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Energies 2017, 10(5), 665;

Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies

Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio, 43, 03043 Cassino, Italy
UNESCO-IHE Institute for Water Education, Westvest 7, 2611AX Delft, The Netherlands
Institute of Biomolecular Chemistry, Italian National Council of Research, Via Campi Flegrei 34, 80078 Napoli, Italy
Department of Civil Engineering, Telematic University Pegaso, Piazza Trieste E Trento, 48, 80132 Naples, Italy
Author to whom correspondence should be addressed.
Academic Editor: S. Kent Hoekman
Received: 14 March 2017 / Revised: 23 April 2017 / Accepted: 5 May 2017 / Published: 10 May 2017
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Solid-liquid extraction (adsorption or ion exchange) is a promising approach for the in situ separation of organic acids from fermentation broths. In this study, a diluted concentration of lactic acid (<10 g/L) separation from a model fermentation broth by granular activated carbon (GAC) as well as weak (Reillex® 425 or RLX425) and strong (Amberlite® IRA-400 or AMB400) base anion exchange resins under various operating conditions was experimentally investigated. Thermodynamic analysis showed that the best lactic acid adsorption performances were obtained at a pH below the pKa value of lactic acid (i.e., 3.86) for GAC and RLX425 by physical adsorption mechanism and above the pKa value for the AMB400 resin by an ion exchange mechanism, respectively. The adsorption capacity for GAC (38.2 mg/g) was the highest, followed by AMB400 (31.2 mg/g) and RLX425 (17.2 mg/g). As per the thermodynamic analysis, the lactic acid adsorbed onto GAC and RLX425 through a physical adsorption mechanism, whereas the lactic acid adsorbed onto AMB400 with an ion exchange mechanism. The Langmuir adsorption isotherm model (R2 > 0.96) and the pseudo-second order kinetic model (R2 ~ 1) fitted better to the experimental data than the other models tested. Postulating the conditions for the real fermentation broth (pH: 5.0–6.5 and temperature: 30–80 °C), the resin AMB400 represents an ideal candidate for the extraction of lactic acid during fermentation. View Full-Text
Keywords: lactic acid; adsorption; kinetics; isotherms; thermodynamics; ion exchange lactic acid; adsorption; kinetics; isotherms; thermodynamics; ion exchange

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Pradhan, N.; Rene, E.R.; Lens, P.N.L.; Dipasquale, L.; D’Ippolito, G.; Fontana, A.; Panico, A.; Esposito, G. Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies. Energies 2017, 10, 665.

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