Recycling Techniques

Despite increasing research efforts it is not yet economical to separate the wide variety of plastics that end up in the waste stream. The ideal is streams of single, clean and homogeneous recyclates, which present little technical effort for recycling. Of course, streams of this type, mainly industrial, can and are recycled. However, mixed waste streams present more of a technical and economic challenge to recover. 

Consider your household rubbish, perhaps even rummage in your bin  

What plastics are present and what form are they in  

You are likely to find items such as packaging films, detergent bottles, carrier bags, milk bottles, food and household containers. 

You may have foimd food debris and residues from the various containers. You may also have noticed paper labels or glue residues or possibly even the use of other materials in combination with plastic, such as aluminium linings or metal closures. Now we have not only a mixed plastics waste stream, it is also contaminated with other materials. 

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It is predicted that by 1979 this nonpolluting recycling technique will not only supplement expl solvation procedures, but will also displace both burning and sea disposal of ordnance to a great degree... 

The problem of carpet recycling is considered and the different methods being proposed or commercially utilised are discussed. The main component of the carpet waste is fibres of nylon-6 and nylon-66. The review of the literature includes a limited amount of journal publications, which focus primarily on fundamental aspects, and a large number of patents, which describe the available technologies. The most promising recycling techniques (depolymerisation, extraction, melt blending and mechanical separation) are described. 48 refs. 

Incineration with energy recovery is examined as a means for the disposal of plastics waste, and data are presented for the calorific values of a number of materials. Chemical recycling techniques are also briefly reviewed. 

The origins and composition of plastics wastes and factors affecting their recycling are discussed. Partieular attention is paid to chemical recycling and incineration, with and without energy recovery, and a number of developments in chemical recycling techniques are examined. 19 refs. 

Improved Materials Processing and Recycling Techniques that Reduce Energy Consumption and GHG Production (e.g., reduction of Portland cement use by substitution of industrial waste products such as fly ash, which has several side-benefits). 

The e-waste issue can be discussed from multiple angles, e.g., international trade, management, and recycling techniques. This chapter is intended to address the environmental consequences of e-waste disposal if not conducted properly. 

The compound of the distinct three oxo processes, all rhodium-based, enables a highly efficient recovery system to be achieved. Figure 5.17 describes the TPPTS manufacture and its use for the preparation of the rhodium catalyst, using either freshly introduced Rh acetate or recycled Rh 2-ethylhexanoate. The recycle technique of the RCH/RP process and its performance is depicted earlier. Spent Rh-TPPTS solutions are worked-up (see Figures 5.18 and 5.19), the resulting TPPTS returns to the RCH/RP process. The rhodium portion passes also a work-up stage and is reformulated as Rh 2-ethylhexanoate. This Rh salt may serve all various oxo processes of the oxo loop and will compensate for possible Rh losses as mentioned earlier. 

To be fair, it should be realized that if a catalyst must be recycled for economic reasons, the recycling efficiency compared to the nonfunctionalized catalyst must be higher in order to compensate for the increased price of the fluorous catalyst itself. However, every recycling technique has its own cost that must be evaluated for each specific case. 

The recycling of PET is an important environmental topic as well as a commercial opportunity due to its widespread use, abundance and availability in bottles, packaging and fibres. While mechanical recycling of PET is now well established, newer chemical recycling techniques rely on depolymerization routes which cleave the polymer chains into new monomer building blocks (see Chapter 16). 

Because evaporation does not remove contaminants from the concentrate, it is necessary that the system have a method of controlling buildup of metallic and organic impurities. Additional recycling techniques such as ion exchange can be used for this purpose. 

If we have to increase load higher, say to obtain a 50-fig sample for NMR analysis, we can use the shave/recycle technique to be described in the true preparative section. These runs must be made isocratic and column overload occurs at 100-150ng for most compounds. If this much material is needed, it is better to switch to a semipreparative column, which can easily produce milligram quantities in a single pass. 

These additional yields point out the added benefits gained from the presence of additional donor hydrogen. The data in Figure 10 also show the sensitivity of increased yield from the bottoms recycle technique to the type of coal being processed. 

Is the shaving-recycle technique useful in preparing pure fractions Refer to your data. 

Biodegradable materials are created specifically with recyclability or disposal in mind. Recycling techniques for post-consumer biodegradable plastic products have two important features, which distinguish them from conventional polymers their biodegradability or compostability and the use of renewable resources in their manufacture. 

As the reader has observed in this review, the innovation process is thriving within this new environment. The focus has been on more cost effective polymerisation plants with an improved environmental profile, the replacement of lead stabilisers, scientific studies and support for phthalates, a greater understanding of and an increasing role for impact modifiers, recycling techniques and waste management possibilities. 

Spanish initiatives in PVC recycling are examined with particular reference to mechanical recycling, and developments in chemical recycling techniques are also reviewed. Statistics are presented for sources of PVC waste and forms and applications of the recycled materials, and a map shows the geographical distribution of PVC recyclers in Spain. 

For the PFC recovery and recycling technique, the most popular concept is to concentrate and recover PFC on site and to purify off-site. 

The Stamicarbon 1 process is a conventional total-recycle technique. Its special feature consists in introducing small amounts of oxygen into the reaction medium to minimize corrosion. 

Toluene is commonly used as the eluent in HPLC separation. Specially designed HPLC columns are necessary. Sometimes recycling techniques are needed to obtain isomer-free samples. Figure 7.4 shows a representative HPLC profile of Gd-EMFs on a 5PYE column... 

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