*2.4. Adsorption Experiments*

The batch adsorption experiments were carried out using 50 mL of the solution containing a 50 mg L−<sup>1</sup> concentration of the pharmaceutical molecules. The effect of pH was studied in the range from 2 to 10, where HCl and NaOH solution adjusts pH. Afterward, a predetermined amount of the adsorbent (0.010–0.8 g) was mixed into the solution before sonication at ambient temperature for 5–180 min. The supernatant was centrifuged at 2000 rpm for 3 min. Then, the absorbance was measured using a UV–vis spectrophotometer (Shimadzu Uv-1900) at λmax of each molecule at 224 and 288 nm for AT and PR, respectively. The results are averages of a minimum of 3 experiments.

The percent removal of contaminant and the adsorption capacity was calculated using Equations (1) and (2).

$$\text{Contaminant removal } \%= \frac{\mathbb{C}\_0 - \mathbb{C}\_t}{\mathbb{C}\_0} \times 100\tag{1}$$

$$\text{The capacity for adsorption} = (\text{C}\_0 - \text{C}\_t) \times \frac{\text{V}}{\text{M}} \tag{2}$$

C0 mg/L and Ct mg/L are the initial concentration and concentration at time "t", respectively. "V" (mL) is the volume of (PR, AT), and "m" (mg) is the mass of the adsorbent.
