<figure><img src="image_31.png" /></figure>

**Figure S6.** Absorption of tetracycline by (A) pristine PP, (B) UV aged PP, and (C) K₂S₂O₈ aged PP. Experimental data (black solid circles) from Ref. [41] for $c_{x,w}^* = 2.25 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_32.png" /></figure>

<figure><img src="image_33.png" /></figure>
<figure><img src="image_34.png" /></figure>

**Figure S7.** Absorption of tetracycline by (A) pristine PE, (B) UV aged PE with inset showing data at short times, and (C) K₂S₂O₈ aged PE. Experimental data (black solid circles) from Ref. [41] for $c_{x,w}^* = 2.25 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_35.png" /></figure>

<figure><img src="image_36.png" /></figure>
<figure><img src="image_37.png" /></figure>

**Figure S8.** Absorption of tetracycline by (A) pristine PBAT, (B) UV aged PBAT, and (C) K₂S₂O₈ aged PBAT.
Experimental data (black solid circles) from Ref. [41] for $c_{x,w}^* = 2.25 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_38.png" /></figure>

<figure><img src="image_39.png" /></figure>
<figure><img src="image_40.png" /></figure>

**Figure S9.** Absorption of tetracycline by (A) pristine PS, (B) UV aged PS, and (C) $K_2S_2O_8$ aged PS. Experimental data (black solid circles) from Ref. [41] for $c_{X,w}^* = 2.25 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_41.png" /></figure>

**Figure S10.** Absorption of atrazine by (A) pristine PE, and (B) aged PE. Experimental data (black solid circles) from Ref. [42] for $c_{x,w}^* = 2.32 \times 10^{-2}$ mol m$^{-3}$ (5 mg dm$^{-3}$). Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_42.png" /></figure>

**Figure S11.** Absorption of atrazine by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [42] for $c_{x,w}^* = 2.32 \times 10^{-2} \text{ mol m}^{-3} (5 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_43.png" /><figcaption>**Figure S12.** Absorption of ciprofloxacin by (A) pristine PS, and (B) aged PS. Experimental data (black solid circles) from Ref. [43] for $c_{x,w}^* = 3.02 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.</figcaption></figure>
<figure><img src="image_44.png" /></figure>

**Figure S13.** Absorption of ciprofloxacin by (A) pristine PVC, and (B) aged PVC. Experimental data (black solid circles) from Ref. [43] for $c_{X,w}^* = 3.02 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_45.png" /></figure>

**Figure S14.** Absorption of Cd(II) by (A) pristine PVC, and (B) aged PVC. Experimental data (black solid circles) from Ref. [44] for $c_{X,w}^* = 8.9 \times 10^{-3} \text{ mol m}^{-3} (1 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_46.png" /></figure>

**Figure S15.** Absorption of carbamazepine by (A) pristine PVC, and (B) aged PVC. Experimental data (black solid circles) from Ref. [45] for $c_{x,w}^* = 4.23 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_47.png" /></figure>

**Figure S16.** Absorption of carbamazepine by (A) pristine PE, and (B) pristine PET. Experimental data (black solid circles) from Ref. [45] for $c_{x,w}^* = 4.23 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line).
See main text for details of the fitting procedures.
<figure><img src="image_48.png" /></figure>

**Figure S17.** Absorption of Cu(II) by (A) pristine PU, and (B) aged PU. Experimental data (black solid circles) from Ref. [46] for $c_{x,w}^* = 0.16 \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_49.png" /></figure>

**Figure S18.** Absorption of oxytetracycline by (A) pristine PU, and (B) aged PU. Experimental data (black solid circles) from Ref. [46] for $c_{x,w}^* = 2.17 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_50.png" /></figure>

**Figure S19.** Absorption of oxytetracycline by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 2.17 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_51.png" /><figcaption>**Figure S20.** Absorption of chloramphenicol by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 3.09 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.</figcaption></figure>
<figure><img src="image_52.png" /></figure>

<figure><img src="image_53.png" /></figure>

**Figure S21.** Absorption of enrofloxacin by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 2.78 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_54.png" /></figure>

**Figure S22.** Absorption of ciprofloxacin by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{X,w}^* = 3.02 \times 10^{-2}$ mol m$^{-3}$ (10 mg dm$^{-3}$). Computed curves correspond to the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_55.png" /></figure>

<figure><img src="image_56.png" /></figure>

**Figure S23.** Absorption of ofloxacin by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 2.77 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_57.png" /></figure>

<figure><img src="image_58.png" /></figure>

**Figure S24.** Absorption of norfloxacin by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 3.13 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_59.png" /></figure>

**Figure S25.** Absorption of sulfamerazine by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 3.78 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_60.png" /></figure>

