Comparison of the Surface Features of Two Wood-Based Activated Carbons

Abstract

The surface features of two carbons of wood origin were compared. One sample was manufactured using phosphoric acid activation and the other using potassium hydroxide activation. To check the susceptibility to oxidation and the stability of the porous structure, the samples were oxidized with ammonium persulfate. Structural properties of carbons and their oxidized counterparts were determined using sorption of nitrogen. Surface acidity was evaluated using Boehm titration, potentiometric titration, inverse gas chromatography, and diffuse reflectance FTIR. It was demonstrated that, despite the same wood origin, the carbons significantly differ in their pore structure and surface chemistry. The carbon obtained using KOH activation is homogeneously microporous with high surface area around 2300 m2/g (BET). On the other hand, the carbon manufactured using phosphoric acid contains a high volume of mesopores and its surface area is significantly lower. The carbons also differ in their surface chemistry and susceptibility to oxidation.

A Study of Acetaldehyde Adsorption on Activated Carbons

“…BAX is the most acidic. This is expected for a phosphoric acid activated carbon (13). In the cases of BPL and MVP, although the total numbers of groups are similar, the distributions of species are different.…”

Surface Chemistry of Activated Carbons: Combining the Results of Temperature-Programmed Desorption, Boehm, and Potentiometric Titrations

“…To better visualize surface changes, the results are presented in terms of the density of groups (molecules per square nanometer of the surface). The results were calculated by dividing the number of groups obtained from the titration experiments (in mmol/g of carbon) by the surface area of adsorbents (21,22,30). As discussed elsewhere, the specific surface area and pore volumes were slightly changed after oxidation, especially when oxidation with nitric acids was applied (21).…”

“…The experimental titration data is transformed into a proton binding curve from which the distribution of acidity constants is obtained by using the numerical procedure SAIEUS (32). The results of titration experiments in terms of the distributions of acidity constants were presented elsewhere (21,30). Here, for the sake of comparison, the results are summarized in Table 2.…”

Surface and porous characterization of activated carbon prepared from pyrolysis of biomass (rice straw) by two-stage procedure and its applications in supercapacitor electrodes

“…The nitrogen adsorptiondesorption data were recorded at liquid nitrogen temperature, 77 K. The surface areas were calculated using the BET equation, which is the most widely used model for determining the specific surface area. In addition, the t-plot method [22] was applied to calculate the micropore volume and the external surface area (mesoporous surface area). The total pore volume was estimated to be the liquid volume of adsorbate at a relative pressure of 0.99.…”