Published on July 31, 2007
Silver nano-particles are now widely used in various kinds of products. When coated on other materials including textiles, kitchenware or medical devices, they provide anti-bacterial features.
Many manufacturers who want to add value to their products have to import silver nano-particles from abroard. With this expense, the cost of production increases.
To assist import substitution, a group of researchers from the Sensor Research Unit at the Faculty of Science, Chulalongkorn University, has found a technique to develop silver nano-particles. The team spent six months discovering a unique process for silver nano-particle production and two months ago they came up with a stable process which can mass produce the particles commercially, according to the project leader Sanong Ekgasit.
By using a technique which is now in the patent-registration process, to produce the nano-size silver particles, the team synthesised silver nano-particles at concentrations between 10 and 100,000 parts per million (ppm) depending on their ultimate purpose.
The team has come up with the development of three nano-particle product lines.
The first is particles for general use. Sanong said these are built at between five and 50 nanometres and could be coated on various kinds of materials including textiles and kitchenware, or even mixed with water to develop a new germ-free spray product for hygiene purposes.
As the synthesis produces yellow particles, in the textiles industry they can be used with coloured textiles, not white textiles, he added. As a result of this limitation, the team then decided to develop a new technique to make the particles with no colour.
Sanong said the team had worked with Nanyan Textiles, a local textile manufacturer, to develop a process to produce colourless silver nano-particles, which were coated on white textiles in particular.
With no colour, when coated on white textiles, the materials retain their original colour but have new anti-bacterial features, he added.
The team can now produce colourless silver nano particles of between 0.1 and 0.5 nanometres, and the technology is now licensed to Nanyan Textiles for use in its products.
The third product is the development of a silver-ion cluster, another kind of silver nano-particle that is used by the textiles industry. Unlike the first two products, which come with neutral ions, this third one has a positive ion and it is associated with three atoms under a clustering model. With this characteristic, the product can be kept longer with no change of properties from any chemical reaction.
Apart from Nanyan Textiles, the team's silver nano-particle synthesis process has also been licensed to a local strainer-manufacturer, which plans to coat silver nano-particles on its filters to make the strainers germ free.
Sanong said having its own technology to produce silver nano-particles would help the country to reduce product imports and boost the adoption of nanotechnology in industry.
Compared to imported silver nano-particle products, the project leader said locally made nano-particles could be 30 times cheaper.
The team is studying putting the synthesis process into real commercial use.
Sanong said the team had also developed a new reactor, an instrument for the nano-particle synthesis process, to serve a production capacity of 10,000 ppm silver nano-particles at 20 litres per hour, increasing from the existing lab-scale reactor, which can synthesise nano-particles at one litre per hour.
"With this new reactor technology, we believe we can synthesise silver nano-particles on a mass-production scale," he said.
Technology developed in the research unit is now at the business-development stage. Sanong said a business model would come in two types - as technology licensing, which would be overseen by Chulalongkorn University Intellectual Property Institute, and for sale as a product through the university's Chamchuree company.