scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1942 ◽  
Vol 25 (3) ◽  
pp. 411-429 ◽  
Author(s):  
Karl Sollner ◽  
Charles W. Carr ◽  
Irving Abrams
Keyword(s):  
Quantitative Measure ◽  
Exchange Capacity ◽  
Electrochemical Activity ◽  
Electrical Behavior ◽  
Exchange Method ◽  
Base Exchange ◽  
High Base ◽  
Different Origins ◽  
Theoretical Considerations ◽  
Exchange Properties

1. Theoretical considerations lead to the conclusion that dissociable acidic groups present to a varying extent in different collodion preparations determine the electrochemical behavior of membranes cast from these preparations. It is further reasoned that the base exchange capacity of the collodion surfaces is the true quantitative measure of the abundance of the dissociable groups. 2. The concept of base exchange capacity and the base exchange method are discussed. The conditions which allow a purposeful application of the latter are stated. 3. The base exchange properties of a number of fibrous collodion preparations of different origins and after various types of treatment, having widely varying electrochemical activities, are determined. 4. With the chemical (titration) and physical (electrometric) methods employed, no regular correlation can be found between electrochemical activity and base exchange. The base exchange capacity which is necessary to cause even great electrochemical activity of collodion is extremely small. 5. Measurable to high base exchange capacity always seems to be associated with good or high electrochemical activity; but base exchange capacity too low to be definitely measurable with the available methods may be found with collodion preparations of high as well as with preparations of low electrochemical activity. 6. The bearing of these results upon the problem of the spatial and electrical structure of the collodion membrane is indicated briefly.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1944 ◽  
Vol 27 (5) ◽  
pp. 433-449 ◽  
Author(s):  
Karl Sollner ◽  
Joan Anderman
Keyword(s):  
Solvent Mixture ◽  
Exchange Capacity ◽  
Acid Number ◽  
Electrochemical Activity ◽  
Time Base ◽  
Equivalent Weight ◽  
Base Exchange ◽  
Electrochemically Active ◽  
Organic Solvent Mixture ◽  
High Base

1. The electrochemical behavior ("activity") of collodion membranes depends upon acidic, dissociable groups located in the interstices of the membranes. The active groups can be determined by base exchange measurements. High base exchange capacity is always found with preparations of great "electrochemical activity;" medium and low base exchange capacities occur with electrochemically active as well as with inactive preparations. The observed base exchange capacity is determined by two factors: the inherent acidity of the collodion (its mean equivalent weight) and the submicroscopic micellar structure of the collodion. A comparison of the base exchange capacity of various collodion preparations and their inherent acidities therefore allows certain conclusions to be drawn concerning the relative availability of the micellar surfaces in the different preparations. 2. The inherent acidity of various collodion preparations, their "acid number," was determined by electrometric titration. Collodion in the acidic state, i.e. after exchange of all other cations for H+ ions, was titrated in an organic solvent mixture with alcoholic KOH using a quinhydrone electrode. Details of the experimental procedure are given in the paper. The acid numbers, expressed in milliliters of 0.01 N KOH per gram dry collodion, vary from 1.0 for a highly purified collodion preparation of very low electrochemical activity to 3.3 for a highly oxidized sample of very high activity. Acid numbers of about 1.5 (corresponding to an equivalent weight of about 67,000) are found both with inactive commercial and with fairly active oxidized preparations. The base exchange capacity of the same preparations in the fibrous state as measured after 48 hours of exchange time varies from 0.0013 ml. 0.01 N NaOH per gm. dry collodion for the most inactive preparation up to 0.26 ml. 0.01 N NaOH per gm. for the most active preparation. Thus the acid numbers over the whole range investigated differ only in the ratio of 1:3.3, whereas the base exchange values differ in the range of 1:200. 3. In the inactive preparation only one in 770 acid groups is available for base exchange, in the most active collodion one group in 13; values between these extremes are found with commercial and alcohol purified oxidized preparations. 4. The high base exchange capacity of the electrochemically active preparations is not so much due to their higher acid number as to their more open structure. This difference in structure is ascribed to the presence of a small fraction of low molecular weight material which inhibits normal formation and arrangement of the micelles. 5. Short time base exchange experiments with fibrous collodion indicate that the number of acid groups available for the typical electrochemical membrane functions may be estimated to be about 50 to 1000 times less numerous than those found in the 48 hour base exchange experiments. It is estimated that in membranes prepared even from the most active collodion not more than one in 500 acid groups may be available for the typical membrane functions; with the less active preparations this ratio is estimated to be as high as one in 1,000,000 or more.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1944 ◽  
Vol 28 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Karl Sollner ◽  
Charles W. Carr
Keyword(s):  
Experimental Data ◽  
Electrochemical Activity ◽  
Structural Factors ◽  
Electrical Behavior ◽  
Base Exchange ◽  
Basic Assumptions ◽  
Potentiometric Selectivity ◽  
Concentration Potential ◽  
Order Of Magnitude ◽  
Concentration Levels

