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أوابك العلمية لعام
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ص لبحوث العلمية الفائزة بجائزة
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عدد خا
مجلة النفط والتعاون العربي
161
العدد
- 2017
أربعون
المجلد الثالث و ال
Re-refining of Used Lubricating Oil and its Economic and Environmental Implications
15
Detergents: Detergents are alkaline in nature and react with acids which form during
the combustion of fuel.
Anti-wear agents: They keep soot and combustion products in suspension thereby
preventing their precipitation as sludge.
Corrosion inhibitors: They protect metal surface from corrosion
Viscosity improvers: They are additives that increase the viscosity of the fluid
throughout its useful temperature range.
Antifoam additives: these substances prevent foaming which can occur as a result of air
entrapment in lube oil.
Pour point depressants: they are used to prevent rapid increase in the viscosity which
can occur due to crystallization, at low temperatures, of the paraffinic waxes present in
lube oil.
3.2.2 Contaminants of used lubricating oil
As pointed out earlier, lubricating oils lose their initial properties as a result of
accumulation of contaminants and chemical changes experienced during their use. The
presence of degraded additives and by-products of degradation render used lubricating
oils more toxic and harmful to health and environment than virgin base oils
(Motshumiet et al, 2013). The main types of contaminants of potential concern are
caused due to the following reasons (UNEP, 2012):
- Normal engine wear produces metallic particles w
- hich contaminate the lubricating oil.
- Water resulting from the combustion of fuel in the engine may pass into the
lubricating oil and can ultimately lead to sludge formation.
- Incomplete fuel combustion in the engine may result in the contamination of the
lube oil
- As a result of the combustion process, carcinogenic substances such as Polycyclic
Aromatic Hydrocarbons (PAH), are formed.
- Soot and carbon may form as a result of incomplete combustion, especially during
warm-up with a rich mixture.
- Unburnt gasoline or diesel can pass into the lubricant.
- Metals (Iron, Copper, and Aluminium) which are released due to normal engine
wear, road dust, can find their way into the lubricating oil.