Abstract: Comparative adsorption of dyes (bromophenol blue and methyl orange solution) was performed using activated carbon prepared from maize stem and sugarcane stem as low cost agricultural waste adsorbents. The two adsorbents were chemically activated using orthophosphoric acid, potassium hydroxide and zinc chloride. The ash content, percentage fixed carbon and effect of particle sizes were determined. The adsorption capacity of each sample was determined by decolourization of bromophenol blue solution. Three
particle sizes (0.5 – 0.3μm, 0.3 – 0.125μm, and 0.125 – 0.112μm) were studied out of which 0.125 – 0.112μm
has the highest quantity of solute adsorbed and this particle size was chosen for the adsorption studies. Of the
six activated carbon samples prepared, activated carbon produced from maize stem using orthophosphoric acid,
PMA, and activated carbon produced from sugar cane stem using orthophosphoric acid, PSA, have the highest quantity of solute adsorbed, 2.67mg/l and 2.66mg/l respectively and these compete comparatively with the
commercial activated carbon (CAC) with 2.76mg/l. Their adsorption capacity is due to the highest percentage
fixed carbon they both possess from the list of activated carbon prepared. The percentage fixed carbon of PMA
and PSA were 84.88% and 84.80% respectively. The ability of these activated carbon samples to decolourise
dye as compared with commercial activated carbon, CAC, and their low cost make them recommendable for
treatment of dye from industrial effluent
Keywords: Activated carbon, adsorption, chemical activation, dye
