scholarly journals The migration law of magnesium ions during freezing and melting processes

2021 ◽  
Author(s):  
Zhang Yan ◽  
Liu Tongshuai ◽  
Tang Yuanqing ◽  
Zhao Wanli ◽  
Ren Fangyun ◽  
...  
Keyword(s):  
Water Layer ◽  
Melting Process ◽  
Freezing Temperature ◽  
Laboratory Simulation ◽  
Ice Thickness ◽  
Magnesium Ions ◽  
Initial Concentration ◽  
Ice Melt ◽  
Initial Ph ◽  
Migration Law

AbstractTo explore the migration law of magnesium ions (Mg2+) during freezing and melting processes, laboratory simulation experiments involving freezing and melting were carried out to investigate the influence of ice thickness, freezing temperature, initial concentration, and initial pH on the distribution of Mg2+ in the ice-water system. The distribution coefficient “K” (the ratio of the Mg2+ concentration in the ice layer to the Mg2+ concentration in the water layer under ice) was used to characterize the migration ability of Mg2+. The results showed that during the freezing process, the concentration distribution of Mg2+ in the ice and water two-phase system was as follows: ice layer < water before freezing < water layer under ice; in other words, it migrated from ice layer to the water layer under ice. “K” decreased with increasing ice thickness, freezing temperature, initial concentration, and initial pH; the higher the ice thickness, freezing temperature, initial concentration, and initial pH were, the higher the migration efficiency of Mg2+ into the water layer under ice was. During the melting process, Mg2+ was released in large amounts (50–60%) at the initial stage (0–25%) and in small amounts (25–100%) uniformly in the middle and later periods. According to the change of Mg2+ concentration in ice melt water, an exponential model was established to predict Mg2+ concentration in ice melt period. The migration law of Mg2+during the freezing and melting process was explained by using first principles.

scholarly journals Research on the Migration of the Total Manganese during the Process of Water Icing

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1626 ◽  
Author(s):  
Yan Zhang ◽  
Yuanqing Tang ◽  
Aixin Yu ◽  
Wanli Zhao ◽  
Yucan Liu
Keyword(s):  
Lower Layer ◽  
Water System ◽  
Middle Layer ◽  
Freezing Temperature ◽  
Experimental Methods ◽  
Average Concentration ◽  
Laboratory Simulation ◽  
Ice Thickness ◽  
Ice Water ◽  
Migration Law

Our research focused on the migration law of the total manganese (TMn) during the process of water icing. We utilized two experimental methods: (1) natural icing and (2) simulated icing. While using laboratory simulation, we explored the effects of ice thickness, freezing temperature, and initial concentrations on the migration of TMn in the ice-water system. The distribution coefficient “K” (the ratio of the average concentration of TMn in the ice body to the average concentration of TMn in the under-ice water body) was used to characterize it. The results indicated that TMn continuously migrated from ice to under-ice water during the process of water icing. The concentration of TMn in the ice was the upper layer < middle layer < lower layer, and K decreases as the ice thickness, freezing temperature, and initial concentration increased. We explained the migration of TMn during the process of water icing from the perspective of crystallography. Our research can arouse other researcher’s attention towards the change of TMn concentration in lakes in high latitudes during the icebound period.

scholarly journals Migration Law of Atrazine During Freezing of Water

2021 ◽  
Author(s):  
Yan Zhang ◽  
Wanli Zhao ◽  
Aixin Yu ◽  
Yucan Liu ◽  
Fangyun Ren ◽  
...  
Keyword(s):  
Distribution Coefficient ◽  
High Latitude ◽  
Freezing Temperature ◽  
Freezing Process ◽  
Ice Thickness ◽  
Migration Ability ◽  
Initial Concentration ◽  
Atrazine Concentration ◽  
Freezing Period ◽  
Migration Law

Abstract To explore the migration law of atrazine during the freezing process, an indoor simulated freezing experiment was carried out. The distribution coefficient (K) was used to characterize the migration ability of atrazine and explore the effects of freezing thickness, freezing temperature, and initial concentration on the migration of atrazine between ice and water. The research results showed that the concentration relationship between the ice and water phases was: ice < water before freezing < water under the ice. This indicates that atrazine migrated to the water under the ice during the freezing process in our experiment. The K value decreased as the ice thickness, freezing temperature, and initial concentration increased; thus, the greater the ice thickness, the higher the freezing temperature, the greater the initial atrazine concentration, and the greater the ability of atrazine to migrate to the water under the ice. This study provides a reference for managing natural waterbodies in high-latitude and high-altitude environments during the freezing period.

