*2.1. Preparation of Activated Carbon*

Washed clean STLs (collected from Southern Algeria) were dried in an oven at 110 ◦C for 24 h, which proved effective to facilitate subsequent crushing and grinding. The precursor was impregnated with an 85% H3PO<sup>4</sup> solution at room temperature and dried for 2 h at 110 ◦C. The impregnation ratio, R, (H3PO4/precursor mass) (wt./wt.) was varied from 1 to 3. The samples were activated in a quartz reactor at different temperatures in the range of 400 to 600 ◦C under nitrogen flow at a rate of 100 mL/min and for 1 h as an

activation time. The activated samples were cooled inside the furnace maintaining the N<sup>2</sup> flow. After that, the samples were washed with distilled water at 65 ◦C until neutral pH is achieved before being dried at 110 ◦C. The obtained activated carbons were named Rx-y, where R from ratio, while x and y correspond to the impregnation ratio and activation temperature, respectively.
