Synthesis and application of bimetallic ZIF-11 as an adsorbent for tetracycline: understanding the performance-enhancing role of cobalt in the framework
Year: 2026
Type: article
Abstract: In this study, bimetallic zeolitic imidazolate frameworks with a ZIF-11 structure with different molar ratios (Zn/Co: 3, 2, 1, 0.5, 0.33) were synthesized. Then, tetracycline (TC) adsorption was examined and compared between bimetallic and monometallic samples. Techniques such as XRD, FTIR, FESEM, EDS, and BET were used to determine their characteristics. A slight shift in peak position on XRD patterns for samples with Zn/Co ratios of 1, 2, and 3 was observed, resulting from the introduction of cobalt instead of zinc. FESEM images show that the bimetallic samples, like the monometallic ZIF-11, have a characteristic dodecahedral crystal structure. According to the obtained results and especially in the comparison between single and bimetallic samples, ZIF-11 (Zn/Co:3) appears to have the greatest surface area of 580.4 m 2 .g − 1 . Based on the findings, ZIF-11 (Zn/Co:3) is identified as the best synthetic sample, bearing a 95.1% adsorption efficiency for TC (5 ppm) in 60 min at pH 7, along with a maximum adsorption capacity of 294.1 mg/g. The adsorption efficiency with the bimetallic sample (ZIF-11 (Zn/Co:3)) was about 2.2 times that of the monometallic sample (ZIF-11), which indicated that the addition of cobalt greatly improved the adsorption capacity, probably due to the large supply of metal sites provided by cobalt. According to the pH PZC of ZIF-11 (Zn/Co:3) equal to 7.3, the adsorption process was investigated at normal pH. The best kinetic and isotherm models for TC adsorption on ZIF-11 (Zn/Co:3) are Elovich (R 2 = 0.97) and Langmuir (R 2 = 0.99), respectively. Adsorption mechanisms of ZIF-11(Zn/Co:3) include π-π interactions and hydrogen bonding. The structural properties of the ZIF-11 bimetallic mixture have been improved compared to its monometallic type, which has subsequently been effective in its performance in the adsorption process.
Source: Applied Water Science
Institution: Semnan University
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,490
OpenAlex ID: W7127042948