Surface complexation mechanism and modeling in Cr(III) biosorption by a microalgal isolate, Chlorella miniata

Area of Science:

• Environmental Science
• Biotechnology
• Water Treatment

Background:

• Chromium(III) is a toxic heavy metal pollutant.
• Microalgae show potential for heavy metal remediation.
• Understanding biosorption mechanisms is crucial for effective water treatment.

Purpose of the Study:

• To investigate the mechanism of Cr(III) removal by Chlorella miniata.
• To determine the optimal pH and sorption capacity for Cr(III) biosorption.
• To identify the functional groups involved in Cr(III) uptake.

Main Methods:

• Batch experiments were conducted to study Cr(III) biosorption.
• Microscopic analyses (SEM, TEM, EDX) were used to examine biosorbent-surface interactions.
• Potentiometric titration and surface complexation modeling were employed to identify functional groups and binding mechanisms.

Main Results:

• Cr(III) biosorption increased with pH from 2.0 to 4.5, with maximum sorption capacities ranging from 14.17 to 41.12 mg g(-1).
• Surface complexation was confirmed as the primary removal mechanism.
• Carboxyl, phosphonate, and amine groups were identified as binding sites, with carboxyl groups playing a dominant role.

Conclusions:

• Chlorella miniata is an effective biosorbent for Cr(III) removal.
• Surface complexation, particularly involving carboxyl groups, is the key mechanism.
• The study provides insights for optimizing microalgal-based wastewater treatment for chromium contamination.