scholarly journals Swelling Characteristics of Clay Minerals According to the Ionic Strength in Pore Water

2021 ◽  
Vol 21 (6) ◽  
pp. 201-207
Author(s):  
Seok Gu Gang ◽  
Jongwon Jung
Keyword(s):  
Ionic Strength ◽  
Clay Minerals ◽  
Pore Water ◽  
Distilled Water ◽  
Swelling Ratio ◽  
Swelling Characteristics

An experiment to evaluate the swelling characteristics during saturation of representative clay minerals, kaolinite, illite, montmorillonite, and bentonite, according to the ionic strength of the pore water, was conducted. The results showed that in distilled water (DW), the average swelling ratios of kaolinite, illite, and bentonite were 10.95%, 12.51%, and 26.60%, respectively. However, montmorillonite exhibited a relatively large swelling ratio of approximately 152.6%. In 1 M brine, kaolinite, illite, and bentonite exhibited swelling ratios of 12.42%, 16.23%, and 21.91%, respectively, while that of montmorillonite was relatively small (0.83%). In the case of the ground containing montmorillonite, a high swelling ratio is expected with an increase in saturation and conductivity.

The Influence of Concentration of Pore Water Solution on the Swelling Characteristics of Expansive Soils

2012 ◽  
Vol 238 ◽  
pp. 427-430 ◽  
Author(s):  
Jing Chao Jia ◽  
Huan Li ◽  
Qing Tao Bi
Keyword(s):  
Pore Water ◽  
Expansive Soils ◽  
Water Solution ◽  
Swelling Pressure ◽  
Solution Concentration ◽  
The Other ◽  
Swelling Ratio ◽  
Swelling Properties ◽  
Swelling Characteristics ◽  
Volume Swelling

The influences of pore water solution concentration on the swelling properties of expansive soils were studied using the constant volume swelling pressure experiments and swelling ratio experiments under load. The results indicate that the swelling pressures decrease with the increase of solution concentration. Two specimens made by the same solutions concentration were immersed into solutions with two various concentrations to prepare specimen, one is smaller than the concentration of solution, and the other is same to that. The results show that the swelling pressures and the swelling strains of two specimens are very close. The analysis on the exist state of the pore water shows that the experimental results are agree with the osmotic pressure theory.

scholarly journals Elucidating the Molecular Mechanisms for the Interaction of Water with Polyethylene Glycol-Based Hydrogels: Influence of Ionic Strength and Gel Network Structure

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 845
Author(s):  
Xin Yang ◽  
Bronwin Dargaville ◽  
Dietmar Hutmacher
Keyword(s):  
Polyethylene Glycol ◽  
Ionic Strength ◽  
Molecular Mechanisms ◽  
Repeat Unit ◽  
Bound Water ◽  
Weight Fraction ◽  
Swelling Ratio ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
Hydrogel System

The interaction of water within synthetic and natural hydrogel systems is of fundamental importance in biomaterial science. A systematic study is presented on the swelling behavior and states of water for a polyethylene glycol-diacrylate (PEGDA)-based model neutral hydrogel system that goes beyond previous studies reported in the literature. Hydrogels with different network structures are crosslinked and swollen in different combinations of water and phosphate-buffered saline (PBS). Network variables, polyethylene glycol (PEG) molecular weight (MW), and weight fraction are positively correlated with swelling ratio, while “non-freezable bound water” content decreases with PEG MW. The presence of ions has the greatest influence on equilibrium water and “freezable” and “non-freezable” water, with all hydrogel formulations showing a decreased swelling ratio and increased bound water as ionic strength increases. Similarly, the number of “non-freezable bound water” molecules, calculated from DSC data, is greatest—up to six molecules per PEG repeat unit—for gels swollen in PBS. Fundamentally, the balance of osmotic pressure and non-covalent bonding is a major factor within the molecular structure of the hydrogel system. The proposed model explains the dynamic interaction of water within hydrogels in an osmotic environment. This study will point toward a better understanding of the molecular nature of the water interface in hydrogels.

Experiments on Substrate Selection by Corophium Species: Films and Bacteria on Sand Particles

1964 ◽  
Vol 41 (3) ◽  
pp. 499-511
Author(s):  
P. S. MEADOWS
Keyword(s):  
Ionic Strength ◽  
Sea Water ◽  
Distilled Water ◽  
Substrate Selection ◽  
Corophium Volutator ◽  
Simple Method ◽  
Substrate Preferences ◽  
Solutions Of Electrolytes ◽  
Sand Particles ◽  
Micro Organisms

