Comprehensive adsorption and spectroscopic studies on the interaction of carbon nanotubes with diclofenac anti-inflammatory

The adsorption of medicine from wastewater by carbon nanotubes (CNT) is an issue of growing experimental interest. These nanomaterials show fascinating structures for interactions with this kind of contaminant of emerging concern (CECs). Here we explain the interaction between single (SWCNT) and multi-walled carbon nanotubes (MWCNT) and the diclofenac potassium (DP) anti-inflammatory by adsorption and spectroscopic studies. Raman and Infrared spectroscopic techniques were applied to clarify the interaction between both CNT and DP molecules. Additionally, batch adsorption studies were carried out to evaluate CNT for removing DP from aqueous solutions. The carbon-based nanomaterials present fast kinetics of adsorption of DP. Also, the maximum adsorption capacity (Qmax) for adsorption of the DP medicine at 40 °C, achieving high values such as 77.54 and 150.37 mg g−1 for MWCNT and SWCNT, respectively. The interaction between diclofenac anti-inflammatory and CNT was spontaneous and endothermic, being governed by physisorption. In addition, from the thermodynamic and spectroscopic studies, a mechanism based especially on hydrogen-bond and π-π interactions was proposed to explain the adsorption of DP onto both CNT. With this study, we hope to provide advances in the use of spectroscopic techniques as valuable tools for elucidating processes of interaction between CNT and CECs.