Production and Characterization of Paw-paw Trunk Activated Carbon

Abstract

Low-cost adsorbents were prepared from matured Pawpaw trunk by chemical activation method using ZnCl₂ at various impregnation ratios of 1:2, 1:3 and 1:4 (ZnCl₂/pawpaw). Unwashed Pawpaw Trunk activated Carbon (UPTAC) and Raw Pawpaw Trunk carbon (Raw PTC) (not impregnated) were all carbonized at 400^oC for one hour. The produced carbons were characterized in terms of surface area, porosity, bulk density, ash content, moisture content, iodine number and carbon yield. Proximate analysis was also conducted using Scanning Electron Microscopy (SEM) to detect the surface morphology and Fourier Transform Infra-red (FTIR) to identify the kind of functional groups present on the activated carbon. The results showed that surface area, bulk density, porosity, iodine number, moisture content and carbon yield of UPTAC decreased significantly with increase in impregnation ratio with ratio 1:2 having the highest surface area of 1575m²/g, porosity of 0.89, carbon yield of 69%, bulk density of 0.68g/cm³ and iodine number of 231.1mg/g while Raw PTC had the lowest surface area of 652m²/g. The results of the SEM micrograph showed that UPTAC has a well-developed porous surface with different pores diameter than the Raw PTC indicating the impact of chemical activation in creating well-developed pores. Furthermore, the results of the FTIR transmittance spectra showed several peaks belonging to different functional groups including O-H group in either alcohol, phenol or carboxylic acid; R-OH group and C?C stretching of the alkynes; weak C=O stretching of the carboxylic groups and the twisted region. Comparing the FTIR transmittance spectra of Raw PTC to UPTAC, showed a clear shift in band indicating the effect of ZnCl₂ activation and this shows that UPTAC may be very useful in adsorption processes.