Iron oxide, precipitation

Herbert Jr, R.B. (1996) Metal retention by iron oxide precipitation from acidic ground water in Dalama, Sweden. Appl. Geochem. 11 229-235... 

McCarty, D.K., Moore, J.N. and Marcus, W.A. (1998) Mineralogy and trace element association in an acid mine drainage iron oxide precipitate comparison of selective extractions. Appl. Geochem., 13, 165. 

These reactions will proceed without heating under nitrogen, where the driving force is the more favorable iron oxide precipitate. Following Ostwald s rule of stages, the hydroxide would be the kinetic product and the oxide would be the thermodynamic product. 

Planktonic forms were inhibited, and limited by dissolved iron content of water, and existence of stratified, UV-screen refuges. Sedimentary matforming and stromatolite-forming communities were much more abundant. Iron-oxide precipitation and deposition of screen enzymes may have created UV-free colonies under a shield even in shallow waters. 

During winter months, v/hen the lake was well mixed, humic substances were uniformly distributed throughout the water column (Fig. 14). As the season of thermal stratification proceeded, however, the concentrations became different. The concentrations at a 5 m depth declined to about 1.5 mg/L and remained at this level throughout the summer the concentrations at 14 m increased to reach maxima of 3 mg/L. The maximum values could be due to iron oxide precipitation or to anaerobic decomposition of settled particulate detritus. 

The iron oxide precipitates within the rust film and traps the sodium chloride in the corrosion products. This is a serious problem when using a combination of aqueous and thermal methods of conservation as will be discussed later. 

Based on Fe304-rich iron oxides precipitated by Fe(III)-reduction by thermophilic bacteria in culture. 

Fig. 20 Typical sulfate melt-induced attack of superheater (T sa 550 °C) from a waste fired boiler. The morphology of the scale is typical for a molten salt attack, a thick and dense chromium-rich oxide scales in contact with the metal and iron oxide precipitate and nickel oxide precipitate in the molten salt.

Iron ions/iron oxide Precipitation reaction Simple operation Low removal rate... 

Although iron oxides precipitate out of water readily, it is difficult to control the precipitation process to form uniform particles of the desired size. The variability in the local environment results in variability in the product. Coprecipitation techniques require strict control of many variables (pH, temperature, mixing times, etc.) and provide no guarantees that a uniform solution environment will be obtained in the precipitation reaction. In addition, a period of... 

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