A deeper insight into the evaluation of water-in-oil amicroemulsion templated samarium sulfide nanospheres: exploring its role in pickering emulsion formulation for photocatalytic dye degradation and synthesis of PANI@Sm2S3 nanocomposites

Abstract

This study examines the effectiveness of W/O microemulsion-mediated Sm₂S₃ nanospheres in pickering emulsion-based crystal violet (CV) dye degradation and PANI@Sm₂S₃ nanocomposite synthesis. The evaluation of nanospheres inside the core of reverse micelles was performed through DLS, TEM and FESEM analyses. The formation of nanospheres involve two phases: a nucleation phase (5-30 min) and growth phase (30-120 min). Through in situ hydrophobization of negatively charged (with a zeta value of -4.47 mV at neutral pH) Sm₂S₃ nanoparticles (0.1 wt%) with a suitable amount of a cationic CTAB surfactant, a stable O/W pickering emulsion was developed. 0.1 wt% Sm₂S₃in situ hydrophobized with 2.7 mM CTAB offered a stable pickering emulsion with a diameter of 23 μm after 1 day of storage. This pickering emulsion improves the local concentration of CV by efficiently encapsulating dye molecules inside the core of emulsion droplets. Therefore, dye molecules get numerous opportunities to interact with the Sm₂S₃ photocatalyst and efficiently degrade. The pickering emulsion stabilised by 0.1 wt% of Sm₂S₃ nanoparticles in situ hydrophobized with 2.7 mM of CTAB results in almost 100% degradation. Moreover, using only solid Sm₂S₃ (having wt% of 0.025 or 0.075) as a pickering stabiliser, new PANI@Sm₂S₃ spherical nanocomposites were synthesised via pickering emulsion polymerization. The formation of PANI@Sm₂S₃ composites was identified via UV-vis, IR, and ¹H-NMR investigations. The analysis of FESEM images showed that the amount of nanoparticles used in the dispersion (for 0.025 wt%, 35 nm and 0.075 wt%, 29 nm) strongly influences the size and shape of the composites.