scholarly journals The Migration Law of Iron during the Process of Water Icing

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 441
Author(s):  
Yuanqing Tang ◽  
Yan Zhang ◽  
Wanli Zhao ◽  
Tongshuai Liu ◽  
Yucan Liu
Keyword(s):  
Iron Concentration ◽  
Water System ◽  
Freezing Temperature ◽  
Average Concentration ◽  
Initial Concentration ◽  
Before And After ◽  
Shallow Lakes And Ponds ◽  
Solid Liquid ◽  
Ice Water ◽  
Migration Law

In this study, we utilized simulated icing experiments to investigate the effect of icing thickness, freezing temperature and initial concentration on the migration of iron in the ice–water system during water icing. The distribution coefficient “K” (the ratio of the average concentration of iron in the ice to that in the under-ice water) was used to describe the effect. The results indicated that iron partitioned stronger to under-ice water than to ice during the process of water icing, resulting in the concentration of iron in ice–water system before and after freezing being expressed as: ice < pre-freezing water < under-ice water. K decreased with the increase in icing thickness, freezing temperature and initial concentration. The temperature change in the solution will change the solubility of the solvent, so we explained the migration of iron during the process of water icing from the perspective of solid–liquid equilibrium theory. Too high or too low iron concentration may inhibit the growth of algae, thus affecting the underwater ecological environment. We expect that our study will arouse researcher’s attention to the change in iron concentration in shallow lakes and ponds at high latitudes during the icebound period.

scholarly journals Photocatalytic Degradation of Naphthalene By UV/Zno: Kinetics, Influencing Factors and Mechanisms

2021 ◽  
Vol 37 (1) ◽  
pp. 65-70
Author(s):  
Aram Dokht Khatibi ◽  
Kethineni Chandrika ◽  
Ferdos Kord Mostafapour ◽  
Ali Akbar Sajadi ◽  
Davoud Balarak
Keyword(s):  
Wastewater Treatment ◽  
Reaction Time ◽  
Aqueous Solutions ◽  
Aromatic Hydrocarbons ◽  
Contact Time ◽  
Initial Concentration ◽  
Applied Study ◽  
Batch System ◽  
Initial Ph ◽  
Conventional Wastewater Treatment

Conventional wastewater treatment is not able to effectively remove Aromatic hydrocarbons such as Naphthalene, so it is important to remove the remaining antibiotics from the environment. The aim of this study was to evaluate the efficiency of UV/ZnOphotocatalytic process in removing naphthalene antibiotics from aqueous solutions.This was an experimental-applied study that was performed in a batch system on a laboratory scale. The variables studied in this study include the initial pH of the solution, the dose of ZnO, reaction time and initial concentration of Naphthalene were examined. The amount of naphthalene in the samples was measured using GC.The results showed that by decreasing the pH and decreasing the initial concentration of naphthalene and increasing the contact time, the efficiency of the process was developed. However, an increase in the dose of nanoparticles to 0.8 g/L had enhance the efficiency of the process was enhanced, while increasing its amount to values higher than 0.8 g/L has been associated with a decrease in removal efficiency.The results of this study showed that the use of UV/ZnOphotocatalytic process can be addressed as a well-organized method to remove naphthalene from aqueous solutions.

scholarly journals The Sorption of Ni(II) by Grape Shell Ash from Aqueous Solution: Kinetic and Thermodynamic Studies

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Nahid Ghasemi ◽  
Maryam Ghasemi ◽  
Yaghoub Khosravi-Fard
Keyword(s):  
Rate Constants ◽  
Adsorption Process ◽  
Correlation Coefficients ◽  
Sorption Process ◽  
Maximum Increase ◽  
Equilibrium Sorption ◽  
Initial Concentration ◽  
Initial Ph ◽  
Solution Kinetic ◽  
Kinetic And Thermodynamic Studies

