Preparation and enhanced oil recovery study of amphiphilic Janus nanosheets

Abstract

This study introduced an innovative approach for the synthesis of amphiphilic Janus nanosheets. Thermally expandable microspheres (TEMS) were used as a template, and tetraethyl orthosilicate (TEOS) was used as a silicon source. Janus spheres with TEMS as the core and SiO2 as the shell (TEMS@SiO2) were synthesized under alkaline conditions. Janus spheres (TEMS@SiO2-NH2) were further modified by aminopropyltriethoxysilane (APTES). Janus nanosheets (SiO2-NH2) were obtained by heating to expand the TEMS. Amphiphilic Janus nanosheets C16-SiO2-NH2 (CSAJN) were prepared by modifying Janus nanosheets (SiO2-NH2) with hexadecyltrimethoxysilane (HDTMS). CSAJN was characterized by fourier transform infrared spectroscopy (FT-IR)、thermogravimetry (TG)、a laser particle size analyzer、scanning electron microscopy (SEM)、(tetraethyl orthosilicate) TEM、and a contact angle goniometer. The results indicated that CSAJN had a lamellar structure with a thickness of 41 nm and a size of 260 nm. The interfacial tension of CSAJN nanofluid (1000 mg/L) at the oil–water interface was 1.4 mN/m at 60 °C. CSAJN nanofluid (1000 mg/L) exhibited excellent emulsification ability at 60 °C, with an emulsification index of 0.68 over 240 h. CSAJN nanofluid (1000 mg/L) could maintain stability after 10 days. CSAJN nanofluid (1000 mg/L) demonstrated outstanding wetting properties, transforming from oil-wet to water-wet on core slices (103° to 39.4°). Compared to water flooding, CSAJN nanofluid (1000 mg/L) significantly enhanced oil recovery.