Wet processing method

However, these materials may also be quite corrosive and toxic, as will be discussed later. Finally, unlike wet processing methods, plasma techniques are conducive to fully automated processes. 

By far the most important derivative of sulfuric acid is phosphoric acid. It has been unknowingly used as fertilizer for hundreds of years. The wet process method of manufacture was important until 1920, when furnace acid began increasing in popularity. The wet process, however, has made a comeback because of plant design improvements 60% of phosphoric acid was made by this method in 1954, 88% in 1974, and over 90% currently. The furnace process is used only to make concentrated acid (75-85%) and pure product. It is very expensive because of the 2000 °C temperature required. In the furnace process phosphate rock is heated with sand and coke to give elemental phosphorus, which is then oxidized and hydrated to phosphoric acid. A simplified chemical reaction is ... 

These three equations represent the wet process method in varying degrees of simplicity and depend on the phosphate source used. There is usually a high percentage of fluorine in the phosphate, in which case the mineral is called fluorapatite. It is mined in Florida, Texas, North Carolina, Idaho, and Montana. The United States has 30% of known phosphate reserves. 

Unlike vapor-phase processes, liquid deposition methods are not line-of-sight limited and can be applied to complex substrates. Wet processing methods also have lower equipment costs but often require annealing temperatures that do not allow their application to temperature sensitive substrates. 

Phosphate rock is converted into usable chemicals by two methods. In the first, the rock is -charged to an electric furnace with silica and coke to produce elemental phosphorus. The phosphorus then is converted into phosphoric acid and other compounds. In the second, the phosphate rock is reacted with sulfuric acid in a medium of phosphoric acid and calcium sulfate crystals to form dilute, impure phosphoric acid, The acid is separated and used to make fertilizers. This is known as the wet process method.15... 

About 33% of the U in beneficiated phosphate rock concentrate feed for acidulation by the wet-process method was found in the phosphogypsum (PG) byproduct. The remainder of the U was found mainly in the H2PO4, which subsequently is processed to several types of P fertilizers. 

Judging from the above, the reason for the increase of catalytic activity is due to the well mixed structure of Cu and ZnO nanocrystals and the increase of surface Cu by MA method. We conclude that MA method is an effective method for obtaining high performance Cu/ZnO catalysts compared with conventional metal oxide precipitation method by wet processing method. 

All these wet-processing methods for nanotube films seem to share some common features, as determined by the properties of SWNTs and their networks in the coated films. It is known in the literature that the resistance at an inter-tube junction is higher when the junction is between nanotube bundles. " Therefore, the homogeneous dispersion and individualization of SWNTs are a prerequisite to the formation of more conductive nanotube films in terms of wet-processing methods. Indeed, dispersion strategies in these... 

Fig. 10.10 SEM images of separator membrane produced through (a) dry and (b) wet process methods...

Electrochemistry of LB films of fullerenes has been widely studied and remains the subject of much research effort from both theoretical and experimental approaches. Bard etal. have studied basic electrochemistry of Ceo fullerene LB films on an electrode in acetonitrile solutions [23]. The study indicated that reduction of the fullerene films could form insoluble films with incorporated electrolyte cations or lead to dissolution. The study on Cgo LB films has become a focus of considerable interest however, it is difficult to fabricate high-quality LB films of pure Cgo due to its intrinsic hydropho-bicity. Kajiyama et al. applied a multistep creep method as an LB technique for constructing a fairly homogeneous Ceo monolayer, which is regularly packed in a hexagonal array [44]. Kunitake etal. developed the electrochemical replacement method to form epitaxial adlayers of fullerenes on Au(lll) surfaces [45]. The wet process method consists of the transfer of Langmuir films of fullerene onto iodine-modified Au(lll) surfaces at an air-water interface followed by the electrochemical removal and replacement of iodine adlayers with fullerene adlayers in solution. The fullerene adlayers prepared by this method showed excellent quality and uniformity. A visuahzing... 

Manufacturing of medium-density fiberboards (MDFBs) from hngo-ceUulosic fibers has been increasing in recent years [113-115]. Structural fiberboards are being made from wood, other plant materials, and wastepaper. They are classified by density and can be prepared by dry or wet processes. These boards fall into two main categories high density (hardboard) fiberboards and MDFBs. The fiberboards are prepared by the dry process method, whereas the wet process method is apphed to both hardboards and low density insulation boards [103]. 

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