CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF STUDY
Composite is the combination of a matrix and a reinforcement, which when combined gives properties superior to those of the individual components (Ashori & Nourbakhsh 2009a). Wood plastic composite (WPC) is therefore a combination of wood and plastic with the plastic as the matrix and the wood as the reinforcement. Wood plastic composite, (WPC), can be made from virgin materials as well as recycled ones. In Nigeria, plastic waste is enormous and its disposal has always been a challenge. In using recycled plastic of WPC, the advantages are that; raw materials are readily available, control the plastic waste menace and also save some virgin and natural products. Substantial increase in human population and the consequential strain on natural resources such as forests and the associated harmful results as well as the plastic menace challenging the nation are some of the challenges that make the study of WPC important. The green mentality and the shift in attitude are favouring environmentally-friendly products such as WPC (Azadeh et al., 2011). WPCs can be used in several applications such as profiles, sheathing, Decking, Roof tiles, Window trim, automotive parts, stepping stones etc. Natural fibers such as wood are considered environmentally friendly and sustainable due to their renewability and biodegradability. Natural fillers have other added advantages over artificial fibers in the sense that they have low specific weight, high specific strength and stiffness, safer handling and working conditions; they are also non-abrasive to the processing equipment (Tong et al., 2014).
Development of the oil sorbents made of organic waste materials was initiated in order to provide resources for marine oil spill response with less environmental load and cost (Masaki Saito et al., 2003). Sorbents of the oil spill in water are materials that soak up the oil. They can be used to recover oil through the mechanisms of absorption and adsorption, or both. Absorbents allow oil to penetrate into pore spaces in the material they are made of, while adsorbents attract oil to their surfaces but do not allow it to penetrate into the material. Once sorbents have been used to recover oil, they must be removed from the water and properly disposed of on land or cleaned for reuse. Any oil that is removed from the sorbent materials must also be disposed of or recycled. Sorbents can be divided into three basic categories: natural organic, natural inorganic and synthetic. The first category includes peatmoss, straw, hay, sawdust, ground corncobs, feathers, and other carbon-based products. They are relatively inexpensive and generally readily available. Organic sorbents can absorb 3 to 15 times their weight of oil, but they do present some disadvantages. Some organic sorbents tend to absorb water as well as oil, causing them to sink. Many organic sorbents are loose particles, such as sawdust, and are difficult to collect after they are spread on the water (Ghalambor, 1995).
Natural inorganic sorbents include clay, perlite, vermiculite, glass, wool, sand, and volcanic ash. They can absorb from 4 to 20 times their weight of oil. Inorganic substances, like organic substances, are inexpensive and readily available. Most organic materials can only be used on land and are not adaptable to water use for oil spill clean-up. Synthetic sorbents includes man-made materials that are similar to plastics, such as polyurethane, polyethylene, polypropylene, and nylon fibers. Most synthetic sorbents can absorb as much as 70 times their weight of oil. Synthetic sorbents that cannot be cleaned after use can present difficulties because they must be stored temporarily until they can be disposed of properly. They are best suited to absorb lighter viscosity oils that can perpetrate or wick into its fibre. Sorbents work by either absorption or adsorption (Ghalambor, A. 1995). Absorbents operate like sponges and collect oil by capillary action or suction. Adsorbents rely on the large surface area, the chemical affinity of the sorbents for the spilled oil, and chemical constituents including their porosity, molecular structure and change in volume. Absorbents work best on light, less viscous oils, while adsorbents work best on heavy, sticky, more viscous oils. In some cases, a sorbent material may utilize both techniques for oil recovery.
Walkup et al., 1969 reported that an oil spill clean-up is a question of options and not solutions. Even though no oil spill clean-up system is likely to be completely effective. Sorbents are one of the most widely used methods for compacted oil spills in the sea.
This study looks at WPC made from recycled plastic and wood waste and its absorption capacity
1.2 Problem statement
Plastic waste is a huge challenge confronting this nation; due to the large volumes used and discarded every day and their non-degradable nature. Landfilling has usually been used to dispose of plastic waste but has proved ineffective since it fills up the site quickly. Incineration of the plastic waste can also cause pollution. The need for effective and sustainable method to manage the menace is urgent. Recycling has proven to be the best way to solve the plastic waste problem. Other recycling methods have been used to manage the situation and this work offers an alternative mode of recycling plastic waste, which is the formation of Wood Plastic Composite. Some of the advantages of using WPC in the auto industry are: reduction in material weight and energy consumption, enhancement of acoustic performance and processing time, lowering production cost, improving safety and shatterproof performance under extreme temperature changes, and improving biodegradability of the auto interior parts (Thompson et al., 2010). WPC are used as trim parts in dashboards, parcel shelves, seat cushions, backrests, door panels and cabin linings.
At sawmills, unless reprocessed into particleboard, burned in a sawdust burner or used to make heat for other milling operations, sawdust may collect in piles and add harmful leachates into local water systems, creating an environmental hazard.
Airborne sawdust and sawdust accumulations present a number of health and safety hazards. Wood dust becomes a potential health problem when, for example, the wood particles, from processes such as sanding, become airborne and are inhaled. Wood dust is a known human carcinogen. Certain woods and their dust contain toxins that can produce severe allergic reactions.
This work involves the formation of a composite using low density polyethylene wastes, white sand and sawdust. This composite formed can be used as a sorbent in absorption of crude oil so as to reduce oil spillage.
1.3 Aim of study
- Reduction of oil spillage in Niger Delta using wood plastic composite from saw dust, white sand and low density polyethylene waste.
Objectives of study
- Prepare wood plastic composite from sawdust, white sand and low density polyethylene plastic.
- Calculating the rate of absorption of crude oil, water and crude oil in water using composite.
1.4 Justification of study
Economically, viable recycling and value addition to the plastic waste is of great urgency due to the increasing amount being generated each day. Composite formation is one of the many ways by which plastic waste can be recycled.
WPC products are gaining popularity around the world. Several works have been done on WPC with different plastics and wood waste at different percentages (Santos et al., 2013). But little has been published on the wood specie used and its effects on the properties of products formed. Producing composite materials from recycled plastics of low density polyethylene and sawdust will help Nigeria solve the problem of plastic waste. A look around towns, on the streets, market places, gutters, and even dump sites in Nigeria tells the story better. Some people resort to burning of the plastic which releases toxic substances such as dioxins, mercury and furan. When these toxins gets into the body leads to serious health implications, example is heart disease and can also aggravate respiratory ailments such as Asthma (WEFCF, 2012).
This project propose a key measure to prevent indiscriminate disposal of these principal wastes and absorption of crude oil in water, apart from punitive enforcement of legislature. This is to develop technological solutions by providing alternative use for these waste materials which will place a value on them. Identifying the potential use of waste to create job and inadvertently help in shaping public attitude towards its disposal and create job in the long term.
Saw dust wastes are not normally properly disposed of and therefore end up in landfills. To help put this by-product to good use, it is being incorporated into the project as one of the reinforcements.
