## 2 Materials and Methods  
### Materials  
In this study, the microplastic particles selected as a sorbents for the experiments were commercially available powdered standard polyethylene (PEp) supplied by Thermo Fisher Scientific (Waltham, MA, USA), granulated standard polyethylene (PEg) supplied by Sigma-Aldrich (St. Louis, MO, USA), standard polyethylene terephthalalate (PET) and standard polypropylene (PP). Polylactic acid (PLA), a biodegradable microplastic, was provided by Sigma-Aldrich. Additionally, as microplastic particles are often used to increase the abrasion properties of personal care products, in this research paper, two types of powdered polyethylene extracted from different personal care products (PE_PCPs_1 and PE_PCPs_2) were used. For this purpose, two types of facial scrubs were selected based on their specifications. Isolation of the MPs from the personal care products was conducted using the isolation method provided by [PERSON] et al. (2020), which included mixing the product with boiled water (100 \({}^{\circ}\)C) and the addition of 30% H\({}_{2}\)O\({}_{2}\) to induce degradation of the organic matter [23; 33]. In order to better understand the adsorption behavior of the selected organic pollutants on microplastics, characterization of the selected MPs was conducted. Chemical characterization of all selected all MPs, including the commercially available MPs, PLA and the particles isolated from personal care products was conducted by Fourier transform infrared spectroscopy (FTIR) (Nicolet iS20 FTIR spectrometer, Thermo Fisher Scientific, USA), and the results are presented in Figure S1. The results of the FTIR analysis were compared with the OMNIC 9, Thermo Fisher Scientific, USA, software library (Hummel Polymer Sample Library), confirming the chemical structure of all selected polymers. More details about the chemical characterization of PEp, PE_PCPs_1, PE_PCPs_2, PEg, PET, PPand PLA are given in [PERSON]\(\acute{\text{c}}\)arski et al. (2020, 2021). Furthermore, the physico-chemical properties of the MPs were obtained by Brunner Emmett Teller (BET) analysis, and these results are presented in the Supplementary Materials (Table S1). The unit size of the granulated MPs (PEg, PET, PP and PLA) as provided by the supplier was 3 mm [(23; 24; 33)]. The unit sizes of the powdered MPs (Figure S2) were determined by scanning electron microscopy (TM3030, Hitachi, Tokyo, Japan) and ranged between 49.7 and 259 \(\upmu\)m for the PEp particles and between 80 and 358 \(\upmu\)m for the PE isolated from the two personal care products [(40)]. Additionally, the determination of the point of zero charge (pH\({}_{\text{PZC}}\)) was performed according to the procedure provided by [PERSON] and [PERSON] (2008). The detailed procedure for determination of the point of zero charge is given in the Supplementary Materials [(41)]. HBs (1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, pentachlorobenzene, hexachlorobenzene and trifluralin), CPs (4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) and PAHs (naphthalene, fluorene, fluoranthene and pyrene), manufactured by Pestanaf\({}^{\text{\textregistered}}\), Sigma-Aldrich GmbH (Steinheim, Germany), were selected as sorbate models and their physico-chemical characteristics are presented in Table S2. The selected organic pollutants differed in hydrophobicity and water solubility, suggesting that their behavior in the presence of MPs in water would also be different. Additionally, the physico-chemical characteristics of the synthetic water used in this paper are given in [PERSON] et al. (2019) and are presented in the Supplementary Materials (Table S3) [(24)]. During the experiments and for sample preparations, hexane and methanol (provided by [PERSON]), acetic anhydride, hydrogen peroxide, CaCl\({}_{2}\), NaHCO\({}_{3}\) and MgSO\({}_{4}\cdot\)7H\({}_{2}\)O (provided by Sigma-Aldrich) were used.