Application of regenerated spent bleaching earth as an adsorbent for the carbon dioxide adsorption by gravimetric sorption system

Abstract

The atmospheric level of carbon dioxide (CO2) is indicated to be alarming which in turn has contributed to the worldwide environmental issue such as global warming. The goal of this project was to study the adsorption of CO2 onto regenerated spent bleaching earth (RSBE). Spent bleaching earth (SBE) can be a good adsorbent but it has the weakness in surface area due to the organic impurities left in the pores after being generated from the edible oil processing. Thus, the regeneration processes of SBE by (a) direct heat treatment, and (b) heat treatment followed by nitric acid treatment were studied to enhance the surface area, thus increasing the CO2 adsorption capacity. The SBE were calcined at four temperatures of 400, 500, 650 and 800 °C in the regeneration process. The surface properties of RSBE were characterized using Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) analysis and Brunauer-Emmett-Teller (BET) surface area analysis. The CO2 adsorption capacity on RSBE produced by heat treatment followed by nitric acid treatment was shown to be more effective than RSBE produced by direct heat treatment. RSBE_500_HNO3 offered highest surface area (192.81 m2/g) and give highest CO2 adsorption capacity of 86.67 mg CO2/g. In comparison to the low pressure condition, the high pressure CO2 adsorption values recorded for both RSBE were significantly better.