adsorption studies can provide valuable insight into the mechanism of asphaltene deposition.

ANALYSIS OF ASPHALTENES AND CRUDE

OIL ADSORPTION ON SURFACES USING QCMD

Surface interactions of asphaltenes

in crude oil represent

an important issue for

the petrochemical industry.

QCM-D technology is helpful

for evaluating different approaches

to solve these problems.

In particular, the ability

to monitor different structural

arrangements of adsorbed

materials is useful for understanding

how asphaltenes adsorb

to surfaces.

QS 405-25-1

Introduction

Every day, the complex petroleum

industry faces the challenge of

handling fouling, altered wettability

and coking. A major cause of these

problems is the adsorption of petroleum

heavy ends at solid/liquid

interfaces that occurs at different

stages of oil production. Among

heavy ends in petroleum, asphaltenes

are often considered the

most problematic because of their

chemical nature and their tendency

to aggregate and form deposits under

certain pressure, temperature

and composition conditions.

CONCLUSION

QCM-D enables real-time characterization of asphaltene (in crude oil,

or purified from crude oil) adsorption onto different surfaces. The adsorbed

amounts and characteristics of adsorption depend on the solubility

state of the asphaltene as well as its origin. Furthermore, surface

adsorption varies to a small extent between different hydrophilic sensor

coatings.

Tensiometer Kulim Kht Palm Oil Industry

Cloud point

Cloud Point is the temperature at which the oil begins to cloud resulting from crystallisation under controlled cooling. The CP is related to the unsaturation of the oil. In general the higher is the unsaturation, lower will be the CP. The initial quality of crude palm oil CPO (diglycerides, FFA,…) has strong influence of the CP of the oleins. Due to often misinterpretations here the AOCS Official Method Cc 6-25 . (1993)

Definition : The cloud point is that temperature at which, under the conditions of this test, a cloud is induced in the sample caused by the first stage of crystallization.

Scope : Applicable to all normal animal and vegetable fats.

Apparatus

1. Oil sample bottle–115 mL (4 oz).
2. Thermometer–range –2–68°C, AOCS Specification H 6-40.
3. Water bath-made up of water, chipped ice and water; or chipped ice, salt and water, depending on the temperature required. The temperature of the cloud point bath shall not less than 2˚C, nor more than 5˚C below the cloud point. Either a beaker or insulated container is convenient for the test.

Procedure

1. The sample must be completely dry before making the test. If the sample contains traces of moisture, it should be filtered through suitable filter paper. Heat 60-75 g of sample to 130˚C (see Notes, 1) just before making the test. Pour 45 mL of the heated fat into the oil sample bottle.
2. Begin to cool the bottle and contents in the water bath, stirring enough to keep the temperature uniform. When the sample has reached a temperature about 10˚C above the cloud point, begin stirring steadily and rapidly in a circular motion so as to prevent supercooling and solidification of fat crystals on the sides or bottom of the bottle.
3. From this point on, do not remove the thermometer from the sample : doing so may introduce air bubbles which will interfere with the test. The test bottle is maintained in such a position that the upper level of the sample in the bottle is level with the water in the bath.
4. Remove the bottle from the bath and inspect regularly. The cloud point is that temperature at which that portion of the thermometer immersed in the oil is no longer visible when viewed horizontally through the bottle and sample.
   
   
   Notes

1. It is essential that the sample be heated to 130˚C to destroy any crystal nuclei.

Krafft point

The temperature (more precisely, narrow temperature range) above which

the solubility of a surfactant rises sharply. At this temperature the solubility

of the surfactant becomes equal to the critical micelle concentration. It is

best determined by locating the abrupt change in slope of a graph of the

logarithm of the solubility against t or 1/T.

or in other word

The Krafft temperature (also known as Krafft point, or critical micelle temperature) is the minimum temperature at which surfactants form micelles. Below the Krafft temperature, there is no value for the critical micelle concentration (CMC), i.e., micelles cannot form. The Krafft temperature is a point of phase change below which the surfactant remains in crystalline form, even in aqueous solution.
Surfactants in such a crystalline state will only solubilize and form micelles if another surfactant assists it in overcoming the forces that keep it crystallized, or if the temperature increases, thus causing entropy to have a stronger force and encouraging the crystalline structure to break apart