Abstract:

In decades, the presence of anti-inflammatory drugs diclofenac (DCF) in water resources has become an extremely threatening factor in terms of environmental protection and pollution. In this study, the removal efficiencies of DCF in aqueous sources were studied by adsorption, conventional coagulation, and combined coagulation methods using carbon nanotubes (CNTs). Experimental studies were carried out by adding certain doses of 1 g/L stock DCF solution prepared in the laboratory to water samples. In order to determine the adsorbing capacity of DCF, three different adsorbents as single-walled CNT (SWCNT), multi-walled CNT (MWCNT), and powdered activated carbon (PAC) were used as a function of pH and ionic strength. As a result of batch adsorption experiments performed in both ULW and UDWTP samples, the highest DCF sorption capacity was observed in SWCNT at pH =3 as 4.82 mg.g-1 and 3.82 mg.g-1, respectively, and also DCF adsorption capacity increased when the ionic strength was increased from 6.0×10-1 to 1.0 M. Furthermore, the experimental results showed that the Freundlich equation about correlation coefficient (R2=0.99) is the best isotherm model to describe the adsorption process in all water sources. On the other hand, results in coagulation experiments demonstrated that the maximum removal percentages of DCF in ULW (94.81%) and UDWTP (91.97%) occurred with combined SWCNT with Alum compared to only Alum coagulation. Experimental data obtained in this study reveal that combined coagulation with CNTs is more appropriate to minimize the pollution caused by DCF, especially in the aquatic environment, rather than adsorption and coagulation processes.

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