Synergistic effect between montmorillonite and imidazolium-functionalized carboxylate-based polyelectrolyte for enhancing the removal of methylene blue

The composite of montmorillonite (Mt) and novel imidazolium-functionalized carboxylate-based polyelectrolyte (P(NaAA/VIC)) was formed through the bridging interaction of zwitterionic groups, enabling efficient and rapid removal of industrial cationic dye methylene blue (MB) from aqueous solution. The removal rate of pure P (NaAA/VIC) was difficult to reach 90%, while P(NaAA/VIC)/Mt composites achieved the removal rate of more than 95%. The substantial improvements of removal rate were attributed to the formation of larger adsorbed aggregates, facilitating easy separation. Importantly, Mt laminae, as a rigid structure, could effectively prevent molecular chain of polyelectrolyte curling due to electrostatic shielding after adsorption, which made the adsorption sites play a full role, thus enhancing the adsorption efficiency. The maximum adsorption capacity of composite (80 wt% P(NaAA/VIC) and 20 wt% Mt) was increased by about 20% compared with pure P(NaAA/ VIC). And the excessive zwitterionic groups in polyelectrolyte would lead to a decrease in adsorption capacity. The systematic investigation revealed that the adsorption was a spontaneous exothermic process driven by electrostatic interactions, conforming to the pseudo-second-order kinetic model, in which the adsorption was monolayer coverage. The composite can achieve an high adsorption capacity of 1381.7 mg/g at 20 degrees C, demonstrating enormous potential in the treatment of cationic dye wastewater.

Automated summary

The composite of montmorillonite and novel imidazolium-functionalized carboxylate-based polyelectrolyte showed efficient and rapid removal of cationic dye from aqueous solution. The presence of montmorillonite and rigid structure prevented molecular chain curling, enhancing adsorption efficiency. The composite demonstrated high adsorption capacity and potential in wastewater treatment.