Tailoring Functionalized Lignin-Based Spherical Resins as Recyclable Adsorbents for Heavy Metal Uptake

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Industrial lignin waste presents a significant disposal challenge.
• Effective methods for heavy metal remediation are crucial for environmental protection.
• Developing sustainable adsorbents from waste materials is an active research area.

Purpose of the Study:

• To synthesize a novel mesoporous spherical chelating lignin-based adsorbent.
• To evaluate the adsorption performance of the synthesized material for heavy metal removal, specifically Pb2+.
• To explore the potential of valorizing industrial lignin waste into functional adsorbents.

Main Methods:

• Synthesis of the adsorbent using inverse suspension polymerization of sulfate pine pulping black liquor, followed by graft copolymerization and amination.
• Characterization of the adsorbent's morphology and active sites using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR).
• Conducting adsorption experiments to determine Pb2+ uptake capacity under various conditions and analyzing adsorption kinetics and isotherms.

Main Results:

• A well-defined porous spherical lignin-based resin (aminated cyanoethyl spherical lignin resin - ACSLR) with abundant active sites was successfully synthesized.
• The adsorbent demonstrated a high Pb2+ uptake capacity of 63.98 mg·g−1 under optimal conditions (pH 5.5, 2.0 g·L−1 adsorbent dosage, 150 mg·L−1 initial Pb2+ concentration).
• Adsorption followed Langmuir isotherm and pseudo-second-order kinetics, indicating chemisorption dominated by amino and cyano groups.

Conclusions:

• The novel lignin-based adsorbent efficiently removes Pb2+ from aqueous solutions.
• The synthesis provides a sustainable pathway for utilizing industrial lignin waste.
• The material shows significant potential for practical applications in wastewater treatment for heavy metal remediation.