The sorption of Ni(II) onto grape shell ash (GSA) was studied by performing batch kinetic sorption experiments. The influences of major parameters in Nickel(II) ions sorption on GS such as initial of pH, initial concentration of Ni(II) ions, the initial temperatures of solution, and contact time were investigated. The maximum increase in the rate of sorption of Ni(II) ions on GS was observed at an initial pH = 5, initial concentration of nickel 50 mgL−1, temperature of solution (328 K), and t=90 min. The rate constants and the equilibrium sorption capacities were calculated. The results indicate that the sorption process follows the second-order kinetics and the values of rate constants were found to be 0.224, 0.402, 0.193 and 0.123 min−1 at 298, 308, 318, and 328 K, respectively. The values of correlation coefficients for the adsorption of Ni(II) on GSA from all the systems were found to be 0.999, and the values of predicted equilibrium sorption capacities showed good agreement with the experimental equilibrium uptake values. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) of the adsorption process were calculated, and these parameters showed that the adsorption process is spontaneous.

Cobalt Ion Extraction from Wastewater by P204 Microemulsion Saponified

2012 ◽  
Vol 496 ◽  
pp. 407-410
Author(s):  
Du Shu Huang ◽  
Jin Gang Yu ◽  
Rui Min Xiao ◽  
Zi Jing Li ◽  
Li Da Sun
Keyword(s):  
Organic Phase ◽  
Volume Ratio ◽  
Extraction Process ◽  
Microemulsion System ◽  
Optimum Conditions ◽  
Extraction Coefficient ◽  
Initial Concentration ◽  
Ion Extraction ◽  
Initial Ph ◽  
Cobalt And Nickel

The extraction process of cobalt using microemulsion system saponified with P204 as extracting agent was studied. The influence of initial concentration, the concentration of P204, initial pH, the extracting time and the concentration of cobalt and nickel on extraction coefficient were also studied. Experimental results show that the saponification microemulsion system using P204 as extractant is thermodynamic stable, and it can separate cobalt better. The optimum conditions were achieved as: the initial concentration is 0.05 mol/L, pH is 2; The concentration of P204 is 10%, extraction time is 10 min; The volume ratio of organic phase to water phase is 2:1.

scholarly journals Fast Ice Prediction System (FIPS) for land-fast sea ice at Prydz Bay, East Antarctica: an operational service for CHINARE

2020 ◽  
pp. 1-13
Author(s):  
Jiechen Zhao ◽  
Bin Cheng ◽  
Timo Vihma ◽  
Petra Heil ◽  
Fengming Hui ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Thickness ◽  
Cold Bias ◽  
Prediction System ◽  
Atmospheric Forcing ◽  
Ice Melt ◽  
Fast Ice ◽  
Sar Imagery ◽  
Operational Service ◽  
Snow And Ice

Abstract A Fast Ice Prediction System (FIPS) was constructed and is the first regional land-fast sea-ice forecasting system for the Antarctic. FIPS had two components: (1) near-real-time information on the ice-covered area from MODIS and SAR imagery that revealed, tidal cracks, ridged and rafted ice regions; (2) a high-resolution 1-D thermodynamic snow and ice model (HIGHTSI) that was extended to perform a 2-D simulation on snow and ice evolution using atmospheric forcing from ECMWF: either using ERA-Interim reanalysis (in hindcast mode) or HERS operational 10-day predictions (in forecast mode). A hindcast experiment for the 2015 season was in good agreement with field observations, with a mean bias of 0.14 ± 0.07 m and a correlation coefficient of 0.98 for modeled ice thickness. The errors are largely caused by a cold bias in the atmospheric forcing. The thick snow cover during the 2015 season led to modeled formation of extensive snow ice and superimposed ice. The first FIPS operational service was performed during the 2017/18 season. The system predicted a realistic ice thickness and onset of snow surface melt as well as the area of internal ice melt. The model results on the snow and ice properties were considered by the captain of R/V Xuelong when optimizing a low-risk route for on-ice transportation through fast ice to the coastal Zhongshan Station.

