Mercury in products

Table 5-5. Estimated Discards of Mercury in Products in Municipal Solid Waste...

Reducing or eliminating anthropogenic mercury releases will require the control of releases from mercury-contaminated raw materials and feedstocks, as well as reducing or eliminating the use of mercury in products and processes. 

Anthropogenic sources related to the intentionally use of mercury in products and processes, due to releases during manufacturing, leaks, disposal or incineration of spent products. 

An important source of mercury in the environment is also due to intentional use of mercury in products and processes. The information available is scarce however, and the emission inventories poorly... 

Lawrence B (2000) The mercury marketplace sources, demand, price, and the impacts of environmental regulation. Presentation at USEPA s Workshop on mercury in products, processes, waste, and the environment. Baltimore, MD, 22-23 March 2000, as quoted by USA (comm-24-gov)... 

Mercurous chloride or calomel is insoluble and precipitates from solution. It can be separated in a thickener and removed from the system. Part of the calomel is treated with chlorine to regenerate the mercuric chloride scrubbing solution. The system is capable of achieving less than 0.5 ppm mercury in product acid or lower if reduced gas temperatures are used. It is important for efficient operation that the gas coming forward from the electrostatic precipitators is free from suspended mist and is classed as optically clear , otherwise contamination of the mercury scrabbing circuit will quickly destroy mercury removal efficiency. 

Mercury in Products. Hot, moist chlorine leaving the cell contains small amounts of mercuric chloride. This is almost completely washed out in the subsequent cooling process and may be fed back into the brine with the condensate. In the cooled and dried chlorine gas, there are only minute traces of mercury 0.001-0.01 mgAg. 

M. D. Bingham, Field Detection and Implications of Mercury in Natural Gas, Soc. Petrol Engrs. Production Engrg, 120—124 (May, 1990). 

In 1988 diaphragm cells accounted for 76% of all U.S. chlorine production, mercury cells for 17%, membrane cells for 5%, and all other production methods for 2%. Corresponding statistics for Canadian production are diaphragm cells, 81% mercury cells, 15% and membrane cells, 4% (5). for a number of reasons, including concerns over mercury pollution, recent trends are away from mercury cell production toward the more environmentally acceptable membrane cells, which also produce higher quality product and have favorable economics. 

The catholyte from diaphragm cells typically analyzes as 9—12% NaOH and 14—16% NaCl. This ceUHquor is concentrated to 50% NaOH in a series of steps primarily involving three or four evaporators. Membrane cells, on the other hand, produce 30—35% NaOH which is evaporated in a single stage to produce 50% NaOH. Seventy percent caustic containing very Httie salt is made directiy in mercury cell production by reaction of the sodium amalgam from the electrolytic cells with water in denuders. 

Secondary. Scrap material, industrial and municipal wastes, and sludges containing mercury are treated in much the same manner as ores to recover mercury. Scrap products are first broken down to Hberate metallic mercury or its compounds. Heating in retorts vaporizes the mercury, which upon cooling condenses to high purity mercury metal. Industrial and municipal sludges and wastes may be treated chemically before roasting. 

Regulations. In order to decrease the amount of anthropogenic release of mercury in the United States, the EPA has limited both use and disposal of mercury. In 1992, the EPA banned land disposal of high mercury content wastes generated from the electrolytic production of chlorine—caustic soda (14), accompanied by a one-year variance owing to a lack of available waste treatment faciUties in the United States. A thermal treatment process meeting EPA standards for these wastes was developed by 1993. The use of mercury and mercury compounds as biocides in agricultural products and paints has also been banned by the EPA. 

Electrolytic Preparation of Chlorine and Caustic Soda. The preparation of chlorine [7782-50-5] and caustic soda [1310-73-2] is an important use for mercury metal. Since 1989, chlor—alkali production has been responsible for the largest use for mercury in the United States. In this process, mercury is used as a flowing cathode in an electrolytic cell into which a sodium chloride [7647-14-5] solution (brine) is introduced. This brine is then subjected to an electric current, and the aqueous solution of sodium chloride flows between the anode and the mercury, releasing chlorine gas at the anode. The sodium ions form an amalgam with the mercury cathode. Water is added to the amalgam to remove the sodium [7440-23-5] forming hydrogen [1333-74-0] and sodium hydroxide and relatively pure mercury metal, which is recycled into the cell (see Alkali and chlorine products). 

