Potentiometric Titration of Fulvic Acid: Equivalence Point Calculations and Acidic Functional Groups

1972 ◽  
Vol 50 (16) ◽  
pp. 2680-2690 ◽  
Author(s):  
Donald S. Gamble
Keyword(s):  
Fulvic Acid ◽  
Potentiometric Titration ◽  
Functional Groups ◽  
Acid Dissociation ◽  
Carboxyl Groups ◽  
Chemical Information ◽  
Equivalence Point ◽  
Iterative Calculation ◽  
Detailed Chemical

Gran's functions corrected for buffering and H2O dissociation have been incorporated into the iterative calculation for the two equivalence points and the acid dissociation equilibria. The experimental and mathematical conditions required for accurate, dependable operation of the method have been examined. The resulting equivalence point calculations are based directly on a chemical interpretation of the system, without approximations. The first equivalence point is shigher than previously reported, and is displaced upward by KCl. Detailed chemical information has been obtained for some of the acidic functional groups, from plots of KA = (mHδmA/δmAH) vs. mequiv./g. Carboxyl groups at the chelating sites are essentially all ionized for H+ concentrations less than 1 × 10−5 m.

ATRAZINE HYDROLYSIS IN SOILS: CATALYSIS BY THE ACIDIC FUNCTIONAL GROUPS OF FULVIC ACID

1985 ◽  
Vol 65 (3) ◽  
pp. 435-443 ◽  
Author(s):  
DONALD S. GAMBLE ◽  
SHAHAMAT U. KHAN
Keyword(s):  
Fulvic Acid ◽  
Functional Groups ◽  
Natural Waters ◽  
Acid Catalysis ◽  
Carboxyl Groups ◽  
Acid Solutions ◽  
Predictive Equation ◽  
Hydrogen Ions ◽  
Soil Solutions ◽  
Humic Materials

The catalysis of atrazine hydrolysis at 25.0 °C by the types of acidic functional groups found in humic materials has been investigated. No evidence of catalysis by carboxylate ions was observed. From a knowledge of the types and numbers of acid functional groups in a quantitatively characterized fulvic acid, and the distributions of their KA values it was found that hydrogen ions and undissociated carboxyl groups were the only catalytic agents. The carboxyl groups have a second-order kAH of 7.88 days −1∙M−1. Weakly acidic functional groups having [Formula: see text]showed no catalysis. A predictive equation has been produced for the half-life of atrazine in fulvic acid solutions at 25.0 °C. It represents a general class of equations which should permit the practical prediction of atrazine persistence in soil solutions and other natural waters. Key words: Atrazine hydrolysis, atrazine persistence, fulvic acid, fulvic acid carboxyls, acid catalysis, carboxyl catalysis

scholarly journals Detecting levels of polyquaternium-10 (PQ-10) via potentiometric titration with dextran sulphate and monitoring the equivalence point with a polymeric membrane-based polyion sensor

2016 ◽  
Vol 8 (29) ◽  
pp. 5806-5811 ◽  
Author(s):  
Stephen A. Ferguson ◽  
Xuewei Wang ◽  
Mark E. Meyerhoff
Keyword(s):  
Potentiometric Titration ◽  
Polymeric Membrane ◽  
Dextran Sulphate ◽  
Equivalence Point

This manuscript reports a novel and facile method for PQ-10/SLS separation and subsequent PQ-10 quantification via potentiometric titration.

scholarly journals Self assembled nanocages from DNA–protoporphyrin hybrid molecules

RSC Advances ◽  
2015 ◽  
Vol 5 (108) ◽  
pp. 89025-89029 ◽  
Author(s):  
Vandana Singh ◽  
Mohan Monisha ◽  
Roy Anindya ◽  
Prolay Das
Keyword(s):  
Functional Groups ◽  
Protoporphyrin Ix ◽  
Building Blocks ◽  
Carboxyl Groups ◽  
Dna Oligomers ◽  
Organic Hybrid ◽  
Molecular Building Blocks ◽  
Modified Dna ◽  
Hybrid Molecules ◽  
Self Assembled

DNA–organic hybrid molecular building blocks are generated by covalent conjugation of the carboxyl groups of protoporphyrin IX with the amine functional groups of modified DNA oligomers.

