Role of grinding method on granular activated carbon characteristics
Gulizhaer Abulikemu,
David G. Wahman,
George A. Sorial,
Mallikarjuna Nadagouda,
Eva K. Stebel,
Erika A. Womack,
Samantha J. Smith,
Eric J. Kleiner,
Brooke N. Gray,
Rose D. Taylor,
Cameron X. Gastaldo,
Jonathan G. Pressman
Affiliations
Gulizhaer Abulikemu
Pegasus Technical Services, Inc., Cincinnati, OH 45219, USA; Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA
David G. Wahman
Center for Environmental Solutions and Emergency Response, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA
George A. Sorial
Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA
Mallikarjuna Nadagouda
Center for Environmental Solutions and Emergency Response, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA
Eva K. Stebel
Pegasus Technical Services, Inc., Cincinnati, OH 45219, USA; Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA
Erika A. Womack
Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA; Procter and Gamble Company, Cincinnati, OH 45202, USA
Samantha J. Smith
Center for Environmental Solutions and Emergency Response, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA
Eric J. Kleiner
Center for Environmental Solutions and Emergency Response, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA
Brooke N. Gray
Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA; Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA
Rose D. Taylor
Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA; Department of Civil and Environmental Engineering, University of Maryland, College Park, MD 20742, USA
Cameron X. Gastaldo
Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA; Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA
Jonathan G. Pressman
Center for Environmental Solutions and Emergency Response, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr., Cincinnati, OH 45268, USA; Corresponding author.
A coconut shell (AC1230CX) and a bituminous coal based (F400) granular activated carbon (GAC) were ground with mortar and pestle (MP), a blender, and a bench-scale ball milling unit (BMU). Blender was the most time-efficient for particle size reduction. Four size fractions ranging from 20 × 40 to 200 × 325 were characterized along with the bulk GACs. Compared to bulk GACs, F400 blender and BMU 20 × 40 fractions decreased in specific surface area (SSA, –23% and –31%, respectively) while smaller variations (–14% to 5%) occurred randomly for AC1230CX ground fractions. For F400, the blender and BMU size fraction dependencies were attributed to the combination of (i) radial trends in the F400 particle properties and (ii) importance of shear (outer layer removal) versus shock (particle fracturing) size reduction mechanisms. Compared to bulk GACs, surface oxygen content (At%-O1s) increased up to 34% for the F400 blender and BMU 20 × 40 fractions, whereas all AC1230CX ground fractions, except for the blender 100 × 200 and BMU 60 × 100 and 100 × 200 fractions, showed 25–29% consistent increases. The At%-O1s gain was attributed to (i) radial trends in F400 properties and (ii) oxidization during grinding, both of which supported the shear mechanism of mechanical grinding. Relatively small to insignificant changes in point of zero charge (pHPZC) and crystalline structure showed similar trends with the changes in SSA and At%-O1s. The study findings provide guidance for informed selection of grinding methods based on GAC type and target particle sizes to improve the representativeness of adsorption studies conducted with ground GAC, such as rapid small-scale column tests. When GACs have radial trends in their properties and when the target size fraction only includes larger particle sizes, manual grinding is recommended.
