Abstract

The adsorption capacities of iron oxide, aluminum oxide, and activated carbon sorbents for the removal of copper ions were compared by down flow method. For this purpose, the 20 mg L^-1aqueous solution of Cu (II) with initial pH of 6.5 was fed through three different packed columns at bed depth of 10 cm and flow rate of 1.85 ml min^-1. The experimental breakthrough curves were drawn from the adsorption data of packed bed columns. The breakthrough time comparison of the three columns revealed that the uptake capacity of Cu (II) was highest for activated carbon (16.24 mg g^-1) followed by aluminum oxide (5.60 mg g^-1) and iron oxide (5.41 mg g^-1). The maximum amounts of Cu (II) removal were attained as follows: 94.0% for aluminum oxide, 95.2% for iron oxide, and 99.7% for activated carbon. The computed adsorption capacity per unit bed volume (N₀) and the kinetic constant (K_AB) were, respectively 1202, 1045 (mg L^-1) and 3 × 10^-4, 4 × 10^-4 (L mg^-1 min^-1) for iron oxide and aluminum oxide. Regression coefficient value (0.98) indicated that Thomas model fitted well with the experimental data for the iron oxide and aluminum oxide sorbents. The theoretical adsorption capacities obtained by Thomas model were in good agreement with experimental capacities determined by adsorption data. In a short time after running the experiment, the equilibrium concentration of Cu (II) reached to 1.2 mg L^-1 using these sorbents. Hence, the packed bed column with continuous down flow method can be successfully applied for the removal of heavy metals from contaminated waters in practical use.

Key words: Adsorption, breakthrough curve, continuous down flow, copper (II), packed bed column, Thomas model, Bohart-Adams, Yoon-Nelson.