Mercuric Nitrate. Mercuric nitrate [10045-94-0] Hg(N02)2, is a colorless dehquescent crystalline compound prepared by the exothermic dissolution of mercury in hot, concentrated nitric acid. The reaction is complete when a cloud of mercurous chloride is not formed when the solution is treated with sodium chloride solution. The product crystallizes upon cooling. Mercuric nitrate is used in organic synthesis as the starting material and for the formulation of a great many other mercuric products. 

The solubility product, [Hg +][S ] = 10 moPdm but the actual solubility is greater than that calculated from this extremely low figure, since the mercury in solution is present not only as Hg + but also as complex species. In acid solution [Hg(SH)2] is probably formed and in alkaline... 

The Minamata disaster in Japan, when 52 people died in 1952, occurred because fish, which formed the staple diet of the small fishing community, contained abnormally high concentrations of mercury in the form of MeHgSMe. This was found to originate from a local chemical works where Hg salts were used (inefficiently) to catalyse the production of... 

There have been numerous reports of possible allergic reactions to mercury and mercury salts and to the mercury, silver and copper in dental amalgam as well as to amalgam corrosion products Studies of the release of mercury by amalgams into distilled water, saline and artificial saliva tend to be conflicting and contradictory but, overall, the data indicate that mercury release drops with time due to film formation and is less than the acceptable daily intake for mercury in food . Further, while metallic mercury can sensitise, sensitisation of patients to mercury by dental amalgam appears to be a rare occurrence. Nevertheless, there is a growing trend to develop polymer-based posterior restorative materials in order to eliminate the use of mercury in dentistry. 

We want to find the relation between the height, h, of the column of mercury in a barometer and the atmospheric pressure, P. Suppose the cross-sectional area of the column is A. The volume of mercury in the column is the height of the cylinder times this area, V = bA. The mass, ttt, of this volume of mercury is the product of mercury s density, d, and the volume so m = dV = dhA. The mercury is pulled down by the force of gravity and the total force that its mass exerts at its base is the product of the mass and the acceleration of free fall (the acceleration due to gravity), g F = mg. Therefore, the pressure at the base of the column, the force divided by the area, is... 

The behavior of Hg(CN)2 toward the dinuclear gold(I) amidinate complexes requires comment. In the case of the dinuclear gold(I) ylide, oxidation of the Au(I) to Au(II) resulted in the formation of a reduced mercury(O) product. Figure 1.19(a) [36]. In the mercury(II) cyanide reaction with the dinuclear gold(I) dithiophosphinate. Figure 1.19(b), the stability of the gold(I)-carbon bond compared... 

Mercury in various cement products was determined with a special mercury oven for solid samples. Calibration was performed with four BCR CRMs and one NIST SRM with different Hg content as well as with a reference solution and excellent agreement found (Bachmann and Rechenberg 1991). 

The incorporation of certain excipients in products is deemed to be undesirable. Examples are the inclusion of mercurial preservatives, the inclusion of benzyl alcohol in parenteral products for use in children, the use of benzoic acid esters in injections, and the inclusion of sulfites and metabisulfites in products in general. If it is intended to use any of these materials, then a full justification will be required. 

How can the Ecodesign Directive be further developed to handle the RISKCYCLE-topic So far, pollution issues are involved in the context of product evaluation and the derivation of product standards, but rather in the sense of LCA to capture the energy side and the other relevant environmental indicators. The topic of mercury in compact fluorescent lamps (CFL) has made it clear that pollution issues can be quite important in the context of this Directive. However, relevant limits for energy saving lamps were first set by a waste-related regulation, namely the Annex of the WEEE Directive [7]. 

Again, the waste treatment scenario with incineration has by far to the highest score for human toxicity. The scores for the other scenarios are more or less the same. The incineration of EoL PVC will lead to toxic emissions of metals (arsenic, lead, chromium, see Table 5) causing human health effects. However, the most important contribution to the human health effect is caused by the emission of mercury in the upchain processes of the production of mercury and sodium hydroxide. Sodium hydroxide is an auxiliary material in the waste incineration process. Mercury... 

---