1. The Teorell, Meyer-Sievers theory characterizes the electrochemical behavior of membranes by their selectivity constant "Ap" which is derived conventionally from concentration potential measurements at various concentration levels. The selectivity constant may, however, be derived also from entirely independent, different experimental data, namely base exchange studies. The constants arrived at in this second way are designated as "Ab." The selectivity constants derived by these two methods must be in reasonable, at least semiquantitative agreement if the basic assumptions of the theory are correct. 2. The selectivity constants Ap and Ab were determined for eleven different sets of membranes of different electrochemical activity and of different (8.2 to 80 volume per cent) water content. 3. The potentiometric selectivity constants Ap are in most cases several orders of magnitude greater than the corresponding Ab values. With membranes of great porosity and high electrochemical activity the Ab values approach at least in order of magnitude the Ap values. 4. It is concluded that the unexpectedly large discrepancy between the Ap and Ab values is due to some inherent weakness of the Teorell, Meyer-Sievers theory, most likely to its neglect of any structural factors.

scholarly journals THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1941 ◽  
Vol 25 (1) ◽  
pp. 7-27 ◽  
Author(s):  
Karl Sollner ◽  
Irving Abrams ◽  
Charles W. Carr
Keyword(s):  
Charge Density ◽  
Pore Space ◽  
Electrolyte Solutions ◽  
Exchange Capacity ◽  
Electrochemical Activity ◽  
Porous Membranes ◽  
Calcium Hypochlorite ◽  
Geometrical Structures ◽  
Base Exchange ◽  
Oxidizing Agents

1. The electrochemical behavior (concentration potential, anomalous osmosis, etc.) of collodion membranes is due to its acidic impurities. These impurities determine the possible charge density of the collodion—aqueous solution interfaces. This (possible) charge density is believed to be identical with the base exchange capacity of the interfaces under consideration. 2. The collodion preparations commercially available at present are too pure to yield membranes of sufficient activity for electrochemical membrane investigations. Crude collodion, a product which is only partially purified, shows considerable electrochemical activity because of its content of acidic impurities. 3. The inactive commercial collodion preparations can readily be activated by oxidation by virtue of the fact that oxidation increases the number of dissociable groups (carboxyl groups) on the collodion. The oxidation method of activating collodion may be applied to membranes as such as well as to collodion in bulk. 4. The recommended oxidizing agents are sodium and calcium hypochlorite and sodium hypobromite. A further group of effective and recommended activating agents are solutions of strong alkalies. Alkalies cause a complicated decomposition of nitrocellulose with the formation of nitrites (and probably other nitrous compounds). These nitrites act upon the collodion as oxidizing agents, thus causing activation. 5. Detailed descriptions of tested oxidation procedures for highly dried membranes, porous membranes, and bulk collodion are given in the text, the optimum conditions being different in the three cases. 6. Collodion membranes oxidized as such show a much higher electrochemical activity than any previously described. Highly dried membranes after oxidation give concentration potentials which approach the thermodynamically possible maximum more closely than any given in the literature. Porous membranes after oxidation show greatly increased concentration potentials and yield much greater electroosmosis when a current is passed through. These effects are reflected in the enormous magnification of the extent of anomalous osmosis. 7. The behavior of the porous membranes toward nonelectrolytes changes but little on oxidation. The volume of such membranes, as well as their per cent water content (pore space), remains constant within the limits of experimental error. From this observation and studies on the rate of filtration, it is concluded that the geometrical structure of membranes is but little changed on oxidation. 8. Collodion oxidized in bulk likewise yields very active membranes. Dried membranes prepared from activated bulk collodion consistently yield concentration potentials which approach the thermodynamically possible maximum very closely and are appreciably higher than any previously reported. Porous membranes prepared from bulk oxidized collodion show a degree of electrochemical activity surpassing anything described for the most active commercial collodion preparations. However, these membranes are less active than those oxidized as such. 9. Membranes prepared from different collodion preparations which behave fairly uniformly towards nonelectrolytes but very differently towards electrolyte solutions become similar in their behavior towards electrolytes after oxidation. 10. The geometrical structures of membranes prepared from different collodion preparations are essentially identical. The differences in their behavior towards electrolytes are due entirely to the electrochemical factor; i.e., the charge density at the water/collodion interface. 11. Certain general aspects of the foregoing experimental results are discussed briefly.

