The adsorption kinetics of cu(ii) and cr(iii) by h3po4 activated carbon made from marigold stems

This paper discusses the adsorption of Cu(II) and Cr(III) by H3PO4 activated carbon made from marigold stems. The objective of this research was to determine the optimum condition of the absorption by the activated carbon in terms of contact time, adsorption isotherm, and pH, as well as the kinetics of the absorption of the two metals followed by determining the adsorption capacity at the optimum conditions obtained. All metals measurements were performed by the use of atomic absorption spectrophotometer (AAS) It was found that the optimum contact time for Cu(II) and Cr(III) adsorption occurred at adsorption time for 40 minutes. The adsorption isotherms of activated carbon to both metal ions follow the isotherm pattern of L-type (Langmuir isotherm). The adsorption kinetics patterns for Cu(II) and Cr(III) adsorptions follow the kinetics of second order with adsorption rate constant of 3.09 x 10-5 and 2.49 x 10-5 min-1ppm-1, respectively. The optimum adsorption of the metals occurred at pH 2. The adsorption capacity of the activated carbon to Cu(II) and Cr(III) at the optimum conditions were of 0.2015 mg/g and 0.2259 mg/g, respectively. Under the optimum conditions, the activated carbon could decrease the Cu(II) and Cr(III) contents by 23.10% and 27.77%, respectively.