Response surface optimization of Rhodamine B dye removal using paper industry waste as adsorbent

Abstract

The present investigation describes the conversion of waste product into effective adsorbent and its application for the treatment of wastewater, i.e., chemically modified solid waste from paper industry has been tested for its adsorption ability for the successful removal of Rhodamine B dye from its aqueous solution. The adsorption isotherm, kinetics and thermodynamic parameters of process have been determined by monitoring the different parameters, such as effect of pH, amount of adsorbent dose, concentration, contact time and temperature. The equilibrium data has been well described on the basis of various adsorption isotherms, namely Langmuir, Freundlich and Temkin adsorption isotherm. From Langmuir isotherm, the maximum monolayer adsorption capacity has been found to be 6.711 mg g−1 at 308 K temperature. The kinetics of adsorption has been studied using pseudo-first order, pseudo-second order and intra-particle diffusion model and the results show that kinetics has been well described by pseudo-second order. Thermodynamic parameters, such as free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS), have been evaluated. The free energy has been obtained as −11.9452 kJ mol−1 for 75 mg L−1 concentration at 308 K temperature. Desorption and recycling efficiency of adsorbent has been studied and the adsorbent shows good recycling efficiency.