University of New Hampshire
Mentor: Dr. Jillian Goldfarb
Investigation of Competitive Adsorption Mechanisms of PCBs Onto Biomass-Based Activated Carbon
Polychlorinated biphenyls (PCBs) are emerging contaminants that are ubiquitous across a variety of environmental media, including groundwater and water from mine tailings. One technique to remediate contaminated aqueous streams is removal via adsorption onto activated carbon (AC). To improve the economic and environmental viability of this method, biomass activated carbons (BAC) are fabricated from waste avocado pits via chemical and physical activation techniques using two particle sizes. The physically activated carbon shows surface areas up to 850 m2/g carbon, as compared to in-house purchased activated carbons (PAC) with surface areas upwards of 1,300 m2/g carbon. Following fabrication and characterization of the BAC, laboratory scale experiments explore the competitive adsorption mechanisms of PCBs onto both PAC and BAC; PAC to establish a baseline upon which to compare the BAC, and establish the plausibility of substituting BAC for PAC in environmental applications. Mixtures of PCB congeners 7 and 28 at environmentally relevant concentrations simulate contaminated groundwater. Gerstel’s Twister™ stir bars will be used to extract PCBs remaining in the simulated water after AC treatment; these PCBs are quantified via gas chromatography/mass spectrometery, to determine the extraction efficiency of the activated carbons. Adsorption isotherms of PCB mixtures are expected to deviate from those of individual congeners due to competitive adsorption. Understanding how the adsorption of PCBs in a mixture changes relative to individual behavior has immediate implications in developing efficient remediation schemes. Using biomass may decrease the cost of the production of activated carbons and reduce the amount of organic waste landfilled.