Removal of Cu(2+) by biochars derived from green macroalgae

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Copper contamination in aqueous solutions poses environmental and health risks.
• Fast pyrolysis of biomass, like the green macroalga Enteromorpha compressa, generates char as a byproduct.
• Developing efficient and sustainable adsorbents for heavy metal removal is crucial.

Purpose of the Study:

• To investigate the efficacy of Enteromorpha compressa char as an adsorbent for copper removal from aqueous solutions.
• To evaluate the impact of steam activation on the char's adsorption properties.
• To elucidate the adsorption mechanisms and model the adsorption kinetics and equilibrium.

Main Methods:

• Fast pyrolysis of Enteromorpha compressa to produce char.
• Steam activation of the char to enhance surface properties.
• Batch adsorption experiments to determine copper removal efficiency.
• Analysis using pseudo-second-order kinetic and Langmuir isotherm models.

Main Results:

• Steam activation significantly increased the surface area and cation exchange capacity (CEC) of the char, enhancing adsorption.
• Chemical activation with KOH increased pore volume and surface area but decreased adsorption capacity due to reduced CEC.
• Ion exchange and functional group adsorption were identified as key removal mechanisms.
• The maximum copper adsorption capacity of the char reached 137 mg/g.
• Adsorption kinetics and equilibrium were well described by pseudo-second-order and Langmuir models, respectively.

Conclusions:

• Enteromorpha compressa char, particularly after steam activation, is a promising adsorbent for copper removal.
• Steam activation is a more effective method than KOH activation for enhancing copper adsorption capacity.
• The study provides insights into the mechanisms and modeling of copper adsorption onto algal char.
• This research highlights the potential of utilizing algal biomass waste for environmental remediation.