Recycled knowledge

Waste plastic recycling and renewable method

World production of synthetic resin reached 200 million t, a large number of post-consumer plastic handling problem has become the global focus. At present, the post-consumer plastic processing has the following several ways: 1 filling: 2 burn: 3 composting; 4 recycling; 5 the use of biodegradable plastic.
plastics recycling
plastic recycling regenerative method: melt regeneration, thermal cracking, energy recovery, recovery of chemical raw materials and other methods.
(1) melt melting regeneration regeneration is a waste of plastic heating plasticization and used again. Sources of waste plastic, this method can be divided into two categories: one is made of resin factory, factory cleaning waste plastic recycling scrap recycling; the second is after using mixed in with the recycling of all kinds of plastic products. Former simple regeneration, can produce plastic products with better performance; the latter complex regeneration, only relatively poorer performance requirements for preparation of plastics, and the recycling process is more complicated.
(2) pyrolysis pyrolysis is the selection of waste plastics by pyrolysis of burning oil, gas method.
(3) energy recovery energy recovery is to use the heat generated by the burning of waste plastics method.
(4) recycling of chemical raw materials, some varieties of plastic, add the polyurethane can be obtained through the hydrolysis of materials synthesis monomers. This is a chemical decomposition method for recycling waste plastic into chemicals.
(5) other, in addition to the recycling of waste plastics method, there are a variety of methods of waste plastics, waste foamed polystyrene plastics crushed dug in to improve the soil's water retention, aeration and drainage, and mixed with cement or as a filler made of light concrete, or join the adhesive pressing cushion materials, etc.
plastic plastic solid waste disposal and recycling of
used oil and coal as raw material to produce plastic instead of the natural polymer, had experienced a difficult course, a whole generation of distinguished chemists in order to achieve the current plastics has excellent physical and chemical properties and durability to do hard work. Plastic to its light weight, durable, beautiful, inexpensive and so on, instead of a large number of traditional packaging material, led to a revolution in the packaging industry. But something people get expected is precisely these fine performances of plastic generate vast quantities of durable plastic waste does not. After a lot of discarded plastic packaging has become a scourge against the environment, the main reason is that these plastics are difficult to deal with, unable to make it down and turn to dust. The existing municipal solid waste, plastic has reached 15%-20%, most of which are single use plastic packaging products. Processing of plastic waste is not only the problem of plastic industry, pollution-has become a widespread concern in the international community.
in order to meet the need of protecting the Earth's environment, plastics processing industry developed many environmental technologies in the world. In save resources aspects, main is improve products resistance old performance, and extended life, and multifunctional of, and products amount design; in resources again using aspects, main is research plastic waste of efficient points selected, separation technology, and efficient melting regeneration using technology, and chemical recycling using technology, and completely biological degradation material, and water-soluble material, and can food film; in reduction quantitative technology aspects, main is research abandoned plastic compression reduction capacity technology, and film bagged container technology, in ensure application performance of premise Xia, as will products thin type of technology And in the development of CFC substitutes, focuses on carbon dioxide foaming technology alternatives research, primarily to develop alternatives to PVC and PVDC.
plastic solid waste disposal in the city, mainly through landfill, incineration and recycling three ways. Due to different national conditions, countries vary, United States dominated by landfill, Europe, and Japan dominated by burning. Using landfill, plastic products quality is light, and not easily rot, soft texture Foundation leads to landfill becomes, it is difficult to use in the future. Incineration, plastic heat, easy to damage the stove and burned gases will lead to global warming, some plastic when burned releases harmful gases and pollute the atmosphere. Using the method of recycling, due to the cost of artificial, high recovery cost and the lack of appropriate recycling channels, currently the world recycle only about 15% all consumption of plastics. But due to limited oil resources in the world, from the point of view of saving the Earth's resources, recycling of plastic is of great significance. To this end, countries around the world have put in a lot of manpower and resources, the development of key technologies of waste plastics recycling, is committed to reducing the cost of plastic recycling development its proper application.
heat recovery method
most plastic oil as raw material, primarily composed of hydrocarbons, can burn, such as combustion of polystyrene heat is higher than oil dye. Some experts believe that the plastic waste into incinerator burning, heat to provide heating or power generation, oil dye 86% are burned directly, of which only 4% made plastic products, plastic finish it and then sent to as a thermal burn is very normal, energy use is one of plastic recycling is available, should not be taken lightly. But many environmental groups oppose the burning plastic, they believe that all messy chemical burning combustion will produce toxic gases. As half of chlorine in the PVC components, releasing chlorine gas when burned has a strong erosion damage, and is the culprit causing dioxins.
