By NKECHI ISAAC,
Prof. Hussaini Doko Ibrahim is the director-general of the Raw Materials Research and Development Council (RMRDC). He spoke to some select journalists on the importance of biodegradable grease production in Nigeria and the nation’s interventions to commence production of this very important commodity. NKECHI ISAAC was there for LEADERSHIP. The excerpts.
What is lubricating grease? What are its components and uses?
Grease is what lubricates mechanical systems to avoid friction. There are three components in a lubricating grease. These are oil, thickener and additives. The base oil and the additives are the major components in grease formulations, and as such, exert considerable influence on the behavior of the grease. The thickener is often referred to as a sponge that holds the lubricant. Most grease produced today use mineral oil as their fluid components. The most used thickener in grease formulation is metallic soap. These include lithium, aluminum, clay, polyurea, sodium and calcium. Non-soap thickeners are also gaining popularity in special applications such as in high-temperature environments.
The most common additives used are oxidation and rust inhibitors, extreme pressure, antiwear and friction-reducing agents. The function of grease is to remain in contact with and lubricate moving surfaces without leaking out under the force of gravity, centrifugal action or being squeezed out under pressure. Its major practical requirement is that it retains its properties under shear forces at all temperatures
What is the importance of bio lubricants or biodegradable grease?
As I said before, mineral oils are normally used in grease production. However, research is on, on the utilization of non-edible vegetable oils, which are renewable, less toxic and possess good lubricity characteristics to serve as alternatives for mineral oil-based lubricants. The need to develop bio-based materials as industrial and automotive lubricants has increased in recent years. This is primarily due to the fact that they are biodegradable. The awareness of environmental pollution caused by mineral oil has led the lubricant industries to produce environmental friendly products by replacing mineral oil with biodegradable materials.
In 2004, out of 37.4 million tonnes of lubricants consumed, 53 per cent was utilized by the automotive sector. In 2005, 55 per cent of lubricant was consumed by the automotive sector worldwide. The overall consumption growth rate of lubricants by the automotive sector is about 0.8 per cent on annual basis. In 2012, global demand was 40.5 million tons. This demand is expected to increase by 2.3 per cent annually. This rose to 44,400,000 metric tons in 2018 and in 2019 to 45.4 million metrics. In the US, $6.3 billion was expended on lubricants in 2018. Also, in the US, 60 per cent of the lubricant oil used is lost to the environment which in turn leads to air pollution. Only 25 per cent mineral oil-based lubricant is biodegradable. Besides environmental pollution, the extensive usage of mineral oil has caused depletion of crude oil reserves and this will take millions of years to replenish.
What are the characteristics of the vegetable oils required?
Vegetable oil-based greases are semi-solid colloidal dispersions of thickening agents in a liquid lubricant matrix. The thrust therefore in the world of tribology today is the search for renewable and biodegradable oils that will satisfy the requirements of lubrication. A number of the vegetable oils have the properties required for lubrication. Among these are high index viscosity, low volatility and good lubricity. Although, some of these also have disadvantages such as hydrolytic instability, poor low temperature properties, poor thermal and oxidative properties, these can be solved by combining the oil with additives or through chemical modification such as esterification, epoxidation and hydrogenation. Vegetable oil consists of triacylglycerol which is made up of three fatty acid molecules bounded to a glycerol molecule.
The instability of vegetable oil is caused by the presence of β-hydrogen of the hydroxyl group in the glycerol which makes it unstable at high temperature, thus damaging the oil and cause precipitation. However, the glycerol can be replaced with polyol which does not contain β-hydrogen through the esterification process.
Which are the non-edible vegetable oils that have potential to be used as bio-lubricant in Nigeria?
The country has more than 10 non edible oils that can serve as source of raw materials for lubricating grease production. Among these are jathropha, rubber seed oil, Canarium schweinfurthii oil, Khaya ivorensis, Cucumeropsis edulis, Citrus sinensis, etc,. All these produce non edible oils that can be characterized and developed for lubricating grease production.
Which non edible vegetable oils have you worked on and why?
