IMPROVEMENT OF SORPTION PROPERTIES OF CHITOSAN BASED FILTERS

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