Particle technology

We are working on the synthesis of materials in the form of particles by electrochemical and sol-gel method. Why such form of materials is important. Here we will discuss briefly about it.

Perhaps we don’t realize that everyday we deal with products in the form of particles or powders. Most women and girls are familiar with cosmetics such as face powders, lipstick and moisturizer. Such cosmetics include particulate materials or emulsions that require control and measurement of particle size. If they are well controlled, foundation can fully cover face skin while powder assists the function of foundation by providing additional specific appearance by reflecting light into colors that make skin brighter or diffuse light evenly on skin surface. In addition to enhance skin appearance, face powder can also provide protection against sunlight by incorporating a strong light scattering component such as zinc oxide. The particle size distribution of the component influences appearance, stability and protection against sunlight.

Cosmetics (upper left), paints (upper right) and abrasive tools (lower)

The use of materials in the form of particles has been recognized for very long time. Wheat is milled to reduce their size to become flour before it is baked to make bread. Since the stone and bronze Ages, minerals have been used in the form of particulate to create ceramics and to purify metals. In pharmaceutical industries,  it has been practiced since long ago that medicine ingredients are ground and mixed to cure diseases. Industrial revolution promoted progressive outburst in particles, from advanced mining technique to abrasives, cutting tools and mass production of chemicals and agricultures. The advancement of modern science in paints and coatings is relied on mostly the ability to control dispersion and pigment behavior and other particles in many kinds of basic solvent. Composite materials emerged, coincide with the rise of polymer and plastique industries, that also relied on particulate catalyst.

Currently, particle technology is in the new resurrection point when the potential of nanotechnology began to realize. Design and manipulation of materials on nanoscale involve ultrafine particles or surfaces that possess many attributes as particulate system. The properties of materials are manipulated on nanoscale and particles are assembled themselves into nanostructure to produce photonic crystals, nanoscale catalysts, superhydrophobic surfaces, etc. Particles are stepping forward in many fields. In medical technology, they are used to diagnose diseases, to cure cancers, to deliver drugs and so on. Particle science is recognized as an enable technology to help us creating new energy source, cleaning air and water and building light and strong materials. Particle technology is not at its end, the potential just began.

The important role of particle technology is often forgotten in the society. Water purification, waste treatment, clean air, food preservation and many industrial products results from sophisticated understanding on particle technology. For example, clean drinking water needs filtration across particle bed, adding chemicals and final treatment with many kinds of adsorbent such as activated carbon. Knowledge on particle technology can be used in petroleum industry to design catalytic cracking reactor that produces gasoline from petroleum or can be used in forensic science to relate an accused with the crime scene. Ignoring particle technology can result in production loss, poor product quality, health risk, dust explosion and collapse of silo.

The inherent nature of particle technology comes from various sources of scientific background. Understanding on physics, chemistry, materials and mechanical engineering and many other disciplines is required to control the behaviors of particulate system. Thus, this field is very interdisciplinary with scientists from all types work together to solve a complex problem. For example, magnetic nanoparticles such as magnetite can be used for hyperthermia treatment for cancers. Scientists in the field of particles chemistry, physics, molecular biology, medical, chemical engineering and from other disciplines work together to design the therapy in a complex physiological environment.

Although it is very interdisciplinary area, particle technology has emerged as a separate discipline having unique characteristics and paradigm in describing, modeling and controlling phenomena that involve various discrete matters (e.g., solid particles including nanoparticles, fluid droplets and air bubbles) and their interaction with media (air, water or solvent) at different force field (shear, compression, flow, magnetic, etc.). In general, particles can be defined as small discrete quantities having interface with their surrounding, that can be solid materials in gas or liquid, liquid droplets in air, bubbles in water or emulsion.

Some fields that can be classified into particle technology may include:

  • Particle production (crystallization, atomization, mechanical activation, synthesis in aerosol flame, sol-gel and microemulsion reactor)
  • Communition (crushing, grinding, milling, attrition and erosion)
  • Agglomeration (granulation, pelletization, bricketing, tableting, sintering)
  • Handling of bulk powder (storage, dust collection and transportation)
  • Mixing, granular flow and fluidization
  • Roasting, combustion and smelting reduction
  • Solid-solid separation (gravitational, electrostatic, magnetic and floatation separations)
  • Solid-liquid separation (filtration, drying, membrane separation and thickening)
  • Colloid processing (dispersion, flocculation and rheology)
  • Particle coating and surface modification
  • Particle packing and consolidation in dry/wet condition
  • Design of powder handling, emulsion and aerosol devices
  • Modeling and simulation (CFD, DEM, population balance, molecular modeling, Monte Carlo)
  • Process optimization and advanced control (measurement, automation and sensor)

The above fields need basic knowledge about physics, chemistry, mathematics, engineering, etc., to understand fundamental phenomena to develop efficient and robust processes.

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