Modified activated carbon for the removal of copper, zinc, chromium and cyanide from wastewater

Modified activated carbon are carbonaceous adsorbents which have tetrabutyl ammonium iodide (TBAI) and sodium diethyl dithiocarbamate (SDDC) immobilised at their surface, This study investigates the adsorption of toxic ions, copper, zinc, chromium and cyanide on these adsorbents that have undergone surface modification with tetrabutyl ammonium (TBA) and SDDC in wastewater applications. The modification technique enhance the removal capacity of carbon and therefore decreases cost-effective removal of Cu(II), Zn(II), Cr(VI) and CN- from metal finishing (electroplating unit) wastewater. Two separate fixed bed modified activated carbon columns were used; TBA-carbon column for cyanide removal and SDDC-carbon column for multi-species metal ions (Cu, Zn, Cr) removal. Wastewater from electroplating unit containing 37 mg l(-1) Cu, 27 mg l(-1) Zn, 9.5 mg l(-1) Cr and 40 mg l(-1) CN- was treated through the modified columns. A total CN- removal was achieved when using the TBA-carbon column with a removal capacity of 29.2 mg g(-1) carbon. The TBA-carbon adsorbent was found to have an effective removal capacity of approximately five times that of plain carbon. Using SDDC-carbon column, Cu, Zn and Cr metal ions were eliminated with a removal capacity of 38, 9.9 and 6.84 mg g(-1), respectively. The SDDC-carbon column has an effective removal capacity for Cu (four times), Zn (four times) and Cr (two times) greater than plain carbon. (C) 2002 Elsevier Science B.V. All rights reserved.