Surface characteristics of KOH-treated commercial carbons applied for CO₂ adsorption

Abstract

The effect of an alkali treatment (potassium hydroxide) on the properties of a commercial activated carbon has been studied. The aim of the treatment was to improve the adsorption properties of the material toward carbon dioxide. In the result of the treatment, silica contained in the raw carbon was removed and the density of the material increased. The changes in the surface chemistry were observed as well. The treatment of the activated carbon with KOH resulted in a complete removal of carboxy and lactone groups and a decrease of the general content of the acidic groups (more significant than that of basic groups). Simultaneously, the surface concentration of hydroxyl groups increased. The alkali treatment of activated carbon resulted in an increase of carbon dioxide uptake of 14% (measured using a volumetric method at 0 C). The adsorption of carbon dioxide on activated carbon has a mixed (physicochemical) character and that two types of adsorption sites are present at the surface. The adsorption energy varies roughly from 25 to 60 kJ/mol.

Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

“…It is generally known that with an increase in temperature, there is a transition from physisorption to chemisorption. In one of our previous papers [48], we described CO 2 adsorption studies on commercial activated carbon (pure and modified with KOH) using temperature-programmed desorption method (TPD-CO 2 ) performed under atmospheric pressure at three different temperatures: −30, 0, and 20 • C. Significant changes in adsorption energy were observed with increasing temperature, corresponding to the growing contribution of chemisorption to physisorption. We concluded that at higher temperatures, the adsorption of carbon dioxide on activated carbon had a mixed (physical/chemical) character and that two types of adsorption sites are present at the surface.…”

Enhanced surface activity of activated carbon by surfactants synergism

“…23 The peaks in the range of 2700-3000 cm À1 can be attributed to the C-H bending vibration. 24 Two peaks at 2870 and 2930 cm À1 , associated with the anti-symmetric and symmetric stretching vibration of CH 2 from HDTMA chain. 25 The band in the region 1600-1750 cm À1 can be assigned to C]O group.…”

“…27,28 The broad peaks in the range of 500-750 cm À1 correspond to CH 2 rocking (719 cm À1 ) 29 and C-O stretching. 24 The band at 488 cm À1 can be attributed to the anti-symmetric bending mode of the quaternary (alkyl) mode of the head of the methyl group (CH 3 ) 3 N + in HDTMA. 25,30 The contact angle measurement revealed the wetting behavior, the change of hydrophobic and hydrophilic intensity of both AC and AC-S.…”

Effects of potassium hydroxide and aluminum oxide on the performance of a modified solvay process for CO 2 capture: A comparative study

“…10 Bandi et al 11 investigated the absorption of CO 2 by adding KOH inside a packed column with a total height of 2 m. It was concluded that the CO 2 absorption from ambient air was around 70%. Lendzion-Bielu n et al 12 investigated the effect of KOH treatment on the surface properties of activated commercial carbon to improve the adsorption capacity of CO 2 . They reported an increase in the concentration of hydroxyl groups on the surface, which led to an increase in the uptake value of CO 2 by 14% at 0 C. In another study performed by Keith et al, 13 aqueous KOH solution was combined with calcium caustic recovery loop to capture about 1Mt-CO 2 /year from ambient air in an industrial plant.…”