Abstract
AbstractDeionized, tap and two kinds of commercially available mineralized water, after supplementation with ammonia, were treated with low-pressure, low-temperature glow plasma (GP) of low frequency. Treating hard water with ammonia provided the removal of permanent and temporary water hardness already at room temperature. On such treatment, mineralized water supplemented with ammonia was partly demineralized. Precipitated rhombohedral deposit from hard water did not turn into scale even when maintained in suspension for 3 days at around 90°C. In such manner, the use of other chemicals for prevention from the scale formation and/or for the scale removal is entirely dispensable. The rate and yield of precipitation depended on the concentration of admixed ammonia and the GP treatment time. Ammonia served as a ligand of calcium, magnesium and ferric central atoms of corresponding salts constituting the hardness. Moreover, ammonia constituting the atmosphere of the treatment was arrested inside aqueous clathrates. So, stabilized ammonia solutions could potentially be utilized as an environmental-friendly nitrogen fertilizer. The precipitate could also be utilized for the same purpose.
Highlights
From a chemical point of view, water which is commonly used in everyday life cannot be considered pure
Performed simulations were performed based on SHELX-97 software package [13] and Cambridge Structural Database [14,15]. It was shown in our recent paper [6] that in the Raman spectrum of plain water prior to its glow plasma (GP) treatment, a sharp peak observed around 350 nm was followed by a long weak shoulder and another sharp but less intensive peak around 700 nm
The intensity of the band observed around 400 nm increased with time of the GP treatment, and at the same time, the shoulder around 440 nm has transformed into a separate band
Summary
From a chemical point of view, water which is commonly used in everyday life cannot be considered pure. The gaseous components cannot be fully evacuated from those solutions even under a deep vacuum. Such water, when containing dissolved oxygen, is corrosive which is essential on its technical applications. If not either deionized or distilled, water contains dissolved mineral salts. Sulfates and hydrogen carbonates of calcium, magnesium and iron are responsible for the so-called permanent and temporary water hardness, and the other salts constitute water mineralization. Both kinds of hardness cause a scale deposition in water-heating systems and water-transmitting pipelines. Magnesium and calcium bicarbonates precipitate even from their diluted solutions because of the shift in the equilibrium of the reaction
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