Effects of decreasing activated carbon particle diameter from 30 μm to 140 nm on equilibrium adsorption capacity. (1st November 2017)

• Record Type: Journal Article
• Authors: Pan, Long; Nishimura, Yuki; Takaesu, Hideki; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka
• Is Part Of: Water research. Volume 124(2017)
• Page Start: 425
• Page End: 434
• Publication Date: 2017-11-01
• Subjects: MIB -- Micro-grinding -- Bead mill -- Oxygen content -- Oxidation; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.07.075
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The capacity of activated carbon particles with median diameters (D50s) of >∼1 μm for adsorption of hydrophobic micropollutants such as 2-methylisolborneol (MIB) increases with decreasing particle size because the pollutants are adsorbed mostly on the exterior (shell) of the particles owing to the limited diffusion penetration depth. However, particles with D50s of <1 μm have not been thoroughly investigated. Here, we prepared particles with D50s of ∼30 μm–∼140 nm and evaluated their adsorption capacities for MIB and several other environmentally relevant adsorbates. The adsorption capacities for low-molecular-weight adsorbates, including MIB, deceased with decreasing particle size for D50s of less than a few micrometers, whereas adsorption capacities increased with decreasing particle size for larger particles. The oxygen content of the particles increased substantially with decreasing particle size for D50s of less than a few micrometers, and oxygen content was negatively correlated with adsorption capacity. The decrease in adsorption capacity with decreasing particle size for the smaller particles was due to particle oxidation during the micromilling procedure used to decrease D50 to ∼140 nm. When oxidation was partially inhibited, the MIB adsorption capacity decrease was attenuated. For high-molecular-weight adsorbates, adsorption capacity increased with decreasing particle size over the entire range of tested particle sizes, even though particle oxygen content increased with decreasing particle size. Graphical abstract: Highlights: Micromilling produced carbon particles with D50s as low as 140 nm. Adsorption capacity decreased as D50 decreased from a few micrometers to 140 nm. The adsorption capacity decrease was due to carbon oxidization during micromilling. Inhibition of carbon oxidation attenuated the decrease in adsorption capacity. Adsorption capacity was negatively correlated with particle oxygen content.