Dual-Functional Evaporator: Synergistic Seawater Purification via Photothermal Evaporation and Microplastic Adsorption

Abstract

Freshwater scarcity and microplastic (MP) pollution are two pressing challenges that urgently demand solutions. Integrating solar-driven interfacial evaporation with MP adsorption provides an effective approach for seawater purification. In this work, we fabricated a dual-functional synergistic solar evaporator. This system simultaneously achieves MP adsorption and seawater desalination, overcoming the single-functional water treatment objective of traditional evaporators to establish a composite water purification system. This work assembled PEI-coated viscose fibers, hydrophilic cotton fabric, and a PTFE photothermal layer through sewing techniques. The resulting evaporator features a hydrophobic top layer and a bottom layer that is capable of supplying water and adsorbing MPs. Under 1 kW m^–2 irradiation, the evaporator achieved an evaporation rate of 2.18 kg·m^–2·h^–1 while demonstrating good long-term stability in saline water. Additionally, it exhibits 99.20% adsorption efficiency for low-concentration MPs in water. Notably, the condensate produced by the evaporator contains no MPs due to the double-layer structure separating the adsorption unit and the photothermal component. Therefore, the designed evaporator demonstrates promising potential not only to alleviate freshwater scarcity but also to effectively remove MPs from aquatic environments.