SURFACE AREA ANALYSER FOR POWDERS

Surface Area Analyser for Powder

Surface Area is an intrinsic property of powdered porous materials that can reveal important information regarding the usefulness of a material for an application. Surface area plays critical role in the bio-availability of Pharmaceuticals, dispersion of dyes, adsorption capacity of carbon and many more.

By means of Physical adsorption, Surface Area can be calculated since physically adsorbed molecules are not restricted to specific sites and are free to cover the entire Surface. This process is reversible. Typically nitrogen gas is adsorbed at cryogenic temperatures (liquid nitrogen). Based on the amount of gas adsorbed (adsorbate) at a given pressure, the BET equation is used to calculate the number of adsorbed gas molecules that would be required to form a monolayer on the surface. With knowledge of the cross - sectional area of the gas molecule adsorbed, the Surface Area can be easily calculated.

FEATURES

Wide Range of Surface Area Measurement

Easy to use with direct display of Surface Area after completion of analysis on computer

High Speed Analysis - within 10-15 minutes

Meets USP-824, EP/BP, ASTM D 6556-14, ISO 4652, IS 2752 standards

Special Software is available which complies with 21CFR Part 11

High Accuracy and Reproducibility

Built in micro-controller permits to use the instrument in manual mode

Utilizes a modified BET equation for Single Point Surface Area determination

Ultra stable detector eliminates drift and need for constant readjustment

Separate regenerating system for sample preparation is provided which degas three samples at a time

Total pore volume and multipoint Surface Area determination is possible with additional gas mixtures

Surface area range selection for Low Surface Area to High Surface Area

SPECIFICATION

Surface Area range - 0.1 m²/gm to 1500 m²/gm - Normal. Extendable up to 2500 m²/gm.

Accuracy - Typically better than ± 5%

Reproducibility - Typically better than ± 3%

Sample Holder - Typical Sample holder capacity 7 ml Bigger sizes are available

Dimensions - 45 cm (L) 25cm (B) x 35 cm (H)

Weight - 10 Kg.

Electrical - 230 V AC, 50 HZ

Cement Industries

Regeneration System -  Temperature Range : Ambient to 3000C /  Accuracy : Better than ± 50C of Set Point

Operating temperature - 15 C to 40 C (non condensing)

THEROY AND PRINCIPLE

The instrument Smart Sorb 93 is based on the theory first proposed by Brunaur, Emmet and Teller known as BET theory. The equation for this was modified for fast measurement by dynamic method. In our instrument a gas mixture of 70% He & 30% N2 (i.e. partial pressure of 0.3) is passed over the sample. N2 in this mixture gets adsorbed over the surface of the sample at liquid nitrogen temperature and forms a single molecular layer over the surface of sample. This adsorbed N2 is then measured to calculate surface area of the sample.

We are using dynamic method for measurement of surface area. In this method gas mixture (approximately 30% nitrogen and 70% helium) continuously flows over the sample. The sample is dipped in liquid nitrogen. At liquid nitrogen temperature (- 196°C) nitrogen in this flow gets adsorbed on the surface and forms a mono layer on the surface. This adsorbed N2 is allowed to desorbed by bringing the sample to room temperature. This desorbed nitrogen is proportional to the surface area and so measured to calculate surface area by using following equation.

The BET equation needs some physical parameters such as room temperature, partial pressure of the gas mixture etc. The final derived equation is,

Surface Area , Ss = (4.35/ W) (NCs x Vn / NCn) [273 / (273+t)](1-P/Po)
Where,
W = Weight of the sample in gms.
NCs = number of counts measured on our instrument which are proportional to the quantity of desorbed nitrogen.
Vn = This is the amount of N2 in c.c.s injected for the purpose of calibration.
NCn = number of counts measured which are proportional to the injected N2
t = Room temperature
P/Po = Partial pressure of adsorbed gas. Approximately it is 0.3 for 70% He & 30%N2

Note: The calibration is necessary since all the readings on our instrument are relative. This calibration is done after every sample but if all the parameters such as gas flow, temperature is kept constant throughout the experiment then calibration can be done only once.

APPLICATION

For Quality Control and Research Laboratory -

Catalysts for automotive, fertilizers and petrochemical industries

Carbon for rubber, adsorbents (gas separation and water purification), gas masks, inks, laser printers etc

Minerals such as alumina, clays, pigments, phosphates, silica, zirconia etc used for abrasive, adsorbents, biomaterial, ceramics, cement, desiccants, fillers, paper and paints. Zinc Oxide used in rubber industry

Organic material for adhesive, foodstuffs, chromatography, resins, cosmetics, explosives, ion exchange, plastics and pharmaceuticals

Powdered metals and ferrites for batteries, pressure formed / sintered products