at present, Germany every year, 200,000 tons of PVC waste, 30% burning in incinerators, burning people, the law had to develop this strategy. Germany's Federal Environment Bureau requires all incinerators must comply with waste gas value less than 0.1NG per cubic metre (NG) limited. Germany's air pollution standards has been belonging to the high standard of the world recognized, but still did not dare to say burn method does not produce harmful substances due to mechanical failure, so it can be foreseen that national environmental groups are still strongly oppose the incineration method for heat recovery.
recycling laws
as plastic recycling, is the most important classification. Common plastics, polystyrene, polypropylene, low density polyethylene, high density polyethylene, polycarbonate, PVC, polyamide, polyurethane, which ordinary people could hardly tell the difference between. Now the classification work, mostly done by artificial. Recent classification of the machine with new advances, Germany a society of chemical science and technology invention to infrared rays to identify categories, both quickly and accurately, merely sorting through the higher costs.
chemical reduction
researchers began trying to extract the chemical constituents of plastics for recycling. The methods used are long chain polymer cutting, restoring its original nature, cracked out of raw materials can be used to make new plastic. Some methods are combined by adding chemical chemical decomposition of carbon atoms, or join the energy contributed to its thermal cracking.
Germany Bayer developed a PUC mat from hydrolysis of chemical reduction method to cracking. Tests show that chemical reduction is technically feasible, but it can only be used to clean plastic, such as corner powder produced in the manufacturing process and other plastic waste. And other dirt from the family used contaminated plastics, it is difficult to use chemical treatment. Application of this method, to the 21st century, it will be a lot of utilization method of waste disposal. Some new chemical decomposition method is still in the process of research, United States Ford Motor Company currently applies the ester solution to deal with automobile waste plastic parts.
United States Institute of technology developed a biodegradable plastic waste solution, which has applied for a patent on the solution and mixed with 6 different types of plastics are heated. At different temperatures, 6 polymers were extracted separately. Experiment, Polystyrene plastic fragments and mixed into the dissolved under the relevant solution at room temperature, place it into a sealed container heating, and then into the lower pressure "flashing room", the rapid evaporation of the solution (recycled), the rest is pure polystyrene can be reused.
allegedly, the purification of used devices, purification of 1kg polymer per hour. The State of New York and Niagara. Mohuoke power company is planning to build a small scale pilot plant. Investors claim that the plant is completed, 4t recyclable polymer materials per hour. Its costs only raw materials for the production of 30%, with obvious commercial value.
hydrogenation analysis solution
, many experts believe that hydrogenation used to process mixed plastic products. Mixed plastic fragments into hydrogen furnace, temperature pressure, will be able to produce synthetic crude oil and gas and other raw materials. This method can be used for treatment of PVC waste, the advantage will not produce toxic dioxins and chlorine. Use this method to process mixed plastic items, depending on the plastic components 60%-80& components can be refined into synthetic crude oil. Germany national chemical companies such as BASF pointed out in a joint study, hydrogenation for pyrolysis method the best way, analysis of the synthesis of original oil of good quality, can be used for refining.
United States Lexington Kentucky University have invented a method of waste plastic into high quality plastic fuel oil. In this way production of fuels like oil, or even lighter than crude oil, easier to refine into high octane fuel. The waste plastics to produce fuel oil does not contain sulfur, impurities are rare. Use similar methods and coal liquefaction with plastic. Are able to produce high quality fuel oil.
researchers in the showers all kinds of plastic and zeolite catalyst, tetrahydro-naphthalene mixed together and put in a call "pipe bombs" in the reactor, hydrogen and heat, prompting macromolecular plastic breaks down into low molecular weight compounds, which combine in a process similar to crude oil processing. After this treatment, the waste plastic oil production rates are high, polyethylene plastic bottle of oil is up to 88%. When the proportion of waste plastics and coal at roughly 1:1 mix and liquefied, can get more high quality oil. After a method of assessing the economic benefits of this technology is expected, using waste plastics to produce fuel oil will become transformation of blast furnace in 5-10 ... At present, Germany has begun to establish a promising Nissan 200T plastics in botepu the reactor fuel.
reduction, methods of design
research and development sector is taken into account when designing a product recycling and disposal of demolition, United States for recycled materials, taking into account the emphasis is not on the production of individual components which should be used are the ideal plastic, but the material can be widely used, this is the idea of revolutionary change.
in order to facilitate recycling, designers started designing products avoid the use of a variety of plastics, United States prepared from BMW, in its new car designs reduced 40% of plastics in order to facilitate the recycling of waste plastic. Automotive industry to reduce plastic use categories, plus sex and taken into account in the design, which is expected to win the attention of environmental image, appreciated by consumers. At present, this design concept was gradually infected the entire plastic processing industry.
