Risk-Assessment范例(Acid/Base Piranha/Aqua Regia)

Posted by XiLock on November 18, 2018

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Piranha Solution Information & Safety

Basic Information

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Conducted by:
Approved by: Submitted by/Data:
Approved Data:

Use of piranha soluton

1

Hazard:Chemical
Sub Hazard: Explosive
Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,Body injury,damage to instruments.
Existing Risk Control:

  1. Add H2O2 solution into H2SO4 VERY SLOWLY.
  2. Restrict the preparation volume to less than 100ml each time.
  3. To keep the reactivity of the solution (if required), one should apply heating only after the solution become stabilized. During heating, Do control the temperature to below 100 degree Celsius.
  4. Use open container. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    2

    Hazard:Chemical
    Sub Hazard: Explosive
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,Body injury.
    Existing Risk Control:

  5. Wear lab coat, covered shoes, acid/base protective gloves and safety goggles at all time when handling Piranha solution.
  6. Gently stir the solution using glass rod if it’s unrestful. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    3

    Hazard:Chemical
    Sub Hazard: Oxidision
    Possible Accident/Ill health to persons, fire or proper loss: Other,Initiate or promote combustion, hurt limps.
    Ref MSE/ChenRFL/SOP/201702
    Existing Risk Control:

  7. The process MUST BE conducted in a fume hood with the sash position as low as possible.
  8. Wear lab coat, covered shoes, acid/base protective gloves and safety goggles at all time when handing Piranha solution.
  9. Use clean and open glass container to prepare piranha solution.
  10. A typical mixture in volume ratio is 3:1 of H2SO4:H2O2, there are some other ratio like 4:1 to 7:1. A closely related mixture, sometimes called “base piranha”, is a 3:1 mixture of ammonium hydroxide (NH4OH) with hydrogen peroxide.
  11. Use a clean and dry glass container to collect desired amount of H2O2 (30% aqueous solution), NOT TO USE high concentrated H2O2.
  12. Piranha solution should always be prepared by adding hydrogen peroxide to sulfuric acid SLOWLY, never in reverse for good result.
  13. To keep the reactivity of the solution (if required), one should apply heating only after the solution becomes stabilized. During heating, DO control the temperature to below 100 degree Celsius.
  14. Restrict the preparation volume to less than 100ml each time.
  15. Immersing the substrate (such as a wafer) into the solution should be done slowly to prevent thermal shock that may crack the substrate.
  16. When cleaning glassware, it is both prudent and practical to allow the piranha solution to react overnight. This allows the spent solution to degrade prior to disposal. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4

Disposal of piranha solution

1

Hazard:Chemical
Sub Hazard: Oxidision
Possible Accident/Ill health to persons, fire or proper loss: Other,Initiate or promote combustion, hurt limps.
Existing Risk Control:

  1. Wear proper PPE, including goggles, protective gloves and covered shoes.
  2. Piranha solution should be allowed to cool, and oxygen gas should be allowed to dissipate prior to disposal.
  3. Take a large glass beaker and half fill with water (at least 5 times of the volume of piranha solution), add the piranha solution into water VERY SLOWLY.
  4. The piranha solution must be neutralized before disposed into the waste container.
  5. The neutralization can be done by adding NaOH slowly into a diluted Piranha solution until the solution reach pH range between 4-10. Ice cubes shall be added to cool down the solution if it become very hot during the neutralization process.
  6. Piranha solution should not be disposed with organic solvents (e.g. in waste solvent carboys), as this will cause a violent reaction and a substantial explosion. Severity: Very Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 9
    2

    Hazard:Chemical
    Sub Hazard: Explosive
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,damage to instruments.
    Existing Risk Control:

  7. Wear proper PPE, include googles, covered shoes and protective gloves.
  8. Piranha solution should be allowed to cool, and oxygen gas should be allowed to dissipate prior to disposal.
  9. Never add organic solvent to the solution. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    3

    Hazard:Chemical
    Sub Hazard: Corrosice
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury.
    Existing Risk Control:

  10. Wear proper PPE, including goggles,protective gloves, covered shoes. Severity: Very Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 3

Use of aqua regia solution

1

Hazard:Chemical
Sub Hazard: Corrosive
Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury, including respiratory systems.
Existing Risk Control:

  1. Ref MSE/ChenRFL/SOP/201701
  2. Wear proper PPE, including goggles, acid protective gloves, covered shoes and acid protective mask if possible.
  3. Always operate in fume hood and make the slash position as low as possible. Severity: Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 3
    2

    Hazard:Chemical
    Sub Hazard: Oxisising
    Possible Accident/Ill health to persons, fire or proper loss: Others, Initiate and promote fire, body injury.
    Existing Risk Control:
    Ref MSE/HSE/SWP/01.0

  4. The process MUST BE conduct in a fume hood.
  5. Wear lab coat, covered shoes,acid protective gloves and safety googles ar all time when handing Aqua Regia solution.
  6. Typically, concentrated HNO3 is added into the concentrated HCl slowly in a clean and dry glass container (HCl:HNO3=3:1 v/v).
  7. Restrict the preparation volumn to less than 500 ml each time is recommended.
  8. Aqua Regia quickly loses its effectiveness (yet remains a strong acid), so its components are usually only mixed immediately before use. However, it can be used to remove some metal and metal oxides as well after weeks.
  9. Clean items first to remoe as more contaiminates as possible before wash with aqua regia. Severity: Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 1
    3

