Oxidation and filtration

Waters that may be contaminated with high concentrations of turbidity may want to consider a top layer of anthracite to capture these solids. This protects the greensand and ensures that the greensand is free and clear to proceed with oxidation and filtration of metals. A 15 - 18-inch layer of anthracite is recommended. 

Kainulainen T., Tuhkanen T., Varriainen T., Heinonen-Tanski H., Kalliokoski P. (1994), The effect of different oxidation and filtration processes on the molecular size distribution of humic material. Water Science Technology, 30, 9,169-174. 

Acid hydrolysis with 0.3 M HCl, autoclaving, enzymatic hydrolysis with takadiastase, filtration, oxidation, and filtration through a 0.45 )tm filter Acid hydrolysis with 0.1 N HCl, heating in water bath at 95-100 °C, enzymatic hydrolysis with takadiastase, filtration, oxidation Single extraction by acid hydrolysis with 0.3 M HCl, autoclaving, enzymatic hydrolysis, filtration, post column derivatization... 

As a summary, As can be effectively removed by a combined oxidation and filtration process. The cost of the oxidants is low and easily accessible. However, as a simple coarse depth filtration process, the removal rate of the filtration step strongly depends on the saturation of the filter, and the concentration of the feed streams. An absolute separation approach is essential to achieve a stable and much better separation performance. Nonetheless, it is clear that using iron and manganese chemicals is practical for the oxidation of As(III) to As(V). Better performance may be achieved if a better separation technology is available. 

Potassium permanganate commonly used in conjimction with greensand filters for iron oxidation and filtration. 

Lignite, generally leonardite, and lignite derivatives are appHed in water-based muds as thinners and filtration control agents. Leonardite is an oxidized lignite having a high content of humic acids, which may be described as carboxylated phenoHc polymers (59,60). Litde is known about the chemical stmcture. 

Molecular Weight. Measurement of intrinsic viscosity in water is the most commonly used method to determine the molecular weight of poly(ethylene oxide) resins. However, there are several problems associated with these measurements (86,87). The dissolved polymer is susceptible to oxidative and shear degradation, which is accelerated by filtration or dialysis. If the solution is purified by centrifiigation, precipitation of the highest molecular weight polymers can occur and the presence of residual catalyst by-products, which remain as dispersed, insoluble soHds, further compHcates purification. 

Both ions can be removed by oxidation and subsequent filtration. Aeration is adequate for iron(II) oxidation at above pH 6, but the oxidation of manganese(II) is much too slow, even at higher pH values, for effective removal. Potassium permanganate or chlorine dioxide is frequently used for the oxidation of manganese however, their use must be foHowed by coagulation prior to filtration because of the formation of coHoidal Mn02. 

Beryllium Oxide. Beryllium oxide [1304-56-9], BeO, is the most important high purity commercial beryllium chemical. In the primary industrial process, beryllium hydroxide extracted from ore is dissolved in sulfuric acid. The solution is filtered to remove insoluble oxide and sulfate impurities. The resulting clear filtrate is concentrated by evaporation and upon cooling high purity beryllium sulfate, BeSO 4H20, crystallizes. This salt is... 

Pretreatment For most membrane applications, particularly for RO and NF, pretreatment of the feed is essential. If pretreatment is inadequate, success will be transient. For most applications, pretreatment is location specific. Well water is easier to treat than surface water and that is particularly true for sea wells. A reducing (anaerobic) environment is preferred. If heavy metals are present in the feed even in small amounts, they may catalyze membrane degradation. If surface sources are treated, chlorination followed by thorough dechlorination is required for high-performance membranes [Riley in Baker et al., op. cit., p. 5-29]. It is normal to adjust pH and add antisealants to prevent deposition of carbonates and siillates on the membrane. Iron can be a major problem, and equipment selection to avoid iron contamination is required. Freshly precipitated iron oxide fouls membranes and reqiiires an expensive cleaning procedure to remove. Humic acid is another foulant, and if it is present, conventional flocculation and filtration are normally used to remove it. The same treatment is appropriate for other colloidal materials. Ultrafiltration or microfiltration are excellent pretreatments, but in general they are... 

A mixture of 26 g (0.1 mol) of 0 -(4-pyridyl)-benzhydrol, 1.5 g of platinum oxide, and 250 ml of glacial acetic acid is shaken at 50°-60°C under hydrogen at a pressure of 40-50 Ib/in. The hydrogenation is complete in 2 to 3 hours. The solution is filtered and the filtrate evap-rated under reduced pressure. The residue is dissolved in a mixture of equal parts of methanol and butanone and 0.1 mol of concentrated hydrochloric acid is added. The mixture is cooled and filtered to give about 30 g of 0 -(4-piperldyl)-benzhydrol hydrochloride, MP 283°-285°C, as a white, crystalline substance. 

A mixture of 0.5 gram of platinum oxide and a solution of 2.0 grams (0.0067 mol) of 3,4-dihydroxyphenyl-2-pyridyl ketone hydrobromide in 20 ml of water and 80 ml of ethanol Is hydrogenated on the Parr apparatus using an initial hydrogen pressure of 50 psi at room temperature. The reaction mixture is filtered, the filtrate concentrated in vacuo and the residue triturated with acetone to give erythro-3,4-dihydroxyphenyl-2-piperidinylcarbinol hydrobromide, MP 210° to 211°C (decomposition). 

Where soluble iron is present in condensate, it often is associated with copper. When the problem is considered serious, it usually is removed by a condensate polisher. Soluble iron in MU often is associated with manganese and usually (but not totally) is removed either by ion-exchange resins (often inadvertently) or in an aeration tower, where the process employs a combination of air or chlorine oxidation, followed by precipitation and filtration. 

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