but efforts are still unable to make passage of 20 types of plastics on the market any kind of died out. Category of product diversity has led to the plastic variety, after all, ever-changing, such as production of computers using plastics and production of automotive plastic used is not the same.
for this reason, experts recommend such a recovery standards, provides special industry can only use the specified materials or cannot control the effective recovery, electronic and automobile industries have begun to develop such standards.
world electronic electrical market on abandoned plastic recycling using has caused attention, international commercial machine company (IBM) has began will computer and commercial machine of plastic parts for standard code, and in development can recycling again with of plastic electronic parts and simplified demolition equipment of products structure, while also consider canceled components of surface coloring, control plastic additives of external adhesive of dosage reduced using not using recycling of process parts and the plus parts.
recycling of discarded car parts also have a great deal of progress, many countries are in easy recovery of recyclable auto plastic parts materials selection and product design premise. Some countries have developed effective auto parts standard recycling numbers and recovery plans and consider aid disassembly and sorting plastic unified logo system. European countries is also studying chemical depolymerization of plastic for recovering.
biodegradation
while actively developing plastics recycling technology, research and development of biodegradable hot spot in the plastics processing industry in the world today. Researchers hope to develop a biodegradable plastic in the microbial environment in order to handle a large number of single-use plastic, especially plastic film and packaging waste on farmland, forests, marine pollution. Research goal is to develop a process to ensure that its performance, and once out of waste can be broken down by microbes in the environment, thereby completely into the ecological cycle of plastic. Also, the plastic and low production costs, have a corresponding economy. If this is the case of biodegradable plastic, after use with normal biological waste composting without expensive costs for collection, sorting and recycling. Moreover, the breakdown products into the ecological cycle, does not produce waste.
in the area of research and development of biodegradable plastics, countries around the world have invested considerable financial and human resources, has spent a great deal of energy research. Plastic processing industry generally felt that biodegradable plastics is 21st century technology issues.
The end of the 80, degradation problem in order to solve the garbage bag, United States corn, driven by adding starch polyethylene plastic bags are used as bio-degradable plastics in Europe was all the rage. But due to the degradation of polyethylene does not, so the application has significantly cooled. Just because a rich source of raw materials of starch, and cheap, there are still a number of researchers engaged in this field of study, through a variety of technology, a breakthrough in terms of degradation.
current technology are microbial fermentation synthesis, use of natural polymer (cellulose, lignin and chitin) synthesis chemical synthesis, and biodegradable plastic water soluble resins have been developed, but all in all, their costs of production does not meet the requirements of industrial production.
Germany Bayer experts after years of fiber products, made of a plastic that can completely decompose into humus. Use plastic packaging film, breaks down quickly in the soil "disintegrated", within 10 days of return to nature. According to the environmental organization's identification, this plastic and decomposition of neutralization on the environment and humans is safe and secure. The company developed the new plastics are hard and difficult to extend fiber mixed with polyurethane made. Buried after the new plastics, soil microorganisms in dishes, rapid multiplication of micro-organisms can quickly digest this material into humus.
a household plastic wrap made from this material, after 14 days, may become powder, after 8 weeks of lost 80% pounds. With this kind of material culture of seedling, planted weeks into humus in the soil, as the role of compost. Due to this new technology of the production costs were too high. Several times the ordinary plastic, thus it is difficult to achieve commercial production.
in terms of application, after years of effort, biodegradable polyethylene plastic film in China has achieved initial success in research projects, develops biodegradable plastic film test specimens, and a small area of the trial, it appears from the terms of the maturity of the technology, has not yet reached the extent of the large scale application. Add a our photodegradable plastic has not been involved in the field. United States photodegradable plastics used in bottles-have been for many years, Israel and Canada degradable mulching film of light have a trial, but there is no reports of large scale.
it is predicted that as the industrialization of bio-degradable plastic research counts as 100, the relative phase of current research and development is only 30, is expected after 2000 is expected to achieve industrialization. At present, the United States on the technology research and development of leading Europe in second and Japan third.
in General, in the research and development of biodegradable plastics, also has much to overcome problems. First, awareness of the degradation of plastic, there is no uniform definition, that is what biodegradable means? Decomposition of biodegradable plastic that is what determines how long? In addition, on the decomposition of the product should be what? End products are carbon dioxide and water, and is harmless to the practical application of any form of residues? Secondly, the evaluation of biodegradable plastics, there are no universally recognized and unified approach. Current United States society for testing and materials and the Japan industrial standards associations and the International Organization for standardization are actively carrying out work in this area, although the United States ASTM has promulgated a number of results cannot be applied to the actual processing of plastic waste.
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