    Hazard:Chemical
    Sub Hazard: Explosive
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,damage to instruments.
    Existing Risk Control:

  10. Wear proper PPE, include googles, covered shoes and protective gloves.
  11. Operate in the fume hood.
  12. Never keep aqua regia in a closed vessel as the evelving gases will cause a pressure build-up and possible explosion may occur.
  13. Never add organic solvent to the solution.
  14. Wash items thoroughly before washed with aqua regia. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4

Disposal of aqua regia solution

1

Hazard:Chemical
Sub Hazard: Explosive
Possible Accident/Ill health to persons, fire or proper loss: Other, Bosy injury and damage to instrument.
Existing Risk Control:

  1. Wear proper PPE, including goggles, protective gloves and covered shoes.
  2. Opertate in the fume hood.
  3. The neutralization can be done by add NaHCO3 or Na2CO3 slowly into a diluted aqua regia solution until the solution reach pH range between 4-10. Ice cubes shall be added to cool down the solution if it become very hot during the neutralization process.
  4. Never add organic solvents to aqua regia or add aqua regia to organic solvent. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    2

    Hazard:Chemical
    Sub Hazard: Corrosice
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury including respiratory system.
    Existing Risk Control:

  5. Wear proper PPE, including goggles,protective gloves, covered shoes and acid protective mask if possible.
  6. Always operate in fumn hood and make the slash as low as possible.
  7. Neutralized to pH value of 4-10. Severity: Very Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 3
    3

    Hazard:Chemical
    Sub Hazard: Oxiding
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury.
    Existing Risk Control:

  8. Wear proper PPE, including goggles,protective gloves, covered shoes and protective gloves.
  9. Dilute with water before neutralization. Severity: Very Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 3

Use of base piranha soluton

1

Hazard:Chemical
Sub Hazard: Explosive
Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,Body injury,damage to instruments.
Existing Risk Control:

  1. Add H2O2 and NH4OH solution into H2O SLOWLY.
  2. Restrict the preparation volume to less than 100ml each time.
  3. To keep the reactivity of the solution , one should heat the solution to 60 degree Celsius after the it becomes stabilized.During heating, Do control the temperature to below 100 degree Celsius.
  4. Use open container. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    2

    Hazard:Chemical
    Sub Hazard: Explosive
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,Body injury.
    Existing Risk Control:

  5. Wear lab coat, covered shoes, acid/base protective gloves and safety goggles at all time when handling base piranha solution.
  6. Gently stir the solution using glass rod if it’s unrestful. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    3

    Hazard:Chemical
    Sub Hazard: Oxidision
    Possible Accident/Ill health to persons, fire or proper loss: Other,Initiate or promote combustion, hurt limps.
    Existing Risk Control:
    Ref MSE/ChenRFL/SOP/201702

  7. The process MUST BE conducted in a fume hood with the sash position as low as possible.
  8. Wear lab coat, covered shoes, acid/base protective gloves and safety goggles at all time when handing Piranha solution.
  9. Use clean and open glass container to prepare piranha solution.
  10. A typical mixture in volume ratio is 1:1:5 of ammonium hydroxide (NH4OH) with hydrogen peroxide and DI water.
  11. Use a clean and dry glass container to collect desired amount of H2O2 (30% aqueous solution), NOT TO USE high concentrated H2O2.
  12. To keep the reactivity of the solution , one should heat the solution to 60 degree Celsius after the it becomes stabilized.
  13. Restrict the preparation volume to less than 100ml each time.
  14. Immersing the substrate (such as a gold substrate) into the solution should be done slowly to prevent thermal shock that may crack the substrate.
  15. When cleaning glassware, it is both prudent and practical to allow the base piranha solution to react for more than half an hour. This allows the spent solution to degrade prior to disposal. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4

Disposal of base piranha solution

1

Hazard:Chemical
Sub Hazard: Oxidision
Possible Accident/Ill health to persons, fire or proper loss: Other,Initiate or promote combustion, hurt limps.
Existing Risk Control:

  1. Wear proper PPE, including goggles, protective gloves and covered shoes.
  2. Base piranha solution should be allowed to cool, and ammonia gas should be allowed to dissipate prior to disposal.
  3. Take a large glass beaker and half fill with water (at least 5 times of the volume of base piranha solution), add the base piranha solution into water SLOWLY.
  4. The piranha solution must be neutralized before disposed into the waste container.
  5. The neutralization can be done by adding CH3COOH slowly into a diluted base piranha solution until the solution reach pH range between 4-10. Ice cubes shall be added to cool down the solution if it become very hot during the neutralization process.
  6. Base piranha solution should not be disposed with organic solvents (e.g. in waste solvent carboys), as this will cause a violent reaction and a substantial explosion. Severity: Very Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 3
    2

    Hazard:Chemical
    Sub Hazard: Explosive
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury,damage to instruments.
    Existing Risk Control:

  7. Wear proper PPE, include googles, covered shoes and protective gloves.
  8. Base piranha solution should be allowed to cool, and ammonia gas should be allowed to dissipate prior to disposal.
  9. Never add organic solvent to the solution. Severity: Very Serious,4
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 4
    3

    Hazard:Chemical
    Sub Hazard: Corrosice
    Possible Accident/Ill health to persons, fire or proper loss: Other,Body injury.
    Existing Risk Control:

  10. Wear proper PPE, including goggles,protective gloves, covered shoes. Severity: Very Serious,3
    Likelyhood: Occasional,1
    RPN(Rish Prioritization Number): 3


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