New biobased chitosan/polyvinyl alcohol/graphene oxide derivatives for the removal of pharmaceutical compounds from aqueous mixtures

Abstract

The main scope of this study is synthesis, characterization and implementation of new bio-based chitosan derivatives for the removal by adsorption of pharmaceutical mixtures from aqueous matrices. Six different materials of chitosan/polyvinyl alcohol were synthesized using an increasing quantity of graphene oxide and reduced graphene oxide (0.05%, 0.1% and 0.2%). A combination of different groups of pharmaceuticals was used as a model pollutant. Within this context, four non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen, paracetamol), one anti-epileptic (carbamazepine) and two antihypertensives (valsartan and irbesartan) were selected. The highest adsorption capacity was exhibited by the composites with the highest concentration of GO and rGO (0.2%), while the pollutants that presented the highest adsorption removal were valsartan and diclofenac. The adsorption process was appeared to be finished after 3 h for all compounds of the studied mixture (well-fitted to pseudo-2nd order model). The results indicated that the Langmuir model offered better match for the experimental data, while the adsorption capacity of adsorbents increased with the rise of the temperature. Overall, the highest adsorption capacities achieved at pH 10 (55 °C). Desorption was accomplished by using different aqueous eluents (with pH 2–10) and organic solvents. FTIR, SEM, EDS techniques were used to characterize the composition and morphology, and for the compounds detection the UHPLC system was used.