Dual functionality of partially hydrophobized SnO2 nanoparticles in PEPS for efficient elimination of diverse contaminants

The rapid growth of industries such as pharmaceuticals, textiles, and agriculture, combined with extensive petroleum use, has led to increased wastewater pollution with cyclic organic compounds (COCs) and fuels. To address these issues, new multifunctional materials for existing purification systems are needed. We propose using modified with fatty acids SnO2 nanoparticles to incorporate petroleum products into emulsions joint with photocatalytic decomposition of COCs. SnO2 photocatalyst nanoparticles were synthesized via a precipitation method and subsequent microwave-assisted hydrothermal treatment. Characterization included XRD, FTIR spectroscopy, TEM, SAED, BET, and absorption spectroscopy; oxygen vacancies and defects were assessed using XPS and Raman spectroscopy. Partial surface hydrophobization was performed using capric, lauric, and stearic acids in an aqueous medium under heating. It was established that maintaining the nanoparticle suspension under hydrothermal conditions leads to recrystallization while preserving size. Subsequent modification ensures partial surface hydrophobization, with a contact angle of no less than 110 degrees; the distribution of fatty acids on the surface was investigated using computational experiments revealing differences in optimal positioning of the modifier molecule on the SnO2 surface, and consequent differences in properties. Pickering emulsions with diesel fuel, stabilized by as-prepared samples, demonstrated superior stability over 7 days. Photocatalytic tests revealed that Methylene Blue and Congo Red dyes in the diesel fuel emulsion were decomposes under UV-irradiation within 10 and 30 min, respectively, with minimal by-products amount. Effective simultaneous separation of the photocatalyst and diesel fuel from purified water was achieved through filtration and emulsion breakdown.