scholarly journals The Effect of Ionic Strength and pH on the Dewatering Rate of Cellulose Nanofibril Dispersions

2021 ◽  
Author(s):  
Andreas Fall ◽  
Marielle Henriksson ◽  
Anni Karppinen ◽  
Anne Opstad ◽  
Ellinor Bævre Heggset ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Salt Concentration ◽  
Cellulose Nanofibrils ◽  
Minor Effect ◽  
Cellulose Nanofibril ◽  
Main Aspect ◽  
Industrial Grade ◽  
Barrier Performance ◽  
Chemical Conditions ◽  
Low Charge

Abstract Cellulose nanofibrils, CNFs, show a great potential in many application areas. One main aspect limiting the use of the material is the slow and energy demanding dewatering of CNF suspensions. Here we investigate the dewatering with a piston press process. Three different CNF qualities, two laboratory grades (high and low charge) and one industrial grade (low charge) were tested. The chemical conditions were varied by changing salt concentration (NaCl) and pH. For the original suspensions, the dewatering rate is substantially slower for the high charge CNFs. However, by changing the conditions it dewatered as fast as the two low charge CNFs, even though salt/acid additions also improved dewatering rate for these two CNFs. Finally, by tuning the conditions fast dewatering could be obtained with only minor effect on strength and barrier performance of films prepared from the CNFs.

scholarly journals Alcohol induced gelation of TEMPO-oxidized cellulose nanofibril dispersions

Soft Matter ◽  
2018 ◽  
Vol 14 (45) ◽  
pp. 9243-9249 ◽  
Author(s):  
Marcelo A. da Silva ◽  
Vincenzo Calabrese ◽  
Julien Schmitt ◽  
Duygu Celebi ◽  
Janet L. Scott ◽  
...  
Keyword(s):  
Self Assembly ◽  
Cellulose Nanofibrils ◽  
Oxidized Cellulose ◽  
Cellulose Nanofibril ◽  
Alcoholic Mixtures

Alcohol-induced gelation of partially oxidised cellulose nanofibrils (OCNFs): nanoscale (SAXS) and macroscale (rheology) insights into OCNF self-assembly in aqueous-alcoholic mixtures.

Online determination of anisotropy during cellulose nanofibril assembly in a flow focusing device

RSC Advances ◽  
2015 ◽  
Vol 5 (24) ◽  
pp. 18601-18608 ◽  
Author(s):  
Karl M. O. Håkansson
Keyword(s):  
Cellulose Nanofibrils ◽  
High Strength ◽  
Cellulose Nanofibril ◽  
Flow Focusing ◽  
Strength And Stiffness

In order to utilize the high strength and stiffness of cellulose nanofibrils in a macroscopic material or composite, the structure of the elongated fibrils in the material must be controlled.

scholarly journals Fluorimetric studies on the dimerization equilibrium of protoporphyrin IX and its haemato derivative

1983 ◽  
Vol 209 (2) ◽  
pp. 547-552 ◽  
Author(s):  
R Margalit ◽  
N Shaklai ◽  
S Cohen
Keyword(s):  
Ionic Strength ◽  
Fluorescence Quenching ◽  
Fluorescence Intensity ◽  
Salt Concentration ◽  
Equilibrium Constants ◽  
Protoporphyrin Ix ◽  
Constant Ionic Strength ◽  
Aggregation Process ◽  
Buffer Concentration ◽  
Common Anion

The aggregations of protoporphyrin IX and haematoporphyrin IX in aqueous solutions were studied by fluorimetric techniques. Porphyrin concentrations were limited to 0.001-0.1 microM and 0.01-1 microM for protoporphyrin and haematoporphyrin respectively, where dimerization is the dominant aggregation process. The dimerization equilibrium constants (at 25 degrees C, neutral pH, 50 mM-Tris/HCl buffer) were determined to be 3×10(7) M and 4×10(5) M for the proto and the haemato derivatives respectively. The fluorescence intensity of a given protoporphyrin solution (within the range indicated above) was markedly decreased by salts in the system, over the salt concentration range 0.1-7 mM at constant ionic strength, in the sequence CaCl2 greater than MgCl2 greater than KCl greater than NaCl. The direction of this effect, fluorescence quenching, suggests that these salts promote an increase in aggregation. The differences in the magnitudes of the effect, among different salt species sharing a common anion, at constant ionic strength, imply that the effect is cation-specific. In contrast, the fluorescence intensity of a given solution of haematoporphyrin (within the range indicated above) was unaffected by these salts, under similar concentrations, nor was it sensitive to the total buffer concentration, or to the type of buffer in the system.

scholarly journals Effects of ionic strength on the regulation of Na/H exchange and K-Cl cotransport in dog red blood cells.

