Adsorption of Reactive Red 120 Dye by Polyamide Nylon 6 Microplastics: Isotherm, Kinetic, and Thermodynamic Analysis

In this work, we investigated the effect of various adsorption parameters (solution pH, temperature, contact time, and the presence of phosphate and nitrate ions) on the adsorption of Reactive Red 120 (RR120) dye by Polyamide Nylon 6 (PN6) microplastics (MPs). Maximum uptake was achieved at pH 2.0, and the temperature rise from 295 to 313 K resulted in the decrease of the RR120 sorption by PN6. Equilibrium was achieved after 7 h, and the adsorption kinetic data obeyed the pseudo-second-order kinetic model. The experimental adsorption data were better fitted by the Langmuir isotherm model, and the q(m) was found to be 3.96 mg/g at pH 2.0 and 295 K. Thermodynamic studies pointed out that the adsorption was spontaneous and exothermic, with decreasing entropy at the solution/solid interface. Future work will focus on the effect of aging on the adsorptive properties of PN6 toward RR120 dye.

Automated summary

This study investigated the impact of parameters such as solution pH, temperature, contact time, and the presence of phosphate and nitrate ions on the adsorption of Reactive Red 120 dye by Polyamide Nylon 6 microplastics. The highest uptake was observed at pH 2.0, while increasing temperature led to decreased sorption. Equilibrium was reached after 7 hours, and the adsorption followed a pseudo-second-order kinetic model. The Langmuir isotherm model provided the best fit for the experimental data, with a maximum adsorption capacity of 3.96 mg/g at pH 2.0 and 295 K. Thermodynamic analysis indicated that the adsorption process was spontaneous, exothermic, and associated with a decrease in entropy at the solution/solid interface. Future studies will explore the impact of aging on the adsorptive properties of Polyamide Nylon 6 towards Reactive Red 120 dye.