CHEMICAL STUDIES ON APPALACHIAN UPLAND PODSOL SOILS: I. CONDITIONS GOVERNING BASE-EXCHANGE RELATIONS

1933 ◽  
Vol 9 (4) ◽  
pp. 386-395 ◽  
Author(s):  
G. T. Shaw ◽  
R. R. McKibbin
Keyword(s):  
Organic Matter ◽  
Exchange Capacity ◽  
Acidic Soil ◽  
Soil Conditions ◽  
Base Exchange ◽  
Organic Complexes ◽  
Chemical Studies ◽  
Exchange Properties ◽  
Restoration Of Fertility ◽  
Exchange Relations

The base-exchange properties and the constituent materials of the base-exchange complexes of Quebec Appalachian upland podsol soils have been studied. It has been shown that the "availability" of the acid semihumified organic matter has played the most important part in bringing about existing conditions in these soils. Organic matter is dominating the processes through which these podsol soils pass in their progress from a slightly leached to a severely leached condition. The inorganic base-exchange complexes are superseded by organic complexes. The more "available" iron and aluminium present in these soils the less is their base-exchange capacity. The inorganic base-exchange complexes are unstable under the strongly acidic soil conditions. The restoration of fertility to these soils must be approached through modification of their organic-matter conditions.

scholarly journals Evaluation of the Antimicrobial Protection of Pharmaceutical Kaolin and Talc Modified with Copper and Zinc

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1173
Author(s):  
Fotini Martsouka ◽  
Konstantinos Papagiannopoulos ◽  
Sophia Hatziantoniou ◽  
Martin Barlog ◽  
Giorgos Lagiopoulos ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Photoelectron Spectroscopy ◽  
Antimicrobial Properties ◽  
Exchange Capacity ◽  
Elevated Concentration ◽  
Chemical Mapping ◽  
Exchange Method ◽  
X Ray ◽  
Copper And Zinc ◽  
Antimicrobial Protection

Six pharmaceutical pastes were prepared using chemically modified kaolin and talc powders. Tests were conducted to determine their structural and chemical characteristics as well as their antimicrobial protection, thus rendering them suitable for cosmetic and pharmaceutical uses. Kaolin and talc were treated chemically via the cation exchange method to load the clay particles with copper and zinc ions, two cations well known for their antimicrobial properties. Mineralogical analyses were conducted by using X-ray diffraction (XRD) before and after the modification, confirming the mineralogical purity of the samples. Scanning electron microscopy was also used in conjunction with energy dispersed spectroscopy (SEM-EDS) to obtain chemical mapping images, revealing the dispersion of the added metals upon the clay minerals surfaces. Moreover, chemical analysis has been performed (XRF) to validate the enrichment of the clays with each metal utilizing the cation exchange capacity. All modified samples showed the expected elevated concentration in copper or zinc in comparison to their unmodified versions. From the X-ray photoelectron spectroscopy (XPS), the chemical state of the samples’ surfaces was investigated, revealing the presence of salt compounds and indicating the oxidation state of adsorbed metals. Finally, the resistance of pastes in microbial growth when challenged with bacteria, molds, and yeasts was assessed. The evaluation is based on the European Pharmacopeia (EP) criteria.

