Contaminated seawaters

Depending on the use of the fuel, ash composition has a considerable bearing on whether or not detrimental effects will occur. However, distillate fuels tend to contain only negligible amounts of ash but pick up ash-forming constituents during transportation from the refinery. Water transportation, in particular, presents many opportunities for fuel oils to be contaminated with ash-forming contaminants (seawater, dirt, and scale rust). 

Almost all living creatures were affected by atmospheric pollution by the oil burn products. Also, the oil slick and contaminated seawater in the Gulph affected large areas in... 

Figure 7 Monitoring contaminated seawater level with the use of DC pulse technique...

Al-Obeidani et al. [93] reported on the development of more effective and economical procedures for cleaning polyethylene hollow fiber MF membranes that have been used for removing oil from contaminated seawater. In their study, alkaline cleaning showed higher recovery of operating cycle time but lower permeate flux recovery than acid cleaning. 

Kara A, Syutsubo K, Harayama S (2003) Alcanivorax which prevails in oil-contaminated seawater exhibits broad substrate specificity for alkane degradation. Environ Microbiol 5 746-753... 

Based on a very good pitting potential of Uh = 1.1-1.2 V, the expected excellent pitting resistance equivalent of the steel X2CrNiMoN17-13-5 (317 LMN, 1.4439) was confirmed in every respect in practical application. The material proved resistant to pitting and crevice corrosion, even in subsurface exposure and in contaminated seawater and brackish water [22]. 

The elements listed in the table of Figure 15.2 are of importance as environmental contaminants, and their analysis in soils, water, seawater, foodstuffs and for forensic purposes is performed routinely. For these reasons, methods have been sought to analyze samples of these elements quickly and easily without significant prepreparation. One way to unlock these elements from their compounds or salts, in which form they are usually found, is to reduce them to their volatile hydrides through the use of acid and sodium tetrahydroborate (sodium borohydride), as shown in Equation 15.1 for sodium arsenite. 

Silver reduces the oxygen evolution potential at the anode, which reduces the rate of corrosion and decreases lead contamination of the cathode. Lead—antimony—silver alloy anodes are used for the production of thin copper foil for use in electronics. Lead—silver (2 wt %), lead—silver (1 wt %)—tin (1 wt %), and lead—antimony (6 wt %)—silver (1—2 wt %) alloys ate used as anodes in cathodic protection of steel pipes and stmctures in fresh, brackish, or seawater. The lead dioxide layer is not only conductive, but also resists decomposition in chloride environments. Silver-free alloys rapidly become passivated and scale badly in seawater. Silver is also added to the positive grids of lead—acid batteries in small amounts (0.005—0.05 wt %) to reduce the rate of corrosion. 

The advent of a large international trade in methanol as a chemical feedstock has prompted additional purchase specifications, depending on the end user. Chlorides, which would be potential contaminants from seawater during ocean transport, are common downstream catalyst poisons likely to be excluded. Limitations on iron and sulfur can similarly be expected. Some users are sensitive to specific by-products for a variety of reasons. Eor example, alkaline compounds neutralize MTBE catalysts, and ethanol causes objectionable propionic acid formation in the carbonylation of methanol to acetic acid. Very high purity methanol is available from reagent vendors for small-scale electronic and pharmaceutical appHcations. 

In contrast to external protection, the anodes in internal protection are usually more heavily covered with corrosion products and oil residues because the electrolyte is stagnant and contaminated. The impression can be given that the anodes are no longer functional. Usually the surface films are porous and spongy and can be removed easily. This is achieved by spraying during tank cleaning. In their unaltered state they have in practice little effect on the current output in ballast seawater. In water low in salt, the anodes can passivate and are then inactive. 

Electrochemical corrosion protection of the internal surfaces of reaction vessels, tanks, pipes and conveyor equipment in the chemical, power and petroleum industries is usually carried out in the presence of strongly corrosive media. The range stretches from drinking water through more or less contaminated river, brackish and seawater frequently used for cooling, to reactive solutions such as caustic soda, acids and salt solutions. 

