# Activated Carbons as Effective Adsorbents of Non-Steroidal Anti-Inflammatory Drugs
## 3 Results
### Thermal Analysis  
The thermal stability of GAC, as well as the hybrid materials obtained after the adsorption of naproxen sodium, ibuprofen sodium, and diclofenac sodium, were analyzed. Figure 5 shows a comparison of the TG, DTG, and DSC curves for the tested samples, whereas Table 7 presents data estimated on the basis of these curves (TG, DTG, and DSC). Figure 4: The zeta potential of GAC and hybrid materials after naproxen sodium, ibuprofen sodium, and diclofenac sodium adsorption. Figure 5: Comparison of TG (**a**), DTG (**b**), and DSC (**c**) curves GAC activated carbon before and after naproxen sodium, ibuprofen sodium, and diclofenac sodium adsorption. It was noticed that the GAC activated carbon decomposition process occurs in two stages with a total weight loss of 86.50%. The first of them was in the 30-480 \({}^{\circ}\)C temperature range and with a weight loss of 1.34%. This can be attributed to the desorption of physically bound water and the removal of hydroxyl functional groups of the adsorbent [8]. The other step was registered in the 480-930 \({}^{\circ}\)C range with a weight loss of 85.16%. Here, an exothermic oxidation process of the sample was recorded at 653 \({}^{\circ}\)C [8]. In the case of activated carbon after pharmaceutical adsorption, the decomposition process takes place in three stages. For GAC after the ibuprofen sodium adsorption system, the total weight loss in the studied temperature range was 81.46%. The first decomposition stage recorded in the 30-200 \({}^{\circ}\)C temperature range (weight loss of 1.64%) was endothermic, with a peak at 79.7 \({}^{\circ}\)C related to the desorption of physically adsorbed water and the initial degradation of IBP. In the next stage, at the 200-600 \({}^{\circ}\)C temperature range, with weight loss of 79.24%, the exothermic processes of further decomposition of ibuprofen sodium, dehydration and degradation of the GAC activated carbon took place. In this temperature range, the peak maximum was observed at the temperatures of 274.1, 454.7, and 550.2 \({}^{\circ}\)C, of which the most intensive was registered at the highest temperature given. The last stage occurred in the 600-930 \({}^{\circ}\)C temperature ranges, with weight losses of 0.58%, which can also be correlated with carbon combustion. In GAC activated carbon after the diclofenac sodium adsorption system, the total weight loss in the examined temperature range was 84.85%. The first decomposition step registered in the 30-200 \({}^{\circ}\)C temperature range (weight loss of 2.62%) was endothermic, with the peak at 78.7 \({}^{\circ}\)C and corresponded to the desorption of physically adsorbed water and the initial degradation of the D. In the second step, at the 200-600 \({}^{\circ}\)C temperature range, with weight loss 78.24%, the exothermic processes of further decomposition of diclofenac sodium, dehydration and degradation of GAC occurred. In this temperature range, the peak maximum was recorded at 252.7 and 583.6 \({}^{\circ}\)C, which more intensive was registered at the highest temperature given. The third step, which appeared in the 600-930 \({}^{\circ}\)C temperature range, was endothermic (the peak maximum at 874.3 \({}^{\circ}\)C), with weight losses of 3.99%, which can also be correlated with the carbon combustion. For activated carbon after naproxen sodium adsorption system, the total weight loss in the studied temperature range was 81.79%. The first decomposition step took place in the