scholarly journals Exchange Characteristics of Lead, Zinc, and Cadmium in Selected Tropical Soils

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Tope O. Bolanle-Ojo ◽  
Abiodun D. Joshua ◽  
Opeyemi A. Agbo-Adediran ◽  
Ademola S. Ogundana ◽  
Kayode A. Aiyeyika ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Tropical Soils ◽  
Exchange Capacity ◽  
Exchange Reactions ◽  
Soil System ◽  
Soil Systems ◽  
Wide Range ◽  
Lead Zinc ◽  
High Base

Conducting binary-exchange experiments is a common way to identify cationic preferences of exchangeable phases in soil. Cation exchange reactions and thermodynamic studies of Pb2+/Ca2+, Cd2+/Ca2+, and Zn2+/Ca2+were carried out on three surface (0–30 cm) soil samples from Adamawa and Niger States in Nigeria using the batch method. The physicochemical properties studies of the soils showed that the soils have neutral pH values, low organic matter contents, low exchangeable bases, and low effective cation exchange capacity (mean: 3.27 cmolc kg−1) but relatively high base saturations (≫50%) with an average of 75.9%. The amount of cations sorbed in all cases did not exceed the soils cation exchange capacity (CEC) values, except for Pb sorption in the entisol-AD2 and alfisol-AD3, where the CEC were exceeded at high Pb loading. Calculated selectivity coefficients were greater than unity across a wide range of exchanger phase composition, indicating a preference for these cations over Ca2+. TheKeqvalues obtained in this work were all positive, indicating that the exchange reactions were favoured and equally feasible. These values indicated that the Ca/soil systems were readily converted to the cation/soil system. The thermodynamic parameters calculated for the exchange of these cations were generally low, but values suggest spontaneous reactions.

scholarly journals Secure MQTT PUF-Based Key Exchange Protocol for Smart Healthcare

2021 ◽  
Vol 17 (2) ◽  
Author(s):  
Rizka Reza Pahlevi ◽  
Parman Sukarno ◽  
Bayu Erfianto
Keyword(s):  
Information Security ◽  
Key Exchange ◽  
Authenticated Key Exchange ◽  
Key Exchange Protocol ◽  
Embedded Devices ◽  
Exchange Method ◽  
Smart Healthcare ◽  
Replay Attacks ◽  
Secure Authentication ◽  
Exchange Properties

Replay and eavesdropping attacks threaten the information security that is held by smart healthcare devices. An authenticated key exchange method to provide cryptography sessions is the best way to provide information security and secure authentication. However, smart healthcare devices do not have sufficient computation to perform heavy cryptography processes due to the limitations of the embedded devices used. We propose an authenticated key exchange protocol based on a physical unclonable function (PUF). The proposed protocol aimed to countermeasure from replay and eavesdropping attacks. We designed our protocol with one handshake process and three authentication processes. We evaluated our proposed protocol using Tamarin Prover. From the results of the evaluation, our proposed protocol can exchange properties correctly between communication actors and is valid in proving each lemma in eavesdropping and replay attacks.

scholarly journals Peran Vegetasi Dominan Pada Karakteristik Tanah di Lahan Bera, Kampung Womnowi, Distrik Sidey, Manokwari

2020 ◽  
Vol 20 (2) ◽  
pp. 227
Author(s):  
Slamet Arif Susanto ◽  
Heru Joko Budirianto ◽  
Agatha Cecilia Maturbongs
Keyword(s):  
Soil Fertility ◽  
Soil Analysis ◽  
Exchange Capacity ◽  
Available Phosphorus ◽  
Fallow Land ◽  
Dracontomelon Dao ◽  
High Base ◽  
Important Value Index ◽  
Lansium Domesticum ◽  
Very High

