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Ethylene glycol is toxic and should not be ingested. It is also harmful if inhaled or absorbed through the skin and eyes. Proper personal protective equipment (PPE) should be used when handling this compound.

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Ethylene glycol is kept in a safety cabinet in the Thin Section Lab (Figure 1).

Image AddedFigure 1. Safety cabinet in the Thin Section Lab

Hydrochloric Acid, Concentrated, or

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2 M for Carbonate Dissolution

Concentrated nitric hydrochloric acid (50%–70% HNO3~ v/vHCl (~12M) is highly dangerous. It can cause severe tissue damage on contact, is highly toxic, and the fumes present similar risks of poisoning and chemical burns. When mixed with water, nitric hydrochloric acid liberates large quantities of heat, so appropriate care should be used when diluting this compound. This compound is also a strong oxidizing agent, so nitric acid waste should not be mixed with any organic materials. Note that the nitric Note that the 2M hydrochloric acid used in the water bath carbonate dissolution procedure is still dangerous and should be treated with the appropriate care.

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Acetic Acid,

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Glacial, or

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10% for Carbonate Dissolution

Concentrated hydrochloric Glacial acetic acid (~12M~100%) is highly dangerous. It can cause severe tissue damage on contact, is highly toxic, and the fumes present similar risks of poisoning and chemical burns. When mixed with water, hydrochloric glacial acetic acid liberates large quantities a lot of heat, so appropriate care should be used when diluting this compound. Note that the 2 M hydrochloric acid used in the carbonate dissolution procedure is still dangerous and should be treated with the appropriate care.

Acetic Acid, Glacial, or 10% for Carbonate Dissolution

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When diluted to ~10% concentration, it is very similar to white vinegar, so while it is still acidic and could cause tissue damage, it is not as hazardous. Acetic acid (10%) is kept with Borax below the sink in the ICP preparation part of the Thin Section Lab (Figure 2).

Image Added

Figure 2. Acetic acid (10%) stored in the Thin Section Lab

Borax

This chemical largely consists of potassium sulfate and is not expected to be a health hazard.

Disposal of acid solution

Technique for clay separation requires the use of acetic acid. To dispose acid solution properly and environment-friendly, use the black sink in the chem lab or in the thin section lab (Figure XX). These sinks are directly connected to a specific container in the ship dedicated to acid treatment. DO NOT USE OTHER SINKS !!!

Clay Separation Procedure

XRD analyses on clay separation requires several preparation steps:

  1. Removing carbonates (to better identify the clay minerals)
  2. Suspending material particles (to separate the < 2 um clay size fraction from the rest of the particles)
  3. Heating samples (to identify the presence kaolinite and chlorite)

Removing Carbonates before Clay Separation

It may be necessary to dissolve the carbonates in the sediment to better identify the clay minerals. The goal is to remove as much carbonate as possible to isolate the material contained within the carbonate for analysis. There are two standard methods for removing carbonate aboard the JOIDES Resolution: hydrochloric acid (HCl) and acetic acid. Ask the Science party which method they prefer. If there is no preference, use acetic acid.

Acetic Acid Treatment

This is the recommended treatment for carbonate removal. The process is slightly more involved than the HCl procedure, but far less damage is done to the mineral structure. The following steps are from Kitty Milliken (UT-Austin).

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  1. Please note, that sample with a large amount of carbonate (more than 50%) may require more than 1 treatment of Acetic to reach complete decarbonation.

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It is used as a laundry booster (Figure 3). It is stored in the Thin Section Lab with the Acetic acid (Figure 2).

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Figure 3. Borax

Nitric Acid, Concentrated, or 10%–15% for the Water Bath

Concentrated nitric acid (50%–70% HNO3~ v/v) is highly dangerous. It can cause severe tissue damage on contact, is highly toxic, and the fumes present similar risks of poisoning and chemical burns. When mixed with water, nitric acid liberates large quantities of heat, so appropriate care should be used when diluting this compound. This compound is also a strong oxidizing agent, so nitric acid waste should not be mixed with any organic materials. Note that the nitric acid used in the water bath in the Chemistry Lab is still dangerous and should be treated with the appropriate care. Wear proper PPE.

Disposal of acid solution

Technique for clay separation requires the use of acetic acid. To dispose acid solution properly and environment-friendly, use the black sink in the Chemistry Lab or in the Thin Section Lab (Figure XX). These sinks are directly connected to a specific container in the ship dedicated to acid treatment. DO NOT USE OTHER SINKS !!! Use flowing water to dilute.