1. A simple method is described for determining the substrate preferences of Corophium volutator (Pallas) and Corophium arenarium Crawford. 2. If offered a choice of its own substrate with that of the other species each prefers its own. 3. Level of illumination and colour of substrate have little effect on choice. An animal's size and hence its age has little effect on its substrate preferences. 4. C. volutator prefers a substrate previously maintained under anaerobic conditions, C. arenarium vice versa. 5. Treatments which kill, inactivate, or remove micro-organisms render sands unattractive to Corophium. These include boiling, acid-cleaning, drying, and soaking in fixatives or distilled water. Attempts to make these sands attractive again failed. 6. Distilled water, and solutions of the non-electrolytes sucrose and glycerol at the same osmotic pressure as sea water, induce many bacteria to desorb from sand particles; smaller numbers are desorbed in the presence of solutions of electrolytes at the same ionic strength as sea water (NaCl, Na2SO4, KC1, MgSO4, MgCl2, CaCl2). Of all these, only distilled water and solutions of MgCl2 and CaCl2 reduce the attractive properties of sands. Hence the loss of bacteria from the surface of sand grains, though related to the ionic strength and composition of the medium, is not necessarily associated with a substrate becoming unattractive.

scholarly journals DOC-dynamics in a small headwater catchment as driven by redox fluctuations and hydrological flow paths – are DOC exports mediated by iron reduction/oxidation cycles?

2013 ◽  
Vol 10 (2) ◽  
pp. 891-904 ◽  
Author(s):  
K.-H. Knorr
Keyword(s):  
Ionic Strength ◽  
Pore Water ◽  
Surface Waters ◽  
Iron Reduction ◽  
Stream Water ◽  
Riparian Wetlands ◽  
Pore Waters ◽  
Flow Paths ◽  
Discharge Patterns ◽  
Iron Concentrations

Abstract. Dissolved organic carbon (DOC) exports from many catchments in Europe and North-America are steadily increasing. Several studies have sought to explain this observation. As possible causes, a decrease in acid rain or sulfate deposition, concomitant reductions in ionic strength and increasing temperatures were identified. DOC often originates from riparian wetlands; but here, despite higher DOC concentrations, ionic strength in pore waters usually exceeds that in surface waters. In the catchment under study, DOC concentrations were synchronous with dissolved iron concentrations in pore and stream water. This study aims at testing the hypothesis that DOC exports are mediated by iron reduction/oxidation cycles. Following the observed hydrographs, δ18O of water and DOC fluorescence, the wetlands were identified as the main source of DOC. Antecedent biogeochemical conditions, i.e., water table levels in the wetlands, influenced the discharge patterns of nitrate, iron and DOC during an event. The correlation of DOC with pH was positive in pore waters, but negative in surface waters; it was negative for DOC with sulfate in pore waters, but only weak in surface waters. Though, the positive correlation of DOC with iron was universal for pore and surface water. The decline of DOC and iron concentrations in transition from anoxic wetland pore water to oxic stream water suggests a flocculation of DOC with oxidising iron, leading to a drop in pH in the stream during high DOC fluxes. The pore water did not per se differ in pH. There is, thus, a need to consider processes more thoroughly of DOC mobilisation in wetlands when interpreting DOC exports from catchments. The coupling of DOC with iron fluxes suggested that increased DOC exports could at least, in part, be caused by increasing activities in iron reduction, possibly due to increases in temperature, increasing wetness of riparian wetlands, or by a shift from sulfate dominated to iron reduction dominated biogeochemical regimes.

Importance of site-specific factors for the immobilization of contaminants using biochar and wood-based activated carbon

2021 ◽  
Author(s):  
Sampriti Chaudhuri ◽  
Gabriel Sigmund ◽  
Hary von Rautenkranz ◽  
Thorsten Hueffer ◽  
Thilo Hofmann
Keyword(s):  
Activated Carbon ◽  
Ionic Strength ◽  
Water Chemistry ◽  
Pore Water ◽  
Electrostatic Attraction ◽  
Inorganic Contaminants ◽  
Diverse Range ◽  
Pore Water Chemistry ◽  
Specific Factors ◽  
Carbonaceous Sorbents

