Evaluation of the Potential of Metal-Organic Compounds ZIF-8 and F300 in a Membrane Filtration-Adsorption Process for the Removal of Antibiotics from Water

Abstract

Background/objectives: Antibiotic contamination in water sources is a growing global concern, contributing to environmental degradation and the proliferation of antimicrobial resistance. Traditional treatment methods, such as advanced oxidation or high-pressure membrane processes, are often energy-intensive and economically unsustainable for large-scale or decentralized applications. This study explores the potential of two cost-effective, commercially available metal-organic frameworks (MOFs), ZIF-8 and F300, to improve the performance of membrane-based filtration-adsorption systems for removing tetracycline and sulfadiazine from water.

Methods: Batch adsorption experiments were performed to evaluate the uptake capacities, kinetics, and isotherms of both MOFs toward the selected antibiotics. The membranes were modified using a low-cost silane-assisted deposition of MOF particles and tested in a microfiltration system. Removal efficiencies and water permeability were assessed and kinetic and isotherm models were applied to understand the adsorption mechanisms.

Results: ZIF-8 showed superior adsorption performance, with maximum capacities of 442.2 mg/g for tetracycline and 219.3 mg/g for sulfadiazine. F300 was effective only for tetracycline. Membranes modified with ZIF-8 improved pharmaceutical removal by 187% (tetracycline) and 224% (sulfadiazine) compared to unmodified membranes. Although permeability decreased due to increased hydrophobicity, the materials and processes remained economically favorable.

Conclusions: This study demonstrates that MOF-modified ceramic membranes, particularly those incorporating ZIF-8, offer a low-cost, scalable, and energy-efficient alternative for pharmaceutical removal from water. The approach combines strong environmental impact with economic viability, making it attractive for broader implementation in water treatment systems.

Keywords: MOF; adsorption; filtration; membranes; sulfadiazine; tetracycline; water.

Figure 1

Adsorbed mass of antibiotics (tetracycline and sulfadiazine) as a function of MOF concentration: (a) ZIF-8, (b) F300. A decrease in adsorption at higher MOF concentrations is observed due to particle agglomeration, which reduces active surface area. ZIF-8 adsorbs both drugs effectively, while F300 is selective for tetracycline.

Figure 2

Adsorption kinetics for tested drug–MOF systems: (a) tetracycline on ZIF-8, (b) tetracycline on F300, (c) sulfadiazine on ZIF-8. Experimental data were fitted to kinetic models; complex adsorption mechanism is most probable.

Figure 3

Adsorption isotherms of antibiotics on MOF particles: (a) tetracycline on ZIF-8, (b) sulfadiazine on ZIF-8, (c) tetracycline on F300. Models fitting suggests a predominance of monolayer adsorption.

Figure 4

Effect of pH on the adsorbed mass of tetracycline and sulfadiazine on ZIF-8 and F300. The adsorption of tetracycline was most efficient in the pH range of 6–8, while sulfadiazine showed the highest adsorption at pH 4–6. The colored lines presented in the figure do not possess physical significance; they serve solely to illustrate the trends of change.

Figure 5

Photo of tested membranes: (a) unmodified membrane (Unmod), (b) membrane modified by ZIF-8 (Mod-ZIF-8), (c) membrane modified by F300 (Mod-F300).

Figure 6

SEM images of tested membranes: (a) unmodified membrane (Unmod), (b) membrane modified by ZIF-8 (Mod-ZIF-8), (c) membrane modified by F300 (Mod-F300).

Figure 7

FT-IR spectra of membranes and MOFs. Modified membranes show slight shifts and signal changes compared to the unmodified membrane, indicating MOF presence. A drift in baseline for Mod-F300 supports Fe-based compound integration.

Figure 8

Water permeability of membranes. Hydrophobization through ODTS and MOF coating leads to reduced permeability, with Mod-ZIF-8 showing the lowest value, correlating with its highest contact angle.

Figure 9

Concentration change of antibiotics during filtration: (a) tetracycline, (b) sulfadiazine. ZIF-8-modified membranes exhibit the highest removal, especially in the early phase due to fast surface adsorption.

Figure 10

The removed mass of pharmaceutical substance for tested membrane. ZIF-8-modified membranes show the highest adsorption for both antibiotics; F300 performs well only with tetracycline.

Figure 11

Comparison of adsorption capacity of different membranes based on water permeability coefficient. A significant decline in membrane permeability correlated with enhanced adsorption properties of the membrane. The dashed lines presented in the figure do not possess physical significance; they serve solely to illustrate the trends of change.

Figure 12

Effect of salt ions on the removed mass of tetracycline and sulfadiazine. The presence of ions in water reduces the adsorption capacity of the membranes toward antibiotics.

Figure 13

Amount of antibiotics removed by the studied membranes after successive regeneration cycles. In the case of tetracycline, a noticeable decline in adsorption performance is observed with each regeneration cycle, whereas for sulfadiazine, the adsorption properties remain largely unchanged.