ADSORPTION OF TRIVALENT CHROMIUM FROM AQUEOUS-SOLUTIONS ONTO ACTIVATED CARBON

The adsorption of chromium (III) onto activated carbon was investigated as a possible alternative method for its removal from aqueous solutions. The adsorption data were obtained in a batch adsorber and fitted the Langmuir adsorption isotherm well. The effect of pH on the adsorption isotherm was investigated at pH values of 2, 4, 5 and 6. It was found that at pH values below 2. the Cr(III) was not adsorbed and at pH values above 6.4 the Cr(III) was precipitated as Cr(OH)(3). Maximum adsorption occurred at pH 5. The pH plays a very important role in the adsorption of Cr(III) since Cr(III) can form different complexes in aqueous solutions. The adsorption capacity was increased by about 20% as the temperature was raised from 25 to 40 degrees C. It was concluded that Cr(III) is adsorbed to an appreciable extent on activated carbon and that the adsorption is highly dependent upon pH.