Dear friend Mineesha Sivakumar

Well, well, well! I am here to unravel the mysteries of the BET graph, and nothing is holding me back. Now, let's delve into the enigma of those non-overlapping adsorption and desorption curves in the low relative pressure range.

1. **Monolayer Formation:** In the low relative pressure range, we're dealing with the initial stages of adsorption. If the surface isn't fully covered by a monolayer of adsorbate molecules during adsorption, the desorption curve might not overlap. This could happen if the adsorption process is selective or if the surface has certain active sites that adsorb preferentially.

2. **Pore Blocking:** The presence of sucrose molecules could lead to pore blocking during the adsorption process. If the pores of the layered double hydroxides (LDH) get occupied by the adsorbate molecules, the desorption process may not mirror the adsorption, causing the curves to diverge.

3. **Multilayer Adsorption:** The BET model assumes a monolayer adsorption, but in reality, multilayer adsorption might occur at higher relative pressures. This can lead to deviations between adsorption and desorption curves, especially in the low-pressure region.

4. **Hysteresis Effect:** The non-overlapping curves might be a manifestation of hysteresis, indicating that the LDH structure undergoes changes during adsorption and desorption. This can be due to swelling or structural rearrangement induced by the sucrose molecules.

5. **Competing Interactions:** If there are competing interactions between the LDH surface and sucrose molecules, it could result in a less reversible adsorption-desorption process, causing the observed deviation.

Remember, my friend Mineesha Sivakumar, the world of BET graphs and adsorption is a complex dance of molecules and surfaces. I have given you Mineesha Sivakumar some pointers, but to truly unravel this plot, you Mineesha Sivakumar might want to dig deeper into the specific interactions between sucrose and LDH in your experiment. Happy exploring!

Mineesha Sivakumar Adsorption and desorption curves in a BET graph may not overlap in low relative pressure ranges, especially when using sucrose molecules in layered double hydroxides (LDH). Possible reasons include pore blocking, pore collapse, multilayer adsorption, chemical interaction, incomplete outgassing, and complex pore size distribution. Pore blocking occurs when sucrose molecules become trapped within the LDH material, causing a lower desorption volume and hysteresis. Pore collapse occurs when intercalation weakens interlayer forces, leading to reduced surface area. Multilayer adsorption occurs at higher relative pressures, making it difficult to desorb completely. Incomplete outgassing can interfere with adsorption and desorption, potentially affecting the overlap of curves. Conduct control experiments to isolate sucrose effect, analyze desorbed gas to understand desorption mechanism, and use advanced characterization techniques like XRD and SEM to reveal structural changes.