Wood preservatives mercury

The Lewis ENVIRO-CLEAN process removes and recovers metals such as chromium, copper, nickel, mercury, lead, zinc, iron, and cadmium and has effectively demonstrated that it can treat a matrix of multiple metals in a single stream with positive results. The process treats wastes from wood preserving, metal finishing, mining, surface and groundwaters. The two-step process uses granular-activated carbon and electrolytic metal recovery to yield a salable metallic by-product. 

Discontinued applications. The use of phenylmercuric acetate as a fungicide in interior latex paints was banned in 1990 (Reese 1990), and its use in exterior paint was banned in 1991 (Hefflin et al. 1993). Both of these bans were prompted because of releases of mercury vapors as the paint degraded. Alkyl mercurial compounds were used until the mid-1970s as a treatment to disinfect grain seeds. Most other agricultural applications of mercury compounds in bactericides and fungicides have been banned due to the toxicity of mercury. Mercuric nitrate was used in the production of felt hats to hydrolyze rabbit fur. The use of mercury as a wood preservative has ceased due to the use of polyurethane (Drake 1981). 

C. Mercury The main source of inorganic mercury as a toxic hazard is through the use of materials in dental laboratories and in the manufacture of wood preservatives, insecticides, and batteries. Organic mercury compounds are used as seed dressings and fungicides. 

Historically, almost every chemical or compound known to be toxic has been tried and used to inhibit the action of wood-destroying pests. Among the many chemicals used as wood preservatives are compounds based on creosote, mercury, arsenic, thallium, borate, cyanide, chromium, copper, zinc, nickel, fluorides, and pentachlorophenol. The majority fall into 3 classes ... 

For this reason, heavy metals and metal ions that are used as additives in plastics and rubber (as colorants, stabilisers, plasticisers and so on) should be monitored carefully, and their use as well as the amounts used should be well known and regulated. In addition to their existence in some of the additives used in plastics and rubbers, toxic heavy metals most of which are considered chronic poisons, such as arsenic, lead, mercury, cadmium, nickel, zinc and chromium, are frequently encountered in industrial processing and other manufacturing operations (their main industrial sources include paint, ink, plastic, rubber and plastic film production, leather tanning, wood preserving, battery manufacturing, and so on). 

Arsenic is well known because of its widespread use as a poison in criminal activity. Arsenic has also been widely used for agricultural appHcations, which include herbicides, pesticides, and wood preservatives. These applications have been reduced in recent years due to concerns about its toxicity, and the US EPA has recently reduced the acceptable limit of arsenic in drinking water. Unlike mercury and tin, organometallic forms of arsenic, such as arseno-betaine, arsenocholine, and some arsenosugars, are relatively nontoxic, while inorganic arsenic(III) (arse-nite) and arsenic(V) (arsenate) are highly toxic. 

PMO is in efficacy similar to PMA. As PMO is virtually insoluble in water and of low volatility only, it has been used mainly as an active ingredient in wood preservatives, antifouling coatings, exterior and interior latex paints and sealants. As small amounts of mercury compounds are toxic to many plants, it is recommended not to use PMO in greenhouse paints. 

WOOD PRESERVATIVES. In laboratory tests, wood preservatives were found to vary greatly in their corrouvity to aluminum alloys. Some caused less than 1 mpy attack while others, particularly those containing copper or mercury salts or zinc chloride, were very corrosive. Creosote, zinc napthanate and pentachlorophenol were found to be most compatible with aluminum alloys. None of the w ood preservatives was inhibitive. 

A number of phenols, especially chlorinated phenols and certain metal-organic compounds, such as copper naphthenate and phenyl mercury oleate, are effective preservatives. Pentachlorophenol and copper naphthenate are most commonly used, and are carried into the wood in 1-5 percent solutions in petroleum oil. Pentachlorophenol is colorless, and can be applied in clear volatile mineral oils to mill-work and window sash requiring a clean, nonswelling, and paintable treatment. 

Mercuric chloride is used in preservatives for wood and anatomical specimens, embalming solutions, disinfectants, photographic intensifiers, leather tanning, seed treatments, analytical reagents for organic syntheses, and the manufacture of other mercury-containing compounds. Pharmaceuticals containing mercuric chloride have also been used therapeutically as topical antiseptics and disinfectants. 

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