Application of gradient acid fractionation protocol to improve decolorization technology by lignin-based adsorbent

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Industrial wastewater frequently contains hazardous dyes, necessitating effective removal methods.
• Lignin, a readily available biopolymer, presents a sustainable source for developing novel adsorbents.
• Conventional dye removal techniques often involve high costs and environmental concerns.

Purpose of the Study:

• To develop and characterize low-cost, eco-friendly lignin-based adsorbents for methylene blue (MB) removal.
• To investigate the influence of structural differences on adsorption performance.
• To evaluate the pH responsiveness of the developed adsorbents.

Main Methods:

• Three lignin-based adsorbents (APKL-4, APKL-5, APKL-6) were synthesized using gradient acid precipitation.
• Adsorbent characterization was performed using SEM, FT-IR, and zeta potential analysis.
• Methylene blue adsorption experiments were conducted under varying conditions, including pH.

Main Results:

• Structural variations due to fractionation led to distinct adsorption behaviors among the adsorbents.
• APKL-5 and APKL-6 exhibited enhanced MB loading capacity due to fewer hydrophilic groups.
• APKL-5 showed a significant 3.8-fold increase in adsorption capacity (345 to 1310 mg g⁻¹) in alkaline solutions, indicating excellent pH responsiveness.
• A unique pore structure in APKL-5 facilitated higher MB uptake.

Conclusions:

• Lignin-based adsorbents, particularly APKL-5, offer a promising, cost-effective, and environmentally friendly solution for dye wastewater treatment.
• The pH responsiveness of APKL-5 opens avenues for tunable and efficient dye removal processes.
• This research lays the groundwork for broader applications of lignin-derived materials in environmental remediation.