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Otpadne vode mogu sadržavati velike količine različitih farmaceutika. Dugoročno izlaganje niskim koncentracijama farmaceutika može imati toksičan učinak na ljudsko zdravlje, te ih je iz tog razloga potrebno ukloniti iz ekosustava. Pri uklanjanju farmaceutika, adsorpcija na aktivni ugljen se pokazala učinkovitom metodom. Cilj ovog istraživanja bio je ispitati utjecaj vremena adsorpcije, temperature, mase adsorbensa te utjecaj pH vrijednosti modelne otopine amoksicilina na postotak uklanjanja istog. Serije adsorpcijskih eksperimenata su provedene s ciljem ispitivanja utjecaja početne koncentracije amoksicilina (20, 30, 40, 50, 60, 70, 80, 90 i 100 mg/L), pH (2-9), koncentracija adsorbensa (0,4-16 mg/L), te vremena adsorpcije (1-360 min) na uklanjanje amoksicilina pri 25, 35 i 45 °C. Najveći postotak uklanjanja amoksicilina iznosio je 42,83 %. Dobiveni podaci su potom obrađeni linearnim matematičkim modelima Langmuirove i Freundlichove adsorpcijske izoterme. Izračunati podaci pokazuju bolje slaganje s Freundlichovim modelom adsorpcije pri čemu vrijednost n < 1 ukazuje da se radi o kemisorpciji. Za opisivanje mehanizama adsorpcije ispitani su i kinetički modeli pri čemu je kinetički model pseudo-drugog reda najbolje opisao brzinu adsorpcije. Aktivni ugljen od ljuske oraha pokazao se kao učinkovit adsorbens za uklanjanju amoksicilina. Wastewater can contain large quantities of different pharmaceuticals. Long-term exposure to low concentrations of pharmaceuticals proved to have toxic effects on human health and should therefore be removed from the ecosystem. When removing the pharmaceuticals, adsorption on activated carbon has proven to be effective. The aim of this research was to investigate the effect of adsorption time, temperature, adsorbent mass, and the influence of the pH value of the amoxicillin model solution on the removal rate. A series of adsorption experiments were performed to investigate the effect of the initial concentration of amoxicillin (20, 30, 40, 50, 60, 70, 80, 90 and 100 mg/L), pH (2-9), adsorbent concentration (0.4 -16 mg/L), and adsorption time (1-360 min) to remove amoxicillin at 25, 35 and 45 °C, respectively. The highest percentage of amoxicillin removal was 42.83%. The obtained data were then fitted with linear mathematical models of Langmuir and Freundlich adsorption isotherms. The calculated data show better agreement with Freundlich adsorption isotherm, where n < 1 indicates that the adsorption is a chemisorption process. Kinetic models were also examined to describe the adsorption mechanisms. The pseudo-second order fits well to the experimental data. Activated carbon from walnut shells has proven to be an effective adsorbent for amoxicillin removal. |