The evolution of under-ice melt ponds, or double diffusion at the freezing point

1974 ◽  
Vol 64 (3) ◽  
pp. 507-528 ◽  
Author(s):  
Seelye Martin ◽  
Peter Kauffman
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Water ◽  
Ice Sheet ◽  
Water Layer ◽  
Double Diffusion ◽  
Theoretical Models ◽  
Interfacial Region ◽  
Ice Melt

In an experimental and theoretical study, we model a phenomenon observed in the summer Arctic, where a fresh-water layer at a temperature of 0°C floats both over a sea-water layer at its freezing point and under an ice layer. Our results show that the ice growth in this system takes place in three phases. First, because the fresh-water density decreases upon supercooling, the rapid diffusion of heat relative to salt from the fresh to the salt water causes a density inversion and thereby generates a high Rayleigh number convection in the fresh water. In this convection, supercooled water rises to the ice layer, where it nucleates into thin vertical interlocking ice crystals. When these sheets grow down to the interface, supercooling ceases. Second, the presence of the vertical ice sheets both constrains the temperatureTand salinitysto lie on the freezing curve and allows them to diffuse in the vertical. In the interfacial region, the combination of these processes generates a lateral crystal growth, which continues until a horizontal ice sheet forms. Third, because of theTandsgradients in the sea water below this ice sheet, the horizontal sheet both migrates upwards and increases in thickness. From one-dimensional theoretical models of the first two phases, we find that the heat-transfer rates are 5–10 times those calculated for classic thermal diffusion.

Preparation of Persimmon Tannins Immobilized on Collagen Adsorbent and Research on its Adsorption to Cr(VI)

2013 ◽  
Vol 743-744 ◽  
pp. 523-530 ◽  
Author(s):  
Jian Cui ◽  
Zhong Min Wang ◽  
Feng Lei Liu ◽  
Pei Bang Dai ◽  
Ran Chen ◽  
...  
Keyword(s):  
Adsorption Mechanism ◽  
Ph Value ◽  
Effect Of Temperature ◽  
Major Influence ◽  
Initial Concentration ◽  
Adsorbent Dosage ◽  
Adsorption Data ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Ph Range

Persimmon tannins (PT) were immobilized on a matrix of collagen fiber by cross-linking of glutaraldehyde. The adsorption behaviours to Cr (VI) on PT were investigated including the effects of initial pH, initial concentration of Cr (VI), temperature, adsorbent dosage, adsorption kinetics and the recycling performance of PT adsorbents. The results showed that pH value had a major influence in adsorption. PT showed a strong adsorbability to Cr (VI) in the pH range of 1.0 to 3.0, whereas the effect of temperature on the adsorption was comparatively weaker. The adsorption equilibrium could be well described by Freundlich equation. PT adsorption efficiency of Cr (VI) reached 98.04% and the maximum equilibrium adsorption capacity of Cr (VI) was up to 49.01 mg/g at 303 K with a pH value of 2.0, 100 mg/L of initial concentration of Cr (VI) and 0.1g of adsorbent dosage. The adsorption data could be well fitted by pseudo-second-order rate model. PT adsorbents were characterized by FTIR and EDS. The analysis indicated that the adsorption mechanism was mainly contributed by redox adsorption.

Research of Nano-TiO2 Composites on Malachite Green Decolorizing Effect

2013 ◽  
Vol 734-737 ◽  
pp. 2338-2341
Author(s):  
Ru Qin Gao ◽  
Dou Dou Huang ◽  
Zi Kuo Wang
Keyword(s):  
Malachite Green ◽  
Solid Phase ◽  
Porous Ceramics ◽  
Precipitation Method ◽  
Sintering Process ◽  
Calcination Process ◽  
Initial Concentration ◽  
Influence Mechanism ◽  
Test Conditions ◽  
Initial Ph

A supporting body of diatomite-based porous ceramics was prepared by a solid-phase sintering process and low-temperature calcination process. nanoTiO2 membrane was loaded on the carrier by the hydrolysis precipitation method and using TiCl4 as the precursor. The influences of various parameters such as the initial concentration of malachite green, the amount of composites, and the initial pH had been investigated. Under the same test conditions, the decolorizing rate of malachite green was higher when the initial concentration was 6 mg/L, the composites dosage was 5 g/L, and the initial pH was 8 respectively. The influence mechanism of the initial concentration of malachite green, the amount of composites, and the initial pH for malachite green was discussed.

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