Recycling trend

Compatibilisers are certain to benefit from the recycling trend, but the reuse of polymers for plasties (as opposed to their use as fuel or their conversion to feedstock for chemical intermediates) may be aeeompanied by the reuse of at least a proportion of the additives. Researeh is being earned out to make possible the systematic recovery of additives from used artieles. Several observers believe that energy recovery and feedstock recycling will often be more eeonomie than eonversion to second-life plastics products. 

P. Siafaka, I. Tsagkalias and G. Tsintzou in Material Recycling - Trends and Perspectives, Ed., D.S. Achillas, InTech, Open Access, Rijeka, Croatia, 2012. 

Used oil disposal trends include waste minimisation such as by reclaiming used fluid on site, as well as recycling of mineral oil lubricants instead of disposing by incineration. The recycling effort involves a system where spent mineral oils are collected then shipped to specialty refineries where the materials are distilled, hydrofinished, and re-refined into fresh base stocks. These re-refined materials are virtually identical to virgin feedstocks. 

Economic Aspects. The 1992 MEK nameplate capacity for the United States, East Asia, and Western Europe is Hsted in Table 5. During the period 1980—1989 MEK achieved a negative growth rate as demand dropped from 311,000 (48) to 228, 000 t/yr (49). Stricter VOC regulations were largely responsible for the decline, and the trend will continue as solvent recovery and recycling, as well as substitution away from MEK, take effect. 

Secondary lead production made up over 70% of the lead produced in the United States in 1992 vs 54% in 1980. The amount of secondary lead produced was 698 X 10 t in 1988, 888 x 10 t in 1990, and 878 x 10 t in 1992. Of the 1.2 x 10 t of lead consumed in the United States in 1992, approximately 880,000 t were produced from the recycling of lead—acid batteries and 350,000 t from primary sources. A similar trend exists worldwide. In 1992, for the first time, slightly over half (51%) of the lead produced in the world came from secondary sources. 

Some hquid defoamers are preemulsified relatives of paste defoamers. In addition to the fatty components mentioned above, kerosene [8008-20-6] or an organic cosolvent such as 2-propanol have been used to enhance stabiUty of the oil—water emulsion and the solubiUty of the defoamer s active ingredients. These cosolvents are used less frequently as concerns increase about volatile organic emissions (VOCs) from the paper machine. Additionally, the use of ultrapure mineral oil in defoamers has become commonplace. Concern about the creation of 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) in the pulping process has led to the discovery of unchlorinated precursor molecules, especially in recycled mineral oil and other organic cosolvents used in defoamer formulations (28). In 1995 the mineral oil that is used is essentially free of dibenzodioxin and dibenzofuran. In addition, owing to both the concern about these oils and the fluctuating cost of raw materials, the trend in paper machine defoamers is toward water-based defoamers (29). 

Chlorination can be carried out at 25°C or below. However, the reaction is exothermic and, as mills have used filtrate recycle, operating temperatures have unavoidably risen. Retention times are 30—60 minutes but decrease as temperature increases. In most mills the retention time cannot be changed because the tower is upflow in design. The normal pulp consistency is 3—4%, but the trend is toward higher (ca 10%) consistency or gas-phase chlorination. Target pH in the chlorination stage (also (7 ) is about 1.8. 

Research Trends. Research since the late 1970s appears to have centered on further process modifications and optimization of conventional processes, reduction in pollution, evaluation of potentially more efficient processing technology, increased use of less expensive softwood sources to extend the available hardwood suppHes, and accommodation of recycled newspaper pulp (see Recycling, paper). 

Increased environmental awareness contiaues to create new challenges as well as a variety of new market opportunities for sulfur producers. Further pollution reduction requirements contiaue to iacrease gradually aoadiscretioaary suppHes of sulfur and sulfur products. At the same time, recycling and reengineering have caused slight decreases ia demand. These trends are likely to contiaue ia the future. 

If the feed rate is decreased, the trends of curves in Fig. 13-109 are reversed. The disturbance of other variables such as feed composition, boil-up ratio, and recycle of water-rich effluent from the decanter produces similar shifts in the steep concentration fronts, indicating that azeotropic towers are among the most sensitive separation operations, for which dynamic studies are essential if reli-... 

Snyder, D. D., Landau, U. and Sard, R., Electroplating engineering and waste recycle new developmentsf and trends, Proc. Electrochemical Society (USA), 83-12, Pennington (1983)... 

Bioreactors a) batch stirred tank b) continuous stirred tank c) continuous packed-bed i) downward flow, ii) upward flow and iii) recycle d) continuous fluidised-bed e) continuous ultrafiltration. Redrawn from Katchalski - Katzir E. (1993) Trends in Biotechnology II, 471-477. 

Effects of Cold Gas Recycle and Approach to Equilibrium. Product gases resulting from various CGR ratios were analyzed (Table XI). For the experiments tabulated, a decrease in the cold recycle ratio resulted consistently in increases in the product gas concentrations of water vapor, hydrogen, and carbon dioxide and a decrease in methane concentration. These trends may be noted in experiment HGR-12 as the CGR ratio decreased from 8.7 1 to 1.2 1, in experiment HGR-13 as it increased from 1.0 1 to 9.1 1, and in experiment HGR-14 as it decreased from 3.0 1 to 1.0 1. These trends indicate that the water-gas shift reaction (CO + H20 —> C02 + H2) was sustained to some degree. Except for the 462-hr period in experiment HGR-14, the apparent mass action constants for the water-gas shift reaction (based on the product gas compositions in Table XI) remained fairly constant at 0.57-1.6. These values are much lower than the value of 11.7 for equilibrium conversion at 400°C. In... 

PET recycling, research trends and critical issues in, 533-534 PET resin, 24... 

The trends in environmental research will be considered on the basis of polymers, fillers, oil, and other processing aids, reinforcing fabrics, other chemicals, and recycling technology. Broadly speaking, the following research trends are evident on a global scale ... 

Predicts future trends, including recycling and green materials... 

Re-use, remanufacture and recycle. Focusing on re-use, remanufacture and recycling comes from a number of trends and drivers in society. Because of problems with waste disposal, many companies are trying to work towards a zero to landfill policy. As waste disposal costs rise, this trend will accelerate. At the same time, where raw materials are difficult or expensive to obtain, there is a real commercial incentive to recycle and reuse. Regulators also continue to push for the minimisation or elimination of the release of hazardous materials... 

Another major cause of waste is the use of mineral acids (H2SO4, H3PO4, etc.) and Lewis acids (AICI3, ZnCL), often in stoichiometric amounts, which cannot be recovered and recycled. A typical example is the HNO3/H2SO4 mixture used in aromatic nitrations. Consequently, there is a discernible trend towards the use of solid, recyclable Brpnsted and Lewis acids, e.g. zeolites, acidic clays, etc. (see later) as alternatives to conventional mineral and Lewis acids. 

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