title: Superiority of wet-milled over dry-milled superfine powdered activated carbon for adsorptive 2-methylisoborneol removal.
abstract: Superfine powdered activated carbon (SPAC), which is produced from conventionally sized powdered activated carbon (PAC) by wet milling in a bead mill, has attracted attention for its high adsorptive removal ability in both research and practice. In this study, the performance of dry-milled SPAC was investigated. 2-Methylisoborneol (MIB), an earthy-musty compound commonly targeted by water treatment systems, was used as the target adsorbate. Dry-milled SPAC exhibited lower adsorptive removal of MIB than wet-milled SPAC, even when both SPACs were produced from the same PAC and were composed of particles of the same size. One reason for the lower removal of MIB by the dry-milled SPAC was a higher degree of aggregation in the dry-milled SPAC after production; as a result the apparent particle size of dry-milled SPAC was larger than that of wet-milled SPAC. The dry-milled SPAC was also more negatively charged than the wet-milled SPAC, and, owing to its higher repulsion, it was more amenable to dispersion by ultrasonication. However, even after the dry-milled SPAC was ultrasonicated so that its apparent particle size was similar to or less than that of the wet-milled SPAC, the dry-milled SPAC was still inferior in adsorptive removal to the wet-milled SPAC. Therefore, another reason for the lower adsorptive removal of dry-milled SPAC was its lower equilibrium adsorption capacity due to the oxidation during the milling. The adsorption kinetics by SPACs with different degrees of particle aggregation were successfully simulated by a pore diffusion model and a fractal aggregation model.
authors.affiliation: Graduate School of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan.
authors.forename: Long
authors.initials: L
authors.lastname: Pan
authors.affiliation: Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan. Electronic address: matsui@eng.hokudai.ac.jp.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Matsui
authors.affiliation: Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Matsushita
authors.affiliation: Faculty of Engineering, Hokkaido University, N13W8, Sapporo 060-8628, Japan.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Shirasaki
mesh_terms: D000327:Adsorption; D002244:Carbon; D002606:Charcoal; D010316:Particle Size; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D002606:Charcoal; D002244:Carbon
keywords: Adsorbent; Agglomeration; Aggregation; Grind; S-PAC; Submicron