Adsorption of Copper Ions and Methylene Blue in a Single and Binary System on Wheat Straw

Abstract

A natural wheat straw was used as adsorbent for removal of copper and methylene blue (MB) from aqueous solution. A batch system was applied to study the behavior of Cu 2+ and MB adsorption in single and binary systems on wheat straw. In the single systems, there was no significant difference in the quantity of MB adsorbed onto wheat straw within a pH range of 4.0 to 10.0. But for Cu 2+, the optimal pH is about 5. Kinetic studies indicate that Cu 2+ and MB adsorption on the wheat straw follows the Elovich equation. The Cu 2+ adsorption isotherm follows the Langmuir and Redlich−Peterson models, while MB adsorption follows the Redlich−Peterson isotherm. The adsorption capacities of Cu 2+ and MB at 273 K and pH 5 are (7.05 and 60.66) mg·g −1, respectively. In the binary system, Cu 2+ and MB exhibited competitive adsorption. The adsorption of Cu 2+ or MB is considerably reduced with an increasing concentration of the other. The quantity of Cu 2+ adsorbed is more strongly influenced by MB due to the higher affinity of wheat straw for the latter. As wheat straw is easily obtained and cheap, it will be promising for removal of metal ions and dyes.