Influential adsorption of Congo red using vermiculite/graphene/polyacrylamide composite

Abstract

In aquatic ecosystems, Congo red (CR) dye contamination frequently threatens human health and the aquatic system. In the present research, vermiculite (V)/graphene (G) and polyacrylamide (PA) composite was synthesized as an influential adsorbent for CR dye adsorption from aqueous systems. Central composite design (CCD) in factorial analysis was designed using the standard response surface method to understand optimized parameters with minimal experimentation for CR dye adsorption. Experimental data followed the Langmuir isotherm model with a maximum adsorption capacity of 494.9 mg g−1. The kinetic mechanism is well described for pseudo-second-order kinetics for CR dye removal using V/G/PA composite. Electrostatic attractions, filling pores, and hydrogen bonding are involved in the adsorption mechanism. The adsorption-desorption analysis test revealed that the V/G/PA composite can be still used up to the five cycles with an adsorption/recovery performance of 77/67 %. Thermodynamic functions, ΔG data (between about −19 and −17 kJ/mol.K), ΔH data (−32.0 kJ/mol), and ΔS data (−46 J/mol) proved the spontaneous and exothermic nature of the adsorption process as well as indicating the reduced complexity at the solution-adsorbent interface for 298–338 K. This study exposed the developed V/G/PA composite as an influential sorbent for CR dye adsorption from contaminated water.