Abstrak: Selama proses suksesi, vegetasi merupakan satu dari komponen utama untuk meningkatkan kesuburan tanah. Tujuan penelitian ini adalah untuk menganalisis dan mendeskripsikan peran vegetasi dominan pada karakteristik tanah di lahan bera berumur 15 tahun Kampung Womnowi, Distrik Sidey, Manokwari. Vegetasi dominan ditentukan berdasarkan data indeks nilai penting (INP) analisis vegetasi. Sampel tanah diambil secara komposit pada luasan lahan 1 hektar dari dua kedalaman tanah (0–10 cm dan 10–20 cm). Vegetasi yang mendominasi lahan bera secara berurutan adalah Pometia pinnata, Dracontomelon dao, Octomeles sumatrana, Lansium domesticum, dan Pimelodendron amboinicum. Kehadiran O. sumatrana mengindikasikan lahan bera tanah aluvial, lebih lanjut terbukti karena lahan bera tersebut berdekatan dengan Sungai Womnowi. Karakteristik fisik tanah didominasi oleh fraksi lempung dan unsur makro lebih tinggi pada kedalaman 0–10 cm dibanding kedalaman 10–20 cm. Karakteristik tanah menunjukkan bahwa tanah tergolong masam (pH 5.4–5.6), kadar karbon organik tanah sedang (1.07–3.39%), kadar nitrogen total rendah (0.17–0.53%), kadar fosfor tersedia tergolong tinggi (10.7–22.4 ppm), kapasitas tukar kation (KTK) tergolong tinggi (10.50–20.32 cmol kg-1), kejenuhan basa tergolong sangat tinggi (65.4–66.7%), dan kadar Al3+ and H+ sangat rendah. Secara keseluruhan urutan KTK menunjukkan Ca > Mg > Na > K yang mengonfirmasi tanah aluvial dan pencucian kalium terjadi dengan cepat. Rendahnya kadar kalium dapat dihubungkan dengan penggunaan unsur tersebut untuk pembentukan buah L. domesticum. Selama pemberaan 15 tahun, vegetasi dominan memengaruhi karakteristik tanah.Kata kunci: vegetasi pohon, kesuburan tanah, analisis tanah, aluvial, Papua BaratAbstract: During succesional season vegetation is one of major compound to increase soil fertility. The purpose of this study was to analyzed and description dominant vegetation and their contribution to soil characteristic at fallow land 15 years old Womnowi Village, Sidey District, Manokwari. To determine dominant vegetations we used data important value index (IVI) of vegetation. Two depth of sample soils (0–10 cm dan 10–20 cm) were taken from one hectare area by composite technique. The dominant vegetation on fallow land dominated by Pometia pinnata, Dracontomelon dao, Octomeles sumatrana, Lansium domesticum, and Pimelodendron amboinicum respectively. Presence of O. sumatrana was indicated that the type of aluvial fallow land, further it is proven because the fallow land is close to the Womnowi River. Soil physical characteristic dominated by clay fractions, macronutrient was higher in depth 0-10 cm than 10-20 cm. Characteristic of soil shows acidic soils (pH 5.4–5.6), moderate of soil organic carbon (1.07–3.39%), total of nitrogen was low (0.17–0.53%), high available phosphorus (10.7–22.4 ppm), moderate cation exchange capacity (CEC) (10.50–20.32 cmol kg-1), very high base saturation (65.4–66.7%), and very lows of Al3+ and H+. Overall the order of CEC shows Ca > Mg > Na > K respectively confirmed aluvial soil and fast leached potassium in soil. Low potassium levels are thought be related to the use of the element for fruits formation of L. domesticum. During 15 year fallowed, dominant vegetation had influence to soil characteristic.Key words: tree vegetation, soil fertility, soil analysis, alluvial, West Papua

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