Investigation of antibiotic clarithromycin adsorption potential on microplastics

<p style="line-height:200%;margin-bottom:0cm;margin-left:-14.2pt;margin-right:0cm;margin-top:12.0pt;text-autospace:none;"><span style="color:#292526;font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US"><strong>A</strong></span><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">In this study, it was aimed to investigate the potential of microplastics (MPs) to adsorb antibiotic </span><a name="_Hlk178421500"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">clarithromycin</span></a><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US"> (CLAR) in the water media. For this purpose, two of the most common used plastics; </span><a name="_Hlk178421486"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">polyethylene terephthalate (PET) and polyethylene (PE) </span></a><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">were selected. Batch adsorption experiments were performed under various conditions, i.e., pH, and ionic strength of the solution, type and dimension of MPs. Liquid chromatography equipped with mass spectrophotometry (HPLC-MS) was used for the analysis of CLAR. </span><a name="_Hlk178421664"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">Fourier Transform Infrared Spectrometry (FT-IR) analysis </span></a><a name="_Hlk178421673"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">of adsorbents was performed before and after CLAR adsorption</span></a><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">. </span></p><p style="line-height:200%;margin-left:-14.2pt;text-align:justify;text-autospace:none;"><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;">Results of the experimental studies showed that the adsorption reached the highest value at pH 6-7. Equilibrium adsorption time was 240 min. The adsorption occurred in accordance with pseudo-second-order kinetics. The experimental qe values for CLAR adsorption of <2 mm PET-MPs; <5 mm PET-MPs; <2 mm PE-MPs and <5 mm PE-MPs were </span><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;" lang="EN-US">0.33 mg/g, 0.26 mg/g, 2 mg/g, and 0.2 mg/g,</span><span style="font-family:"Times New Roman",serif;font-size:12.0pt;line-height:200%;"> respectively. It was determined that adsorption with <2 mm PE-MPs fits the Langmuir isotherm model (r2=0.95), while adsorption with <2 mm PET-MPs (r2=0.74) and <5 mm PET-MPs (r2=0.83) fit the Freundlich isotherm model. The findings revealed that CLAR was adsorbed by all tested PET-MPs and PE-MPs, that poses an accumulation and transportation risk in the aquatic environment.</span></p>