• Save
C.Smith IER Lesson
Upcoming SlideShare
Loading in...5
×
 

Like this? Share it with your network

Share

C.Smith IER Lesson

on

  • 662 views

Lesson designed to explain ion exchange resin technology to fellow students in a class on masonry.

Lesson designed to explain ion exchange resin technology to fellow students in a class on masonry.

Statistics

Views

Total Views
662
Views on SlideShare
659
Embed Views
3

Actions

Likes
0
Downloads
0
Comments
0

1 Embed 3

http://englishisapieceofcak.blogspot.mx 3

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • You guys know that everything in the world is made up of atoms and molecules. Well, an ion is simply an atom or molecule which has lost or gained one or more electrons, giving it a positive or negative electrical charge. Ion-exchangers are materials that are able to exchange ions within their structure with ions outside their structure, and it is always an even exchange where it gains the same number of ions as it loses, and the new ions are always of the same charge as the old ones. All exchangers fall into one of three categories: cationic, anionic, or mixed type (cationic + anionic). The exchange type is determined by the type of ion (which are again classified by electrical charge) that the material exchanges.The overall exchange process consists of five stages: (1) diffusion of ions through the solution to the surface of the exchange particles, (2) diffusion of these ions through the gel particle, (3) the exchange of these ions with those already in the exchanger, (4) diffusion of these displaced ions through the exchanger, and (5) diffusion of these displaced ions through the solution.
  • The basic chain (polymeric matrix) structure of ion-exchangers makes the exchange reaction possible. The chain contains fixed ionic groups in equilibrium with a counterions of an opposite charge, each attached to the chain with covalent links. The counterion is the exchangeable part of the structure and, according to its electrical charge, is classified as either cationic (positive) or anionic (negative). The reaction mechanism for cations and anions is as follows:– R–A- H+ + Cation+ → – R–A- Cation+ + H+ – R–C+ OH- + Anion- → – R–C+ Anion- + OH-From these equations it is apparent that counterions are always the opposite charge of the fixed groups or sites, or in other words they compensate for the fixed charge. Cation exchange materials are materials that possess negatively charged fixed groups or sites and exchangeable ions of the opposite charge (cations). Anion exchange materials possess positively charged fixed groups or sites and exchangeable ions of the opposite charge (anions).Coss-linking of the polymeric chains makes ion exchange resins insoluble in water. When dry, the functional groups in ion-exchangers are non-ionised. When in water, cross-linked functional polymers become ionized and swell to hold a high water content.
  • So here are some resins in different forms. A resin’s ionic form is determined by the counterions that are present. For example, here we have cation exchangers in sodium form, meaning they contain exchangeable Na+ ions, and cation exchangers in H+ form.
  • Since I hit you right off the bat with chemistry, I will spare you the history of ion-exchange technology, suffice it to say that by the 1940s, we were capable of synthesizing extremely stable and versatile resins. These “tailor-made” resins could be targeted for very spec By the 1970s, conservationists were adapting resins for use in heritage-related cleaning studies. Since this time, ion-exchange has become widely accepted as a method for salt removal, particularly in carbonate rocks. The studies tend to be connected to more general studies into methods for removing gypsum crusts.Conservators have moved away from traditional methods of ion-exchange, such as the ion-exchange column, to various poultice and gel mixtures. Recent studies do not focus on the applicability of resins, but instead what can be added to them to make them better suited for on-site applications. Slowly resins are being taken out of the lab, and into the buildings. Also in response to these trends, a number of commercial products are being designed and sold specifically for heritage projects. In particular, the European companies Syremont, C.T.S., and InSitu are marketing products for desulfating and the removal of calcareous encrustations.
  • One of the most common targets for desulfation are calcium-containing salts, like calcium sulfate. Conservators concern themselves with these materials for several reasons. Salts like calcium sulfate are partially soluble in water, causing them to cycle through periods of solubility and re-crystallization within masonry exposed to external moisture sources. In stones with low porosity, the salts may accumulate on the surface and mix with atmospheric particles to form dark grey excretions. In stones with a higher porosity, the salts migrate through the surface. When it crystallizes, the force of the expansion causes mechanical compression, and can eventually lead to break-up of the stone surface. Environmental pollution is a major contributing factor to this sulfatation process, particularly in urban areas. Sulfur dioxide in the air reacts with moisture, oxygen, and calcium carbonate (limestone and marble) to create calcium sulfate dihydrate (gypsum). Due to the higher specific volume and solubility of calcium sulfate in comparison to calcium carbonate, calcium sulfate has the ability to incur a lot of damage in a relatively short period of time.

