INTERCALATION AND DEINTERCALATION OF ORGANIC COMPOUNDS AND POLYMERS INTO MINERALS

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1 INTERCALATION AND DEINTERCALATION OF ORGANIC COMPOUNDS AND POLYMERS INTO MINERALS Elizabeth Baker Undergraduate Chemistry and Physics Will Lynch, Delana Nivens - Advisors

2 Abstract Minerals can interact with substrates through a variety of mechanisms including intercalation. The guest molecule substrates enter between the mineral layers to expand the spacing between the mineral networks. Once these bonding networks have been expanded, the guest molecule be substituted further by polymeric materials or simply removed by deintercalation. The purpose of these types of experiments is to better understand the mechanisms of the interactions of organic compounds with soil samples leading to a clearer understanding of the environmental fate and transport of organic pollutants. In this study, we have examined the interactions of bentonite (BENT) and kaolinite (KAO) with dimethylsulfoxide followed by substitution of organic compounds and polymers. These interactions have been monitored by thermal methods (Thermogravimetric Analysis and Differential Scanning Calorimetry) as well as by FT-IR.

3 Thermal Analysis Refers to a group of techniques in which a physical property of a sample is measured as a function of temperature, while subjecting the sample to a predetermined temperature profile. Thermogravimetric Analysis (TGA) Measures a samples weight change as a function of time, temperature and other environmental conditions created within the apparatus. Differential Scanning Calorimetry (DSC) Measures the difference in heat flow in and out of a sample as a function of time, temperature and other environmental conditions created within the apparatus.

4 Kaolinite (KAO) Mineral Properties Chemical Formula: Al 2 Si 2 O 5 (OH) 4 Class: Silicates Color: White, Brownish white, Grayish white, Yellowish white, Grayish green. Extremely Abundant Density: 2.6 Habit: Earthy - Dull, clay-like texture Hardness: Talc-Gypsum Uses: production of ceramics, as a filler for paint, rubber and plastics, the largest use is in the paper industry to produce glossy paper such as in magazines. Kaolinite's structure is composed of silicate sheets (Si 2 O 5 ) bonded to aluminum oxide/hydroxide layers (Al 2 (OH) 4 ) called gibbsite layers.

5 Mineral Properties Bentonite (BENT) Chemical Formula: Al 2 O 3 4SiO 2 H 2 O Class: smectite (montmorillonite) Color: white to light olive green, cream, yellow,red, brown; yellowing rapidly with exposure to air. Density: 2.4 Habit: Clay-like texture, swells in water Uses: well-drilling mud, binder and digestive aid in animal feed, sealing agent for reservoirs, lagoons and other engineering projects, plasticizer in ceramics, carrier of insecticide and pesticide, agent in water and effluent purification, absorbent material for cat litter, cosmetics, vitamins

6 Experimental Intercalation of DMSO into KAO or BENT 2 grams of KAO or BENT was stirred with 20 ml of anhydrous dimethylsulphoxide for 9 days Samples were removed every day to examine the extent of the intercalation via Diffuse Reflectance FT IR (DRIFTS), Thermogravimetric Analysis (TGA) or Differential Scanning Calorimetry (DSC) Samples were dried in the oven at 120 ºC to remove water before analyzing

7 Experimental Intercalation of PEG-3000 into KAO or BENT 1 gram of KAO-DMSO or BENT-DMSO was stirred with 10 g of melted polyethylene glycol, a highly hydrophilic polymer. The temperature was held at 155m ºC for the entire 9 days. Samples were removed every day to examine the extent of the intercalation via Diffuse Reflectance FT IR (DRIFTS), Thermogravimetric analysis (TGA) or Differential Scanning Calorimetry (DSC) Excess PEG was removed by washing with Methanol and centrifuging.

8 IR of Kaolinite, DMSO-KAO and PEG-KAO DRIFT IR Spectra of Kaolinite % T KAO DMSO KAO PEG KAO cm -1

9 IR of Bentonite, DMSO-BENT and PEG-BENT DRIFT IR Spectra of Bentonite % T PEG-BENT DMSO-BENT BENT cm -1

10 TGA of Kaolinite, DMSO-KAO and PEG-KAO Intercalation of Kaolinite Weight % Temperature ( o C) KAO DMSO-KAO PEG-KAO

11 TGA of Bentonite, DMSO-BENT and PEG-BENT Bentonite Intercalation TGA 90 Weight % BENT DMSO-BENT PEG-BENT Temperature ( o C)

12 DSC of Kaolinite, DMSO-KAO and PEG-KAO DSC Intercalation of Kaolinite Heat Flow Endo Up (mw) Temperature ( o C) DMSO-KAO PEG-KAO

13 DSC of Bentonite, DMSO-BENT and PEG-BENT DSC of Bentonite Intercalation Heat Flow Endo Up (mw) Temperature ( o C) DMSO-BENT PEG-BENT

14 Data Analysis KAO OH stretches in the IR at 3694, 3669, 3653 and 3621 cm -1 represent hydroxyl stretching cm -1 is specific to internal hyroxyl stretching. The OH stretech is extremely broad and changes little with PEG addition The major change in peak position is for CH stretching bands of PEG at 2940 and 2880 cm -1. The observance of 3 bands in this region is an indicator of intercalation OH stretches in the IR at 3694, 3669, 3653 and 3621 cm -1 represent hydroxyl stretching cm -1 is specific to internal hyroxyl stretching. DMSO-KAO contains deformation bands at 1428, 1410, 1395 and 1310 cm -1 Other CH 2 wagging and and C-C stretching bands are seen in the 1350 cm -1 range for both PEG and DMSO TGA indicates a loss of DMSO at a lower temperature than for PEG. The PEG loss is exothermic near 330 ºC, indicating a multi step combustion of the PEG, not a melting. The PEG melting peak (at 72 º C) is missing when intercalated. The DMSO loss in exothermic.

15 Data Analysis BENT Most of the IR peaks are at similar positions in bentonite as they were in KAO The broad OH stretch in bentonite is diminished in intensity but not gone. The DMSO and PEG add peaks in the CH stretch region near 2900 cm -1, with the PEG peak being extremely broad. DMSO-BENT contains deformation bands at 1428, 1410, 1395 and 1310 cm -1 Other CH 2 wagging and and C-C stretching bands are seen in the 1350 cm -1 range for both PEG and DMSO TGA indicates a loss of DMSO at a lower temperature than for PEG. The PEG loss is exothermic near 330 ºC, indicating a multi step combustion of the PEG, not a melting. The PEG melting peak (at 72 ºC) is missing when intercalated. The DMSO loss in exothermic.

16 Conclusion and Future Work This experiment shows that both DMSO and PEG can be intercalated into minerals such as bentonite and kaolinite. Our next step is to repeat the experiments using compounds that mimic pesticides and herbicides and other organic pollutants, to examine how minerals interact with these compounds. We will also investigate the interaction of other minerals with DMSO, PEG and other organic molecules. We would also like to develop a laboratory experiment for instrumental analysis or other chemistry course that uses these methods

17 References 1. Tunney, J. J.; Detellier, C. Clays and Clay Minerals 1994, 42, Tunney, J. J.; Detellier, C. Chem. Mater. 1996, 8, Frost, R.L.; Kristof, J.; Horvath, E.; Kloprogge, J.T. Thermochimica Acta ,