**Figure S26.** Absorption of sulfathiazole by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{X,w}^* = 3.92 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial 0-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial 0-absorption point: blue dashed line; excluding the initial 0-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial 0-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
<figure><img src="image_61.png" /></figure>

<figure><img src="image_62.png" /></figure>

**Figure S27.** Absorption of tetracycline by (A) pristine PP, and (B) aged PP. Experimental data (black solid circles) from Ref. [47] for $c_{x,w}^* = 2.25 \times 10^{-2} \text{ mol m}^{-3} (10 \text{ mg dm}^{-3})$. Computed curves correspond to the involved integral fit, eq 18 (including the initial O-absorption point: green solid curve), the mono-exponential, eq 21 (including the initial O-absorption point: blue dashed line; excluding the initial O-absorption point: blue dotted line) and the mono-exponential, eq 20 (including the initial O-absorption point: red dot-dashed line). See main text for details of the fitting procedures.
References

(S1) von Stackelberg, M. O.; Pilgram, M.; Toome, V. Bestimmung von Diffusionskoeffizienten einiger lonen in wäßriger Lösung in Gegenwart von Fremdelektrolyten. *I. Z. Elektrochem.* **1953**, *57*, 342-350.

(S2) Di Cagno, M. P.; Clarelli, F.; Våbeno, J.; Lesley, C.; Rahman S. D.; Cauzzo, J.; Franceschinis, E.; Realdon, N.; Stein, P. C. Experimental determination of drug diffusion coefficients in unstirred aqueous environments by temporally resolved concentration measurements. *Molec. Pharm.* **2018**, *15*, 1488-1494.

(S3) Urík, J.; Paschke, A.; Vrana, B. Diffusion coefficients of polar organic compounds in agarose hydrogel and water and their use for estimating uptake in passive samplers. *Chemosphere* **2020**, *249*: 126183.

(S4) Rudnicki, K.; Poltorak, L.; Skrzypek, S.; Sudhölter, E. J. R. Ion transfer voltammetry for analytical screening of fluoroquinolone antibiotics at the water – 1,2-dichloroethane interface. *Anal. Chim. Acta* **2019**, *1085*, 75-84.

(40) Lang, M.; Yu, X.; Liu, J.; Xia, T.; Wang, T.; Jia, H.; Guo, X. Fenton aging significantly affects the heavy metal adsorption capacity of polystyrene microplastics. *Sci. Total Environ.* **2020**, *722*: 137762.

(41) Guo, C.; Wang, L.; Lang, D.; Qian, Q.; Wang, W.; Wu, R.; Wang, J. UV and chemical aging alter the adsorption behavior of microplastics for tetracycline. *Environ. Poll.* **2023**, *318*: 120859.

(42) Wang, Y.; Liu, C.; Wang, F.; Sun, Q. Behavior and mechanism of atrazine adsorption on pristine and aged microplastics in the aquatic environment: kinetic and thermodynamic studies. *Chemosphere* **2022**, *292*: 133425.

(43) Liu, G.; Zhu, Z.; Yang, Y.; Sun, Y.; Yu, F.; Ma, J. Sorption behavior and mechanism of hydrophilic organic chemicals to virgin and aged microplastics in freshwater and seawater. *Environ. Poll.* **2019**, *246*, 26-33.

(44) Gao, L.; Fu, D.; Zhao, J.; Wu, W.; Wang, Z.; Su, Y.; Peng, L. Microplastics aged in various environmental media exhibited strong sorption to heavy metals in seawater. *Mar. Poll. Bull.* **2021**, *169*: 112480.

(45) Zhang, Y.; Chen, Z.; Shi, Y.; Ma, Q.; Mao, H.; Li, Y.; Wang, H.; Zhang, Y. Revealing the sorption mechanisms of carbamazepine on pristine and aged microplastics with extended DLVO theory. *Sci. Total Environ.* **2023**, *874*: 162480.

(46) Xue, X.-D.; Fang, C.-R.; Zhuang, H.-F. Adsorption behaviors of the pristine and aged thermoplastic polyurethane microplastics in Cu(II)-OTC coexisting system. *J. Haz. Mater.* **2021**, *407*: 124835.

(47) Yao, J.; Wen, J.; Li, H.; Yang, Y. Surface functional groups determine adsorption of pharmaceuticals and personal care products on polypropylene microplastics. *J. Haz. Mater.* **2022**, *423*: 127131.

(48) Chen, C.; Pang, X.; Chen, Q.; Xu, M.; Xiao, Y.; Wu, J.; Zhang, Y.; Liu, Y.; Long, L.; Yang, G. Tetracycline adsorption trajectories on aged polystyrene in a simulated aquatic environment: a mechanistic investigation. *Sci. Total Environ.* **2022**, *851*: 158204.