<p>The use of environmentally friendly low-cost sorbents such as biochar and wood-based activated carbon as soil amendment has shown promising results in immobilizing organic and inorganic contaminants. They can be suitable soil remediation options at sites with residual contamination, where the contaminated hotspot has been removed. The effectiveness of biochar and activated carbon application is site dependent. Specifically, dissolved organic carbon (DOC), pH, and ionic strength in the pore water are important factors which can influence the extent of contaminant immobilization. Although there has been significant progress in developing alternative carbonaceous sorbents, the efficiency of these materials in a diverse range of soil and pore water conditions remains an open question. To address this knowledge gap, the present study investigates the influence of pore water chemistry on sorption of organic and inorganic contaminants to biochar and wood-based activated carbon. Sorption of selected non-polar, polar and ionizable polycyclic aromatic compounds (PACs) and inorganic Cadmium (Cd) to biochar and a wood-based activated carbon was studied under different pore water chemistry conditions. Batch sorption experiments were conducted using an experimental design approach (Box Behnken Design) with three different levels of DOC, pH, and ionic strength, yielding background solutions mimicking a wide spectrum of pore water chemistries. Sorption K<sub>D</sub> values [L/kg] were calculated from aqueous contaminant concentrations after equilibration. Results were analyzed using a response surface methodology (RSM) approach on Minitab 19 and fitted to a model equation using linear, squared and two-way interactions terms.</p><p>Our results show that the ionizable PAC (phenyl phenol) and Cd were most affected by changes in pore water chemistries. For phenyl phenol, the presence of a phenolic group can cause H-bonding and electrostatic attraction and repulsion, while pH-dependent changes in speciation, precipitation and electrostatic attraction can occur for Cd. Sorption of all PACs negatively correlated with DOC, indicating competition of DOC with PACs for sorption sites. Sorption of non-polar (acenaphthene), polar N substituted (carbazole) and ionizable (phenyl phenol) PACs was hindered under acidic conditions, due to precipitation of DOC. For Cd, higher pH and low DOC levels favored sorption. This can be attributed to a lower Cd solubility in the presence of leached phosphate at higher pH, and a predominance of Cd(OH)<sub>2</sub> in the neutral to alkaline regime. Our findings highlight the importance of considering a combination of site- and contaminant-specific factors when planning to apply carbonaceous sorbents for contaminant immobilization, with pH and DOC generally being more important than ionic strength.</p>

scholarly journals A New Evaluation Method of Total Organic Carbon for Shale Source Rock Based on the Effective Medium Conductivity Theory

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jian Fu ◽  
Xuesong Li ◽  
Yonghe Sun ◽  
Qiuli Huo ◽  
Ting Gao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Clay Minerals ◽  
Pore Water ◽  
Effective Medium ◽  
Source Rocks ◽  
Model Parameters ◽  
Hydrocarbon Generation ◽  
Tight Sandstone

In the evaluation of source rocks, the total organic carbon (TOC) is an important indicator to evaluate the hydrocarbon generation potential of source rocks. At present, the commonly used methods for assessing TOC include △ log R and neural network method. However, practice shows that these methods have limitations in the application of unconventional intervals of sand-shale interbeds, and they cannot sufficiently reflect the variation of TOC in the vertical direction. Therefore, a total organic carbon (TOC) evaluation model suitable for shale and tight sandstone was established based on the effective medium symmetrical conduction theory. The model consists of four components: nonconductive matrix particles, clay minerals, organic components (solid organic matter and hydrocarbons), and pore water. The conductive phase in the model includes clay minerals and pore water, and other components are treated as nonconductive phases. When describing the conductivity of rock, each component in the model is completely symmetrical, and anisotropic characteristics of each component are considered. The model parameters are determined through the optimization method, and the bisection iteration method is used to solve the model equation. Compared with the classic TOC calculation method, the new model can evaluate the abundance of organic matter in shale and tight sandstone, which provides a new option to assess the TOC of rocks based on logging methods.

The Influence of Inorganic Salts on Plasma Antithrombin Activity

1963 ◽  
Vol 09 (02) ◽  
pp. 387-394 ◽  
Author(s):  
Frank C Monkhouse
Keyword(s):  
Ionic Strength ◽  
Alpha Tocopherol ◽  
Inorganic Salts ◽  
Distilled Water ◽  
Antithrombin Activity ◽  
Phosphate Ion ◽  
Factors Influencing ◽  
Increased Activity

SummaryA study has been made of factors influencing the activities of plasma antithrombin. Optimal antithrombin activity was obtained between pH 7.8 and 8.5. Dialysis against distilled water reduced the antithrombin activity to less than 30 per cent of normal. The antithrombin activity was restored by the addition, directly or by dialysis, of a number of salts. The increased activity in the presence of the salts seemed to be a function of the polyvalent anions rather than of the ionic strength of the medium. The antithrombin activity of alpha- tocopherol phosphate in vitro appears to be a function of the phosphate ion and not of the vitamin itself.

scholarly journals Synthesis and swelling characteristics of zwitterionic hydrogel

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Meenakshi Singh ◽  
Paresh Kumar Singh ◽  
Vinay Kumar Singh
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Salt Solution ◽  
Repeat Units ◽  
Equilibrium Swelling ◽  
Swelling Characteristics ◽  
Monovalent Salt ◽  
Amine Groups ◽  
Hydrophilic Gel

AbstractHydrogels comprising of zwitterionic repeat units were synthesized. The amine groups of the poly (ester amine) were quaternized with 1,3-propane sultone. The gelation was observed on treatment with sultone. The hydrophilic gel thus formed is sensitive to temperature, pH, ionic strength and nature of electrolytes in aqueous solution. In absence of any electrolyte, the extent of swelling decreased with temperature, but in the monovalent salt solution the equilibrium swelling diminished with temperature and the contrary behaviour was experiential in bivalent electrolytes.

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