RECYCLING OF POLYURETHANE FOAMS : A STRATEGY IN WASTE MANAGEMENT AND CONTROL BY T.E.ODETOYE Department of Chemical Engineering,University of Ilorin, PMB 1515, Ilorin, Nigeria. ABSTRACT Recycling of polymer materials such as polyurethane foam is one of the needed strategies to combat the menace of pollution in our environment. Pollution has been a consequence of ever-increasing massive quantity of wastes generated from household and industrial activities, posing a global challenge to man and the environment. Recycling can also be used to conserve natural resources and reduce the consumption of fresh raw materials therefore having an overall effect on reducing unecessary generation of waste from production processes. In Nigeria today, recycling of polyurethane post consumer product as a means of waste reduction in our society is still grossly underutilised. This paper examines the current trend in recycle as a means in waste management and focuses on various methods of recyling polyurethane foams considering their application(s) to the Nigerian situation. Keywords: waste management; polyurethanes; recycle Telephone number: +234-8054763390 E-mail address: todetoye@yahoo.com 1. INTRODUCTION of such (Akinkurolere and Franklin, 2005; Waste management has been a major Ezeronye, 2000; Longe & Williams, 2006; challenge in the Nigerian Society as well Ossai, 2006). as in most African countries owing to the In Nigeria today , the municipal solid dual problem of increase in waste wastes which are garbages generated by generation as well as the poor management individuals, firms and organizations 1 Nigerian Society of Engineers, ABUJA, 2010 consisting of packagings, clothings, Day to day open incineration of wastes plastics, newspapers, batteries, funiture, generated has also caused pollution which ceramics, polyurethane foams, etc., have has brought about the depletion of the been mainly disposed by incineration and ozone layer as a result of green house land fill as is the common practice in many gases emission. These forms of pollution other countries (Miller, 2000; Yanyin, resulting from poor waste management 2002). have been regarded as major factors However,a lot of pollution problems are leading to climatic change all over the actually associated with this system of world in recent times. For these above and waste diposal in the sense that most dump many other reasons a drastic step has to be sites actually pose health hazards to the taken to put the situation under control entire populace in the vicinity. and protect our dear environment. Nigeria is plagued by the existence of Consequently, in the developed world numerous waste dump sites dotting the ,concerted efforts have been directed urban landscape of the cities towards minimizing wastes through (WAMASON, 2008). reduce, reuse and recyling of post The necessity of improving our waste consumer products of various industries management is more basic for many with collection centres for specific wastes reasons ranging from that of community like polyurethane foams and other post health to provision of essential amenities consumer products (PURR,U.S.A., 2005; like potable water. Pollution of ground Recyclers world, 2010: Yanyin,2002). water needed to be avoided since over 75% Therefore, it is more pertinent to of the Nigerian populace depend on judiciously minimize the quantity of waste surface or individually mined ground water generated by recyling in a relatively low as sources of drinkable water income country like Nigeria. This enables (WAMASON, 2008). us to harness the attending benefits in term Much more, potential farmlands which of the effects on the community health as could have been utilised alternatively to well as the process economics in the alleviate the problem of food shortage are industry capable of indirect positive effect being encroached upon day by day because on poverty alleviation. of the increase in the wastes generated. 2 Nigerian Society of Engineers, ABUJA, 2010 However, practices to reduce, reuse or Primary or close loop recycling involves recycle has neither received widespread conversion of post-consumer waste awareness nor implementation due to materials into new products while various reasons such as; lack of secondary or open-loop has to do with information on the need to minimize converting the waste materials into entirely wastes, lack of information on the benefits different products. of re-use, reduce and recycle One of the advantages that can be derived (Akinkurolere & Frankling, 2005) when materials are recycled is the decrease in raw material input, because using recycled 2. Recycling as a Method of Waste material will reduce the amount of new Management material needed to manufacture a new Recyling is one of the waste management product , reducing about 20-90% virgin measures that can be effective in the bid to material consumption in primary recyling conserve our natural resources as well as and up to 25% virgin material consumption save our deteriorating environment. in secondary recycling (Yanyin 2002). Recycling has been defined as “the process Recycling also promotes significant through which materials previously used are reduction in quantity of resources such as collected, processed, remanufactured, and utilities (water usage and energy) as well reused” (Schultz et al., 