The council in collaboration with the University of Agriculture, Markudi has worked on Canarium schweinfurthii and rubber seed oil. Canarium schweinfurthii Engl. belongs to the family Burseraceae which is also known as black date, torchwood, frankincense or incense tree family. In English it is commonly known as African Elemi, Incense tree and Bush candle tree, Purple canary tree, or Gum resin tree. In the African region it is also known as ‟elemier d Afrique” or ‟elemi de Moahum” in French, ‟muwafu” in Luganda and ‟mpafu”/‟mbani” in Swahili. In Nigeria, it is known by quite a number of local names which include; Berom (Pwat), Hausa (Atile or Atilis), Igbo (Ube agba) and Yoruba (Origbo, Elemi or Agbabubu). It thrives well in Bauchi, Southern Kaduna, Niger, Oyo and Plateau states of Nigeria. The tree is a major source of Elemi, an oleoresin that is used in food, medicinal and a range of other industrial applications.
Another important non food oil seed we worked on is Hevea brasiliensis which is commonly referred to as natural rubber. The Hevea tree is a member of the spurge family (Euphorbiaceae) and a native of the Amazon valley in South America. Hevea seedlings were introduced into Nigeria from Brazil. The plant thrives in deciduous rain-forest regions of the lowland tropics with temperatures of between 21 – 35°C with a well distributed rainfall of between 1800 – 2000mm. At present, plantation estate owners in Nigeria are Pamol (1903), Rubber Estates Nig. Ltd (1980), Okomu Plc (2006), Imoniyame Enghaut, Sapele Intergrated Ltd, Ogun State ADC Faststride Ltd, Royal International Farms & Estates Ltd, Accrubal and Presco to name a few. Rubber plant seeds are sources of rubber seed oil.
Kernels (50 per cent – 60 per cent of the seed) contain 40 per cent – 50 per cent of a semidrying pale-yellow oil, used in soap making, paints, varnishes and it is effective against houseflies and lice. Press cake or extracted meal can be cautiously used as fertilizer or feed for stock. Nigeria has about 200,000 ha of rubber plantations in the country. Estimates of rubber seed production from 200,000 ha of rubber plantations in Nigeria are about 20 000 tonnes per annum. Thus, there is adequate raw material for rubber seed oil production.
How far have the council and other stakeholders gone on this project?
The council in collaboration with University of Benin embarked on this project to develop biodegradable grease/lubricants from black-date and rubber seed oils with the aim of building capacity in the auto industry and to eradicate or reduce the environmental problem occasioned from the use of mineral oil as base oil for lubricating grease production.
The research project is to develop bio-degradable grease or lubricants of different categories from black date and rubber seed oil with wide range of industrial applications especially for use in automobile industry due its environmental friendliness. Through this project, the collaborators extracted and characterize crude vegetable oils from the seeds of black date and rubber seed oil, formulated and developed biodegradable grease/lubricants of different categories for different functions. Through this project, we determined the chemo-physical properties of the oils and the fatty acid and free fatty acid compositions. The council has also developed formulations for the different categories. Through the project, we have obtained the optimal formulation for each grease and conducted applicability and comparative tests/analysis with conventional greases.
The council has developed five types of grease. These are biodegradable grease/lubricants from rubber seed oils (LiOH), biodegradable grease/lubricants from black date (LiOH), hybrid biodegradable grease/lubricants from black date and rubber seed oils and semi-solid biodegradable grease/lubricants from rubber seed oils (Sodium Stearate). We have conducted performance evaluation and biodegradability tests on the products. The results indicated that the grease produced has comparable properties with non-biodegradable grease/lubricants. The next stage is promoting investment in large scale industrial production of the formulations, with the hope that credible interested investors would bring about commercialization of the project.
What is your take on this project?
Well, I will like to say that this project apart from solving environmental problems, has the capacity of fostering economic growth in the country. Overtime, Nigeria has depended on importation of lubricating oils and the demand for it is increasing annually. Development and production of this grease locally from wastes has multiple advantages for the growth of the economy. The first and perhaps, most important is a cleaner environment which we cannot compromise for any reason.