Desenvolvimento de tecnologia magnética de baixo custo para remoção de microplásticos usando Luffa Cylindrica

Abstract

Microplastics in the environment are becoming ubiquitous, and their widespread distribution in aquatic environments poses a global environmental concern. Given the rising trend of this contamination, it is necessary to develop removal technologies that combine efficiency with low cost. In this context, adsorption combined with magnetic separation emerges as a promising strategy, as it enables both the capture of microplastics (MPs) and the recovery of the adsorbent from the aqueous medium. Thus, this study aimed to develop and evaluate a magnetic bioadsorbent—designated LCMAGNaOH—composed of Luffa cylindrica (LC) fruit (commonly known as vegetable sponge) modified with NaOH and combined with natural micrometric magnetite (MAG), for the removal of polystyrene (PS) and polyethylene terephthalate (PET) microparticles. Synthesis was carried out without organic solvents and at temperatures below 100 °C. The resulting material was characterized using physicochemical and morphological techniques—including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD)—to assess its morphology and confirm the presence of the magnetite phase. The removal efficiency of LCMAGNaOH was evaluated using PS and PET MPs ranging from 75 to 600 µm in size across three aqueous matrices: drinking water, simulated seawater, and water collected from a eutrophic lake in Dourados, Mato Grosso do Sul, Brazil. Tests were conducted with short contact times and without continuous agitation, and residual MP concentrations were determined via ultraviolet-visible (UV-Vis) spectroscopy and gravimetry. Additionally, the stability of the magnetic phase, the recovery of the bioadsorbent via magnetic separation using a neodymium magnet, and its reusability over three cycles were evaluated. LCMAGNaOH demonstrated high removal capacity with a short contact time, achieving approximately 82% for PS and 81% for PET within 10 minutes. Magnetic separation also enabled the recovery of over 90% of the material mass, demonstrating the feasibility of its removal from the aqueous medium after treatment. The results show that LCMAGNaOH is an efficient magnetic bioadsorbent for capturing microplastics in various aqueous matrices, representing a promising strategy for microplastic removal in aquatic environments.magnetic separation, representing a promising strategy for microplastic removal in aqueous environments.