Ftir, ndir and flame photometry

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FTIR, NDIR and flame photometry P MANOJ 713MN1117 MINING DEPT NIT ROURKELA

Transcript of Ftir, ndir and flame photometry

Page 1: Ftir, ndir and flame photometry

FTIR, NDIR and flame photometry

P MANOJ713MN1117MINING DEPT NIT ROURKELA

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SPECTRUM

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INTERACTIONInteraction between Matter and Electromagnetic radiation

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SPECTROSCOPY

Measuring and interpreting spectra arising from the interactionsEnergy used :1. EMR2. Particles of low de broglie wave length3. Acoustic / Pressure waves4. Mechanical

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INSTRUMENTS

Spectrometer Correlates intensity with property of radiation

Spectroscope Spectrometer operating in Visible region

Spectrograph Disperses incoming radiation to different frequencies

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DISPERSIVE SPECTROSCOPY

Interaction of monochromatic light with object, repeated for every wavelength

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FTIR

Fourier Transform Infrared Spectroscopy

Shining of various wavelengths of light at once as combination to obtain data

Uses Michelson Interferometer setup

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Michelson interferometer basically consists of 2 mirrors, a beam splitter with certain angle. When a light beam falls on beam splitter it transmits half the light to stationary mirror and reflects the other half to movable mirror. When the light hits both the mirrors it gets reflected. The two beams combine (Interference) and reach the detector with different path lengths where the intensity is measured.

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INTERFEROGRAM

Plot between Intensity/Energy vs Path difference

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DISCOVERY AND APPLICATION

In 1965, Cooley and Turkey were able to convert the interferogram to spectra by the application of Fourier analysis as function of Wavenumber (inverse of wavelength).

Used in gaseous pollutant monitoring of CO, VOC, N2O, CH4 etc. difference in the absorption.

Used in identifying pollutants in untreated wastewater before treatment for compounds like oils, grease etc.

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NDIR

Non Dispersive Infrared sensor

It is a spectroscopic sensor used as gas detector

Infrared energy is allowed to pass through the atmospheric sampling chamber without deformation.

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NDIR sensor uses 2 chambers, one for the sample and other is with reference gas (typically non-absorbing gas like Nitrogen).

Radiation from Infrared source (lamp) passes through the sample chamber where the absorption of the radiation takes place before reaching the other end where filter is fitted.

The filter blocks all other wavelengths except of the gases to be analysed.

Since the reference gas is non-absorbing, the detection end receives 100% signal while the analysed gas signal is attenuated due to absorption.

The difference in energies is used to measure absorption and correlate with the quantity of particular gas present by the sensor.

Gases : CO, CO2,HCHO, NO, SO2, H2O, CH4 and other hydrocarbons.

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FLAME PHOTOMETRY

Flame atomic emission spectroscopy

Used for detection of metals (particularly Group 1 and 2) of periodic table. Detectors used are photovoltaic cells and photoemissive cells.

Principle

Every metals emits certain spectrum of light on application of thermal energy.

Steps involved are

Nebulization/vaporization,

Passing over flame and

Analysis of light produced.

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Schematic diagram

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Liquid salt of metal salt solution is vaporized to get metal salts which are moved towards flames getting vaporized to gaseous states.

The gases absorb to get to higher states which on de-excitation emit their characteristic spectra which can be used in identification.

I = K x C

I= intensity of light emitted

C= concentration of metal METAL Emission

wavelength(nm)Colour

Potassium 766 Violet

Lithium 670 Red

Calcium 620 Orange

Sodium 589 Yellow

Barium 554 Green

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