Fabrication and performance evaluation of polyaniline/N-doped graphene nanocomposite as adsorbent in removing carmine red dye from wastewater

One effective method for removing common dye pollutants is the use of nano-adsorbents. Among these, polymer-based nanocomposite adsorbents are gaining popularity due to their ease of fabrication and application. In this study, a polyaniline (PANI)/nitrogen-doped graphene (NG) nanocomposite was synthesized at various weight percentages using in situ polymerization and employed for the removal of carmine red dye from aqueous solutions. To analyze the properties and performance of the optimal adsorbent, several characterization techniques were utilized, including FTIR, XRD, FESEM, EDX, TEM, TGA, and BET analyses. The findings demonstrated that the PANI/NG nanocomposite with 3 wt% NG exhibited superior dye adsorption compared to those with 1 wt% and 5 wt% loadings. Thermodynamic analysis revealed that the adsorption of carmine dye onto the synthesized adsorbent was an exothermic process. Key parameters influencing the adsorption process-such as temperature, contact time, dye concentration, adsorbent dosage, and pH-were systematically investigated. The PANI/NG 3 wt% nanocomposite achieved an adsorption capacity of 23.81 mg/g. The optimal conditions for the adsorption process were determined to be a temperature of 20°C, a contact time of 30 minutes, a dye concentration of 27.5 mg/g, an adsorbent dosage of 0.03 g per 100 mL, and a pH of 7. Under these conditions, the PANI/NG 3 wt% nanocomposite removed 97.86% of carmine dye from aqueous solutions. The equilibrium data fitted well with the Freundlich isotherm model, indicating the effectiveness of this nanocomposite for dye removal from wastewater.