Sorption of Phenolic Acids on Powdered Carbon Prepared by Complex Processing of Spent Coffee Grounds

Autor: N. V. Sych, L. I. Kotynskaya, V. M. Vikarchuk, N. N. Tsyba, M. F. Kovtun
Rok vydání: 2020
Předmět:
Zdroj: Journal of Water Chemistry and Technology. 42:88-93
ISSN: 1934-936X
1063-455X
Popis: Activated carbons are prepared by conventional two-stage carbonization–activation processing and complex processing of spent coffee grounds. The latter method includes preliminary solvent extraction of organic compounds. The samples prepared by conventional and complex processing methods have a high BET (Brunauer–Emmett–Teller) surface area (SBET = 864 and 1089 m2/g, respectively), specific surface area of mesopores (400 and 464 m2/g), and total pore volume VΣ (0.68 and 0.87 mL/g). It is shown that the complex processing produces activated carbons with a specific surface area 27% higher, compared to the conventional method. We propose that this sorption material can be used in purification of pharmaceutical production effluents. The capacity of the carbons to adsorb phenolic acids, in particular, salicylic and sulfosalicylic acids, which represent pharmaceutical microimpurities, is studied. The equilibrium concentrations of salicylic and sulfosalicylic acids are determined spectrophotometrically at λ = 296 and 294 nm, respectively, using a UV-2450 instrument (Shimadzu, Japan). The carbon produced by complex processing exhibits the most effective sorption properties (18 mg/g). The carbon prepared by conventional method displays intermediate characteristics (13.3 mg/g), and a reference Natural Brand adsorbent derived from lignocellulose material has the lowest characteristics (11.4 mg/g). The same pattern is observed for adsorption of sulfosalicylic acid, with the saturation adsorption being lower for sulfosalicylic than salicylic acid. We can state that substances with good solubility in water exhibit poorer physical adsorption than those with limited solubility. Processing the experimental data within the Langmuir and Freundlich adsorption models suggests that adsorption of the phenolic acids on the highly porous sorbents follows the Langmuir model, i.e., adsorption occurs at active sites where a dynamic equilibrium is established between adsorption and desorption processes.
Databáze: OpenAIRE
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