Relation between the adsorbed quantity and the immersion enthalpy in catechol aqueous solutions on activated carbons

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Activated carbon is a widely used adsorbent for water purification.
• Catechol is a phenolic compound with potential environmental and health impacts.
• Surface modification of activated carbon can enhance its adsorption properties.

Purpose of the Study:

• To investigate the effect of chemical and thermal modification of activated carbon on catechol adsorption.
• To evaluate the influence of solution pH on the adsorption of catechol onto modified activated carbons.
• To understand the solid-solution interaction through immersion enthalpy measurements.

Main Methods:

• Chemical and thermal treatment of activated carbon (Carbochem(TM)-PS230) with H(2).
• Adsorption isotherm studies at 298 K and pH 7, 9, and 11.
• Measurement of immersion enthalpies of activated carbon in catechol solutions.

Main Results:

• Adsorption capacity of activated carbon for catechol increases as solution pH decreases.
• Reduced activated carbon showed higher catechol retention near its maximum adsorption pH compared to oxidized carbon.
• Immersion enthalpy values correlate positively with the amount of catechol retained, indicating stronger solid-solution interactions at higher adsorption levels.

Conclusions:

• Surface chemistry modifications of activated carbon significantly impact catechol adsorption.
• Solution pH is a critical factor controlling catechol adsorption, with acidic conditions favoring higher adsorption.
• Immersion enthalpy is a useful thermodynamic parameter for characterizing the adsorption process and solid-solution interactions.