1995 ◽  
Vol 105 (6) ◽  
pp. 677-699 ◽  
Author(s):  
J C Parker ◽  
P B Dunham ◽  
A P Minton
Keyword(s):  
Ionic Strength ◽  
Salt Concentration ◽  
Mechanistic Model ◽  
Regulatory Protein ◽  
Thermodynamic Activity ◽  
Common Mechanism ◽  
Model Parameters ◽  
Set Point ◽  
Weight Percentage ◽  
Empirical Expressions

Dog red cell membranes contain two distinct volume-sensitive transporters: swelling-activated K-Cl cotransport and shrinkage-activated Na/H exchange. Cells were prepared with intracellular salt concentration and weight percentage of cell water (%cw) varied independently by transient permeabilization of the cell membrane to cations. The dependence of transporter-mediated Na and K influxes upon %cw and upon extracellular salt concentration (c(ext)) was measured in cells so prepared. It was found that the critical value of %cw at which transporters are activated, called the set point, is similar for the two transporters, and that the set points for the two transporters decrease similarly with increasing extracellular salt concentration. These findings suggest a common mechanism of regulation of these two transporters. Cellular Na, K, and Cl concentrations were measured as functions of %cw and c(ext). Using these data together with data from the literature for other solute concentrations, empirical expressions were developed to describe the dependence of the intracellular concentrations of all significant small molecule electrolytes, and therefore the intracellular ionic strength, upon %cw and c(ext). A mechanistic model for the dependence of the set point of an individual transporter upon intracellular ionic strength is proposed. According to this model, the set point represents a critical extent of association between the transporter and a postulated soluble regulatory protein, called regulator. Model functions are presented for the calculation of the thermodynamic activity of regulator, and hence extent of regulator-transporter association, as a function of total intracellular protein concentration (or %cw) and ionic strength. The experimentally observed dependence of set point %cw on c(ext) are simulated using these functions and the empirical expressions described above, together with reasonable but not uniquely determined values of model parameters.

The chemical composition and ionic strength of soil solutions from New Zealand topsoils

Soil Research ◽  
1985 ◽  
Vol 23 (2) ◽  
pp. 151 ◽  
Author(s):  
DC Edmeades ◽  
DM Wheeler ◽  
OE Clinton
Keyword(s):  
Soil Moisture ◽  
New Zealand ◽  
Ionic Strength ◽  
Soil Solution ◽  
Soil Type ◽  
Ionic Composition ◽  
Soil Samples ◽  
Minor Effect ◽  
Solution Composition ◽  
Soil Solutions

In preliminary experiments a centrifuge method for extracting soil solutions was examined. Neither the time nor speed of centrifuging had any effect on the concentrations of cations in soil solution. The concentration of cations increased with decreasing soil moisture content, and NO3, Ca, Mg, and Na concentrations increased with increasing time of storage of freshly collected moist soils. It was concluded that to obtain soil solutions, which accurately reflect the soil solution composition and ionic strength (I) in situ, requires that soil samples are extracted immediately (<24 h) following sampling from the field. Prior equilibration of soil samples, to adjust soil moisture contents, is therefore not valid. The effect of time of sampling and soil type, and the effects of fertilizer and lime applications, on soil solution composition and ionic strength, were measured on freshly collected field moist topsoils. Concentrations of Ca, Mg, K, Na, NH, and NO, were lowest in the winter and highest in the summer. Consequently, there was a marked seasonal variation in ionic strength which ranged from 0.003 to 0.016 mol L-1 (mean, 0.005 s.d. 0.003) over time and soil type. Withholding fertilizer (P, K, S, Ca) for two years had only a minor effect on ionic composition and strength, and liming increased solution Ca, Mg and HCO3, but decreased Al, resulting in a twofold increase in ionic strength. These results suggest that the ionic strength of temperate grassland topsoils in New Zealand lie within the range 0.003-0.016 and are typically 0.005.

scholarly journals Affinity chromatography of immobilized actin and myosin

1975 ◽  
Vol 149 (2) ◽  
pp. 365-379 ◽  
Author(s):  
R C Bottomley ◽  
I P Trayer
Keyword(s):  
Ionic Strength ◽  
Salt Concentration ◽  
Free Solution ◽  
Heavy Meromyosin ◽  
Chemical Modifications ◽  
Low Concentrations ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
One Step ◽  
Low Ionic Strength

Actin and myosin were immobilized by coupling them to agarose matrices. Both immobilized G-actin and immobilized myosin retain most of the properties of the proteins in free solution and are reliable over long periods of time. Sepharose-F-actin, under the conditions used in this study, has proved unstable and variable in its properties. Sepharose-G-actin columns were used to bind heavy meromyosin and myosin subfragment 1 specifically and reversibly. The interaction involved is sensitive to variation in ionic strength, such that myosin itself is not retained by the columns at the high salt concentration required for its complete solubilization. Myosin, rendered soluble at low ionic strength by polyalanylation, will interact successfully with the immobilized actin. The latter can distinguish between active and inactive fractions of the proteolytic and polyalanyl myosin derivatives, and was used in the preparation of these molecules. The complexes formed between the myosin derivatives and Sepharose-G-actin can be dissociated by low concentrations of ATP, ADP and pyrophosphate in both the presence and the absence of Mg2+. The G-actin columns were used to evaluate the results of chemical modifications of myosin subfragments on their interactions with actin. F-Actin in free solution is bound specifically and reversibly to columns of insolubilized myosin. Thus, with elution by either ATP or pyrophosphate, actin has been purified in one step from extracts of acetone-dried muscle powder.

