Ion exchangers in the removal of caffeine from aqueous solutions

Download
index.pdf
2006
Didinedin, Gürcan
Show full item record
292
views
727
downloads
Caffeine is a commercially important member of a group of purine alkaloids found in coffee, tea and cacao particularly. It is an important ingredient in beverages and most important chemical element of stimulating pharmaceuticals. Caffeine is either manufactured by total synthesis or as a by-product from the decaffeinated coffee manufacturing. To investigate the equilibrium relationship of caffeine in ion exchange systems, which are widely used for recovery and purification processes, was the aim of this study. The effects of initial caffeine concentration and pH of the solution on equilibrium were also investigated. Stock solutions of caffeine were prepared for screening of available adsorbents and cation exchange resins. A batch type operation was carried out in a shaker bath at 40 oC with 200 rpm agitation rate. After preliminary experiments, only Lewatit S100, which is a strongly acidic cation exchange resin with s-dvb copolymer matrix, was studied. For the analysis of samples, HPLC equipment with Shimadzu PDA Detector at 254 nm and Nucleosil 100 C18 column was used. As mobile phase, a mixture of 8% acetonitrile, 8% 2-Propanol, and 1% acetic acid was introduced at 1.5 mL/min flow rate. Results showed that, the caffeine uptake capacity of cation exchange resin was poor. A set of experiments were performed at three initial concentrations (0.005 M, 0.0075 M, and 0.01 M) and four different pH regions (acidic, slightly acidic, neutral, and basic). It was found that, at extreme pH conditions, the caffeine loading capacity of the resin was slightly increased. A significant effect of initial caffeine concentration, however, couldn’t be observed. Due to the poor performance of gel type cation exchange resin and large molecular structure of caffeine molecule, Lewatit’s SPC 112 macroporous resin was studied briefly for caffeine uptake performance. It was observed that SPC 112 has also poor but better loading capacity than S100 cation exchange resin.
Chemical Engineering.
http://etd.lib.metu.edu.tr/upload/2/12607602/index.pdf
https://hdl.handle.net/11511/16110
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Ion exchangers in the recovery of tartaric acid from aqueous solutions
Başaran, Tolga Yener; Öztin, Osman Cevdet; Department of Chemical Engineering (2006)
Tartaric acid is a dicarboxylic acid naturally present in grapes, and has many application areas with its salts. It can be produced synthetically, manufactured as a by-product in wine industry, or can be recovered by electrodialysis and solvent extraction methods. Since, ion exchange is one of the oldest processing techniques for the recovery and purification of valuable materials, it can be applied to obtain this valuable organic acid. In this study it is aimed to investigate the effects of resin basicity,...
Synthesis of zeolite-polymer composites for biological applications
Kamışoğlu, Kübra; Baç, Nurcan; Department of Chemical Engineering (2007)
Zeolites are nanoporous crystalline aluminosilicates that are tasteless, odorless and nontoxic to humans. They can be tailored into antibacterial agents that are more cost effective than other conventional alternatives. Considering the increasing demand for enduring antibacterial agents, the potential uses of antibacterial zeolites are numerous in medical applications and for everyday household products. To produce antibacterial zeolites, the extra framework cations in the zeolite structures can be exchange...
Pervaporation of organic/water mixtures by MFI type zeolite membranes synthesized in a flow system
Dede, Özlem; Kalıpçılar, Halil; Department of Chemical Engineering (2007)
Zeolite membrane synthesis is conventionally carried out in batch systems. Recently, several attempts have been performed to synthesize zeolite membranes in flow systems which can allow preparation of membranes with large specific surface areas. Membranes synthesized in the recirculating flow system had comparable N2/SF6 and n- C4H10/i-C4H10 ideal selectivities with the membranes prepared in the batch system, indicating that good quality membranes can be produced by this method. The objective of this study ...
Synthesis of low silica/alumina zeolite membranes in a flow system
Akbay, Sezin; Kalıpçılar, Halil; Department of Chemical Engineering (2007)
Zeolite A-type membranes are usually synthesized from hydrogels and rarely synthesized from clear solutions mostly in batch systems. Few studies were carried out using semi-continuous systems for zeolite A membrane synthesis. Zeolite A membranes are mainly used in pervaporation processes for separation of water from water/organic mixtures because of their hydrophilic property. In this study, zeolite A membranes were synthesized on -alumina supports from a clear solution with a molar composition of 49Na2O: ...
Color formation in wheat starch based glucose syrups and use of activated carbons for sugar decolorizaiton
Çelebi, İpek; Kıncal, Suzan; Department of Chemical Engineering (2006)
Glucose syrups were produced from wheat starch at 45-90 min liquefaction times followed by 18 h saccharification to study the effect of liquefaction time on color formation and the use of several amounts (0.25%-1%) and types (NORIT, commercial; and hazelnut husk, apricot stone, hazelnut shell based; prepared in Chemical Engineering Department) of activated carbons for color removal. The fractional conversion values and color levels of glucose syrups increased with increasing liquefaction time. However, to r...
Citation Formats
G. Didinedin, “Ion exchangers in the removal of caffeine from aqueous solutions,” M.S. - Master of Science, Middle East Technical University, 2006.
METU IIS - Integrated Information Service open@metu.edu.tr