The overall goal of this procedure is to demonstrate the utility of simple milli fluidic based lab on a chip devices for high throughput synthesis of nanomaterials time resolved investigation of their formation and demonstration of continuous flow catalysis. This is accomplished by first demonstrating the synthesis of copper nanoparticles using a milli fluidic reactor. Next, the formation of gold particles within the milli fluidic channel is visualized using time resolved in C two x-ray absorption spectroscopy in order to observe reaction intermediates.
In the final part, continuous flow catalysis is demonstrated by the conversion of four nitro phenol to four amphenol as it is flowed over gold nano structures within the milli fluidic chip. Ultimately, these three experiments demonstrate that simple milli fluidic systems offer opportunities for high throughput synthesis in C two investigation of formation and carrying out continuous flow catalysis. The main advantage of this technique or existing methods like traditional microfluidics, is that they can accommodate higher flow rates due to wider channels without compromising on fluid properties.
They also enable easier scale up of reacting volumes for larger scale synthesis, and they provide an effective platform for pro probing reactions in C two using different spectroscopy tools. This Method can help answer key questions in the field of flow-based devices, such as real time institute, monitoring of chemical reactions, mapping the growth of nanoparticles and kinetics of a catalytic reaction. For those researchers who are not familiar with lab on a chip devices, these experiments at first may seem a little complicated, but once they get familiarized, these are pretty easy to carry out and can be applied easily to their own unique investigations.
While these experiments are relatively simple to carry out, it's important to look at them visually first in order to understand the intricacies of these experiments, especially when you're carrying out in C two analysis of both synthesis of nanomaterials as well as for in C two catalytic probing. These reactions need to be observed carefully, so that's why the visualization is extremely important and the need for us to provide these visual observations To begin fabricate or purchase a milli fluidic chip like the one shown here with serpentine channels that are two millimeters wide, 0.15 millimeters high and 220 millimeters in length. Then connect the milli fluidic chip to a Mitoses P pump using FEP tubing with an inner diameter of 0.25 millimeters and an outer diameter of one 16th of an inch.
Regulate the P pump under nitrogen pressure for pulseless flow during the experiment. Next test the pumps using water as a solvent to correlate different pressures with their corresponding flow rates in milliliters per hour. Once calibrated, rinse the milli fluidic reactor and tubing with the ionized water before initiation of the experiment in a clean vial dissolve 174 milligrams of copper two nitrate and add 610 milligrams of 5, 000 molecular weight eg into 28 milliliters of nano pure water.
In a separate vial mix a solution consisting of 111 milligrams of sodium or hydride, and 102 milligrams of sodium hydroxide into 28 milliliters of nano pure water. This will result in a solution with a pH of around 13. Next, connect both solutions through the P pump to the milli fluidic device using separate input channels.
Flow both the solutions simultaneously within the milli fluidic reactor using 50 millibar of pressure. This will result in a combined flow rate of around 6.81 milliliters per hour. Collect two to three milliliters of the resulting ultra small copper nano clusters at the outlet in a glass vial.
Purge this resulting solution with nitrogen and store it under nitrogen as well. Repeat this process under different constant pressures of 100 millibar, 200 millibar and 300 millibar at room temperature for the synthesis of ultra small copper nano clusters at different flow rates. First, prepare a 10 millimole solution of chloro ORIC acid by adding 118.2 milligrams of gold.
Three chloride hydrate into 30 milliliters of nano pure water and a 20 millimoles solution of meso two three dimer CAPTO SIC acid or DMSA by adding 109.2 milligrams of it to 30 milliliters of nano pure water. Then add 50 milligrams of sodium hydroxide to the DMSA solution so that it reaches a pH of 12. Load the two solutions into separate syringes and place them into high precision, fully automated pulsation free pumps.
Then connect the pumps to the milli fluidic chip using tubing. Next couple the milli fluidic chip to the synchrotron beam line for X-ray absorption spectroscopy using a metal stage that has access to movement in the X, Y, and C directions. Feed the two solutions through the two separate syringes and into the milli fluidic chip at a constant flow rate of 10 milliliters per hour.
Using the automated pumps. Collect data at different zones shown here as zones one through five as the solutions are pumped through the chip. Prepare all gold catalyst solutions using nano pure water mix a 10 milli mole solution of chloro ORIC acid and a 20 milli mole solution of DMSA as previously shown.
Additionally, prepare a 10 millimoles solution of sodium oral hydride by adding 11.34 milligrams of it into 30 milliliters of water. Then transfer 10 milliliters each of the chloral ORIC acid and DMSA solutions into two separate vials and flow them within the chip using a handheld milli fluidic device with a uniform flow rate of 12 milliliters per hour for 45 minutes. Next, flow the 10 milli ole solution of sodium boro hydride within the chip at a 12 milliliter per hour flow rate for 15 minutes.
To reduce the gold one to gold zero, then wash the chip with nano pure water for 30 minutes at a flow rate of 12 milliliters per hour. Next, mix 15 milliliters of nine times 10 to the negative five molar solution of four nitro APH phenol with 3.3 milliliters of 0.65 molar sodium oral hydride. To form a solution of four nitro pholate ion connect this mixture to the Millie fluidic gold coated chamber via the input files.
Flow the solution through the prepared gold catalyst chamber at five milliliters per hour to reduce the solution of four nitro phenol to four amphenol within the coated milli fluidic channel and collect the flow through in a vial. Place three milliliters of the collected product into a UV visible spectrophotometer and measure the wavelength range of 250 to 500 nanometers. Compare the resulting spectrum to the original mixture to confirm the conversion of four nitro pholate.
Next, estimate the catalytic activity of the reaction by plotting the experimentally observed absorption intensity of four nitro pholate ion at different standard concentrations. The change in the 399 nanometer peak height represents a corresponding change in its concentration. Using a scanning electron microscope, the gold nanoparticle catalyst can be resolved from the surface of the milli fluidic channel.
A high gold surface area can be achieved using this process. The x-ray absorption near edge structure spectra shown here is reflective of the gold L three edge at zone three, zone five, and zone five. After 12 hours, the peak shows the presence of the precursor chloro orric acid, which has a gold three oxidation state.
As described earlier. The UV visible spectra can be used to determine the conversion of four nitro phenol to four amphenol. Shown here is a representative spectra of four nitro phenol, four nitro pholate ion, and four amphenol.
The rate of conversion of four NPH pholate ion to four amphenol without the presence of the gold catalyst is very poor compared to the same reactant with the gold catalyst. While attempting these experiments, one has to remember that the nanoparticles formed within the redic channels can also get attached to the channel vault Following this procedure. Other methods like in city investigation of cataly reactions can be performed in order to answer additional questions like time solve kinetics of a catalytic reaction.
