scholarly journals Mobility of Cellulose Nanocrystals in Porous Media: Effects of Ionic Strength, Iron Oxides, and Soil Colloids

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 348 ◽  
Author(s):  
Shuang Xu ◽  
Chongyang Shen ◽  
Xueyong Zhang ◽  
Xijuan Chen ◽  
Mark Radosevich ◽  
...  
Keyword(s):  
Porous Media ◽  
Ionic Strength ◽  
Iron Oxides ◽  
Cellulose Nanocrystals ◽  
Solution Chemistry ◽  
Water Remediation ◽  
Natural Soils ◽  
Ionic Strength Effect ◽  
Red Earth ◽  
Soil Colloids

Understanding the dispersivity and migration of cellulose nanocrystals (CNCs) in porous media is important for exploring their potential for soil and water remediation. In this study, a series of saturated column experiments were conducted to investigate the coupled effects of ionic strength, iron oxides (hematite), and soil colloids on the transport of CNCs through quartz sand and natural soils (red earth and brown earth). Results showed that CNCs had high mobility in oxide-free sand and that iron oxide coating reduced the mobility of CNCs. An analysis of Derjaguin-Landau-Verwey-Overbeek interactions indicated that CNCs exhibited a deep primary minimum, nonexistent maximum repulsion and secondary minimum on hematite-coated sand, favorable for the attachment of CNCs. The maximum effluent percentage of CNCs was 96% in natural soils at 5 mM, but this value decreased to 4% at 50 mM. Soil colloids facilitated the transport of CNCs in brown earth with larger effect at higher ionic strength. The ionic strength effect was larger in natural soils than sand and in red earth than brown earth. The study showed that CNCs can travel 0.2 m to 72 m in porous media, depending on soil properties, solution chemistry, and soil colloids.

Comparative study on sorption/desorption of radioeuropium on alumina, bentonite and red earth: effects of pH, ionic strength, fulvic acid, and iron oxides in red earth

2001 ◽  
Vol 54 (4) ◽  
pp. 603-610 ◽  
Author(s):  
Dong Wenming ◽  
Wang Xiangke ◽  
Bian Xiaoyan ◽  
Wang Aixia ◽  
Du Jingzhou ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Comparative Study ◽  
Fulvic Acid ◽  
Iron Oxides ◽  
Effects Of Ph ◽  
Red Earth

Transport and Retention of Cadmium in Biochar-Amended Sand Porous Media

2020 ◽  
Vol 36 (5) ◽  
pp. 629-638
Author(s):  
Lurui Xiao ◽  
Daojing Wang ◽  
Wenjing Sang ◽  
Mengyuan Ji ◽  
Lei Zhou ◽  
...  
Keyword(s):  
Porous Media ◽  
Ionic Strength ◽  
Ion Exchange ◽  
Column Experiment ◽  
Scientific Basis ◽  
Solution Chemistry ◽  
Batch Experiment ◽  
List Type ◽  
Retention Model ◽  
Surface Precipitation

HighlightsBatch experiment indicated that sorption of Cd on biochar was highly pH-dependant.The main mechanism of Cd-biochar sorption were surface precipitation and ion exchange.Biochar affected the transportation of the attached Cd.At the same ionic strength, the transportation is faster in the presence of Ca2+ than Na+.Abstract. Cadmium (Cd) is toxic to plants and animals, leaching of Cd through soil profiles can affect its accumulation and pollute the ground-water. In this study, we performed batch and column experiments to study the effect of biochar on the retention and transport of Cd in saturated porous media under different solution chemistry. Specific factors were considered including pH, ionic strength, and biochar dosages. The results of batch experiment indicated that sorption of Cd on biochar was highly pH-dependant, but ionic strength had negligible effect on the adsorption of Cd to biochar. The mechanism of the adsorption process of biochar for Cd mainly involves surface precipitation and ion exchange. In the column experiment, the increase in pH and biochar dosages made the Cd more stable, whereas the increase in ionic strength improved the migration of Cd. The increased retention time of Cd was related to the greater retarded coefficient value (R) based on two-site kinetic retention model. The decrease of partitioning coefficient (ß) and fraction of instantaneous sorption sites (f) were in favor of the continuous and dynamic adsorption under column conditions. This study will provide a theoretical and scientific basis for the rational assessment of cadmium-related risks in biochar-modified environments. Keywords: Adsorption, Biochar, Cadmium, Porous media, Transport.

