Nanodiamonds Dispersed in Aqueous Suspension with Sonication

Nanodiamond dispersions are efficient and quickly produced using ultrasonic dispersers. Ultrasonic deaggregation and dispersion of nanodiamonds can be reliably performed in an aqueous suspension. The ultrasonic dispersion technique uses salt for pH modification and is thereby a facile, inexpensive, and contaminant-free technique, which can be easily used on industrial scale.

Ultrasonically dispersed nanodiamonds in aqueous colloidal suspension using Hielscher Ultrasonics probe-type homogenizers.

Nanodiamonds can be efficient and reliably dispersed using Hielscher ultrasonicators.

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Ultrasonic milling and dispersing is an efficient method to produce nanodiamond slurries.

Ultrasonic flow-through reactors for industrial inline production of aqueous nanodiamond slurries.

How Does Ultrasonic Milling and Dispersion of Nanodiamonds Work?

Ultrasonic dispersion uses the nanodiamonds itself as milling media. Acoustic cavitation generated by high-power ultrasound waves creates high-speed liquid streaming. These liquid streams accelerate the particles (e.g., diamonds) in the slurry so that the particles collide with up to 280km/s and shatter into minute nano-sized particles. This makes ultrasonicmilling and dispersion a facile, inexpensive, and contaminant-free technique, which reliably deagglomerates nanodiamond into nano-sized particles stable in aqueous colloidal solution in a wide pH range. Salt (sodium chloride) is utilized to stabilize the nanodiamonds in an aqueous slurry.


Ultrasonic Dispersion of Carbon Nanotubes: The Hielscher ultrasonicator UP400S (400W) disperses and detangles CNTs fast and efficiently into single nanotubes.

Dispersing of Carbon Nanotubes in Water using the UP400S

Advantages of Ultrasonic Nanodiamond Dispersion:

  • highly efficient nano-sized dispersion
  • rapid
  • non-toxic, solvent-free
  • no difficult-to-remove impurities
  • energy- and cost-saving
  • linear scalability to any production size
  • environmental-friendly

Ultrasonic Nanodiamond Milling Excels Bead Mills

Probe-type ultrasonicators are highly efficacious mills and are an established milling technique for the large-scale production of nanodiamond suspensions on industrial scale. Since ultrasonic mills utilize the nanodiamonds as milling media, contamination through milling media, e.g. from zirconia beads, is completely avoided. Instead, ultrasonic cavitational forces accelerate the particles so that the nanodiamonds collide violently with each other and break down to uniform nano-size. This ultrasonically induced interparticle collision is a highly efficient and reliable method for the production of uniformly distributed nanodispersions.
The ultrasonic dispersion and deaggregation method uses water-soluble, nontoxic, and non-contaminating additives such as sodium chloride or sucrose for pH regulation and stabilization of the ultrasonic dispersion. These crystal structures of sodium chloride or sucrose act additionally as milling media thereby supporting the ultrasonic milling procedure. When the milling process is completed, this additives can be easily removed by a simple rinsing with water, whichis a remarkable advantage over a process ceramic beads. Traditional bead milling such as attritors use insoluble ceramic milling media (e.g. balls, beads, or pearls), whose abrased residuals contaminate the final dispersion. Removal of contamination caused by milling media involves complex after-processing and is time-consuming as well as costly.

Ultrasonically dispersed nanodiamonds in aqueous colloidal suspension

Ultrasonic dispersing technology efficaciously produces aqueous nanodiamond suspensions with narrow particle size distribution.
(Study and graphic: ©Turcheniuk et al., 2016)

Probe-type ultrasonicator UP400St for nanodiamond dispersion in water-based suspension.

UP400St ultrasonicator dispersing nanodiamonds in aqueous colloidal solution


 

Particle size reduction of nanodiamonds under ultrasonication using the ultrasonic homogenizer UIP1000hdT.

Particle size reduction of nanodiamonds with the ultrasonicator UIP1000hdT. The red curve shows the unsonicated sample, the other curves demonstrate the progressing dispersion process with increasing ultrasound energy input.

Exemplary Protocol for Ultrasonic Nanodiamond Dispersion

Salt-Assisted Ultrasonic Deaggregation of Nanodiamonds in Water:
A mixture of 10 g of sodium chloride and 0.250 g of nanodiamond powder was briefly ground by hand using a porcelain mortar and pestle and placed into a 20 mL glass vial along with 5 mL of DI water. The prepared sample was sonicated using a probe-type ultrasonicator for 100 min at 60% output power and 50% duty cycle. After sonication, the sample was equally split between two 50 mL plastic Falcon centrifuge tubes and dispersed in distilled water up to 100 mL total volume (2 × 50 mL). Each sample was then centrifuged using an Eppendorf centrifuge 5810-R at 4000 rpm and 25°C for 10 min, and the clear supernatant was discarded. The wet ND precipitates were then re-dispersed in distilled water (100 mL total volume) and centrifuged a second time at 12000 rpm and 25 °C for 1 h. Once again the clear supernatant was discarded and the wet nanodiamond precipitates were re-dispersed, this time in 5 mL of distilled water for characterization. A standard AgNO3 assay showed complete absence of Cl in salt-assisted ultrasonically deag
gregated nanodiamonds washed with distilled water twice as described above. After evaporation of water from the samples, formation of black solid nanodiamond “chips” was observed with a yield of ∼200 mg or 80% of the initial nanodiamond mass. (see picture below)
(cf. Turcheniuk et al., 2016)

