Response Surface Optimization of Ultrasonic-Assisted NYPA Fruticans Activated Carbon for Lead(II) Adsorption from Aqueous Solution

Abstract

Aims: The main objective of this study was to review and analyse the use of ultrasonically activated Nypa fruticans activated carbon (NFAC) for Pb(II) removal from aqueous solutions by applying Response Surface Methodology (RSM). Methodology and results: NFAC was synthesised from Nypa fruticans shells using potassium hydroxide (KOH) as an activating agent under ultrasonic treatment and characterised using SEM, BET surface area measurement, and FTIR spectroscopy. The optimal conditions of ultrasonic-assisted activation and adsorption variables were optimised using response surface methodology (RSM). The prime conditions for activation involved a 20 kHz ultrasonic frequency, 120 W ultrasonic power, and 15 min sonication, giving the highest BET surface area of 1328.74 m²/g. Through batch assay studies, the dose of adsorbent greatly affected the binding of Pb(II) ions. Equilibrium results were best fitted to the Langmuir isotherm model, indicating monolayer adsorption with a maximum saturated adsorption loading of 137.17 mg/g. The rate of reaction study showed that the pseudo-second-order kinetic model best represented the experimental results. Conclusion, significance and impact study: The ultrasonic-assisted activation using KOH greatly improved the performance of NFAC in Pb(II) adsorption, and hence the material can operate effectively as a feasible and promising removal agent for eliminating Pb(II) ions.