I studied the adsorption of methylene blue by fongic biomass, i found that adsorption capacity of the biomass decreases in increasing temperature from 20°C to 40°C, is that useful in wastewater treatment, and how can I explain that phenomenon?
Generally, as temperature increases, the adsorption capacity decreases due to the following reasons:
Energy Content
As the temperature rises, the energy content increases, therefore, the adsorbent requires more energy to remain in a liquid state, thus directly affecting the adsorption balance.
Saturated Vapour Pressure
As the temperature rises, the vapour pressure increases making it more difficult to keep the adsorbent in its liquid state.
Adsorbate Density
As the temperature rises, the density of the adsorbent decreases.
The decrease of sorption effectiveness caused by increased temperature indicated the exothermic nature of the sorption process.
The adsorption capacity may increase or decrease at higher temperatures, It all depends on the nature of the reaction and other controlling variables. If the reaction process is endothermic then adsorption may increase at higher temperature. This may be attributed to increased surface coverage at higher temperature, expansion and creation of reactive and active sites. Where the reaction is exothermic, then you may have a decrease in adsorption as at higher temperature. Therefore, you may want to double check the enthalpy and entropy values at different temperatures
Hello Mohamed,
Effect of temperature on the capacity of adsorbent, Qo, indicates whether the adsorption process is endothermic or exothermic. If Qo increases with increase in temperature, then the adsorption process is endothermic, and if Qo decreases with increase in temperature, then it denotes an exothermic reaction. further more if one does the batch experiment at different temperatures and plots Ks versus 1/T (T in Kelvin) one can determine thermodynamic constants such as delta H, delta G and delta S. For endothermic process, delta H decreases with increase in temperature, while delta G also decreases with increase in temperature. For exothermic processes, delta H increases with increase in temperature and delta G increases with increase in temperature. In your case since the adsorption capacity decreases with increase in temperature, it indicates an exothermic process. Plot the data in a graph of Kd versus 1/T and calculate thermodynamic constants and draw conclusions from the data.
- Badges
- Science topic
- Similar topics
- Social Psychology
- Attitude