Removal of Bisphenol-A from Aqueous Solution Using Rice Husk Nanosilica: Adsorption Kinetics, Equilibrium and Thermodynamic Studies

Subject Areas : Polymer

Benjamin Olawale Orimolade ¹ (Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa/Department of Industrial Chemistry, University of Ilorin, PMB 1515, Ilorin, Nigeria)
Folahan Amoo Adekola ² (Department of Industrial Chemistry, University of Ilorin, PMB 1515, Ilorin, Nigeria)
Aderonke Aminat Mohammed ³ (Department of Industrial Chemistry, University of Ilorin, PMB 1515, Ilorin, Nigeria)
Azeez Olayiwola Idris ⁴ (Department of Applied Chemistry, University of Johannesburg, Johannesburg, South Africa)
Oluwaseyi Damilare Saliu ⁵ (Department of Industrial Chemistry, University of Ilorin, PMB 1515, Ilorin, Nigeria)
Taofeek Yusuf ⁶ (Department of Industrial Chemistry, University of Ilorin, PMB 1515, Ilorin, Nigeria)

Received: 2018-06-04 Accepted : 2018-06-04 Published : 2018-07-01

Keywords:

Abstract :

This study evaluates the adsorption of bisphenol-A (BPA) from aqueous solutions using nanosilicaobtained from rice husk. Nanosilica (79 nm) was extracted from acid and thermal treated rice huskwaste. The rice husk nanosilica (RHS) was fully characterized through X-Ray DiffractionSpectroscopy (XRD), Scanning Electron Microscopy (SEM), X-Ray Fluorescence Spectroscopy(XRF) and Fourier Transmittance Infrared Spectroscopy (FTIR). The spectroscopic analyses resultsrevealed that the rice husk ash contains large fraction of amorphous silica. Batch adsorptionexperiments were carried out on BPA as a function of initial concentration, contact time, pH,adsorbent dosage and temperature. The maximum amount of BPA adsorbed was 4.267 mg/g withan optimum contact time of 45 min for 50 mg/L BPA solution at pH 8. The adsorption data wereanalyzed with adsorption isotherms and fitted best into the Langmuir model with R2 value of 0.994.The adsorption process followed the pseudo second order kinetics and was exothermic while thenegative value of Gibbs free energy obtained revealed that the process is feasible at lowertemperature.