Simultaneous removal of cationic and anionic dyes from aqueous solution by double functional groups modified bagasse

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Industrial wastewater often contains a mixture of cationic and anionic dyes, posing significant treatment challenges.
• Bagasse, a lignocellulosic biomass, is an abundant and renewable resource with potential as an adsorbent material.
• Existing adsorbents may struggle with simultaneous removal of oppositely charged pollutants.

Purpose of the Study:

• To synthesize and characterize novel double functional groups modified bagasse (DFMBs) with both carboxyl and amine groups.
• To investigate the simultaneous adsorption performance of DFMBs for cationic (basic magenta) and anionic (Congo red) dyes.
• To explore the influence of functional group ratios on dye adsorption capacity and kinetics.

Main Methods:

• Grafting tetraethylenepentamine (TEPA) onto pyromellitic dianhydride (PMDA) modified bagasse using DCC/DMAP method.
• Fourier-transform infrared (FTIR) spectroscopy and Zeta potential analysis for material characterization.
• Batch adsorption experiments in single and binary dye systems to evaluate adsorption capacities and kinetics.

Main Results:

• Successful grafting of PMDA and TEPA onto bagasse confirmed by FTIR and Zeta potential.
• Adsorption capacity for cationic dye decreased while for anionic dye increased with higher TEPA dosage.
• Adsorption equilibrium was reached within 300 minutes, following pseudo-second-order kinetics.
• Electrostatic attraction and hydrogen bonding were identified as primary adsorption mechanisms.

Conclusions:

• DFMBs demonstrate effective simultaneous removal of cationic and anionic dyes from aqueous solutions.
• The ratio of carboxyl and amine groups can be tuned to optimize adsorption for specific dye mixtures.
• DFMBs present a viable and efficient adsorbent for treating wastewater containing mixed cationic and anionic dyes.