The Recycling Process

When the new product to be manufactured is the same as what it started as, for example a new bottle made from bottle scrap, the recycling is referred to as closed-loop. When the new application is different from the starting one, the process is referred to as open-loop recycling, as is the case when the polyethylene terephthalate bottle is used to produce polyester fiber for carpeting. 

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The hterature is hiU of detailed evaluations of recycled petroleum products (2,6,17,18,23,28) and investigations into the environmental ramifications of the recycling processes themselves (30). 

Plastics have many advantages. Included are the facts that they have the lowest energy consumption in the recycling processes of about 2 MJ/kg (2 to 2.5 MJ/I) and when incinerated the highest recovery energy content exists of about 42 MJ/kg. Some comparisons with other materials are provided. (1) Processing waste paper requires 6.7 MJ/kg and as a general rule about twice as much paper is needed compared to plastics for... 

A feasibility study has been earried out by EPI Asia on behalf of PACOA s Plastics Environment Council into the viability of energy recovery from municipal waste. It is claimed to have demonstrated that a 250,000 tpa plant processing from a population catchment of 500,000, would generate a new 15M We of electricity, and that given a gate fee of 50 Australian dollars per tonne for delivered waste, and power sales of 6 cents per Kwh, the plant would be viable. The recycling process is described. 

While RCRA specifically exempts some wastes when recycled, some recycling processes may still pose enough of a hazard to warrant some degree of regulation. However, due to the nature of the recycling process itself or the nature of the materials being recycled, these processes may require a specialized set of standards. These processes are as follows2 ... 

Waste fractions leaving the recycling process of waste as a recovered material have to fulfill the obligations of the REACH regulation, but with certain privileges. Article 2(7d) provides under certain conditions for an exemption from registration (Title II), downstream user regulations (Title V), and evaluation (Title VI) [10] ... 

In addition, the concern about e-waste not only focuses on its vast quantity generated daily, but also more on the need to handle the toxic chemicals embedded in it. It is well known that e-waste contains lead, beryllium, mercury, cadmium (Cd), and brominated flame retardants (BFRs) among other chemical materials [3]. Furthermore, highly toxic chemicals such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated dibenzo-p-dioxins and dibenzo-furans (PBDD/Fs) can be formed during the recycling process [4]. 

In respect of designing an economic production process, the stoichiometric cofactor required in carbonyl reductions or the respective oxidation reactions needs to be minimized that is, enabled by recycling of the cofactor. The measure for the efficiency of the recycling process is the total turnover number (TTN), which describes the moles of product synthesized in relation to the moles of cofactor needed. The different approaches in cofactor recycling were recently reviewed by Goldberg et at. [12]. 

The recycling process of Ran between its GDP and GTP complexed state is supported by another class of Ran-binding proteins, which support GTP-hydro-lysis by RanGAP and are either soluble proteins [ 143] or part of the nuclear pore complex [144]. 

The effects of added C02 on mass transfer properties and solubility were assessed in some detail for the catalytic asymmetric hydrogenation of 2-(6 -meth-oxy-2 -naphthyl) acrylic acid to (Sj-naproxen using Ru-(S)-BINAP-type catalysts in methanolic solution. The catalytic studies showed that a higher reaction rate was observed under a total C02/H2 pressure of ca. 100 bar (pH2 = 50bar) than under a pressure of 50 bar H2 alone. Upon further increase of the C02 pressure, the catalyst could be precipitated and solvent and product were removed, at least partly by supercritical extraction. Unfortunately, attempts to re-use the catalyst were hampered by its deactivation during the recycling process [11]. 

A lot of solvents and non-solvents for ABS are known. Among these solvents, acetone and tetrahydrofuran (THF) were chosen, because these solvents dissolve ABS already at room temperature. Therefore, the costs of the recycling process and further the risk of thermal degradation during the process are decreased. Acetone is somewhat more advantageous then THF because of the costs of the solvent. 

In the recycling process both the free and the bound sulfuric acid (as metal sulfates) can be recovered from the weak acid in the calcination furnace (Fig. 17, k) and in metal sulfate calcination (Fig. 18). The process consists of two stages ... 

Amphetamines and cocaine work the same way in the body, but cocaine is much more vigorous at blocking the reuptake of dopamine. How cocaine works is illustrated in Figure 14.26. The great buildup of dopamine in synaptic clefts in the brains reward center is the source of cocaines euphoric effect. As cocaine keeps dopamine from being reabsorbed by the presynaptic neuron, the dopamine remains active in the synaptic cleft, and as a result the reward center stays stimulated. This euphoric state is only temporary, however, because enzymes in the deft metabolize, and hence deactivate, the dopamine. Once the cocaine is metabolized by enzymes, dopamine reuptake is again permitted. By this time, however, there is very little dopamine in the deft to be reabsorbed. Nor is there an adequate supply of dopamine in the presynaptic neuron, which is unable to make sufficient quantities of dopamine without the recycling process. The net result is a depletion of dopamine that causes severe depression. 

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