Removal of Metals from Waste Oils Process

Petroleum-derived oils used in vehicles and machinery are removed after a certain period of use because they cause damage to engines. These removed oils are disposed of as waste.

As the number of vehicles and machinery in the world increases, the demand for petroleum-based mineral oils is growing day by day. Therefore, the disposal of used oils as waste is seen as a loss. At the same time, waste oils pollute the environment. For this reason, waste oils must be recovered through a series of recycling processes.

With the development of environmental awareness from an ecological perspective, waste oils coming out of machines and engines have become contaminated with metal. These contaminated oils were used for a long time for dust suppression. In addition, they were used for road oiling.

Method Used to Separate Metal Ions from Waste Oil

A standard has been established for the removal of contamination within the oil. According to this standard, the oil must not have a metal content higher than the required amount.

In this method, the waste oil must first be hydrated. The hydrated oil is heated to a temperature suitable for processing.

Continuing with this method, a substance required to demetallize the oil is added. With this substance added to the waste oil, some of the metals in the oil are collected in the sludge. After the cooling process, this sludge is precipitated and separated from the oil.

At this stage, the contaminated metals in the waste oil have not been fully separated to the desired standard. For this, a complexing agent must be used for the other suspended metal ions.

Removal of Metal Ions by Forming a Complex Structure in Waste Oil

Primarily, the demetallizing agent from the waste oil is selected from the following group. First of all, this substance must have good solubility in water.

These are;

Ammonium Dihydrogen Phosphate
Diammonium Hydrogen Phosphate
Diammonium Sulfate
Ammonium Hydrogen Sulfate

In the first stage, an ammonium salt can be used alone or in combination with sulfuric acid and phosphoric acid .

During the second metallized precipitation process, the solution is heated to a temperature of 80-100 °C. Meanwhile, EDTA (Ethylenediaminetetraacetic Acid), n-hexylamine, ethylenediamine, citric acid, and water-soluble salts of alkyl benzene sulfonic acid are added to the solution.