scholarly journals Facile Preparation and Characteristic Analysis of Sulfated Cellulose Nanofibril via the Pretreatment of Sulfamic Acid-Glycerol Based Deep Eutectic Solvents

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2778
Author(s):  
Weidong Li ◽  
Yu Xue ◽  
Ming He ◽  
Jiaqiang Yan ◽  
Lucian A. Lucia ◽  
...  
Keyword(s):  
Cellulose Nanofibrils ◽  
Deep Eutectic Solvent ◽  
Sulfamic Acid ◽  
Deep Eutectic Solvents ◽  
Uv Resistance ◽  
Cellulose Nanofibril ◽  
Characteristic Analysis ◽  
Maximum Reduction ◽  
High Degree ◽  
Original Crystal

A deep eutectic solvent (DES) composed of sulfamic acid and glycerol allowed for the sustainable preparation of cellulose nanofibrils (CNF) with simultaneous sulfation. The reaction time and the levels of sulfamic acid demonstrated that fibers could be swelled and sulfated simultaneously by a sulfamic acid-glycerol-based DES and swelling also promoted sulfation with a high degree of substitution (0.12). The DES-pretreated fibers were further nanofibrillated by a grinder producing CNF with diameters from 10 nm to 25 nm. The crystallinity ranged from 53–62%, and CNF maintained the original crystal structure. DES pretreatment facilitated cellulose nano-fibrillation and reduced the energy consumption with a maximum reduction of 35%. The films prepared from polyvinyl alcohol (PVA) and CNF showed good UV resistance ability and mechanical properties. This facile and efficient method provided a more sustainable strategy for the swelling, functionalization and nano-fibrillation of cellulose, expanding its application to UV-blocking materials and related fields.

Micro-mechanics of electrostatically stabilized suspensions of cellulose nanofibrils under steady state shear flow

Soft Matter ◽  
2016 ◽  
Vol 12 (6) ◽  
pp. 1721-1735 ◽  
Author(s):  
F. Martoïa ◽  
P. J. J. Dumont ◽  
L. Orgéas ◽  
M. N. Belgacem ◽  
J.-L. Putaux
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Cellulose Nanofibrils ◽  
Oxidized Cellulose ◽  
Cellulose Nanofibril ◽  
Aqueous Suspensions

In this study, we characterized and modeled the rheology of TEMPO-oxidized cellulose nanofibril (NFC) aqueous suspensions with electrostatically stabilized and unflocculated nanofibrous structures.

scholarly journals The effects of ionic strength on the toxicity of aluminium to Atlantic salmon (Salmo salar) under non-steady state chemical conditions

2002 ◽  
Vol 61 (1) ◽  
pp. 69 ◽  
Author(s):  
Espen LYDERSEN ◽  
Sigurd ØXNEVAD ◽  
Kjartan ØSTBYE ◽  
Ronny A. ANDERSEN ◽  
Frode BJERKELY ◽  
...  
Keyword(s):  
Steady State ◽  
Ionic Strength ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar ◽  
State Chemical ◽  
Chemical Conditions

scholarly journals Chitosan/Cellulose Nanofibril Nanocomposite and Its Effect on Quality of Coated Strawberries

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
N. S. Resende ◽  
G. A. S. Gonçalves ◽  
K. C. Reis ◽  
G. H. D. Tonoli ◽  
E. V. B. V. Boas
Keyword(s):  
Water Vapor ◽  
Cellulose Nanofibrils ◽  
Water Vapor Permeability ◽  
Solid Content ◽  
Postharvest Quality ◽  
Vapor Permeability ◽  
Soluble Solid Content ◽  
Anthocyanin Content ◽  
Cellulose Nanofibril ◽  
Significant Difference

The aim of this study was to develop a chitosan/cellulose nanofibril (CNF) nanocomposite and evaluate its effect on strawberry’s postharvest quality after coating. From the results of color, thickness, and scanning electron microscopy (SEM) and permeability to water vapor analyses, the best film formulation for coating strawberries was determined. Three coating formulations were prepared: 1% chitosan, 1% chitosan + 3% CNF, and 1% chitosan + 5% CNF. The strawberries were immersed in the filmogenic solutions and kept under cold storage (1 ± 1°C). The color of the film was not affected by increased concentration of cellulose nanofibrils; however, the thickness and water vapor permeability were affected by the CNF addition. The coating with the highest CNF concentration performed better in reducing fruit mass and firmness loss. The color was positively influenced by the addition of the coating, regardless of formulation, as well as soluble solid content, PG enzymatic activity, and the fruit appearance. The pH and titratable acidity showed no significant difference among treatments. It was observed that the vitamin C, phenolic compounds, and anthocyanin content, as well as the PAL activity and the antioxidant activity (except for % protection), were affected by chitosan coating, however not by the addition of CNFs.

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