Comparative study of copper sulfide hydrophobic textile treatment: hierarchical structures versus nanostructures

Abstract This study compares membranes coated with hierarchical structures and copper sulfide nanostructures for water and oil separation. Copper was synthesized by a REDOX reaction, followed by sulfidation by a solid vapor method to produce copper sulfide hierarchical structures. A high-energy mechanical milling process was then applied to obtain copper sulfide nanostructures. Both types of copper sulfide structures were applied to cotton textiles by a dip coating method with varying copper sulfide concentrations (1–4%). The morphology of copper sulfide was characterized by scanning electron microscopy before and after milling, and the coated membranes were also analyzed to confirm the presence of polydimethylsiloxane (PDMS) and copper sulfide. Fourier transform infrared spectroscopy analysis confirmed the presence of PDMS and copper sulfide through their characteristic functional groups, while X-ray diffraction analysis confirmed the formation of the anilite phase. Membranes with hierarchical copper sulfide structures and copper sulfide nanostructures showed high hydrophobicity and stability through multiple filtration cycles. Contact angle measurements showed that copper sulfide nanostructure coatings provided a higher degree of hydrophobicity, achieving superhydrophobic angles of 155–165°, depending on the concentration. In contrast, membranes with hierarchical structures exhibited slightly lower hydrophobicity, with contact angles ranging from 146° to 154°. Filtration tests further supported these findings: membranes with copper sulfide nanostructures retained 96% efficiency even after ten cycles, while those with hierarchical structures dropped to 87%, underscoring the superior durability and performance of copper sulfide nanostructured membranes for separation applications.