Perfect 👍 — next in **periodic table order** is **Krypton (Kr, atomic number 36).**
Krypton is a **noble gas** that does **not occur free in significant amounts** in nature. It is primarily obtained from **liquefied air** through **fractional distillation** because it exists in very low concentrations in the atmosphere (\~1 ppm).
Here are the **20 most common methods of extracting Krypton**:
---
# **20 Most Common Methods of Extracting Krypton**
### **A. Industrial / Large-Scale Methods**
1. **Fractional Distillation of Liquid Air** – Primary industrial method.
2. **Cryogenic Separation of Oxygen and Nitrogen from Air** – Concentrates noble gases including Kr.
3. **Sequential Fractional Distillation (Multiple Stages)** – Further isolates Kr from Xe and Ar.
4. **Distillation Using Low-Temperature Columns** – Enhances Kr purity.
5. **Adsorption of Other Gases (O₂/N₂) on Zeolites/Activated Carbon** – Pre-concentration step.
6. **Rectification of Liquid Air Mixtures** – Industrial refinement of Kr.
---
### **B. Cryogenic / Low-Temperature Methods**
7. **Cryogenic Pumping of Air Mixture** – Separates heavier noble gases.
8. **Fractional Condensation at Controlled Temperatures** – Kr condenses after N₂/O₂ removal.
9. **Vacuum Distillation Techniques** – Enhances Kr separation efficiency.
10. **Pressure Swing Adsorption** – Partial industrial separation method.
11. **Low-Temperature Molecular Sieve Adsorption** – Pre-concentrates Kr before distillation.
12. **Cascade Cryogenic Distillation** – Multiple stages for higher purity.
---
### **C. Laboratory / Small-Scale Methods**
13. **Separation Using Activated Charcoal at Low Temperatures** – Lab-scale Kr collection.
14. **Fractional Distillation of Liquefied Air in Small Columns** – Lab-scale isolation.
15. **Cold Trap Collection from Liquefied Air** – Laboratory method.
16. **Gas Chromatography for Minor Purification** – Analytical and small-scale extraction.
---
### **D. Specialized / Experimental Methods**
17. **Laser Isotope Separation** – Produces specific isotopes of Kr.
18. **Membrane Separation at Low Temperatures** – Experimental method for minor Kr enrichment.
19. **Cryogenic Distillation of Industrial Argon or Oxygen Production Streams** – Byproduct recovery.
20. **Plasma or Ionization-Based Noble Gas Separation** – Experimental method for research-level Kr recovery.
---
✅ **Summary:**
* **Main industrial method:** Fractional distillation of liquid air after removal of N₂ and O₂.
* **Cryogenic separation:** Key step to concentrate Kr from other noble gases.
* **Laboratory-scale:** Cold traps, activated charcoal adsorption, small distillation columns.
* **Specialized/experimental:** Membranes, laser isotope separation, plasma separation.
* **Sources:** Atmospheric air (\~1 ppm Kr), byproduct of industrial oxygen/argon production.
---
Next in periodic order is \*\*Rubidium (Rb, atomic number 37).
Do you want me to continue with **20 extraction methods for Rubidium**?