Dealkalization content

A pre-boiler treatment process such as dealkalization (DA) to reduce the alkalinity content of a naturally high alkaline water source may also be suitable. There are various methods of dealkalizing MU water A common process is by weak acid, hydrogen-cycle cation... 

Any of various processes for reducing the alkalinity content of water, especially the use of ion-exchange processes for dealkalizing boiler MU water. 

Under these conditions, cooling water cycles of concentration are likely to be restricted to a maximum of only 2.5 to 4x without some innovative chemical treatment and operations programming. Sources of subsurface water with hardness and alkalinity contents much higher than those cited are likely to be unsuitable for cooling systems without some form of additional pretreatment, such as dealkalization, partial softening, use of RO, or blending with lower alkalinity/lower hardness supplies. 

This investigation was mainly concerned with the influence of water content on the rate of dealkalization at 50 C and a pH of 8. Further experimentation centered around dealkalization variables such as temperature, pH, leach solution concentration and time. This was accomplished by using a Metrohm End Point/pH Stat Titrator. The predetermined pH was controlled by automatic addition of titrant to the leach solution. 

The effects of water content and pH of the dealkalization solution(0,6M NHi NOa) on sodium ion release are shown in Figure... 

H2O were prepared by either dehydrating commercial sodium silicate solutions or by autoclaving anhydrous glasses of comparable compositions. Regardless of their origin, dealkalization kinetics of these hydrosilicates favored high water content and lower alkali content. 

Microprobe elemental mapping of a cross section of the fully densified gel (Fig. 19) shows both that considerable Cl is retained in the densified gel and that chlorine removal causes essentially complete dealkalization of the exterior gel surface. Quantitative elemental analysis (Fig. 20) indicates that the interior of the sample contains 1.5 wt Vo Cl and 0.9 wt Vb Na20 (compared to 1.2 wt% Na20 in the original gel), whereas the exterior surface (—300 m thick) contains 0.6 wt% Cl and 0wt% Na20. A Cl content of 1.5 wt% corresponds to replacement of 38% of the surface hydroxyls with Cl, based on a hydroxyl coverage at 450°C of 1.2 0H/nm [56] and a BET specific... 

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