Preparation and characterization of graphitic carbon nitrides/ polyvinylidene fluoride adsorptive membrane modified with chitosan for Rhodamine B dye removal from water: Adsorption isotherms, kinetics and thermodynamics

In the present study, a PVDF/g-C3N4/chitosan (PCC) membrane was used for the removal of Rhodamine B from aqueous solutions. Water flux for PCC membrane decreased from 49.87% to 14.76% by the addition of chitosan from 2% to 4%. Afterward, batch adsorption conditions were optimized for a PVDF/g-C3N4/chitosan membrane applying Box-Behnken design algorithm. The maximum RB removal efficiency was 72.74% at 2 mg/L of initial RB concentration, pH = 3, 2 g of g-C3N4 and 3% of chitosan at the optimum conditions. The Freundlich isotherm and pseudo-second order models were satisfactorily describing the equilibrium and kinetic of adsorption, respectively. Thermodynamic parameters were disclosed that the adsorption of RB onto PCC was exothermic (Delta H degrees = -21.35 kJ mol-1) and spontaneous (Delta G degrees < 0) with the generation of energy (Delta S = +92.42 kJ mol- 1) at the interface of solid/liquid. Thus, this novel membrane could be employed as an effective adsorbent to remove of RB dye from aqueous solutions.

Automated summary

The study showed that the addition of chitosan had an impact on the water flux of the PCC membrane, with a maximum RB removal efficiency of 72.74%. The Freundlich isotherm and pseudo-second order models were used to describe the equilibrium and kinetics of adsorption, indicating that the adsorption of RB onto PCC was exothermic and spontaneous.