Keywords: separation, heavy metals, electroplating rinsing solutions, ion exchange resin, purification, wastewater treatment, pollution control, adsorption isotherms, modelling, chromium, cadmium, zinc, nickel
Separation of some heavy metal species from electroplating rinsing solutions by ion exchange resin
A strongly basic anion exchange lewatit MP 600 resin was tested to separate metal species from electroplating rinsing wastewater. An azo resorcinol 4–(2–pyridylazo) dyestuff was used as a complexing agent. Adsorption isotherms were modelled in an ethanol/acetic acid/water media. The loaded resin is regenerated using 4 M HCl whereby the eluted metal species are recovered. Results revealed that mere anion exchangers could not uptake metal ions unless they reacted with the dye to form negatively charged complexes. Trivalent chromium showed significant uptake at pH range of 3.5–4.5. Cadmium, zinc and nickel ions formed complex compounds in the alkaline medium. The electrostatic interaction and formation of complex compounds identified the major adsorption mechanisms. The uptake capacity of the sorbent is directly proportional to the electro negativity of the metal–dye complexes.