Image Added

Figure XX. Black sink to dispose acid solution

Clay Separation Procedure

XRD analyses on clay separation requires several preparation steps:

  1. Removing carbonates (to better identify the clay minerals)
  2. Suspending material particles (to separate the < 2 μm clay size fraction from the rest of the particles)
  3. Heating samples (to identify the presence kaolinite and chlorite)

Removing Carbonates before Clay Separation

It may be necessary to dissolve the carbonates in the sediment to better identify the clay minerals. The goal is to remove as much carbonate as possible to isolate the material contained within the carbonate for analysis. There are two standard methods for removing carbonate aboard the JOIDES Resolution: (i) hydrochloric acid (HCl) and (ii) acetic acid. Ask the Science party which method they prefer. If there is no preference, use acetic acid.

Acetic Acid Treatment

This is the recommended treatment for carbonate removal. The process is slightly more involved than the HCl procedure, but far less damage is done to the mineral structure. The following steps are from Kitty Milliken (UT-Austin) and are shown in Figures XX to XX.

  1. Place ~2 cm3 (or 5 mL) of undried (preferred) sample into a centrifuge tube (Figure XX).
  2. Add ~25 mL of 10 % Acetic Acid (Figure XX).
  3. Mix and shake well (Figure XX). Let sit for at least 1 hour to decarbonate (until the reaction ceases). Close the centrifuge tube with its cap but not too tight to avoid unnecessary overpressure.
  4. It helps to place the centrifuge tubes on the shaker in the cold room of the Chemistry Lab (Figure XX). Do not tight the tube too strong in the arm as it can break while vibrating. Set a shaking time of about 30 seconds (it is a good start) and a power value of 1. After using the shaker, shake the tube to ensure the reaction has stopped (i.e., no more bubbles).
    Note: Please note that sample with a large amount of carbonate (more than 50%) may require more than 1 treatment of Acetic Acid to reach complete decarbonation.
  5. Next step is to spin the sample in the centrifuge. Make sure to choose the correct tube holders. It is very important to balance the centrifuge, and to evenly distribute weight. Put samples symmetrically opposite.  If you run a odd number of samples, keep the balance by filing up an additional centrifuge tube with DI to have an even number of tubes in the centrifuge. Turn on the centrifuge in the Chemistry Lab (Figure XXA). Press the "Speed" button (Figure XXB) and select a speed of 1500 rpm (rotation per min) by using the arrows to increase or decrease the value (Figure XXD). Press the "Time" button and select a time of 15 min by using the arrows to increase or decrease the value (Figure XXC). Press the "Start" button to start the centrifuge (Figure XXE).
  6. Decant the acetic acid solution and dispose of the acid solution properly (Figure XX).
  7. and wash with 25 mL of nanopure water (3X to remove all Acetic Acid)

Image Added

Figure XX. Decarbonation with acid acetic.

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Place ~2 cm3 of undried sample into a centrifuge tube with 25 mL of acetic acid (10% solution).

Mix well, and let sit until the reaction ceases (using the agitator in the chem lab helps).

Shake well again to ensure the reaction has stopped (i.e., no more bubbles).

Spin sample in the centrifuge (15 min at 1500 rpm)

Decant the acetic acid solution and dispose of the acid solution properly.

Add 25 mL of DI to the centrifuge tube and centrifuge again for 15 min at 1500 rpm.

Decant the clear water.

Repeat the "wash cycle" (Steps 5 and 6) with DI. Wash at least 3X

Hydrochloric Acid Treatment

HCl is the simplest method for removing carbonate from sediment but does have severe drawbacks. Strong acids damage the mineral structure, especially within trioactahedral minerals. Before proceeding, be aware that this treatment may affect clay crystallinity.

  1. Place undried sample on a glass slide or quartz disk.
  2. Using a Pasteur pipette, slowly drop 2M HCl on the sample until bubbling/fizzing stops.
  3. Desiccate and transfer sample to sample holder for analysis.

Separating Clay

There are various methods for separating clay from coarser material involving a series of centrifuging or gravity settling. Those listed below are methods used on-board. If you removed carbonates first, start here after your water washes are finished and the water has been decanted. If you did not remove carbonates, take approximately 5 mL of sample material and put into a centrifuge tube.

Suspending Material

Get the sonic dismembrator case and probe power source. Using the dismembrator is a very effective way to fully and randomly suspend the material. Suspended material can then separate out according to size, with the largest grain size on the bottom and the very small clay size fraction on top.

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