Effect of solution ph and influence of water hardness on caffeine adsorption onto activated carbons

O. M. Couto, I. Matos, I. M. Fonseca, P. A. Arroyo, E. A. Silva, M. A.S.D. Barros

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Citation (Scopus)

Abstract

There has been little research into the effects of the water hardness and pH of surface waters on the adsorption of caffeine on activated carbons. The aim of this study was to determine the influence of these water characteristics on different activated carbons. Caffeine adsorption from the aqueous phase was studied using biomass derived activated carbons (DD: dendě coco and BB: babassu coco) and a commercially available activate carbon (NO: norit® GAC 1240 plus). The functionalized carbons in an inert atmosphere was also studied and were denominated DI, BI, NI. Results highlight the importance of pH in caffeine adsorption: the highest removals were obtained for pH 3.0 and decrease for higher pH. The adsorption isotherms obtained were fitted to the Freundlich and Langmuir equation. Calcium and magnesium ions were adsorbed to a varied extent on the activated carbons. The hardness in solution decreased their adsorption due to a competition effect. KF and qm from the Freundlich equation linearly decreased with water hardness due to salt-screened electrostatic repulsions between charged molecules. The amount adsorbed from deionized water was largest, because there was no competition between inorganic ions and molecules.

Original languageEnglish
Title of host publication21st International Congress of Chemical and Process Engineering, CHISA 2014 and 17th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2014
PublisherCzech Society of Chemical Engineering
Pages1681-1700
Number of pages20
Volume3
ISBN (Electronic)9781510828131
Publication statusPublished - 1 Jan 2014
Event21st International Congress of Chemical and Process Engineering, CHISA 2014 and 17th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2014 - Prague, Czech Republic
Duration: 23 Aug 201427 Aug 2014

Conference

Conference21st International Congress of Chemical and Process Engineering, CHISA 2014 and 17th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction, PRES 2014
CountryCzech Republic
CityPrague
Period23/08/1427/08/14

Keywords

  • Activated carbons
  • Adsorption kinetics
  • Caffeine
  • Water hardness

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