18F-25

M. AHMEDNA¹, M. Nori², J. Yu¹, S. Ilias², and I. Goktepe¹. (1) Dept. of Human Environment and Family Sciences, North Carolina A&T State Univ., 161 Carver Hall, Greensboro, NC 27411, (2) Dept. of Chemical Engineering, North Carolina A&T State Univ., 104 McNair Hall, Greensboro, NC 27411

Pecan shells are low-cost byproducts of the nut industry that remain underutilized. However, given their relatively high lignin content, pecan shells could be an excellent precursor for value-added activated carbons. The latter can be used for purification applications, including drinking and waste waters through selective adsorption of organic and inorganic contaminants. The objectives of this study were to (1) produce pecan shell-based activated carbons (PSACs) for drinking water purification via physical and chemical activation methods; (2) evaluate physical, chemical, and surface properties of PSACs, and (3) determine the efficiency of PSACs in removing common pesticides and heavy metals from well water. Chemically activated pecan shells were prepared by soaking in 50% phosphoric acid followed by pyrolysis at 400 to 500º C under nitrogen. Physically activated PSACs were produced by pyrolysis at 700º C under nitrogen followed by activation with either steam or CO₂ activation at 800 to 900º C. Physico-chemical (pH, bulk density, and ash); surface (total surface area, micropore surface area, micropore volume, and surface charge); and adsorption (metal and pesticides uptakes) properties of PSACs were determined and compared to two commercial references. The results indicated that PSACs yield was about 20 and 34% for physically activated and chemically activated carbons, respectively. Acid-activated carbons exhibited higher surface area, bulk density, and lowest ash content, compared to steam or CO₂-activated carbons and the two commercial reference carbons. Regardless of the activation method, PSACs had higher total surface area than the commercial references (900 m2/g vs. 700 m2/g), better pore size distribution, and more available surface charges. Adsorption data show that PSACs were significantly more effective in removing metal ions and pesticide/herbicide than the commercial references. This study showed that pecan shells can be used as precursors of value-added activated carbons that are custom designed for efficient removal of typical well water contaminants.

Session 18F, Product Development: General
2:00 PM - 5:30 PM, Sunday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana