptive treatment offers a practical route for extracting synthetic dyes from wastewater, although the preparation of some Cr-based MOFs relies on hazardous chemicals. In this study, a novel NH2-MIL-101(Cr) was synthesized through a HF-free solvothermal route using aminoterephthalic acid as the linker and subsequently post-modified with terephthalaldehyde. The resulting material was characterized by XRD, FT-IR, FE-SEM, TEM, EDS, and BET analysis to evaluate its structural, morphological, elemental, and textural properties. The efficiency of the modified adsorbent was tested on aqueous solutions of crystal violet, rhodamine B, and methyl orange. Under the selected experimental conditions, the highest experimentally determined adsorption capacities were 662.87, 673.75, and 863.67 mg g−1 for CV, MO, and RhB, respectively. These values were calculated directly from the measured concentration data and are not model-derived theoretical capacities. The adsorbent maintained substantial structural integrity after repeated adsorption–desorption cycles and under the investigated pH and temperature conditions. Treatment of real textile wastewater achieved 67% color removal and 68% COD reduction. The material also exhibited detectable antimicrobial activity against Pseudomonas aeruginosa, Bacillus cereus, and Aspergillus fumigatus, while limited activity was observed against the other tested strains. Overall, the combined HF-free synthesis, post-synthetic functionalization, dye adsorption, regeneration capability, and ancillary antimicrobial activity support the efficiency of the designed adsorbent for wast water treatment.