Improving the pore structure and adsorption properties of industrial active carbons

Abstract

The paper describes the possibility of improving the pore structure and adsorption properties of industrial active carbons (AC) by means of their modification with ɛ-caprolactam (CL). Application of ɛ-caprolactam (a product of large-scale organic synthesis) as a modifying substance allows the targeted regulation of the specific surface area and volume of AC mesopores, while the conditions of modification change the chemical composition of the surface of carbon adsorbents and, as a result, their adsorption properties. The process of modification includes three stages. The first is the adsorption of CL from aqueous solution and heating at 300°C in the presence of atmospheric oxygen. The second is carbonization in an argon flow at 900°C, and the third is the vapor-gas activation of the resultant adsorbents at 900°C. Each stage is followed by determining the parameters of the pore structure by N2 adsorption and the adsorption parameters with respect to benzene, iodine, aqueous solutions of ɛ-caprolactam, and copper sulfate (CuSO4). When modifying the carbonized samples with an initial ɛ-caprolactam content of 2%, we observe the growth of mesopores over 100% of volume, relative to AG-OV-1 original industrial activated carbon. Depending on the stage of modification, an increase in adsorption is observed, relative to the AG-OV-1 original carbon: benzene adsorption rises by 50%, the adsorption of iodine from aqueous solution rises by 20%, the adsorption of ɛ-caprolactam from aqueous solution grows by more than 30%, and the adsorption of copper(II) ions rises by more than 70%. The procedure for the production of the described modified adsorbent has no rivals abroad; it is protected by a patent and can be used in industry. It is possible to use inexpensive industrial carbons as the original material. The procedure allows the production of carbon adsorbents with predetermined structural and adsorption properties.