Removal of bisphenol a from aqueous solution by adsorbing onto an activated carbon of the agricultural waste

Abstract

Adsorption of bisphenol A (BPA), an endocrine disrupting compound, from aqueous media was studied using activated carbon derived from oil palm empty fruit bunch (EFB) waste. Oil palm EFB waste is a readily available biomass in Malaysia. Annually, Malaysia palm oil mill generates millions tonnes of oil palm EFB waste which is not effectively utilized. In this work, activated carbon was prepared by impregnating EFB for 24 hours in 10% of zinc chloride solution. The impregnated EFB was heated in a horizontal tube furnace under nitrogen flow at 500oC for 1 hour. The samples were characterized by means of Fourier Transform Infrared Spectrometry, Brunauer-Emmett-Teller, and Field Emission Scanning Electron Microscopy. The proximate analysis including moisture content, ash content, bulk density, pH, conductivity and pH at zero charge was conducted to identify the psychochemical properties of the adsorbent. Batch adsorption test was carried out by varying contact time, activated carbon dose, agitation speed, initial BPA concentration, temperature and pH of the solution. The analyses showed that the oval-shaped micro pores were developed in carbon surface causing increase in surface area from 4.29 m2/g to 86.62 m²/g. The highest adsorption removal of BPA achieved up to 96.1% for 48 hours. The equilibrium data were perfectly represented by Langmuir isotherm with maximum monolayer adsorption capacity of 41.98 mg/g. Kinetic studies indicated that the adsorption process followed the pseudo-secondorder kinetic with a rate constant of 0.3 x10-3 mg/g min. The thermodynamic studies showed that the adsorption capacity increased by the increase in temperature. The results indicate that the activated carbon prepared from EFB has potential as a low cost bio-adsorbent for the removal of BPA from aqueous solution.