The function of carboxyls in the structure of humic acids to binding of organic substances

2020 ◽  
Author(s):  
Jiri Smilek ◽  
Anna Belusova ◽  
Michal Kalina ◽  
Petr Sedlacek
Keyword(s):  
Humic Substances ◽  
Organic Compounds ◽  
Humic Acids ◽  
Hydrophobic Interactions ◽  
Organic Dyes ◽  
Strong Impact ◽  
Spectroscopic Techniques ◽  
Surface Active Agents ◽  
Physico Chemical ◽  
Surface Active

<p>The humic substances, the major and the most important part of soil organic matter, are responsible for the immobilization of organic compounds (e.g. heavy metal ions, organic dyes, surface active agents, etc.) in the soil. Unfortunately, there are a lot of gaps in the knowledge in the complex mechanism of binding of organic charged compounds by humic substances.</p><p>The unconventional diffusion and dialysis (transport) techniques have been developed for the purpose of study on the interactions between humic substances and organic charged substances.  In our contribution we are focusing on one fraction of humic substances – humic acids. The binding between humic acids with/without selectively blocking of carboxylic functional groups (methylation by –CH3) with organic charged compounds (e.g. organic dyes, surface active agents) has been studied by diffusion and dialysis approach using the spectroscopic techniques as analytical method. The strong impact of methylation on the positive affinity of humic acids towards organic compounds has been expected. These expectations were not confirmed by diffusion and dialysis techniques. The role of carboxyls in the structure of humic acids is not so essential as was expected and mentioned in the literature. The other effects (e.g. hydrophobic interactions, pi-pi stacking, etc.) are more important in the binding of organic compounds as was expected. The positive binding as well as kinetics of this process is also strongly depending on the physico-chemical circumstances of the system (e.g. pH, ionic strength, temperature, etc.).</p>

Properties and applications of palygorskite-sepiolite clays

Clay Minerals ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 443-453 ◽  
Author(s):  
E. Galan
Keyword(s):  
Clay Minerals ◽  
Crystal Morphology ◽  
Industrial Applications ◽  
Chemical Parameters ◽  
Principal Characteristics ◽  
Surface Active Agents ◽  
Physico Chemical ◽  
Wide Range ◽  
Surface Active ◽  
Fabric Surface

AbstractThe palygorskite-sepiolite group of clay minerals has a wide range of industrial applications derived mainly from its sorptive, rheological and catalytic properties which are based on the fabric, surface area, porosity, crystal morphology, structure and composition of these minerals. For assessing potential industrial uses, the mineralogical and chemical composition of the clay and its basic physical and physico-chemical parameters must be determined. Then some particular properties of commercial interest can be modified and improved by appropriate thermal, mechanical and acid treatments, surface active agents, organo-mineral derivatives formation, etc. In this paper, a revision of the principal characteristics of commercial palygorskite-sepiolite clays is presented, and potential uses are suggested according to these data. New products and applications are being investigated and those concerning environmental protection in particular, are noted. Finally, possible health effects of these elongate clay minerals are discussed.

scholarly journals Density and surface tension of aqueous solutions of adjuvants used for tank-mixes with pesticides

2012 ◽  
Vol 58 (No. 12) ◽  
pp. 568-572 ◽  
Author(s):  
J. Janků ◽  
L. Bartovská ◽  
J. Soukup ◽  
M. Jursík ◽  
K. Hamouzová
Keyword(s):  
Surface Tension ◽  
Aqueous Solutions ◽  
Chemical Properties ◽  
Calculated Density ◽  
Surface Active Agents ◽  
Physico Chemical ◽  
Pesticide Formulations ◽  
Density Values ◽  
Surface Active

Adjuvants are surface active agents that are added to pesticide formulations or tank-mix to facilitate the mixing, application, or efficacy of these products. Addition of adjuvants changes the physico-chemical properties of spray liquid. In this work, we have focused in particular on surface tension and density of aqueous solutions of different adjuvants registered for mixing with herbicides. Eleven different adjuvants were subject of this study under laboratory conditions. An equation which enables determination of density of aqueous solutions in concentration range of 0–15 g/kg was designed. Average difference between the experimental and calculated density values amounts to ± 0.006%. The concentration dependence of surface tension was utilized to determine the critical micelle concentration (cmc). Evidently, the cmc of most tested adjuvants was lower than the amount recommended by manufacturer, especially in case of adjuvants Dedal 90 EC and Mero 33528. For adjuvant Trend 90 EC the recommended rate is even lower than that obtained for the cmc. Maximum reduction of the surface tension of water was achieved with adjuvants Silwet L-77 and Break Superb.    

scholarly journals OBTAINING DERIVATIVES OF HUMIC SUBSTANCES FROM OXIDIZED COAL AND STUDY OF PHYSICO-CHEMICAL AND ADSORPTION PROPERTIES

