Submitted to: Journal of American Water Works Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2004
Publication Date: 7/23/2004
Citation: Lima, I.M., Marshall, W.E., Wartelle, L.H. 2004. Hardwood-based granular activated carbon for metals remediation. Journal of American Water Works Association. 96(7):95-102. Interpretive Summary: Granular activated carbon is usually the adsorbent of choice for removing toxic pollutants from air and water. Its ability to remove toxic metals from wastewater is considered secondary to its ability to remove other pollutants. A hardwood-based, granular activated carbon was produced with metals adsorption exceeding that of commercially available carbons made from coal. This research will benefit companies who need to remove metals from their wastewater in a less expensive manner than is currently possible.
Technical Abstract: Granular activated carbon is usually the adsorbent of choice for removing organic pollutants from air and water waste streams. Its ability to remove metal ions from aqueous media is considered secondary to its ability to remove organics. Only recently was a coal-based, commercial carbon (Minotaur) marketed to specifically target the removal of toxic metals such as lead. Our laboratory at the Southern Regional Research Center has developed a hardwood-based, granular activated carbon with metal ion adsorption exceeding that of Minotaur and other commercially available adsorbents. Hardwood particles (0.85-2.00 mm) were dehydrated and activated in the presence of 30% phosphoric acid to produce granular activated carbons with copper ion adsorption capacities from 1.1-1.2 mmoles/g of carbon with surface areas from 650-750 m2/g and surface charges of 3.44 to 4.16 mmol H+ eq/g at pH 5. In contrast, using the same copper ion assay conditions, Minotaur had an adsorption capacity of 0.96 mmole/g carbon of copper ion with a surface area, SA of 726 m2/g and surface charge, SC of 2.62 mmol H+ eq/g. Several different commercial adsorbents were also evaluated for performance comparison purposes. We are currently investigating alternative activation methods using combinations of steam activation and air oxidation to match the effectiveness of the acid activation method, but to increase surface area, and reduce process costs.