Solutions And Technologies To Recycling, Up-Cycling, And Biodegrading Of Plastics

Sources of waste products

Title: Solutions And Technologies To Recycling, Up-Cycling, And Biodegrading Of Plastics

In the past years, the use of plastics has been increasing at a very high rate over many parts of the world. Most countries have been using rare varieties of petroleum products in manufacturing a wide range of products for different uses. Most of the plastic products do not even last for a year, and large quantities of these products are gotten rid of. The recovery of plastic waste is in most cases not economical for the concerned organizations. Many companies have invented new technologies and come up with effective programs to enhance the reprocessing of plastic waste for both economic benefits and the benefits of the surroundings (Niaounakis, 2013). Plastics are made from unrecoverable materials, and the decomposition rate of the waste plastic is very slow. The plastic waste is the most unpleasant junk people can have around and have to keep seeing it for a long period since it does not decompose easily.

The main source of plastic junk is the large industry activities such as processing manufacturing and packaging. The scrap has desirable features and can be recovered for the other uses. The plastic waste is usually in low amounts but keep in increasing with the increase in their demand.

Plastic waste from commercial settings such as the business units like wholesalers the retail shops and crafts work. The plastic junk from these sources is usually polluted (Embalagens, 2014).

The agricultural waste can be recovered from farms found within the urban settings. The agricultural plastic waste is usually in the form of pipes from irrigation activities and plastics used in packaging seeds and fertilizer. (Harbers, 2014)

The municipal sources of waste plastics refer to the plastic waste obtained from domestic activities within residential areas. The concerned individuals can collect the plastic litter from the residential path or even agree with the residents to collect from their homesteads.

The technology and procedures used by small enterprises in recycling plastic waste.

Primary improvement, after the collection of the plastic they are cleaned and classified. The strategy used in the washing is usually determined available plastic waste. In the small operations, hand washing is used while in large operations the washing and sorting can be done by use of machines (Atala, 2012).

• Strategies for cutting the plastics into required sizes. There are various purposes of reducing the plastic sizes such as, coming up with a product that can be efficiently processed and for the storage and movement reasons. The achievement of the required dimensions is achieved at by use of several methods.

.The large objects are then cut into required sizes by use of simple cutting objects such as scissors and other sharp objects.

.A typical shredder is used for the small pieces. The shredder has several blades and is operated by an electric motor. The shredding results into the uneven portions of plastics which can be processed further.

.The agglomeration process involves heating and exposing the heated content under low temperatures within a single machine to plastic grains usually named crumbs.

This is the mostly used technology in the recycling of plastics it is mainly represented   by their low cost and their simplicity. This technique refers the reuse of the products in their original structures. The key disadvantage of this method is that the number of each cycle of plastics is limited. (Al-Salem, 2015).

Processing of reclaimed plastics

This method involves the collection of the waste plastics and then remolding them into the final new product. This technique does not involve the alteration of  the practice during remolding .The technique is usually represented  by a physical  technique , via  which the  waste plastics  will be formed  by washing, shredding  or cutting  into the granules, flakes or pellets of the correct  quality for the purpose of manufacturing  and after that  the plastics are remolds through melting  to be processed new products through the process  of extrusion. The plastics can be reprocessed and be blended with other new materials to obtain an outcome which is more superior. After the plastics are cleaned, dried and sorted they are processed into the new products. At the same time, the quantity of the waste plastics will greatly reduce .The main disadvantage of this technology is the heterogeneity of the plastics which occurs as a result of

The low molecular weight of the recycled plastics. It occurs due to the chain-scission reaction caused by the presence of traces of acidic impurities and water. In order to the chances of occurrences of this reaction drying of the waste plastics is highly recommended. The figure below illustrates the steps involved in mechanical recycling.