scholarly journals A critical evaluation of short columns for estimating the attachment efficiency of engineered nanomaterials in natural soils

2021 ◽  
Author(s):  
Knapp Karin Norrfors ◽  
Vesna Micić ◽  
Olga Borovinskaya ◽  
Frank von der Kammer ◽  
Thilo Hofmann ◽  
...  
Keyword(s):  
Porous Media ◽  
Theoretical Approach ◽  
Critical Evaluation ◽  
Packed Columns ◽  
Engineered Nanomaterials ◽  
Natural Soils ◽  
Attachment Efficiency ◽  
Short Columns ◽  
Homogeneous Porous Media

Short, saturated packed columns are used frequently to estimate the attachment efficiency (α) of engineered nanomaterials (ENMs) in relatively homogeneous porous media, but a combined experimental and theoretical approach to...

scholarly journals Transport and retention of colloidal particles in partially saturated porous media: Effect of ionic strength

2009 ◽  
Vol 45 (12) ◽  
Author(s):  
Yuniati Zevi ◽  
Annette Dathe ◽  
Bin Gao ◽  
Wei Zhang ◽  
Brian K. Richards ◽  
...  
Keyword(s):  
Porous Media ◽  
Ionic Strength ◽  
Colloidal Particles ◽  
Saturated Porous Media ◽  
Media Effect ◽  
Partially Saturated ◽  
Partially Saturated Porous Media

Synergistic effect of glycerol and ionic strength on the rheological behavior of cellulose nanocrystals suspension system

2017 ◽  
Vol 102 ◽  
pp. 1073-1082 ◽  
Author(s):  
Yang Qin ◽  
Ranran Chang ◽  
Shengju Ge ◽  
Liu Xiong ◽  
Qingjie Sun
Keyword(s):  
Ionic Strength ◽  
Synergistic Effect ◽  
Rheological Behavior ◽  
Cellulose Nanocrystals ◽  
Suspension System

Biosorption-mediated reduction of Cr(VI) using heterotrophically-grown Chlorella vulgaris: Active sites and ionic strength effect

2013 ◽  
Vol 231 ◽  
pp. 94-102 ◽  
Author(s):  
Francesca Pagnanelli ◽  
Nohman Jbari ◽  
Franco Trabucco ◽  
Ma Eugenia Martínez ◽  
Sebastián Sánchez ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Chlorella Vulgaris ◽  
Active Sites ◽  
Ionic Strength Effect ◽  
Mediated Reduction ◽  
Strength Effect

Nanofiltration performance of lead solutions: effects of solution pH and ionic strength

2010 ◽  
Vol 10 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Wuthikorn Saikaew ◽  
Supatpong Mattaraj ◽  
Ratana Jiraratananon
Keyword(s):  
Ionic Strength ◽  
Membrane Surface ◽  
Aromatic Polyamide ◽  
Solution Chemistry ◽  
Lead Ion ◽  
Solution Ph ◽  
Dead End ◽  
Flux Decline ◽  
Charged Membrane ◽  
Double Layer Thickness

Nanofiltration performance (i.e. rejection and flux decline) of lead solutions was investigated using a dead-end test cell at room temperature. An aromatic polyamide NF-90 membrane was chosen to determine the impacts of solution chemistry. The experimental results revealed that solution flux decline was dependent on solution pH, ionic strength, and type of lead solutions. Solution flux conducted with different types of lead solutions (i.e. PbCl2 and Pb(NO3)2) decreased with increased solution pH. Solutions having high pH exhibited greater flux decline than those having low solution pH, while lead ion rejections were relatively high. Increased ionic strengths resulted in a greater flux decline, while lead ion rejections decreased with decreasing solution pH and increasing ionic strengths. Such results were related to low solution pH, suggesting an increase in fixed charge of proton (H+), decreasing electrical double layer thickness within membrane, thus allowing increased lead concentration passing through the membrane surface. Solution flux and rejection decreased further at higher ionic strengths, which caused a reduced negatively charged membrane, and thus decreased rejections. It was also found that lead ion for PbCl2 solution exhibited higher rejections than that of Pb(NO3)2 solution.

