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IMPROVEMENT OF SORPTION PROPERTIES OF CHITOSAN BASED FILTERS

IMPROVEMENT OF SORPTION PROPERTIES OF CHITOSAN BASED FILTERS. O. Gylienė. I. Latv ė naitė, R. Binkienė, A. Jagminien ė Institute of Chemistry, A. Goštauto 9, Vilnius 01108; e-mail: gyliene@ktl.mii.lt. Filters used for the purification of drinking water.

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IMPROVEMENT OF SORPTION PROPERTIES OF CHITOSAN BASED FILTERS

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  1. IMPROVEMENT OF SORPTION PROPERTIES OF CHITOSAN BASED FILTERS O. Gylienė. I. Latvėnaitė, R. Binkienė, A. JagminienėInstitute of Chemistry, A. Goštauto 9, Vilnius 01108; e-mail: gyliene@ktl.mii.lt COST ACTION 637 - LISBON 2008

  2. Filters used for the purification of drinking water • Charcoal filters act as sorbents for organics; remove the taste of chlorine. • Reverse osmosis filters remove all mineral salts from water. • Ion exchangers remove all mineral salts from water. • Catalytic conversion water filters convert chlorine, organic matter, pollutants and microorganisms into a harmless oxidized form. Heavy metals in these filters are precipitated as metal oxides. COST ACTION 637 - LISBON 2008

  3. The limitations of purification applying filtering • Charcoal filters do not sorb heavy metals. • Reverse osmosis filters remove all minerals. Water without minerals can cause health problems. • Ion exchangers lack the selectivity for essential microelements and hazardous substances. • Catalytic conversion filters remove all heavy metal pollutants, as well as microelements. COST ACTION 637 - LISBON 2008

  4. Chitosan • Relevance: -high selectivity for the removal of heavy metal ions; the alkaline and earth alkaline metal ions remain in water; -biodegradability. • Reasons of limited use : - low sorption rate, - possible mouldiness. COST ACTION 637 - LISBON 2008

  5. Objective • To increase the sorption of heavy metals by using chemical and physical treatment - The heavy metals investigated: Cu(II), Ni(II), Zn(II) - Methods used for treatment of chitosan: an increase of surface boiling in NaCl solution electrochemical treatment COST ACTION 637 - LISBON 2008

  6. Metal sorption onto chitosan • Sorption capacity depends on deacetylation degree, i.e. free –NH2 groups Chit-NH2 + H3O+↔ Chit-NH3+ + H2O Chit-NH2 + Mn+→(Complex)n+ Chit-NH3+ + Mn+ + H2O→ (Complex)n+ + H3O+ COST ACTION 637 - LISBON 2008

  7. Metal sorption onto chitosan COST ACTION 637 - LISBON 2008

  8. Equilibrium studies Influence of the chitosan structure on the sorbed quantities (qm calculated from Langmuir equation) A t equilibrium conditions, the additional treatment only slowly increases the sorbed quantities COST ACTION 637 - LISBON 2008

  9. Relation to sorbent surface Cu(II) sorption onto chitosans COST ACTION 637 - LISBON 2008

  10. Summing-up the experiments under equilibrium conditions • There are not strong relations between the surface of chitosan and sorbed quantities of heavy metal ions COST ACTION 637 - LISBON 2008

  11. Effect of contact time • Sorption onto chitosan beads from solutions containing 100 mg L-1 Cu(II) COST ACTION 637 - LISBON 2008

  12. Effect of contact time • Sorption onto chitosan plates from solutions containing 100 mg L-1 Cu(II) COST ACTION 637 - LISBON 2008

  13. Fixed bed-column experiments (continuous flow experiments) Sorption efficiency depends on: • column height; • flow rate; • influent adsorbate concentration. COST ACTION 637 - LISBON 2008

  14. Breakthrough curve • Removal of Cu(II) from its 100 mg L-1 solutions; column height 15 cm; diameter 1.2 cm; loading 10 g COST ACTION 637 - LISBON 2008

  15. Sorption from mixture Cu(II) 40 mg L-1Ni(II) 30 mg L-1Zn(II) 30 mg L-1 COST ACTION 637 - LISBON 2008

  16. Composite sorbent (ceramics coated with chitosan) COST ACTION 637 - LISBON 2008

  17. Summing-up of kinetic experiments • The strong influence of the chitosan structure indicates the importance of interior diffusion on the sorption rate COST ACTION 637 - LISBON 2008

  18. Conclusion • The possibilities exist to obtain chitosan filtering material suitable for effective removal of heavy metals from drinking water COST ACTION 637 - LISBON 2008

  19. Thank you for your attention! COST ACTION 637 - LISBON 2008

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