DESORPTION OF PHENOLIC COMPOUNDS ON ACTIVATED CARBONS

Transcription

1 DESORPTION OF PHENOLIC COMPOUNDS ON ACTIVATED CARBONS J. M A D U R E I R A ( 1 ), R. M E L O (1 ), S. C A B O V E R D E ( 1 ), I. M A T O S ( 2 ), J. P. N O R O N H A ( 2 ), I. M. F O N S E C A ( 2 ), F. M. A. M A R G A Ç A (1) (1) Centro de Ciências e Tecnologias Nucleares, IST-UTL, Portugal. (2) REQUIMTE/FCT, UNL, Portugal. FACULDADE DE CIÊNCIAS E TECNOLOGIA UNIVERSIDADE NOVA DE LISBOA União Europeia Fundo Europeu de Desenvolvimento Regional

2 MOTIVATION Phenolic compounds are the major components present in cork cooking wastewater. Not easy to degrade by conventional treatments - increasing its toxicity POTENTIAL AS ANTIOXIDANTS Extraction and recovery of phenolic compounds as a potential way to valorise the wastewater. Adsorption/Desorption onto activated carbons

3 METHODOLOGIES ADSORBATES Four model compounds (abundant in wastewaters) Gallic acid (GA) Protocatechuic acid (PA) Vanillic acid (VA) Syringic acid (SA) ADSORBENTS Three different activated carbons Norit GAC 1240 Plus Norit AZO From coconut shells AC-C A-20 SE-B

4 METHODOLOGIES IRRADIATION EXPERIMENTS 60 Co experimental source facility (Radiation Technology Unit in Centro de Ciências e Tecnologias Nucleares) Dose rate: 1.8 kgy/h Absorbed dose: 50 kgy Samples: Aqueous solution N 2 saturated-solution N 2 O saturated-solution ADSORBENT CHARACTERIZATION Chemical characterization Elemental Analysis (CHNS Analyser) Point of zero charge (ph PZC ) FTIR analysis

5 METHODOLOGIES ADSORPTION/DESORPTION STUDIES To saturate activated carbons 400 mg AC + 50 ml phenolic aqueous solution (500 mg L -1, ph=4.5) 24h to reach the equilibrium state AC filtered and dried at 333 K Desorption 100 mg AC + 15 ml solvent (ethanol, acetonitrile, ultrapure water) Sonication bath (Samples collection: 5min 3h) HPLC Analysis: - Detection at 280nm - Mobile phase: A - 90% ultrapure water (0.1% Formic acid) B - 10% acetonitrile - Flow rate: 1 ml min -1 - Isocratic mode

6 % (w/w) % (w/w) % (w/w) RESULTS AND DISCUSSION CHEMICAL CHARACTERIZATION ph PZC Elemental analysis AC-C AC-C SE-B Non-irradiated N 2 H 2 O N 2 O A-20 Non-irradiated N 2 H 2 O N 2 O SE-B Non-irradiated N 2 H 2 O N 2 O A Gamma Radiation: O 2 content slightly decrease H 2 content significantly increases for AC-C and decreases for SE-B O H C N

7 RESULTS AND DISCUSSION FTIR analysis AC-C A-20 SE-B Gamma radiation: No functional changes in the surface of ACs

8 Amount of compound (mg/g) Amount of compound (mg/g) Amount of compound (mg/g) RESULTS AND DISCUSSION Desorption studies No positive effect of gamma radiation on adsorbents performance. Pure water: low concentration desorbed. Gallic acid cannot be desorbed with any of the used solvents. Ethanol: is more efficient. Protocatechuic acid Vanillic acid Syringic acid AC-C A-20 SE-B 0 AC-C A-20 SE-B 0 AC-C A-20 SE-B Desorbed amount in ethanol Adsorbed amount

9 CONCLUSIONS Adsorption-desorption studies: the best AC is AC-C, except for PA which is SE-B. Irradiation dose seems to be enough to induce slight surface chemistry modifications on ACs. These modifications do not contribute to the enhancement of performance for adsorption/desorption of phenolic compounds. FUTURE: Textural characterization, SEM and XPS analysis. To study the best conditions to desorb phenolic compounds (e.g. ultrasound frequency, desorption solvents). To test other ACs (textural and surface modifications) in order to increase AC selectivity and performance for desorption of phenolic compounds.

10 REFERENCES F.J. Benitez, J.L. Acero, J. Garcia, A.I. Leal, Water Res., 37, (2003) p Heredia, J.B., Domínguez, J.R., López, A.R., J. Agric. Food Chem. 52, (2004), P. Podkoscielny, A. Dadrowski, O.V., Marijuk, Appl. Surface Sci. 205, (2003), M. N. Rashed, Adsorption Technique for the Removal of Organic Pollutants from Water and Wastewater in "Organic Pollutants - Monitoring, Risk and Treatment" I. Velo-Gala, J.J. López-Peñalver, M. Sanchéz-Polo, J. Rivera- Utrilla, Carbon, 67, (2014) p S. Chakma, V.S. Moholkar, Chem Eng J, 175, (2011), p

11 ACKNOWLEDGMENTS Portuguese Foundation of Science and Technology (FCT, Portugal): RECI/AAG-TEC/0400/2012 Application of Ionizing Radiation for a Sustainable Environment project. International Atomic Energy Agency (IAEA, Austria): CRP 1539 F23029 Radiation Treatment of Wastewater for Reuse with Particular Focus on Wastewaters Containing Organic Pollutants project. União Europeia Fundo Europeu de Desenvolvimento Regional

12 THANK YOU FOR THE ATTENTION! FACULDADE DE CIÊNCIAS E TECNOLOGIA UNIVERSIDADE NOVA DE LISBOA União Europeia Fundo Europeu de Desenvolvimento Regional