Characterization of Activated Carbon Adsorbents – State of the Art and Novel Approaches

Abstract

Activated carbons are widely used as commercial adsorbents. Thermal or chemical activation creates a pore system and functional groups on the inner surface which may significantly change adsorption properties. Therefore, in addition to knowledge of the structural properties, a sound understanding of surface chemistry is indispensable. This paper summarizes the state of art as well as new developments in both fields. Standardized methods for characterizing structural properties are volumetric measurements and mercury porosimetry. To get a more detailed insight into the region of micropores, a probe molecule method was developed. For characterization of surface chemistry, methods such as IR spectroscopy, temperature-programmed desorption, and Boehm titration are subject of research. Novel methods were developed such as measuring of excess isotherms and calorimetric measurement of heat of adsorption, which are presented and discussed in greater detail in this paper. As each single method can only provide limited information, a better description of surface chemistry requires combination and careful interpretation of complementary information from different methods. Property Standard Limitation Apparent density ASTM D 2854-09 Total ash content ASTM D 2866-11 Moisture ASTM D 2867-17 Ball-pan hardness ASTM D 3802-16 pH-value ASTM D 3838-05 Electrical conductivity ASTM D 1125-14 Water soluble components ASTM D 5029-98 Volatile matter content ASTM D 5832-98 Acid extractable content ASTM D 6385-99 Particle size distribution ASTM D 2862-16 granular activated carbon ASTM D 5158-98 powdered activated carbon Ignition temperature ASTM D 3466-06 granular activated carbon Dusting attrition ASTM D 5159-04 granular activated carbon www.ChemBioEngRev.de

Impact of H2O on the Adsorption of Hg0 on Activated Carbon

“…Nitrogen isotherms at 77 K and carbon dioxide isotherms at 273 K were measured using a volumetric measurement device (Belsorp-max from Bel Japan, Inc.) to characterize the adsorbents. 46 The samples were prepared at 175 °C under vacuum (<10 −3 Pa) for 6 h. The pore size distribution (Figure 12) was defined by quenched solid density functional theory (QSDFT) with a slit and cylindrical pore model. 47 The specific surface area was calculated using the Brunauer−Emmett−Teller (BET) method according to DIN ISO 9277.…”

Effects of Moisture on NH3 Capture Using Activated Carbon and Acidic Porous Polymer Modified by Impregnation with H3PO4: Sorbent Material Characterized by Synchrotron XRPD and FT-IR

“…With the loop of upward curvature at a relative pressure (P/P0) between 0.8 and 0.98 (H 1 hysteresis loop), the pore of the acidic porous polymer is of cylindrical type. In contrast, with a slow jump in the H 4 hysteresis loop at 0.45-0.95 P/P0 region, the activated carbon is a mesoporous material with slit-type porosity [37].…”

“…M presence of IR peaks at 3600 and 1650 cm −1 for PA0 and PA14 (Figure 4b) su was unlikely to be desorbed in the NH 3 capture process by using Amberlyst As shown in Figure 6, the N 2 isotherm for activated carbon (GAC830) is (P/P0) axis in the range of P/P0 = 0.0 to 0.40 and the isotherm is then convex The sample is assigned as IV(a) type isotherm. For acidic porous polymer (A the N 2 isotherm only has a slight convex to the x-axis in the range of P/P0 = 0. sample is assigned as mixed IV(a) and V type [36,37]. The characteristics of the water species on PA0 and PA14 are similar to PC0; peaks at 3600 and 1665 cm −1 suggest water associated with H 3 PO 4 (H 3 PO 4 • • • H 2 O).…”

“…For acidic porous polymer (Amberlyst 35), the N 2 isotherm only has a slight convex to the x-axis in the range of P/P0 = 0.0 to 0.20. The sample is assigned as mixed IV(a) and V type [36,37].…”

“…For acidic porous polymer (Amberlyst 35) the N 2 isotherm only has a slight convex to the x-axis in the range of P/P0 = 0.0 to 0.20. Th sample is assigned as mixed IV(a) and V type [36,37]. After impregnating H 3 PO 4 and breakthrough testing, the hysteresis loop changed to H 2 type (PC0) (Figure 7).…”