Dried sample od ultrasonically dispersed nanodiamonds

Dried sample od ultrasonically dispersed nanodiamonds.
(Study and graphic: ©Turcheniuk et al., 2016)

Ultrasonicator UP200St (200W) dispersing carbon black in water using 1%wt Tween80 as surfactant.

Ultrasonic Dispersion of Carbon Black using the ultrasonicator UP200St


 

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High-Performance Ultrasonicators for Nanodiamond Dispersions

Ultrasonic flow cell with 4x 4kW power-ultrasound for nanodiamond dispersions.Hielscher Ultrasonics designs, manufactures and distributes high-performance ultrasonic milling and dispersing equipment for heavy-duty applications such as the manufacturing of nanodiamond slurries, polishing media and nanocomposites. Hielscher ultrasonicators are used world-wide for dispersing nano-materials into aqueous colloidal suspensions, polymers, resins, coatings, and other high-performance materials.
Hielscher ultrasonic dispersers are reliable and efficient in processing low to high viscosities. Depending on the input materials and the targeted final particle size, ultrasonic intensity can be precisely adjusted for optimal process results.
In order to process viscous pastes, nano-materials and high solid concentrations, the ultrasonic disperser must be capable to produce continuously high amplitudes. Hielscher Ultrasonics’ industrial ultrasonic processors can deliver very high amplitudes in continuous operation under full load. Amplitudes of up to 200µm can be easily run in 24/7 operation. The option to operate an ultrasonic disperser at high amplitudes and to adjust the amplitude precisely is necessary to adapt the ultrasonic process conditions for the optimum formulation of highly filled nano-slurries, nano-reinforced polymer mixtures and nanocomposites.
Besides the ultrasonic amplitude, pressure is another very important process parameter. Under elevated pressures, the intensity of ultrasonic cavitation and its shear forces is intensified. Hielscher’s ultrasonic reactors can be pressurized thereby obtaining intensified sonication results.
Hielscher ultrasonicators can be remotely controlled via browser control. Sonication parameters can be monitored and adjusted precisely to the process requirements.Process monitoring and data recording are important for continuous process standardization and product quality. Pluggable pressure and temperature sensors wire to the ultrasonic generator for monitoring and controlling the ultrasonic dispersion process. All important processing parameters such as ultrasonic energy (net + total), temperature, pressure and time are automatically protocolled and stored onto a built-in SD-card. By accessing the automatically recorded process data, you can revise previous sonication runs and evaluate the process results.
Another user-friendly feature is the browser remote control of our digital ultrasonic systems. Via remote browser control you can start, stop, adjust and monitor your ultrasonic processor remotely from anywhere.
Contact us now to learn more about our high-performance ultrasonic homogenizers for milling and nano-dispersions!
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:

Batch Volume Flow Rate Recommended Devices
1 to 500mL 10 to 200mL/min UP100H
10 to 2000mL 20 to 400mL/min UP200Ht, UP400St
0.1 to 20L 0.2 to 4L/min UIP2000hdT
10 to 100L 2 to 10L/min UIP4000hdT
15 to 150L 3 to 15L/min UIP6000hdT
n.a. 10 to 100L/min UIP16000
n.a. larger cluster of UIP16000

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In this video we show you a 2 kilowatt ultrasonic system for inline operation in a purgeable cabinet. Hielscher supplies ultrasonic equipment to almost all industries, such as the chemical industry, pharmaceutical, cosmetics, petrochemical processes as well as for solvent based extraction processes. This purgeable stainless steel cabinet is designed for operation in hazardous areas. For this purpose, the sealed cabinet can be purged by the customer with nitrogen or fresh air to prevent flammable gases or vapors from entering the cabinet.

2x 1000 Watts Ultrasonicators in Purgeable Cabinet for Installation in Hazardous Areas

Ultrasonic high-shear homogenizers are used in lab, bench-top, pilot and industrial processing.

Hielscher Ultrasonics manufactures high-performance ultrasonic homogenizers for mixing applications, dispersion, emulsification and extraction on lab, pilot and industrial scale.



Literature / References


High performance ultrasonics! Hielscher's product range covers the full spectrum from the compact lab ultrasonicator over bench-top units to full-industrial ultrasonic systems.

Hielscher Ultrasonics manufactures high-performance ultrasonic homogenizers from lab to industrial size.