Preparation of eco-friendly adsorbents from Port Jackson (Acacia saligna) and its application in removal of basic dyes

Abstract

In this study, the potential of two adsorbents prepared from Port Jackson (PJ) plant for the removal of Janus Green (JG) and Victoria Blue (VB) dyes from wastewater was investigated. One of the adsorbents was prepared from Port Jackson by employing the plant’s leaves in their natural form after washing while the second one was obtained by treating the leaves with concentrated sulphuric acid. The adsorbents were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Batch adsorption experiments were conducted with different initial concentrations of dyes, adsorbents doses, temperatures and contact times to determine their effects on the process efficiency. Equilibrium isotherm, kinetics and thermodynamics of the processes were also evaluated. The percentage removal of the dyes by the two adsorbents increased with increasing contact time and adsorbent dosage but decreased with increasing temperature. The kinetics parameters obtained were found to follow pseudo-second order model, suggesting that the rate limiting step may be chemisorption. Thermodynamic studies reveal that the adsorption processes were spontaneous and exothermic in nature as evident from the negative values of Gibbs free energy (G0) and enthalpy (H0) obtained. The processes were accompanied with decreased randomness as shown in the negative change in entropy (S0). It can be concluded that the two adsorbents have good potentials for remediating JG and VB dye-contaminated wastewater.