Function of Water Molecule for Tritium Behavior on the Water-Metal Boundary

The scarcity of safe drinking water is one of the problems faced by the majority of cities in the world. Kirkuk city is one of these cities, which suffer from a shortage of drinking water. People have adopted the use of different rooftop tanks to overcome this problem. This research focuses on studying the effect of storage time on the five main characteristics of drinking water, which include, acid index (pH), electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), and turbidity (Tr). Three types of tanks were used predominantly (galvanized metal, plastic, and aluminum tanks). By analyzing the results, the characteristics of three samples of municipal source water obtained. Three samples were taken from each tank at different periods (4, 8, and 12 days). The results showed that the storage time affected the characteristics of drinking water. These characteristics differed from one tank to another. Metal tanks showed an increase in total dissolved solids, due to the evaporation process, even as plastic and aluminum tanks showed an increase in pH. The properties of all storage water tanks changed with times, but overall, the results were within the Iraqi limitation for drinking water. It was not easy to only depend on the results of this study to believe that any one type of water tank was better than the other, as the values of most of the variables studied had varied from one type to other. However, many studies have indicated a number of health risks, and most significantly with regard to plastic tanks, which are said to contain dangerous organic compounds that can be transferred to water. Metal tanks can cause zinc leakage, caused by a number of environmental factors at high levels. Aluminum tanks also can have an effect on the water in tanks.

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Gas-Phase Clustering of NO+ with H2S and H2O

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20071122 ◽

2007 ◽

Vol 72 (8) ◽

pp. 1122-1138 ◽

Cited By ~ 2

Author(s):

Milan Uhlár ◽

Ivan Černušák

Keyword(s):

Hydrogen Bonds ◽

Water Molecule ◽

Gas Phase ◽

Saddle Points ◽

Solvent Molecule ◽

Local Minima ◽

Additional Water ◽

Three Body ◽

Rain Formation ◽

Stable Structures

The complex NO+·H2S, which is assumed to be an intermediate in acid rain formation, exhibits thermodynamic stability of ∆Hº300 = -76 kJ mol-1, or ∆Gº300 = -47 kJ mol-1. Its further transformation via H-transfer is associated with rather high barriers. One of the conceivable routes to lower the energy of the transition state is the action of additional solvent molecule(s) that can mediate proton transfer. We have studied several NO+·H2S structures with one or two additional water molecule(s) and have found stable structures (local minima), intermediates and saddle points for the three-body NO+·H2S·H2O and four-body NO+·H2S·(H2O)2 clusters. The hydrogen bonds network in the four-body cluster plays a crucial role in its conversion to thionitrous acid.

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DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633618500505 ◽

2018 ◽

Vol 17 (08) ◽

pp. 1850050 ◽

Cited By ~ 1

Author(s):

Qiuhan Luo ◽

Gang Li ◽

Junping Xiao ◽

Chunhui Yin ◽

Yahui He ◽

...

Keyword(s):

Free Energy ◽

Water Molecule ◽

Carbonyl Group ◽

Energy Barrier ◽

Density Functional ◽

Free Energy Barrier ◽

Functional Theory ◽

Metsulfuron Methyl ◽

Catalytic Role ◽

Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

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