The removal of Cr (III) and Mn (IV) from a tannery wastewater was evaluated using atomic absorption spectrophotometer (AAS). Activated carbon prepared from sorghum (bicolor) chaff was used to remove Cr (III) and Mn (IV). The evaluated physicochemical properties of the activated carbon were pH (6.30), bulk density (0.33 g/cm3), moisture content (4.40%), Iodine Adsorption Ratio (0.28 mol/g), porosity (13.00), attrition factor (11.00%), and surface area (797.4 m2/g). Optimum percentage adsorption and equilibrium adsorption capacity for the effect of pH, inlet flow rate, bed height, inlet concentration and particle size gave, (89.796, 90.116, 93.046) % and (2.245, 2.253, 2.326) mg/g, (74.720, 84.990, 91.346) % and (2.277, 2.275, 2.284) mg/g, (88.192, 89.994, 90.190) % and (2.205, 2.249, 2.255) mg/g, (88.934, 90.002, 90.634) % and (2.223, 2.250, 1.266) mg/g, (91.346, 89.964, 88.936) % and (2.284, 2.249, 2.223) mg/g for Cr (III) and (84.630, 87.830, 82.507) % and (1.269, 1.317, 1.238) mg/g, (47.770, 74.425,83.790) % and (0.239, 0.744, 1.257) mg/g, (85.590, 84.023, 83.167) % and (1.284, 1.260, 1.248) mg/g, (82.473, 83.790, 85.230 ) % and (1.237, 1.257, 1.278) mg/g, (88.497, 87.220, 84.420) % and (1.327, 1.308, 1.266) mg/g for Mn (1V) respectively. The results therefore, shows that percentage adsorption increases with the effects mentioned and the kinetic data fitted well to the model for the effect of particle size.
Keywords: Chromium (III), Fixed-bed column adsorption, Kinetics, Manganese (IV), Particle Size, Tannery wastewater
