Adsorption of lead, ethylenediaminetetraacetic acid and lead- ethylenediaminetetraacetic acid complex onto granular activated carbon

This study investigated simultaneous removal of lead and ethylenediaminetetraacetic acid from synthetic wastewater samples using granular activated carbon adsorption. Data from a 1 x 10^-4 M lead-ethylenediaminetetraacetic acid adsorption isotherm study fitted well to Freundlich isotherm. Furthermore, for the pH-dependent 1 x 10^-4 M lead-ethylenediaminetetraacetic acid study both lead and ethylenediaminetetraacetic acid adsorptions increased reaching values of 82 % and 93 % respectively at pH 5.8. However, a further increase in pH resulted in decreasing but near equal lead and ethylenediaminetetraacetic acid removals. Results for the 2 x 10^-4 M lead-ethylenediaminetetraacetic acid system showed a behavior that was qualitatively similar to the 1 x 10^-4 M lead-ethylenediaminetetraacetic acid findings. However, the 1 x 10^-3 M lead-ethylenediaminetetraacetic acid study showed only a decreasing adsorption trend. An increasing-decreasing type lead/ethylenediaminetetraacetic acid adsorption behavior was also noted for the 1 x 10^-4 M lead/2 x 10^-4 M ethylenediaminetetraacetic acid system. Nevertheless for the 2 x 10^-4 M lead/1 x 10^-4 M ethylenediaminetetraacetic acid system, lead removal at increased pH was comparatively higher. Furthermore, results from a continuous column study completed at 1 x 10^-4 M lead and 0.75 x 10^-4 M ethylenediaminetetraacetic acid showed high saturation times both for lead and ethylenediaminetetraacetic acid. Results from the present work show that a notable removal of aqueous phase lead and ethylenediaminetetraacetic acid could be achieved using activated carbon adsorption. The details related to the effect of pH and pollutants' concentration on the overall adsorption efficiency, as reported in the present work, would be of much use for an effective carbon adsorption process design for the treatment of respective wastewaters.