Determination of the amount of oil and grease in kitchen water

Objective:

1. To determine the amount of oil and grease present in the kitchen water

2. To determine the amount of impurities in distilled water

Introduction:

Oil and grease are defined as the organic constitutuents in produced water in which includes dispersed droplets of crude oil, dissolved carboxylate material, dissolved aromatic compounds and residual treating chemicals. Oil and grease in produced water which is discharged along with oil is not defined as a chemical substance. Instead, it is might be the oil droplets emulsion that dispersed in the water.

Dissolved and emulsified oil and grease is extracted from water by intimate contact with an extracting solvent. Some sample are extractable, especially unsaturated fats and fatty acid, oxidize readily, hence special precautions regarding temperature and solvent vapor displacement are included to minimize this effect. Organic solvent shaken with some samples may form an emulsion that is very difficult to break. This method includes a means for handling such emulsions.

Oil concentrations in water are usually reported as a mass or volume unit in a given volume of water, either as milligrams per litre (mg/l) or microlitres per litre (µl/l). Each analytical method measures a property of oil that can be related to this mass or volume value. The problem is that the composition of oil in produced water varies for a number of reasons, such as changes of source due to opening and closing wells, level of separation treatment and use of treating chemicals.

Materials:

Hydrochloric acid (HCl), trichlorotriflouroethane, n-hexane, methyl-tert-butyl ether

Apparatus:

Separatory funnel, distilling flask, liquid funnel, filter funnel, filter paper, water bath, vacuum pump, distilling adapter with drip tip, ice bath, dessicator, waste receptacle

Procedure:

1. Kitchen water was taken.

2. Tap water was added to kitchen water.

3. 1:1 HCl was added.

4. The mixture was transferred to separatory funnel.

5. n-hexane was added.

6. The mixture was shaken.

7. The upper layer was transferred to a clean conical flask and the lower layer was extracted with hexane.

8. The upper layer was transferred to the same conical flask.

9. Sodium sulphate anhydrous was added to the conical flask.

10. The empty distilling flask was weighed.

11. The distilling flask was distilled at 63-69 °C.

12. The distilling flask was cooled to room temperature before dessicator.

13. The distilling flask was weighed.

14. The procedures were repeated by using distilled water.

 

Results and calculations:

Weight of beaker + weight of distilling flask = 191.5529g

Weight of beaker + weight of distilling flask + weight of distilled water residue = 191.5698g

Weight of distilled water residue = 0.0169g

Weight of beaker + weight of distilling flask = 203.4712g

Weight of beaker + weight of distilling flask + weight of kitchen oil residue = 204.2424g

Weight of kitchen oil residue = 0.7712g

 

Mg oil and grease/ L = (A-B) / (mL sample/1000)

Mg oil and grease/ L = (A-B) x 1000/ mL sample

 

A: Gross weight of residue, mg

B: Gross weight of blank determination, mg

Mg blank residue/ L = (C-D)/ (mL sample/1000)

Mg blank residue/ L = (C-D) x 1000/ mL sample

C: weight of distilling flask + weight of residue, mg

D: weight of empty distilling flask, mg

 

Mg blank residue/ L = (C-D) x 1000 / mL sample

= (191569.8 mg – 191552.9 mg) x 1000 / 200

= 84.5 mg/ L

 

Mg oil and grease/ L = (A-B) x 1000/ mL sample

= (771.2 – 16.9) x 1000/ 50

= 15086mg / L