30 Questions
Which type of adsorption involves stronger valence forces?
Chemical adsorption
At what temperature does heat of adsorption decrease rapidly?
Low temperature
Which type of adsorption forms unimolecular layers on the adsorbent surface?
Chemical adsorption
Which type of adsorption is reversible?
Physical adsorption
What is involved in chemisorption?
Ion exchange with basic groups
Which process has no activation energy involved?
Physical adsorption
What is the main difference between adsorption and absorption?
Adsorption is the accumulation of a substance at the interface between two phases, while absorption implies penetration throughout a substance.
Which term is customarily used when referring to a gas/solid or gas/liquid interface?
Adsorption
In adsorption, what does the term 'adsorbent' refer to?
The substance that adsorbs another substance at its surface
Which of the following is an example of adsorbent?
Activated Charcoal
What is the main role of adsorption in emulsion formation and stability?
To accumulate substances at the boundary between two phases
Which pair represents a heterogeneous phase in the context of adsorption?
Solid-Gas
What term is used when there is no distinction between adsorption and absorption?
Sorption
Which type of adsorption occurs when the surface concentration is greater than the volume concentration?
Positive adsorption
What factor affects adsorption based on the solute-solvent bonds?
Solubility of the adsorbate
What is the role of activated charcoal in respirators for civilians and forces?
Solid-Gas adsorption
Which term is used to describe when both adsorption and absorption occur simultaneously?
Sorption
What happens to adsorption if the surface concentration is less than the bulk concentration?
Negative adsorption
What factor affects the solubility of drugs by influencing ionization?
pH
Why does adsorption increase in drugs with single molecules when ionization is suppressed?
Decrease in ionization
Which type of particles have more adsorption capacity due to increased surface area?
Finely divided particles
How does an increase in temperature affect adsorption?
Decreases adsorption
What happens to adsorption when pressure decreases?
Causes desorption
Which factor influences the total amount of gas adsorbed by a solid?
Nature of gas
What is the purpose of using activated charcoal, MgO, and Tannic acid orally?
To remove toxic elements from the blood
How are toxic elements removed from the blood using adsorbents?
By subjecting dialysis through hemodialysis membrane over charcoal and adsorbents
What is the method developed for the treatment of severe drug overdoses?
Hemoperfusion
How does microencapsulation of activated charcoal prevent embolism and platelet removal?
By encapsulating in Arcylic Hydrogel
What is an outcome of administering drugs containing antacids and other drugs together?
Decreased adsorption capacity
Why does giving promazine with or without an adsorbent lead to a problem?
Because adsorbents are non-specific nutrients, drugs, and enzymes when taken orally
Study Notes
Types of Adsorption
- Physical Adsorption: weak intermolecular forces, small heat of adsorption (about 5 Kcal/mol), reversible, no activation energy involved, rapid at low temperature
- Chemical Adsorption (Chemisorption): stronger valence forces, large heat of adsorption (20-100 Kcal/mol), irreversible, may involve activation energy, increases with increase of temperature
Characteristics of Adsorption
- Surface phenomenon: uniform distribution of a substance through another at the surface
- Important in: adjuncts in dosage forms, penetration of molecules through biological membranes, emulsion formation, stability and dispersion of insoluble particles in liquid media
Components of Adsorption
- Adsorbent: substance that adsorbs another substance at its surface (e.g., Kaolin, pectin, attapulgite, talc, Magnesium trisilicate, Al(OH)3, Simithicone, CaCO3, Activated Charcoal)
- Adsorbate: substance that is adsorbed on the adsorbent's surface (e.g., Strychnine HCl onto Activated Charcoal)
Types of Sorption
- Sorption: when there is no distinction between adsorption and absorption, or when both occur simultaneously
- Positive Adsorption: surface concentration is greater than volume concentration
- Negative Adsorption: surface concentration is less than volume concentration
Factors Affecting Adsorption
- Solubility of adsorbate: inversely proportional to solubility (Lundelius' Rule)
- Nature of adsorbate: physio-chemical nature affects rate and capacity of adsorption
- Nature of adsorbent: surface area and physio-chemical nature affect adsorption
- Pressure: increases adsorption, decreases desorption
- Temperature: exothermic process, increases temperature decrease adsorption
- pH: affects ionization, which affects solubility of drugs
- Surface area: increases adsorption capacity
- Nature of gas: more easily liquefiable gases are more readily adsorbed
Applications of Adsorption
- Adsorption of noxious substances from the alimentary canal: uses universal antidotes like activated charcoal, MgO, and Tannic acid
- Removal of toxic elements from blood: uses hemodialysis membrane and adsorbents
- Treatment of severe drug overdoses: uses extracorporeal method (Haemoperfusion) and microencapsulation of activated charcoal
- Adsorption problems in drug formulation: effects of adsorbents on drug absorption and utilization
Learn about the surface phenomenon of adsorption where substances distribute uniformly on another surface. Explore how ions, molecules, or molecular aggregates condense on surfaces. Understand the importance of adsorption in dosage forms and biological processes.
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