ULTRASONIC:Introduction & Application in Chemical

Engineering

Ananto Wimbaji

Exploring the Power of Sound

ULTRASONIC

Ultrasonic:Sound @ frequency > 20 kHz

Human hearing : 20 Hz – 20 kHzConventional Ultrasonic: 20 – 100 kHzExtended range of Sonochem: 20kHz-2MHzDiagnostic Ultrasonic: 5 – 10 MHz

Ultrasonic Application

Medical : diagnostic, corrective medicine

Engineering : measurement (flow, thickness, volume), welding

Chemical : Laboratory equipment cleaning

Biology : cell disruptionIndustrial : Welding, dispersion of ink

and pigment

Sonochemistry

Application of power of sound to chemical processes:

Ultrasound can increase chemical reactivity besides heat, pressure, light and catalyst

Chemical changes by power of ultrasound @lower frequency as a result of generated cavitation

Cavitations

Formation, growth & implosive collapse of bubbles in a liquid. Cavitational collapse produces intense local heating (~5000 K), high pressures (~ 1400 atm) , enormous heating & cooling rates (~>109 OK/sec) and liquid jet stream (~400 km/hr)

Cavitation

• Illustration of bubble generation and collapse

Occurrence of cavitations

• Within the bubble itself which can be thought of microreactor

• In liquid region immediately adjacent to bubble where the temperature are not so great

• In the immediate vicinity of bubble when shockwave produce on collapse will create enormous shear force

Chemical Synthesis

Type of chemical synthesis of ultrasonic:

- Reactions involving Metal or Solids Surface

- Reactions involving powder and particulate matter

- Emulsions reaction- Homogeneous reaction

Rule of Sonochemistry

Luche,JL formulated empirical rule of sonochemistry:

Possible Benefit of Ultrasonic for Chemistry

- Might accelerate reaction or only required less forcing condition

- Induction period are often significantly reduced as are exothermic normally associated with such reactions

- Reactions are often initiated by ultrasound without the need for additives

- The number of steps that are normally required can sometime be reduced

- A reaction can be directed to alternative pathway

Sonochemistry Apparatus

Generator

Transducer

Reaction chamber

Sonoprobe / horn

In Lab /development :

Courtesy: Telsonic Ultrasonic

Sonochemistry Apparatus

In industry

Courtesy: Hielscher Ultrasound Technology

Current Application

Cavitation & Biodiesel

• (Trans)-esterification of vegetable oil by alcohol can be assisted with ultrasound

• Reaction carried out in near ambient condition, can yielded > 98% in significantly lower reaction time(~15 min) and possible to use only little excess of alcohol

• Power required are significantly lower that conventional reaction

Biodiesel Process

Hielscher Ultrasound Technology

Ultrasonic Compare to Other Technique

Reference

• Sarpong,R, “Ultrasound Applications in Organic Synthesis”, Stoltz Literature Meeting,2003

• Mason,TJ & Lorimer,JP,”Applied Sonochemistry: Uses of Power Ultrasound in Chemistry and Processing”, Wiley VCH,2002

• Jones,C, “ Sonochemistry Group”, Royal Society of Chemist Presentation,England

• Gogate,P et.al,”Cavitation: A technology on the horizon” Current Science,Vol 91 No 1, 2006

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