C.Smith IER Lesson Presentation Transcript

  • 1. Chemistry 101: Utilizing Ion Exchange Resins to Chemically Clean Masonry
    HSPV 743 - Conservation Seminar: Masonry Caitlin Smith Spring 2009
    Disclaimer: I am not now, nor have I ever been, a chemist…
  • 2. Ion Exchange Resins  Introduction
    Natural Ion-Exchangers have been around since the dawn of time...
    Source: Robert Kunin, Ion Exchange Resins(New York: John Wiley & Sons, Inc.,1958), 2-3.
  • 3. Ion Exchange Resins  Chemistry
    • Ions are just electrically charged atoms!
    Three Types of Resins:
    Cationic
    Anionic
    Mixed
    It’s All Even Stevens
    Source: Robert Kunin, Ion Exchange Resins (New York: John Wiley & Sons, Inc.,1958), 328;Andrei A. Zagorodni, Ion Exchange Materials Properties and Applications (Oxford, UK: Elsevier BV, 2007), 223.
  • 4. Ion Exchange Resins  Chemistry
    Basic polymeric chain matrix
    Fixed ionic groups and exchangeable counterions
    Water activates ionisation
    Structure makes it INSOLUBLE in water!!!
    Cation Exchange
    – R–A- H+ + Cation+ -> – R–A- Cation+ + H+
    Anion Exchange
    – R–C+ OH- + Anion- -> – R–C+ Anion- + OH-
    E = What?!
    Source: Andrei A. Zagorodni, Ion Exchange Materials Properties and Applications (Oxford, UK: Elsevier BV, 2007), 20.
  • 5. Ion Exchange Resins  Chemistry
    Show and Tell
    Source: Andrei A. Zagorodni, Ion Exchange Materials Properties and Applications (Oxford, UK: Elsevier BV, 2007), 84, 155.
  • 6. Ion Exchange Resins  Masonry Trends
    1940s – Synthetic Resins
    1970s – Adapted for Conservation
    Expanding the technology
    Focus on improving field applications
    Development of commercial industry
    I <3 Chemistry
    Source: Robert Kunin, Ion Exchange Resins (New York: John Wiley & Sons, Inc.,1958), 83; IN SITU Conservation Restoration & Preservation Materials & Equipment, http://www.insituconservation.com/catalog/advanced_search_result.php?osCsid=615d56153b725c042caace82fd01187 5&keywords=ion+exchange&categories_id=&inc_subcat=1&x=0&y=0 (accessed April 13, 2009).
  • 7. Ion Exchange Resins  Advantages
    Requires less water than other cleaning treatments
    Does not alter morphology (no mechanical action)
    Does not alter porosity of entire material, only acts on surface
    Replaces harmful ions with inocuous ones
    Can act as a natural consolidant
    Can be regenerated and reused
    Cleaning action easily controlled by operator
    Easy application
    A +
    Source: Robert Kunin, Ion Exchange Resins (New York: John Wiley & Sons, Inc.,1958), 86, 328, 329.
  • 8. Ion Exchange Resins  Disadvantages
    Can be damaging to surface of calcareous stones
    Could cause alternation and dissolution of rock-forming minerals
    May not be able to contain ions of a certain size
    May not be cost effective
    May require multiple applications to remove high concentrations
    Could be too acidic
    D-
    Source: Nicola Berlucchi, Ricardo GinanniCorradini, Roberto Bonomi, EdoardoBemporad, and Massimo Tisato, “’La Fenice’ Theatre – Foyer and Apollinee Rooms – Consolidation of Fire-Damaged Stucco and Marmorino Decorations by Means of Combined Applications of Ion-Exchange Resins and Barium Hydroxide,” in Proceedings of the 9th International Congress on Deterioration and Conservation of Stone, Venice, June 19-24, 2000, vol. 2, ed. Vasco Fassina (Amsterdam,
    The Netherlands: Elsevier Science B.V., 2000), 27.
  • 9. Ion Exchange Resins  Cleaning
    Desulfation/Encrustation Removal
    Target calcium-containing salts
    2R+––OH- + Ca SO4 -> R+2 ––SO42- + Ca ( OH )2
    Target calcareous crusts, including gypsum
    Focus on calcareous substrates: limestone, marble, and gypsum
    Source: VivianaGuidetti and MaciejUminski, “Ion exchange resins for historic marble desulfatation and restoration,” in Proceedings of the 9th International Congress on Deterioration and Conservation of Stone, Venice, June
    19-24, 2000, vol. 2, ed. Vasco Fassina (Venice: Elsevier Inc., 2000), 331.
  • 10. Ion Exchange Resins  Cleaning
    Source: VivianaGuidetti and MaciejUminski, “Ion exchange resins for historic marble desulfatation and restoration,” in Proceedings of the 9th International Congress on Deterioration and Conservation of Stone, Venice, June
    19-24, 2000, vol. 2, ed. Vasco Fassina (Venice: Elsevier Inc., 2000), 332.
    Consolidation/Stabilization
    Calcium carbonate forms a natural consolidant when:
    Ca ( OH )2 + CO2 -> CaCO3 + H2 O
    Stabilization of clay minerals by replacing ions reduces swelling capacity
  • 11. Ion Exchange Resins  Cleaning
    Removal of Biological Growth
    Target and remove water soluble phosphates in an effort to remove biological growth and prevent re-growth
    Source: Caitlin Smith, April 9, 2009.
    Source: Andrei A. Zagorodni, Ion Exchange Materials Properties and Applications (Oxford, UK: Elsevier BV, 2007), 48.
  • 12. Ion Exchange Resins  Evaluation
    Properties:
    Rheological
    Adhesion to substrate
    Fissuration on drying
    Water retention
    Quantity of ions removed
    Tests run:
    Ion chromatography
    EDS/SEM
    Water absorption
    Morphology
    Thin-section light microscopy
    CIELab
    Source: Robert Kunin, Ion Exchange Resins (New York: John Wiley & Sons, Inc.,1958), 86, 328, 329.
  • 13. Ion Exchange Resins  Questions?
    I will not run over my time…
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run over my time
    I will not run o…
    The End