2020 ◽  
Vol 6 (444) ◽  
pp. 57-64
Author(s):  
B.T. Yermagambet ◽  
◽  
M.K. Kazankapova ◽  
Zh.M. Kassenova ◽  
A.T. Nauryzbayeva ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Humic Substances ◽  
Humic Acids ◽  
Aqueous Media ◽  
Amino Groups ◽  
Chelate Complexes ◽  
High Adsorption ◽  
Oxidized Coal ◽  
Physico Chemical ◽  
Derivatives Of

In the work, a chemical analysis of humic substances based on oxidized coal of the Maikuben basin (Kazakhstan) is carried out. Humic acids were obtained on the basis of potassium humates by acidification with a 20% acid solution to pH = 3-4.5. The optimal conditions for obtaining nitrohumic acids from oxidized coals are: the duration of the process is 3 hours, the ratio of S:L = 1:5, the content of nitric acid is 64%, sulfuric acid is 96% and the composition of the nitrating mixture is 1:1 (g/g). Amminohumic derivatives were obtained in the presence of a 3% aqueous solution of ammonia using mechanical activation and ultrasonic treatment. The samples obtained were tested as an adsorbent for water purification from heavy metals. Humic acids and aminohumate showed the highest degrees of purification for zinc (99.0-100.0%) and cadmium (80.0-96.7%), and nitrohumic acid showed a high adsorption capacity for heavy metals like copper - 100.0 % and lead 82.9%. This is due to the fact that when interacting with heavy metals, humic acids and their derivatives (amino and nitro) form chelate complexes due to carboxyl, phenolic, nitro and amino groups. As a result of the study, the possibility of using them as non-toxic available sorbents for the purification of heavy metals in aqueous media has been shown.

scholarly journals FTIR AND NMR STUDIES OF ADSORBED CETHYLTRIMETHYLAMMONIUM CHLORIDE IN MCM-41 MATERIALS

2010 ◽  
Vol 8 (1) ◽  
pp. 1-6
Author(s):  
Paulina Taba ◽  
Russell F. Howe ◽  
Graine Moran
Keyword(s):  
Cationic Surfactants ◽  
Hydrophobic Interactions ◽  
Head Group ◽  
Methyl Groups ◽  
Nmr Studies ◽  
Surface Active Agents ◽  
Modified Surface ◽  
Surface Active ◽  
Nmr Methods ◽  
Mcm 41

The high use of surface-active agents (surfactants) by industry and households today leads to environmental pollution, therefore treatments are required to remove such substances from the environment. One of the important and widely used methods for removal of substances from solution is adsorption. In this research, MCM-41 and its modified product of MCM41-TMCS were used to adsorb cationic surfactants, cethyltrimethylammonium chloride, CTAC. FTIR and NMR methods were used to study the interaction between the surfactants and the adsorbents. MCM-41 was synthesized hydrothermally at 100 oC and its modification was conducted by silylation of MCM-41 with trimethylchloro silane (MCM41-TMCS). Both unmodified and modified MCM-41 can adsorb the surfactant. The interaction of CTAC with MCM-41 was mostly the electrostatic interaction between the electropositive end of the surfactant and MCM-41, whereas in modified MCM-41 hydrophobic interactions become more dominant. These hydrophobic interactions appear however to involve the methyl groups on the head group of the surfactant interacting with the modified surface.   Keywords: FTIR, NMR, adsorbed CTAC, MCM-41 materials

Actinide Sorption onto Silica in the Presence of Humic Substances: Proposal of Retentionmechanisms

1991 ◽  
Vol 257 ◽  
Author(s):  
N. Labonne ◽  
V. Moulin ◽  
D. Stammose
Keyword(s):  
Ionic Strength ◽  
Humic Substances ◽  
Humic Acids ◽  
Surface Complexation ◽  
Complexing Agents ◽  
Complexation Constants ◽  
Surface Complexation Model ◽  
Physico Chemical ◽  
Ph Range ◽  
Geological Formations

ABSTRACTThe experimental investigation and modelling of radionuclides sorption processes is an essential part of safety analyses of an underground repository of radioactive wastes in geological formations. Physico—chemical phenomena at oxide/solution interfaces have been studied in the case of the system constituted by amorphous silica and americium (III) in the presence of humic substances as organic complexing agents. The retention behaviour of Am(III) onto silica appears dependent on pH, ionic strength and in particular humic concentration. At a ionic strength of 0.1 M, the presence of low concentration of humic acids (1 mg/l) enhances the Am(III) retention in the pH range 3-5.5, whereas at higher pH, its uptake is largely decreased. At lower ionic strength (0.001 M), Am(III) retention on silica is highly lowered, in the pH range 3-7 in the presence of humic acids. Reversibility experiments show the desorption of americium in the absence of humic substances, and also the desorption of the humics on the silica with respect of the pH. The surface complexation model has been applied to our results in the different systems and apparent surface complexation constants have been determined.

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