Stable and sensitive stimuli-responsive anisotropic hydrogels for sensing ionic strength and pressure

2018 ◽  
Vol 5 (6) ◽  
pp. 1076-1081 ◽  
Author(s):  
Takayuki Hiratani ◽  
Osamu Kose ◽  
Wadood Y. Hamad ◽  
Mark J. MacLachlan
Keyword(s):  
Ionic Strength ◽  
Cellulose Nanocrystals ◽  
Stimuli Responsive ◽  
Responsive Hydrogels

Stimuli-responsive hydrogels that respond to pressure and ionic strength were prepared with large mono-domain, nematic organization of cellulose nanocrystals (CNCs).

Impact of selected cement additives and model compounds on the solubility of Nd(III), Th(IV) and U(VI): screening experiments in alkaline NaCl, MgCl2 and CaCl2 solutions at elevated ionic strength

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nicole Adam ◽  
Katja Hinz ◽  
Xavier Gaona ◽  
Petra J. Panak ◽  
Marcus Altmaier
Keyword(s):  
Ionic Strength ◽  
Ethylene Glycol ◽  
Adipic Acid ◽  
Methyl Acrylate ◽  
Phthalic Acid ◽  
Solution Chemistry ◽  
Model Compounds ◽  
Screening Experiments ◽  
Acid Methyl ◽  
The Impact

Abstract The solubility of Nd(III), Th(IV) and U(VI) was studied from undersaturation conditions in the presence of selected organic cement additives and model compounds: adipic acid, methyl acrylate, citric acid, melamine, ethylene glycol, phthalic acid and gluconic acid. Experiments were performed under Ar atmosphere in NaCl (2.5 and 5.0 M), MgCl2 (1.0 and 3.5 M) and CaCl2 (1.0 and 3.5 M) solutions with 9 ≤ pHm ≤ 13 (pHm = −log[H+]). Initial concentrations of organic ligands in solution were set constant in all systems to [L]0 = 0.025 M, except in specific cases (e.g. adipic acid, melamine and phthalic acid) where the ligand concentration in the matrix solutions was lower and controlled by solubility. Adipic acid, methyl acrylate, melamine, ethylene glycol and phthalic acid do not impact the solubility of Nd(III), Th(IV) and U(VI) in the investigated NaCl, MgCl2 and CaCl2 systems. Citrate significantly enhances the solubility of Nd(III), Th(IV) and U(VI) in NaCl systems. A similar effect was observed for Th(IV) and U(VI) in the presence of gluconate in NaCl systems. The impact of pH on the stability of the complexes is different for both ligands. Because of the larger number of alcohol groups in the gluconate molecule, this ligand is prone to form more stable complexes under hyperalkaline conditions that likely involve the deprotonation of several alcohol groups. The complexation of gluconate with U(VI) at pHm ≈ 13 is however weaker than at pHm ≈ 9 due to the competition with the highly hydrolysed moiety prevailing at pHm ≈ 13, i.e. UO2(OH)4 2−. The impact of citrate and gluconate in MgCl2 and CaCl2 systems is generally weaker than in NaCl systems, expectedly due to the competition with binary Mg-L and Ca-L complexes. However, the possible formation of ternary complexes further enhancing the solubility is hinted for the systems Mg/Ca-Th(IV)-GLU and Ca-U(VI)-GLU. These observations reflect again the differences in the complexation properties of citrate and gluconate, the key role of the alcohol groups present in the latter ligand, and the importances of interacting matrix cations. The screening experiments conducted within this study contribute to the identification of organic cement additives and model compounds potentially impacting the solution chemistry of An(III)/Ln(III), An(IV) and An(VI) under intermediate to high ionic strength conditions (2.5 ≤ I ≤ 10.5 M). This shows evident differences with respect to investigations conducted in dilute systems, and thus represents a very relevant input in the safety assessment of repositories for radioactive waste disposal where such elevated ionic strength conditions are expected.

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