The global production of plastics began in the 1950s with the aim of improving daily life. Various plastic products, such as packaging, disposable dishes, and device components, have become increasingly useful. However, most plastic products through out in the environment after use, either through wastewater discharge or improper disposal (Pham et al., 2021). Also, in the environment can be found microplastics, which are particles smaller than 5 mm. These particles are found in water, soil, and the atmosphere. Every year, tons of primary and secondary microplastics are released into aquatic ecosystems, including oceans, seas, rivers, and lakes (Henderson & Green, 2020). Due to their widespread distribution and potential toxicity to living organisms, it is crucial to explore effective methods for removing these particles from water. One way is to apply the sorption process by using natural materials from nature.
This study investigates the sorption of microplastic particles using lignin and lignin-magnetite nanomaterials. One of the most important sorption parameters are time and sorbent concentration. In order to understand the sorption behavior and mechanism, it is essential to analyze the kinetics and isotherms. Two kinetic models, the pseudo-first order and pseudo-second order models, were applied in this study. Additionally, Langmuir and Freundlich isotherms were used to examine the impact of sorbent concentration on the sorption.
The results showed that the sorption of both lignin and lignin-magnetite nanomaterials is best described by the pseudo-second-order kinetic model, as correlation coefficient (R²) values close to 1. The rate constants showed that the sorption reaction of lignin-magnetite in water occurs faster than that of lignin. Furthermore, theoretical sorption capacity values were found to be consistent with the experimental results. Sorption isotherms revealed the relationship between lignin and lignin-magnetite concentrations and their sorption capacities. The dominated sorption mechanism of both nanomaterials is chemisorption.