Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating
Activated carbons were obtained by physical and chemical activation of the residue of supercritical extraction of green tea leaves. All the adsorbents obtained were characterized by: elemental analysis, low-temperature nitrogen adsorption, and the contents of acidic and basic oxygen functional group...
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2022-08-01
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| author | Aleksandra Bazan-Wozniak Judyta Cielecka-Piontek Agnieszka Nosal-Wiercińska Robert Pietrzak |
| author_facet | Aleksandra Bazan-Wozniak Judyta Cielecka-Piontek Agnieszka Nosal-Wiercińska Robert Pietrzak |
| author_sort | Aleksandra Bazan-Wozniak |
| collection | DOAJ |
| description | Activated carbons were obtained by physical and chemical activation of the residue of supercritical extraction of green tea leaves. All the adsorbents obtained were characterized by: elemental analysis, low-temperature nitrogen adsorption, and the contents of acidic and basic oxygen functional groups on the surface of activated carbons by the Boehm method. The activated carbons were micro- or micro-mesoporous with well-developed surface area ranging from 520 to 1085 m<sup>2</sup>/g and total pore volume from 0.62 to 0.64 cm<sup>3</sup>/g. The physical activation of the precursor led to the strongly basic character of the surface. Chemical activation with 50% solution of H<sub>3</sub>PO<sub>4</sub> of the residue of supercritical extraction of green tea leaves promoted the generation of acidic functional groups. All adsorbents were used for methylene blue and methyl red adsorption from the liquid phase. The influence of the activation method, pH of the dye solution, contact time of adsorbent with adsorbate, the temperature of adsorption, and rate of sample agitation on the effectiveness of organic dyes removal was evaluated and optimized. In the process of methylene blue adsorption on adsorbents, an increase in the sorption capacity was observed with increasing pH of the adsorbate, while in the process of methyl red adsorption, the relation was quite the reverse. The adsorption data were analyzed assuming the Langmuir or Freundlich isotherm models. The Langmuir model better described the experimental results, and the maximum sorption capacity calculated for this model varied from 144.93 to 250.00 mg/g. The results of the kinetic analysis showed that the adsorption of organic dyes on activated carbon was following the pseudo-second-order model. The negative values of the Gibbs free energy indicate the spontaneous character of the process. |
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| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T13:01:34Z |
| publishDate | 2022-08-01 |
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| series | Materials |
| spelling | doaj.art-3a121164c3c04727bc3c6c72ed07ba452023-11-30T21:53:19ZengMDPI AGMaterials1996-19442022-08-011516566410.3390/ma15165664Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave HeatingAleksandra Bazan-Wozniak0Judyta Cielecka-Piontek1Agnieszka Nosal-Wiercińska2Robert Pietrzak3Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 61-614 Poznań, PolandDepartment of Pharmacognosy, Poznan University of Medical Sciences, Rokietnicka 3, 60-806 Poznan, PolandFaculty of Chemistry, Maria Curie-Sklodowska University in Lublin, Maria Curie-Sklodowska 3, 20-031 Lublin, PolandFaculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 61-614 Poznań, PolandActivated carbons were obtained by physical and chemical activation of the residue of supercritical extraction of green tea leaves. All the adsorbents obtained were characterized by: elemental analysis, low-temperature nitrogen adsorption, and the contents of acidic and basic oxygen functional groups on the surface of activated carbons by the Boehm method. The activated carbons were micro- or micro-mesoporous with well-developed surface area ranging from 520 to 1085 m<sup>2</sup>/g and total pore volume from 0.62 to 0.64 cm<sup>3</sup>/g. The physical activation of the precursor led to the strongly basic character of the surface. Chemical activation with 50% solution of H<sub>3</sub>PO<sub>4</sub> of the residue of supercritical extraction of green tea leaves promoted the generation of acidic functional groups. All adsorbents were used for methylene blue and methyl red adsorption from the liquid phase. The influence of the activation method, pH of the dye solution, contact time of adsorbent with adsorbate, the temperature of adsorption, and rate of sample agitation on the effectiveness of organic dyes removal was evaluated and optimized. In the process of methylene blue adsorption on adsorbents, an increase in the sorption capacity was observed with increasing pH of the adsorbate, while in the process of methyl red adsorption, the relation was quite the reverse. The adsorption data were analyzed assuming the Langmuir or Freundlich isotherm models. The Langmuir model better described the experimental results, and the maximum sorption capacity calculated for this model varied from 144.93 to 250.00 mg/g. The results of the kinetic analysis showed that the adsorption of organic dyes on activated carbon was following the pseudo-second-order model. The negative values of the Gibbs free energy indicate the spontaneous character of the process.https://www.mdpi.com/1996-1944/15/16/5664activated carbonmicrowave heatingcationic and anionic dyeskinetic and equilibrium studythermodynamic study |
| spellingShingle | Aleksandra Bazan-Wozniak Judyta Cielecka-Piontek Agnieszka Nosal-Wiercińska Robert Pietrzak Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating Materials activated carbon microwave heating cationic and anionic dyes kinetic and equilibrium study thermodynamic study |
| title | Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating |
| title_full | Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating |
| title_fullStr | Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating |
| title_full_unstemmed | Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating |
| title_short | Adsorption of Organic Compounds on Adsorbents Obtained with the Use of Microwave Heating |
| title_sort | adsorption of organic compounds on adsorbents obtained with the use of microwave heating |
| topic | activated carbon microwave heating cationic and anionic dyes kinetic and equilibrium study thermodynamic study |
| url | https://www.mdpi.com/1996-1944/15/16/5664 |
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