Comparison Adsorption of Cd (II) onto Lignin and Polysaccharide-Based Polymers

Area of Science:

• Environmental Science
• Materials Science
• Biochemistry

Background:

• Heavy metals, such as cadmium (II) (Cd (II)), pose significant risks to ecosystems and human health.
• Conventional methods for heavy metal removal are often costly or inefficient for large-scale applications.
• Lignin, an abundant aromatic biopolymer from lignocellulosic biomass, presents a potential sustainable adsorbent.

Purpose of the Study:

• To evaluate the adsorption performance of unmodified Sarkanda grass lignin for Cd (II) removal from aqueous solutions.
• To compare lignin's efficiency with chemically functionalized and native polysaccharide polymers.
• To investigate the influence of experimental parameters on Cd (II) adsorption by lignin.

Main Methods:

• Static batch adsorption experiments were conducted.
• Adsorption equilibrium was modeled using Freundlich and Langmuir isotherms.
• Adsorption kinetics were analyzed using Lagergren I and Ho and McKay II models.
• Biological tests on tomato seeds (Lypercosium esculentum) assessed lignin's impact.

Main Results:

• Unmodified Sarkanda grass lignin demonstrated significant Cd (II) adsorption capacity.
• Lignin proved to be a cost-effective alternative to expensive polysaccharide adsorbents.
• Kinetic and isotherm models provided insights into the adsorption mechanism.
• Biological tests indicated lignin's potential for mitigating heavy metal stress on seeds.

Conclusions:

• Unmodified Sarkanda grass lignin is a promising, economical adsorbent for Cd (II) removal from aqueous solutions.
• Lignin can effectively replace less economical polysaccharide-based adsorbents in water treatment.
• Further research into lignin's application in heavy metal remediation is warranted.