This technology is defined as a process through which the plastics are chemical to monomers or partially depolymerized to the oligomers through a chemical reaction. The formed monomers can be applied for the new polymerization to reproduce the original or related plastic product. This technology can transform the plastic material into the smaller molecules which are suitable for the application as feedstock material starting with the monomers, oligomers or a mix of any other hydrocarbon compounds (Golinska, 2013).

The chemical reactions which are used to convert the plastics into the monomers are:

• Hydrogenation
• Gasification
• Degradation in a microwave reactor
• Pyrolysis
• Catalytic cracking
• Thermal cracking
• Photodegrading
• Mentanolysis
• Ultrasound degradation
• Chemical depolymerization

The technology of chemical recycling is  not well developed  and because  of that  not many companies have adopted  this  technology because this technology requires intense investments and trained workforce which is very expensive to acquire. Currently, many technologies are under investigation such as, pyrolysis and gasification to establish their suitability and the process which have reached commercial maturity currently are Mentanolysis and glycolysis (Grunwald, 2014).

This is a reutilizing technology which includes a reaction of plastic with water in an acid, natural or alkaline environment, resulting in total depolymerization into its monomers. The main limitation of this technology are the high temperatures which are required, i.e., between 200 and 250^oC and pressure of between 1.4 and 2 MPa and the long period which is required to complete the depolymerization. This technology is not widely applied, due to its high cost.

The chemical recycling of plastic by Mentanolysis involves the plastic degradation by methanol at temperatures ranging between 180 and 280^oC and at a pressure ranging from 2 to 4 MPa with the main products being terephthalate and the ethylene glycol. The optimal conditions refer to the temperatures between 260 and 270-degree Celsius, and the pressure of 9.0 to 11.0MPa and the weight ratio from 6 to 8. The moment the main products are obtained the dimethyl terephthalate is purified by distillation to remove all the physical contaminants and then it can be reused to produce plastics (Clark, 2016).

The chemical salvaging of plastics by glycolysis involves the ethylene glycol insertion into the plastic chains to give hydroxyethyl, which is a substrate for the plastic synthesis and other oligomers. From the researches that have been carried out by other researches regarding the recycling of plastics by use of this technology, many basic ionic liquids, and ionic liquids were used as a catalyst.

Great technological advancements have been achieved in the last few years on the depolymerization of plastic wastes which have made it possible to convert one type of plastic into another which is more valuable.

In this technology of plastic pyrolysis, the macromolecular structures of polymers are crashed into smaller oligomers molecules and at other times into monomeric units. Additional dilapidation of these succeeding molecules relies on some different factors which include; residence time, temperature and the presence of catalysts and other process conditions. The pyrolysis reaction can be conducted with or without the presence of a catalyst. Accordingly, the reaction will be thermal and catalytic pyrolysis. Since most of the plastics are a polyolefin, with that a lot of research has been done in the past decade for the better outcome.

This method is a recovery technology of plastic energy .Incineration is the most effect method of reducing the volume of the organic material that are involved in the recovery of energy content. This technology is among the best solutions because it usually generates a lot of energy  from the waste plastics, at the same time it does not pollute the environment.

References

Al-Salem, S. (2015). Plastics to Energy: Fuel, Chemicals, and Sustainability Implications. Chicago: Elsevier Science.

Atala, A. (2012). Synthetic Biodegradable Polymer Scaffolds. Sydney: Springer Science & Business Media.

Clark, J. H. (2016). Feedstock Recycling of Plastic Wastes. London: Royal Society of Chemistry,

Embalagens, I. d. (2014). Better Packaging: Better World. Chicago: Instituto de Embalagens.

Golinska, P. (2013). Environmental Issues in Automotive Industry. Paris: Springer Science & Business Media.

Grunwald, P. (2014). Industrial Biocatalysis. Texas: Pan Stanford.

Harbers, H. (2014). Inside the Politics of Technology: Agency and Normativity in the Co-production of Technology and Society. London: Amsterdam University Press,

Niaounakis, M. (2013). Biopolymers: Reuse, Recycling, and Disposal. London: William Andrew.