Surfactant effects on the synthesis of durable tin-oxide nanoparticles and its exploitation as a recyclable catalyst for the elimination of toxic dye: a green and efficient approach for wastewater treatment

Abstract

A green synthesis of SnO₂ nanoparticles was successfully developed using urea by a microwave heating method. This method resulted in the formation of spherical, microcrystalline SnO₂ nanoparticles with an average size of ∼4.0 nm. The role of cationic and non-ionic surfactants, namely cetyl pyridinium chloride (CPC) and triton X-100, in the synthesis of SnO₂ nanoparticles are investigated. In this reaction, surfactants act as capping agents. The addition of a surfactant along with urea leads to the formation of spherical and microcrystalline SnO₂ nanoparticles. The average particle size of the CPC assisted SnO₂ nanoparticles is ∼4.5 nm, while that of triton X-100 assisted SnO₂ nanoparticles is ∼5.8 nm. An increase in band gap energy is observed with a decrease in particle size because of three dimensional quantum confinement effect shown by synthesized SnO₂ nanoparticles in their electronic spectra. The band gap energy of SnO₂ nanoparticles synthesized using urea is ∼4.30 eV, whereas that of CPC assisted SnO₂ nanoparticles and triton X-100 assisted SnO₂ nanoparticles are ∼4.25 and ∼4.15 eV, respectively. The synthesized SnO₂ nanoparticles were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transformed infrared spectroscopy (FT-IR). The optical properties were investigated using UV-visible spectroscopy. The synthesized SnO₂ nanoparticles act to be an efficient photocatalyst in the degradation of rhodamine B and methyl violet 6B dye under direct sunlight. For the first time, methyl violet 6B and rhodamine B dye were degraded by solar irradiation using SnO₂ nanoparticles as catalyst.