Prediction of physical properties of thermosetting resin by using machine learning and structural formulas of raw materials

MRS Advances ◽  
2020 ◽  
Vol 5 (29-30) ◽  
pp. 1567-1575
Author(s):  
Kokin Nakajin ◽  
Takuya Minami ◽  
Masaaki Kawata ◽  
Toshio Fujita ◽  
Katsumi Murofushi ◽  
...  
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Physical Properties ◽  
Functional Groups ◽  
Raw Materials ◽  
Functional Materials ◽  
Industrial Applications ◽  
Chemical Information ◽  
Thermosetting Resins ◽  
Mixing Ratios

AbstractThermosetting resins are one of the most widely used functional materials in industrial applications. Although some of the physical properties of thermosetting resins are controlled by changing the functional groups of the raw materials or adjusting their mixing ratios, it was conventionally challenging to construct machine learning (ML) models, which include both mixing ratio and chemical information such as functional groups. To overcome this problem, we propose a machine learning approach based on extended circular fingerprint (ECFP) in this study. First, we predicted the classification of raw materials by the random forest, where ECFP was used as the explanatory variable. Then, we aggregated ECFP for each classification predicted by the random forest. After that, we constructed the prediction model by using the aggregated ECFP, feature quantities of reaction intermediates, and curing conditions of resin as explanatory variables. As a result, the model was able to predict in high accuracy (R^2 = 0.8), for example, the elastic modulus of thermosetting resins. Furthermore, we also show the result of verification of prediction accuracy in first step, such as using the one-hot-encording. Therefore, we confirmed that the properties of thermosetting resins could be predicted using mixed raw materials by the proposed method.

scholarly journals The adsorption of phosphate-buffered saline to model films composed of nanofibrillated cellulose and gelatin

2019 ◽  
Vol 17 (1) ◽  
pp. 228080001982651 ◽  
Author(s):  
Sedat Ondaral ◽  
Elif Çelik ◽  
Orçun Çağlar Kurtuluş
Keyword(s):  
Frequency Shift ◽  
Functional Groups ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Nanofibrillated Cellulose ◽  
Adsorption Rate ◽  
Carboxyl Groups ◽  
Trend Model ◽  
Phosphate Buffered Saline

Phosphate-buffered saline (PBS) adsorption on model films composed of gelatin and nanofibrillated celluloses (NFCs) with different aldehyde and carboxyl contents was studied by means of the quartz crystal microbalance with dissipation (QCM-D) technique in this study. The results showed that frequency shift (Δ f) due to PBS adsorption increased with increasing gelatin content to 50% in NFC-containing films. The dissipation shift and adsorption rate of PBS followed the same trend. Model films with NFC-1 having 1.22 mmol/g aldehyde and 0.6 mmol/g carboxyl groups adsorbed more PBS than those consisting of NFC-2 with 0.25 mmol/g aldehyde and 1.15 mmol/g carboxyl groups except for film composed of 50% gelatin. However, adsorption rate of PBS was found to be slower for NFC-1 containing film because the acetal and amidol bonds formed by functional groups in the network of cellulose and gelatin needed more time to let PBS migrate into the films.

Kinetics and Equilibrium of Binding of Fe3+ by a Fulvic Acid: A Study by Stopped Flow Methods

1975 ◽  
Vol 53 (20) ◽  
pp. 2979-2984 ◽  
Author(s):  
Cooper H. Langford ◽  
Tahir R. Khan
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Fulvic Acid ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Acid Dissociation ◽  
Stopped Flow ◽  
Solution Ph ◽  
Sulfosalicylic Acid ◽  
Flow Measurements

The first report of a rate of binding of a metal ion (Fe3+) by a soluble fulvic acid is derived from stopped flow measurements. The rate of complex formation is normal in Wilkins' sense and similar to that for sulfosalicylic acid. Dissociation is slow (t1/2 > 10 s). The binding of Fe3+ by the fulvic acid in acid solution, pH = 1–2.5, was investigated by kinetic analysis in which the reaction of free Fe3+ with sulfosalicylic acid was followed by stopped flow spectrophotometry on a time scale short compared to release of Fe3+ by fulvic acid. Conditional equilibrium constants found were 1.5 ± 0.3 × 104 at pH = 1.5 and 2.5, and 2.8 ± 0.3 × 103 at pH = 1.0 at 25 °C (ionic strength 0.1).

scholarly journals Chemical abundances of field halo stars - Implications for the building blocks of the Milky Way

2019 ◽  
Vol 14 (S351) ◽  
pp. 24-33
Author(s):  
Miho N. Ishigaki
Keyword(s):  
Milky Way ◽  
Building Blocks ◽  
Chemical Information ◽  
Wide Field ◽  
Chemical Abundance ◽  
Chemical Abundances ◽  
Halo Stars ◽  
Dimensional Phase Space ◽  
Stellar Halo ◽  
Detailed Chemical

AbstractI would like to review recent efforts of detailed chemical abundance measurements for field Milky Way halo stars. Thanks to the advent of wide-field spectroscopic surveys up to a several kpc from the Sun, large samples of field halo stars with detailed chemical measurements are continuously expanding. Combination of the chemical information and full six dimensional phase-space information is now recognized as a powerful tool to identify cosmological accretion events that have built a sizable fraction of the present-day stellar halo. Future observational prospects with wide-field spectroscopic surveys and theoretical prospects with supernova nucleosynthetic yields are also discussed.

Sign in / Sign up

Export Citation Format

Share Document