(708e) Effect of Surfactant in Continuous Milllifluidic Green Synthesis of One-Dimensional Silver Nanostructures Using Tannic Acid

Continuous flow processes for the synthesis of nanomaterials have been regarded as more versatile techniques compared to conventional batch processes as they allow better control over the synthesis process, and have a stronger potential for scale-up. Increased mass and heat transfer facilitated by their high surface-to-volume ratio with the ability to allow accurate flow control, and being inherently safer are among their other benefits. Millifluidic flow-reactors, compared to microfluidic chips, are typically more advantageous for particularly the synthesis of metallic nanostructures due to their significantly-lower cost, simpler design and installment procedures, and more resistance to fouling.

However, although millifluidic reactors are more resistant to fouling compared to microfluidic chips, they are still prone to fouling, which hinders the effective production of nanomaterials and affects the size and morphology of the synthesized nanostructures. One of the methods to overcome this issue is to entrap the movement of droplets in order to minimize the interaction of synthesis species with the reactor inner wall. This allows a more accurate control over the synthesis process that is being confined within tiny milli-droplets. This is often facilitated by a secondary-phase flow (e.g. silicone oil) that is inert, and immiscible with water. However, it is highly likely that the synthesized nanoparticles migrate to the water-oil boundary, and resulting in less nanoparticles being present in the aqueous phase, thus limiting the production rate. One particular way to address this issue is to use a non-ionic surfactant that can prevent the diffusion of nanoparticles to the oil-water boundary. In this work, we report the synthesis of silver nanowires (AgNWs) via the millifluidic system by using tannic acid as both the reducing and capping agent, and silicone oil as the secondary-phase flow. We investigate how the synthesis of silver nanowires is affected both with and without the presence of the surfactant (triton X-100). In addition, different flow patterns, flowrates, and other conditions (i.e. pH, tannic acid concentration, and silver precursor concentration) are investigated to observe how the yield of silver nanowires is affected.

The characterization tools used to analyze the resultant silver nanostructures are Ultraviolet–visible Spectroscopy (UV-vis), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy Dispersive X-Ray (EDX). The yield of synthesized AgNWs in continuous millifluidic reactor using surfactant is also compared with batch reactor.