Heavy Metal Removal from Wastewater Using Poly(Gamma-Glutamic Acid)-Based Hydrogel

Area of Science:

• Environmental Science
• Materials Science
• Polymer Chemistry

Background:

• Heavy metal contamination in wastewater poses significant environmental and health risks.
• Poly(gamma-glutamic acid) (PGA) is a biocompatible, biodegradable polymer with functional groups suitable for metal ion binding.

Purpose of the Study:

• To develop and characterize water-insoluble PGA-based hydrogels for heavy metal ion removal.
• To investigate the adsorption performance and mechanisms of PGA hydrogels for toxic heavy metals.

Main Methods:

• Preparation and characterization of poly(gamma-glutamic acid) hydrogels.
• Adsorption experiments for Cu²⁺, Cr⁶⁺, and Zn²⁺ removal.
• Investigation of adsorption parameters (temperature, pH, concentration, time) and adsorption kinetics/isotherms.
• Analysis of adsorption mechanisms and hydrogel reusability.

Main Results:

• PGA hydrogels demonstrated effective adsorption of Cu²⁺, Cr⁶⁺, and Zn²⁺.
• Adsorption of Cu²⁺ was spontaneous, exothermic, and followed pseudo-first-order kinetics and Langmuir isotherm models.
• Adsorption mechanisms involved electrostatic and coordination interactions between Cu²⁺ and PGA functional groups.
• The hydrogel maintained high adsorption capacity for Cu²⁺ over five cycles, indicating excellent reusability.

Conclusions:

• PGA-based hydrogels are efficient and recyclable adsorbents for heavy metal removal from wastewater.
• The study highlights the potential of PGA hydrogels as a sustainable material for environmental remediation applications.