Since the reliability of gas turbines in the power industry has been lower than desired in recent years because of hot-corrosion problems, techniques have been developed to detect and control the parameters that cause these problems. By monitoring the water content and corrosive contaminant in the fuel line, any changes in fuel quality can be noted and corrective measures initiated. The concept here is that Na contaminants in the fuel are caused from external sources such as seawater thus, by monitoring water content, Na content is automatically being monitored. This on-line technique is adequate for lighter distillate fuels. For heavier fuels, a more complete analysis of the fuel should be carried out at least once a month using the batch-type system. The data should be input directly to the computer. The water and corrosion detecting systems also operate in conjunction with the batch analysis for the heavier fuels. 

The losses, and hence the effective resistance, are also increased by passing the line in close proximity to a nonmsulatmg surface—for example, passing the line over seawater. The metal from which the conductor is made is also vei y important—for example, copper has a lower resistance, for the same geometry, than aluminum does. Also related to the losses of the transmission Hue is the shunt resistance. Under most circumstances, these losses are negligible because the conductors are so well insulated however, the losses become much more significant as the insulators supporting the transmission line become contaminated, or as atmospheric and other conditions result in corona on the line. 

Nickel is usually alloyed with elements including copper, chromium, molybdenum and then for strengthening and to improve corrosion resistance for specific applications. Nickel-copper alloys (and copper-nickel alloys see Section 53.5.4) are widely used for handling water. Pumps and valve bodies for fresh water, seawater and mildly acidic alkaline conditions are made from cast Ni-30% Cu type alloys. The wrought material is used for shafts and stems. In seawater contaminated with sulfide, these alloys are subject to pitting and corrosion fatigue. Ammonia contamination creates corrosion problems as for commercially pure nickel. 

There have been instances reported in the literature where the breakdown potential for Nb and Ta in seawater has been found to be lower than the generally accepted value of 120 V, with reported values in extreme instances as low as 20- V . This has been attributed to contamination of the niobium surface from machining operations, grit blasting or traces of copper lubricant used in anode manufacture. These traces of impurities, by becoming incorporated in the oxide film, decrease its dielectric properties and thus account for the lower breakdown voltage. Careful control of surface contamination in the manufacture of platinised niobium is therefore essential to minimise the lowering of the breakdown potential of niobium. 

Seawater contamination (e.g., MgCl2, CaCl2) from seawater or estuarine condenser leaks. 

Capodaglio, G., Scarponi, G., P. Cescon. Lead contamination of seawaters with different anthropic influence. Ill International Conference "Environmental Contamination", Venice, Sept. 1988, pp. 505-407. 

A multi-residue method for 25 selected pesticides including propanil using an SPE disk has also been developed as a rapid screening method for organic contaminants in river, lake and seawater samples. Cig SPE disks are conditioned with 10 mL of acetone for 3 h. Water samples (1L) are allowed to percolate through the disks in order to trap the residues at a fiow rate of 50 mL min under vacuum. Residues trapped in the disks are extracted twice by eluting with 5 mL of dichloromethane-ethyl acetate (1 1, v/v). The more hydrophobic compounds (log/fow>3) seem to show no... 

Cl and Ba consistently argue that the U-series disequilibria in MORB do not reflect secondary contamination. One important check that all U-series studies of MORB routinely perform is analysis of ( " U)/( U). Since of seawater is well... 

Boron concentrations and isotopes are also useful geochemical tracers of contamination in MORB. Boron concentrations are low (<2 ppm) in unaltered ocean floor basalt but high in altered basalts (>8 ppm B) (Spivack and Edmond 1987 Ryan and Langmuir 1993). Goldstein et al. (1989) measured B concentrations in their samples and found them to be less than 1.6 ppm, inconsistent with contamination. More recently, B isotopes have been used to assess contamination since large differences in 5 B are known to exist between seawater, sediments, and unaltered MORB. Sims et al. (2002) reported that 6 B for their 9°N EPR samples were inconsistent with incorporation of any seawater or seawater-derived material. 

Seawater interaction is a potential source of several U-series nuclides, and is strongly enriched in B, Cl and Sr. Thus, abundances of these elements and/or their isotopes can often be used to test for seawater contamination (e.g.. Turner et al. 2000a). Because will be located in mineral sites that have been damaged by recoil effects, " U is likely to... 

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