Chemical cleaning procedures

For the determination of weight loss, the corrosion products have to be removed. Inhibited acids are normally used for this purpose, but it is important to be sure that such acids remove only the corrosion products and do not attack the base metal. For example, the following acids could be used inhibited hydrochloric acid for iron, sulfuric acid for copper, and chromium trioxide solutions for zinc. The chemical cleaning procedures for the removal of corrosion products are further described in ISO 8407 (3). The removal of corrosion products is also necessary to confirm homogenous corrosion and exclude possible local corrosion attack. 

On the other hand, with the use of MF followed by NF, Marcucci et al. (2003) observed that significant flux decline was only recorded in the NF system after 60 h of operation. The NF flux was reported to decrease from -500 1/h to -450 1/h and to -400 1/h at 80 and 100 h, respectively. However, the decline in water flux of the NF was able to be recovered through a simple chemical cleaning procedure. After cleaning, a flux that was close to the initial value of the water flux was... 

The incidents related to failures in proper vessel and piping cleaning are common. However, in today s world there are API guidelines and a CSB Safety Bulletin Removal of Hazardous Material from Piping Systems available which can be very helpful to review equipment chemical cleaning procedures such as ... 

Chemical Cleaning Procedures for Removal of Corrosion Products ... 

CHEMICAL CLEANING PROCEDURES FOR REMOVAL OF CORROSION PRODUCTS 45... 

ITO. ITO is the most widely used transparent conductive material in optoelectronic devices based on PW derivatives due to its transparency in the visible region of the spectrum. In LEDs, ITO is used as an anode, owing the similarity of its work function with the electroaffinity of PPV and several of its derivatives. The ITO work function depends on the preparative method and is also sensitive to chemical cleaning procedures [194-197], so that it can be matched with the polymer HOMO level. It is observed that the In/Sn ratio can be modified, depending on the substrate cleaning procedure [194,195]. 

Recently, we had a refinery precondenser that had a 25 mm Hg AP. We tried the following chemical cleaning procedure ... 

Ingots of EGS are evaluated for resistivity, crystal perfection, and mechanical and physical properties, such as she and mass. The iagots are sHced iato wafers usiag at least 10 machining and polishing procedures. These wafers are sHced sequentially from the iugot, and evaluated for the correct surface orientation, thickness, taper, and bow. As a final procedure, the wafers are chemically cleaned to remove surface contaminants prior to use. 

Gleaning. Fouling films are removed from the membrane surface by chemical and mechanical methods. Chemicals and procedures vary with the process, membrane type, system configuration, and materials of constmction. The equipment manufacturer recommends cleaning methods for specific apphcations. A system is considered clean when it has returned to >75% of its original water flux. 

The materials selection procedure should take into account the commissioning requirements of all parts of the plant in order not to include any materials that cannot safely be degreased or chemically cleaned. 

Improved nucleation within the phosphate solution itself can produce smoother coatings without the necessity of recourse to preliminary chemical treatment. This may be accomplished by introducing into the phosphating bath the sparingly soluble phosphates of the alkaline earth metals or condensed phosphates such as sodium hexametaphosphate or sodium tripolyphosphate. Such modified phosphating baths produce smoother coatings than orthodox baths and are very much less sensitive to cleaning procedures. 

Second, following a cleaning procedure with formalin, wet-chemical impregnation with palladium was performed [17]. The micro channels were exposed to a solution of 200 mg of PdCl2 in 40 ml of distilled water for 5 h. The PdCl2 was reduced to elemental Pd by formalin still present in the nanopores of the oxide layer which were generated one step before. This was followed by calcination. 

C. M. Carr, R. Mitchell and D. Howell, Surface chemical investigation into the cleaning procedures of ancient tapestry materials. Part 1, Journal of Materials Science, 39, 7317 7325 (2004). 

The reasons will be clearer after Section 16.4, where AMS radiocarbon sample preparation procedures will be described. Now we would simply like to recall that in preparing graphite pellets for the sputtering source, after a physical chemical cleaning, samples to be dated are usually combusted to obtain C02, which is then converted to graphite by a further step. In this process, the main problem with small samples (a few tens of micrograms) is the possible introduction of contamination. 

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