Usage of activated carbon based biocomposites for the removal of pharmaceutical micropollutant naproxen

In the present thesis, removal of the non-steroidal anti-inflammatory drug-naproxen using adsorption method was investigated. Activated carbon embedded chitosan-polyvinyl alcohol biocomposites (AC/KTS-PVA), activated carbon embedded alginate beads (AC/ALG) and activated carbon and silica aerogel embedded chitosan biocomposites (KTS:AEO:AC) were synthesized to be adsorbants. Batch adsorption process parameters were evaluated in terms of adsorbent amount, pH, temperature, and time. In addition, the process parameters were optimized using response surface methodology based on the Box-Behnken surface statistical design. At an initial naproxen concentration of 50 mg/L and optimum processing conditions, the adsorption capacities and equilibrium naproxen removal percentages were determined to be 12.17 mg/g and 97 % for AC/KTS-PVA biocomposites; 3.48 mg/g and 97 % for AC/ALG biocomposites; and 3.8 mg/g and 90 % for KTS:AEO:AC biocomposites, respectively. The mechanism of naproxen adsorption on the synthesized biocomposites was investigated using four isotherm models such as Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The adsorption rates were determined using pseudo first order, pseudo second order, Weber-Morris intraparticle diffusion, Elovich and Banghamham kinetic models. Thermodynamic parameters such as ΔGo, ΔSo and ΔHo were calculated and it was determined that ΔGo and ΔSo were negative and ΔHo was positive. Based on these results, the adsorption of naproxen onto the synthesized biocomposites was endothermic, feasible and spontaneous. In addition, there was no significant decrease in adsorption capacity in at least four reuses of the synthesized biocomposites.