Recycling markings

Recycling marks on products (Fig. 1.11) allow the common plastics to be identified (Table 1.1). Sometimes numbers are used in place of the abbreviation for the polymer name. 

Other problems related to the flame retardants in plastics appear because of recycling, marking, ecolabelling and product take-back [47]. Incineration and processing raised questions about formation of toxic products when brominated flame retardants are used, so environmentally preferable products have to be found. 

Recycling of the ligands was investigated for ligands D, E and J. over four recycles the conversions dropped for all three phosphites, however the most marked decrease was with E (<10% conversion in the fourth recycle). The selectivity of the catalysts to aldehyde products did not decrease so drastically but a decrease in the selectivity of E was most notable in the second recycle. This suggests that some leaching of the three phosphites to the organic phase does occur. 

In 1975, the total world tin production was 236,000 tons, of which 72% was produced by China (10%), Indonesia (8%), Malaysia (35%), Thailand (7%), and 6% each by the U.K. and the former Soviet Union (WHO 1980). Annual mine production of tin in the United States is a comparatively low 3300 metric tons (USPHS 1992). The world production of recycled tin was about 20,000 tons, of which France produced about half (WHO 1980). About 25% of the tin used in the United States is recovered from scrap materials containing tin. This secondary production occurs in the United States at 7 detinning plants and 162 processing plants (USPHS 1992). The production and consumption of tin chemicals, especially organotins, has increased markedly in the past several decades (Table 8.2). 

Independent conversion processes may not employ the Claus reaction for sulfur production and do not recycle the captured sulfur compounds to the Claus plant. Examples are the Beavon Mark I Process (Hydrogenation + Stretford) (13), the Beavon Mark II Process (Hydrogenation + Claus) (13), and the SNPA/Haldor-Topsoe Process (Catalytic Oxidation to SOi.) (9,10). 

Earle, M. J., McCormac, P. B. Seddon, K. R. Diels-Alder reactions in ionic liquids a safe recyclable green alternative to lithium perchlorate-diethyl ether mixtures. Green Chem., 1999, 1(1), 23-25 Doherty, S. Goodrich, P. Hardacre, C. et al. Marked enantioselectivity enhancements for Diels-Alder reactions in ionic liquids catalysed by platinum diphosphine complexes. Green Chem., 2004, 6(1), 63-67. 

Scheme 1 The ethylene biosynthetic pathway. The enzymes catalyzing each step are shown above the arrows. SAM S-adenosyl-L-methionine SAMS S-adenosyl-i-methionine synthetase ACC 1-aminocyclopropane-1-carboxylic acid ACS 1-aminocyclopropane-1-carboxylate synthase ACO 1-aminocyclopropane-1-carboxylate oxidase Ade adenine MTA methylthioadenosine. The atoms of SAM recycled to methionine through methionine cycle are marked in red and the atoms of methionine converted to ethylene are marked in bold. For details see text.

The atoms of SAM recycled to methionine are marked in red and the PLP atoms are marked in blue. Notations are as in Scheme 1. For details see text. 

Most organic waste can be recycled on to the compost pile. Large guantities of items marked are best dealt with in piles of their own. Other miscellaneous compostable items include wood ash and eggshells. 

The immobilization of the sensitizer and catalyst is especially effective, because contamination of the materials (NBD and QC) with a sensitizer or catalyst markedly lower the efficiency of this system. 4-(N,N-dimethylamino)benzophenone was immobilized on poly(styrene) (30) and silica gel to use it as insoluble sensitizer 101 The polymer pendant sensitizer (30) was much more active than the monomeric compound when used in acetonitrile. Usually, the sensitizing activity of the sensitizer remained almost unchanged through immobilization, but sometimes decreased depending on their structure. As a catalyst of back reaction to release heat, Co(II)-tetraphenylporphyrine was anchored on polystyrene) beads (31), and showed good activity in its immobilized form10Z>. Activity decrease was observed- after several times recyclings of the catalyst. 

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