Removal of hexavalent chromium in aqueous solution using organic iron-based composites synthesized and immobilized by natural dried willow leaves

A kind of organic iron-based composites, synthesized and immobilized by natural dried willow leaves, was used to remove Cr(VI) in aqueous solution. When the mass ratio of iron to willow leaves was 1:50 in the preparation, the proportion of iron was minimized, and willow leaves was also sufficient to reduce and immobilize iron in various valence states, under the premise of achieving a good removal efficiency of 100.0%. In addition, through taking an impact on reaction rate and efficiency, the dosage of material, initial pH, Cr(VI) concentration and temperature achieved impressive results. At the temperature of 288.15 K, 293.15 K, 298.15 K and 303.15 K, the removal was well conformed to the first-order kinetic model with apparent rate constants of 0.0412, 0.0428, 0.0738 and 0.1822 min−1, respectively. The removal mechanisms of Cr(VI) were mainly due to adsorption (or complexation), reduction and co-precipitation. Obvious cost advantage and removal efficiency enable this new synthetic material to meet the needs of cleaner production.