Which of the following materials are commonly employed as adsorbents for enzyme immobilization by adsorption?

Introduction:
Adsorption immobilization attaches enzymes to solid surfaces through noncovalent interactions. Selecting a suitable adsorbent support is critical for binding strength, activity retention, and process stability across operating conditions such as pH and ionic strength.

Given Data / Assumptions:

• Supports listed include inorganic and organic materials.
• Surface chemistry can be tuned to favor electrostatic or hydrophobic interactions.
• Mechanical robustness and availability matter for scale-up.

Concept / Approach:
Calcium carbonate, alumina, and cellulose-based materials have all been used successfully as adsorbents. Inorganics like alumina offer high surface area and mechanical strength; calcium carbonate provides benign chemistry; cellulose provides abundant hydroxyl groups and can be derivatized for tailored interactions. Hence multiple families of supports are commonly employed in adsorption strategies.

Step-by-Step Solution:

Verification / Alternative check:
Comparative binding isotherms and reuse studies across these supports confirm practical applicability of all listed materials.

Why Other Options Are Wrong:

• Each single material alone is valid, but the comprehensive answer is that all are commonly used.

Common Pitfalls:
Neglecting to pre-equilibrate supports to process pH can reduce binding. Excess ionic strength during operation may desorb enzyme; consider post-adsorption cross-linking.

Final Answer:
All of these