VATIS UPDATE Article

A team of researchers from Shandong University (SDU), China, have developed a novel dye absorbent called hybrid nano-particles of silver and silver sulfide (Ag2S@Ag hybrid nano-particles) using laser-induced fabrication technique and demonstrated the nanomaterial’s superior adsorption performance for removing methyl blue and methyl orange from wastewater. The new adsorbents can be removed directly from solutions by filters without absorbent purification procedures, as the silver-based hybrid nano-particles will be agglomerated and deposited on the bottom after adsorbing dyes, providing a simple solution for water purification.

“Without using any expensive chemical reagents or facilities, the laser-induced fabrication method is a low-cost and versatile route for fabricating Ag2S@Ag hybrid nano-crystals. After adsorbing dyes such as methyl blue and methyl orange, the agglomerated and deposited adsorbents can be easily removed from solutions by filters, which are very beneficial to the practical wastewater treatment plants,” said Ming Chen, at SDU. Chen’s team used a technique called laser ablation to fabricate silver-based hybrid nano-crystals in liquid, which is a process of removing materials from a solid or liquid surface by irradiating it with a laser beam.

The team’s early study showed that the electron distribution of the highly excited silver species can be influenced by Ag2S@Ag nanoparticles, resulting in “polarized” silver species, or silver species with positive charges as dye adsorption sites. Since dye molecules such as methyl blue and methyl orange have negatively charged functional groups, due to strong electrostatic force between positive charges and negative charges, the enhanced adsorption sites on the hybrid material’s surface will stick more dye molecules, leading to the material’s enhanced capability of removing dyes.