Abstract
Traces of antibiotics within domestic and industrial effluents have toxic impact on human health as well as surrounding flora and fauna. Potential increase in antibiotic resistance of microorganisms is likely to rise due to the incomplete removal of antibiotics by traditional wastewater processing, methods such as membrane filtration and biological treatment. In this study, we investigated a novel class of material termed Polymer of Intrinsic Microporosity (PIM) that is based on amorphous microporous organic materials for the application of antibiotic removal form aqueous environments. The adsorption of four commonly used antibiotics (doxycycline, ciprofloxacin, penicillin G, and amoxicillin) was evaluated and found that at least 80% of the initial concentrations was eliminated under the optimized conditions. Langmuir and Freundlich models were then employed to correlate the equilibria data; the Freundlich model fit well the data in all cases. For kinetic data, pseudo-first and second order models were examined. Pseudo-second order model fit well the kinetic data and allowed the calculation of the adsorption rate constants. Thermodynamic parameters were obtained by conducting the adsorption studies at varied reaction temperatures. Surface potential, adsorption at various solution pHs, thermogravimetric analysis (TGA), Infrared spectroscopy (IR), and surface area experiments were conducted to draw possible adsorption mechanisms. The removal of antibiotics from water by PIM-1 is likely to be governed by both surface and pore-filling adsorption and could be facilitated by electrostatic interactions between the aromatic rings and charged functional groups as well as hydrogen bond formation between the adsorbent and adsorbate. Our work shows that the application of such novel microporous material could contribute to the removal of such challenging and persistent contaminants from wastewater with further optimizations of large-scale adsorption processes.
Highlights
Such issues have motivated active research in recent years to develop new alternative technologies that are simple and more efficient in eliminating antibiotics from the bodies of water
Polymer of Intrinsic Microporosity (PIM)-1 is synthesized from the reaction of 5,5′,6,6′ tetrahydroxy-3,3,3′,3′ tetramethylspirobisindane with 1,4 dicyanotetrafluoro benzene
Thermal stability of PIM-1 was confirmed by conducting thermogravimetric analysis (TGA) experiment where the polymer backbone degradation was observed at 450 °C, indicating a thermally stable adsorbent material
Summary
Such issues have motivated active research in recent years to develop new alternative technologies that are simple and more efficient in eliminating antibiotics from the bodies of water. PIM possesses unusual structural features with a backbone composed of fused rings and site of contortion resulting in high free volume as they cannot pack space efficiently[44] Investigations of this materials showed high surface area, high thermal and chemical stability, and potential application in adsorption as it is soluble in common organic solvents and can be readily processed in various application-driven forms including powders, membranes and fibers[45,46,47]. Application of PIM-1 in the removal of emerging organic contaminates such as antibiotics has yet to be explored and demonstrated With this background, the objective of this study was to examine the behavior of PIM-1 at different experimental conditions to remove four commonly used antibiotic compounds: doxycycline, ciprofloxacin, penicillin G, and amoxicillin; from aqueous solutions in an agitated batch regime. The reported adsorption data points in this study represent the average values of three individual experiments with standard deviations not exceeding 5%
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