Manganese oxide coagulation

Previous studies (7, 10) on manganese oxides have established that H+ and OH are potential-determining for the Mn02 series for 10A. manga-nite, electrophoresis and coagulation measurements (Figure 2) both gave a value of pH 1.8 0.5 for the z.p.c. (7). 

Others recommend treatment to remove the compound. Hydrogen sulfide can be removed or reduced from RO feed water using some iron filters (such as manganese greensand and Filox, see Chapter 8.1.5) or a complicated combination of oxidation, coagulation and filtration, sulfite addition, and rechlorination.9... 

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. 

Inorganic compounds including manganese and iron usually are oxidized by preozonation to form insoluble species. Preozonation must be followed by a filtration or a coagulation-flocculation-decantation step to finally remove those inorganics. ... 

The oxidation mixture is now divided into two equal portions and each portion is treated as follows To the mixture is added a solution of 200 g. of concentrated sulfuric add in 600 cc. of water (Note 4). The mixture is heated on a steam bath for 15 minutes to coagulate the manganese dioxide which is filtered while still very hot (Note 5). After filtration the manganese dioxide is placed in a 4-I. beaker and boiled with 2 1. of water to dissolve any azelaic add that may adhere to it. This mixture is filtered while hot, and the filtrate is added to the main portion. 

The peptization capabilities of polyphosphates depend on their sorption on aluminosilicates and colloidal particles of hydrated oxides of iron, aluminium and manganese. In practice, this causes problems in water treatment by coagulation when already rather low concentrations of polyphosphates can cause improper agglomeration of colloidal particles into sedimentable floccules. 

This can be colored, as turbid surface water may contain humus as well as iron and manganese, either in the oxidized form or bound to organic matter. Water of this type is treated by aeration + coagulation + addition of alkali + clarification + sand filtration. The removal of color and organic compounds usually requires a method based on chemical precipitation. Some reduction in organic matter content, of course, can be achieved by simple filtration. The removal of iron and manganese, on the other hand, usually requires ... 

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