1995). as in air pollution created during In actual fact ,waste is the other side of production processes, lowering green production because garbages/solid wastes house gases emissions compared to that of can be regarded basically as a waste of virgin production. raw materials and energy in the light of Another advantage is that recycling, when recycling (George, 2007). used as a solid waste reduction and There are two basic types of recycling management strategy, minimizes the (Behrendt and Naber, 2009; PURRC, amount of wastes ending up at the dump 2005;Yanyin 2002); sites and incinerators, hence, preventing Primary or Close-Loop Recycling useful materials from being wasted. Such Secondary or Open-Loop materials include polyurethanes which can Recycling be reused even at the end of their original intended service life as funiture, shoe, car 3 Nigerian Society of Engineers, ABUJA, 2010 upholstery component, etc. They can still consisting of chains of organic units joined be as valuable at the point when they are by urethane links. Polyurethanes can be ready to be discarded (CPI-ACC,2010) . formed by reacting a polyol (a polymeric alcohol with more than two reactive 3. Polyurethanes hydroxyl group per molecule) with Polyurethanes are a major plastic materials diisocyanate or polymeric isocyanate (e.g. with an annual world production capacity methylene diphenyl isocyanate, toluene of over 12 million tons (Berendt and diisocyanate) in the presence of suitable Naber, 2009). They are polymers catalyst and additives. Polyol + Diisocyanate Polyurethane Polymer + Heat Polyurethane Consumption by End Use Building & Construction Transportation Funiture & Bedding Appliances Packaging Textile , Fibres & Apparel Fig. 1. Polyurethane Consumption by End Use Market in the United States (PURRC, 2005). They can also be made from renewable widely used in flexible and rigid foams, source (Ogunniyi et al.,1998).They are 4 durable elastomers and high performance Nigerian Society of Engineers, ABUJA, 2010 adhesives. Polyurethanes have found refrigerators,vehicle upholstery,etc. application in household as well as However, the recyling of the post- industrial products due to their various consumer polyurethane products still durable properties. Fig.1. shows remains a challenge in most countries polyurethanes consumption by end use in (Behrendt and Naber, 2009; Knight,2006; the United States market. Yanyin,2002). As the amount of waste generated is However, in the developed world, increasing day by day, polyurethane recycling of post-consumer polyurethane products have also found their way to the products has been encouraged especially in dump sites after serving their intended Europe and the United States where it has purposes, constituting waste diposal been in existence for over 15 years problem, much more, since they are not (George, 2007; Recycle.net, 2010). readily biodegradeable (CPI-ACC, 2010) . Various effort are already being directed towards the utilisation of this aspect of 4. Polyurethane recycle as a strategy of waste management Significant portions of polyurethane foams recycling in waste management strategy (Polyurethane Recyle & Recovery are used in the production of funiture, car Council,U.S.A.,2005; Knight,2006; upholstery, in vehicle assembly factories, Yanyin,2002). footwear and bedding industries, to name a The form of polyurethane recycle system few. They make up to existing in Nigeria, with our considerable 5% of all plastics, and are made from number of foam industries (ADCB UAE, petrochemicals (Knight,2006). Waste 2010) is mainly that used during the generated from such uses sometimes production process whereby, off comes as a mixture with other polymer polyurethane products, shaping and cutting materials such as nylon, polyester, wastes are ground and re-used as cellulose, films, glass fibres which can be component of another production output. separated for the purpose of On the contrary, pre-consumer, recycling recycle.Waste-polyurethane scraps can be is a popular waste minimization method obtained from discarded materials by used by foam manufacturers all over the collection from soles of shoes, parts of world.They are already into the business of toys, parts of funiture, parts of recycling wastes generated from cutting 5 Nigerian Society of Engineers, ABUJA, 2010 and shaping of foams in the industry i.e. which is capable of improving the foam pre-consumer polyurethane wastes manufacturing process economics (Polyurethane Foam Association,1994). (Cannon, 2009). These polyurethane scraps have been Polyol has been recovered from waste successfully processed into useful products polyurethane by hydroglycolysis (Gebreselassie et al. 2001), thereby (Brawslaw and Gerlock,1984). The polyol generating revenue, reducing raw material thus recovered was purified by liquid- cost, and alleviating solid waste disposal liquid extraction. The process was claimed problems. Recycled pre-consumer to produce a material capable of replacing polyurethanes wastes are made into as much as 50% of the virgin polyol used bonded carpet underlay, they are used for in high quality, low density polyurethane the production of car seatbacks and head foam formulations with a reasonable rest where the physical and mechanical process economics when no other markets properties are less demanding (compared exist for the waste foam material. to car seat cushion). Conversion of waste polyurethane There is a an international niche market for material was also done with the use of recylcing both pre-consumer and post- phosphonic acid diester as a degradation consumer polyurethane foam scraps. Pre- agent in the polyurethanes which was consumer polyurethane sells for about claimed (Troev,K., et al 1999) to be 0.80USD /kg in South Africa, 0.1 - 0.3 applicable for the preparation of useful USD /lbs (recycle.net, 2010) in the United polymers product with reduced States, while Post-consumer PU scrap flammability. recently sells for about 0.24 Euro/ kg in Another work(Gebreselassie et al. 2001) Romania,Timis (recycle.net, 2010). involves shredding of the polyurethane waste into fluff having a particle size of 5. Some Research works on Polyurethane 0.25 -1.0 inch and molding the material at Recycle elevated temperature and pressure such Many researchers have investigated that the foam exceeds its glass temperature various methods of recycling which occurs at 600-1200psi and 400- polyurethanes wastes so as to provide 475oF. Then the hydrogen bonds in the inexpensive raw materials for foam plants hard segment of the polymer are broken 6 Nigerian Society of Engineers, ABUJA, 2010 under the elevated temperature and Polyols obtained has also been used as pressure. The bonds are then re-established components in the preparation of binders on cooling sometimes leading to chemical for composites of high textural and arrangement of the polar groups in the hard flexural strength (Berndt and Naber, 2009). segement. This method was claimed not to Datta and Rohn, in 2007, investigated require the use of a binder. The physical thermal transitions and thermal stability of properties of the resulting material was polyurethanes and polyurethane varied by controlling the mold intermediates. temperature, pressure and time so that the However,some of the aforementioned resultant product was tailored towards a methods are yet to be adopted in the particular application. industries, because they have not been cost Hulrich et al, in 2004, reported an emission effective. free recyle process which involves heating Polyurethane manufacturing companies are the waste material with glycol mixture to also rising up to the challenge. A process obtain polyol that can be completely to glycolyze mixed polyurethanes has been reused in the manufacture of rigid developed by Troy Polymers, polyurethane. The process was claimed not Inc.(PURRC,2005). The new to be sensitive to varing product mixes. polyurethanes produced from waste scraps Attempts (Kang, 2006) had also been made retained most of the properties and to use waste polyurethane as road and functionality of the original materials. building construction materials. An elastic Equipment manufacturers are already permeable pavement comprising waste- facing the challenges of designing new polyurethane chips for use on new roads equipment and retrofitting the existing and pavings was prepared using a binder ones to recycle polyurethane wastes. specially developed to secure the binding Cannon has recently designed a new between an upper waste-polyurethane chip Cannon Filler Injection Kit (Cannon,2009) layer and a lower permeable concrete which was claimed to reduce wear layer.The pavement was reported to have problems in existing machines and which excellent strength, durability, elasticity and can use up to 7% of the recycled material permeability suitable for sporting activities in the new polyurethane foam walking and outdoor exercises. 7 Nigerian Society of Engineers, ABUJA, 2010 manufactured without affecting the Main Methods of Recycling mechanical and physical properties. Polyurethane Foam Research efforts are also towards The major ways of polyurethane foam converting post-consumer polyurethane recycle are by mechanical and chemical waste into valuable energy like electricity processes (Berndt and Naber, 2009; by modern technology incineration (CPI- Cannon, 2009; Center for the ACC,2009; WAMASON, 2008). polyurethanes Industry(CPI)- American Chemistry Council, 2010): POLYURETHANE RECYCLE METHODS CHEMICAL PROCESS MECHANICAL PROCESS REGRINDING REBONDING ADHESIVE PRESSING COMPRESSION MOULDING GLYCOLYSIS Fig. 2.Polyurethane recycle methods Uses of Recycled Polyurethanes Scraps Polyurethane wastes can be used for Pump housing special products based on the extra- Automotive parts ordinary properties that they exhibit by Tyre cover using the unique recycling proceedures. Car seatbacks The products generated have found Car head rest, etc. application in (PFA,1994; CPI,2009); PYROLYSIS HYDROGENATION Paving material 6. Lessons From Other Countries: New Bonded carpet underlay Stuffings for pillows Zeland, Sweden, Packagings Singapore,Canada,United States, etc. Sound insulation (CPI-ACC,2009;George, 2007; Knight, Mats 2006;Yanyin,2002;) 8 Nigerian Society of Engineers, ABUJA, 2010 HYDROLYSIS Presently in the United States of America, In Singapore and Sweden, they recognized polyurethane recycling business has been that efforts at instilling environmental encouraged to the extent that the demand consciousness need to start early in order to for flexible polyurethane foam wastes now have long-term effects on children exceeds the supply through domestic scrap (Yanyin,2002).Therefore, environmental recovery.They now engage in importation consciousness has been included in their of scrap polyurethane from Europe thereby educational curricula with a view to contributing to the global polyurethane producing a next generation of wastes minimisation. environmentally conscious citizens. In the United States and Canada, Recycled New Zealand (Knight,2006) embarked on Polyurethane Markets Database of contacts a Zero Waste Programme involving and companies who recycle polyurethane investigation of several possibilities for have been compiled to enable the trade to local foam collection,including the thrive more.The post-consumer mattress- feasibility of setting up collection centres recycling programme has also been for citizens to drop off materials developed in the United States and containing polyurethane foam. Canada. “Currently, there are 89 Waste -To-Energy European markets are rapidly developing facilities in the US that dispose of 81, 000 innovative uses for polyurethane wastes to metric tonnes of solid waste per day and provide generate 2700 MW of electricity (enough high-value products for their consumers. to “In Singapore, one of the strategies was to WAMASON, 2008 improve the operational aspects of recycling Various schemes improving waste management is going on around the convenience like placing recycling bins in globe on polyurethane recyling and other more accessible strategies of waste minimization. Now the by (Yanyin,2002). 9 providing and and visible location”. supply 2.3 million homes)” research and developement on big question is- Where are we in Nigeria? Nigerian Society of Engineers, ABUJA, 2010 •Industrial Scrap •Post Consumer Polyurethane •Collection,Processing for Export P O LY U R E T H A N E WASTES Recycle • Generation of Electricity Energy Recovery •more research to be done Other Uses Land Fill To be minimised Fig. 3.Effective Polyurethane Waste Management CONCLUSION More efforts should be made by the Government through the Federal Ministry of Environment towards a cleaner Nigerian environment as we strive to acheive vision 20:2020 Nigeria as the giant of Africa should take a leading step and set the pace for others to follow in this bid to rescue our environmement through emphasis on recycle,borrowing a leaf from UK., U.S. A., Canada, Singapore, Sweden, etc With the Nigerian population and increasing urbanization, for the problem of poor waste management that bedevils Nigeria and most of the African Countries to be overcome, all hands should be put on deck in order to achieve a sustainable development in waste management 10 Nigerian Society of Engineers, ABUJA, 2010 In a nutshell, if recyling of post-consumer polyurethanes and other materials are given the much desired attention, recyling will be one of the appropriate strategies to improve waste management as well as to combat the problems of pollution and global warming in Nigeria. RECOMMENDATIONS Some of the beneficial educating the masses about the programmes/measures put in place attending benefits to our to manage waste in Nigeria, environment already launched by the Federal Public Private Partnership Government should be reviewed enterprises in waste management and reactivated to emphasize should be encouraged reclying of polyurethanes and other post consumer products . Government and Non- Federal Ministry of Environment should promote recycling from source, sorting the waste from Governmental Organizations homes, factories, establishment or (NGOs), professional bodies e.g. at collection points before getting NSE,WAMASON, should launch to dumpsites. recycle campaigns and champion “Scavengers” should not be seen the cause of recyling of as out-casts but should be polyurethane and other post- encouraged by creating recycle consumer products. agency where they can be Recycling Agency should be absorbed, as they contribute to the established to create collection recycle process by sorting the points for polyurethane and other rubbish before it gets to the specific materials such as; plastic, dumpsites . paper, metal, glass, wood, and Useful and accessible waste rubber in our community, creating generation and recyling data should recycling bins in accessible be made available through more locations. research.This is needed to monitor A sense of social responsibilty should be inculcated into the 11 citizenry concernining recycling, the progress of waste management in Nigeria. Nigerian Society of Engineers, ABUJA, 2010 Data base of existing recycling agents in Nigeria should be created. There should be a review of relevant legislations, policies and Braslaw, J.and Gerlock, J.L. (1984) Polyurethane Waste Recycle,Polyol Recovery and Purification, Industrial Engineering and Chemistry Process Design and Development. 23(3), 552557. regulation in order to promote recycle (of polyurethanes and other materials) as an important strategy in achieving effective and sustainable waste management and control in Nigeria. REFERENCES ADCB UAE 2010 Directory . Retreived July, 12, 2010 from http://www.adcbuae.com/directory/foa m_industry_in_nigeria.html , Akinkurolere,O.O. and Franklin S.O.(2005) Investigation into Waste Management on Construction Sites in South Western Nigeria, American J. Applied Sci., 2 (5), 980-984. 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