scholarly journals Adsorption of Metallic Ions on Amidoxime-Chitosan/Cellulose Hydrogels

Separations ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 202
Author(s):  
Takaaki Tatsumi ◽  
Yoshiro Tahara ◽  
Michiaki Matsumoto
Keyword(s):  
Metal Ions ◽  
Metal Chelate ◽  
Aqueous Media ◽  
Physical Stability ◽  
Reaction Model ◽  
Proton Exchange ◽  
Environmentally Benign ◽  
Metallic Ions ◽  
Rate Determining Step ◽  
Natural Polysaccharide

Adsorption using natural compounds is an attractive separation technique for recovering heavy metals from aqueous media. Although chitosan, which is a natural polysaccharide, is an environmentally benign adsorbent, it dissolves in an acidic aqueous medium. In this study, we prepared adsorbents consisting of chitosan modified with amidoxime groups for improving metal adsorptivity, and cellulose for improving gel stability using an ionic liquid, and examined their adsorption characteristics for metal ions. The prepared amidoxime-chitosan/cellulose hydrogels had a mechanical strength without cross-linking. All the investigated metals were adsorbed on the amidoxime-chitosan/cellulose hydrogels in the following adsorptivity order: Cu ≈ Ag > Ni > Zn. The adsorptivity of the metal ions increased with pH due to a proton exchange reaction. From the Langmuir adsorption isotherm, the Langmuir constant for Cu exceeded those of other metals because amidoxime has higher Cu affinity. The pseudo-second-order reaction model best described the adsorption kinetics with metal chelate formation being the rate-determining step. Because amidoxime-chitosan/cellulose hydrogels had higher physical stability and higher Cu selectivity, they were found to be a promising, environmentally benign adsorbent.

PREDICTIVE SIMULATION AND OPTIMIZATION ORIENTED MODELING FOR THE EXTRACTION OF METAL IONS FROM SOLUTIONS INTO A NOVEL BIS-SCHIFF BASE

2019 ◽  
pp. 1-8
Author(s):  
F. S. Nworie ◽  
S. O. Ngele ◽  
J. C. Onah
Keyword(s):  
Metal Ions ◽  
Metal Concentration ◽  
Acid Concentration ◽  
Aqueous Media ◽  
Industrial Effluents ◽  
Ligand Concentration ◽  
Simulation And Optimization ◽  
Chemometric Technique ◽  
Model Equations ◽  
Level Of Significance

Metal ions present in waste samples, industrial effluents, acid mines and other aqueous media constitute a serious challenge in different human activities. Solvent extraction a technique for preconcentration, separation and identification of trace amount of metal ions coupled with multivariate chemometric technique was used for the determination of Fe(II) and Cr(III) from solutions in the presence of bis(salicylidene)ethylenediamine (SALEN). The influence of main extraction variables affecting the extraction efficiency was simultaneously studied and regression model equations illustrating the relationship between variables predicted. The extraction parameters (time of extraction, acid concentration, ligand concentration, temperature and metal concentration) were optimized using experimental designs with the contributions of the various parameters to extraction of the metal ions bound to the complexone evaluated using SPSS19.0 software. The statistically determined simulated models for the parameters were R2 = 0.946, 0.727, 0.793, 0.53, 0.53, 1.000 and F- values of 70.400, 13. 285, 15.348, 4.646 and 2.569×105 respectively for time of extraction, acid concentration, ligand concentration, temperature and metal concentration for Cr (III). For Fe (II), R2 = 0.243, 0.371, 0.519, 0.446, 1.000 and F-values of 0.964, 2.953, 4.310, 3.216 and 2.516×105 for time of extraction, acid concentration, ligand concentration, temperature and metal concentration respectively. The level of significance of the models as predicted was both lower than 5% making it feasible, efficient, reproducible and accurate. This means that metal ions at the conditions stated could be removed from waste samples, industrial effluents, acid mines and other aqueous media with extension in industrial scale application.

Gas Cell Infrared and Attenuated Total Reflection Infrared Spectroscopic Studies for Organic–Inorganic Interactions in Adsorption of Fulvic Acid on the Goethite Surface Generating Carbon Dioxide

2021 ◽  
pp. 000370282199121
Author(s):  
Yuki Nakaya ◽  
Satoru Nakashima ◽  
Takahiro Otsuka
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Fulvic Acid ◽  
Spectroscopic Studies ◽  
Reaction Model ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Gas Cell ◽  
Rate Determining Step ◽  
Ir Spectroscopic

The generation of carbon dioxide (CO2) from Nordic fulvic acid (FA) solution in the presence of goethite (α-FeOOH) was observed in FA–goethite interaction experiments at 25–80 ℃. CO2 generation processes observed by gas cell infrared (IR) spectroscopy indicated two steps: the zeroth order slower CO2 generation from FA solution commonly occurring in the heating experiments of the FA in the presence and absence of goethite (activation energy: 16–19 kJ mol–1), and the first order faster CO2 generation from FA solution with goethite (activation energy: 14 kJ mol–1). This CO2 generation from FA is possibly related to redox reactions between FA and goethite. In situ attenuated total reflection infrared (ATR-IR) spectroscopic measurements indicated rapid increases with time in IR bands due to COOH and COO– of FA on the goethite surface. These are considered to be due to adsorption of FA on the goethite surface possibly driven by electrostatic attraction between the positively charged goethite surface and negatively charged deprotonated carboxylates (COO–) in FA. Changes in concentration of the FA adsorbed on the goethite surface were well reproduced by the second order reaction model giving an activation energy around 13 kJ mol–1. This process was faster than the CO2 generation and was not its rate-determining step. The CO2 generation from FA solution with goethite is faster than the experimental thermal decoloration of stable structures of Nordic FA in our previous report possibly due to partial degradations of redox-sensitive labile structures in FA.

scholarly journals Non-Enzymatic Desymmetrization Reactions in Aqueous Media

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 720
Author(s):  
Satomi Niwayama
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Functional Groups ◽  
Organic Compounds ◽  
Recent Progress ◽  
Aqueous Media ◽  
Building Blocks ◽  
Organic Reactions ◽  
Environmentally Benign ◽  
Enzymatic Desymmetrization

Symmetric organic compounds are generally obtained inexpensively, and therefore they can be attractive building blocks for the total synthesis of various pharmaceuticals and natural products. The drawback is that discriminating the identical functional groups in the symmetric compounds is difficult. Water is the most environmentally benign and inexpensive solvent. However, successful organic reactions in water are rather limited due to the hydrophobicity of organic compounds in general. Therefore, desymmetrization reactions in aqueous media are expected to offer versatile strategies for the synthesis of a variety of significant organic compounds. This review focuses on the recent progress of desymmetrization reactions of symmetric organic compounds in aqueous media without utilizing enzymes.

Assembly Modulation of PDI Derivative as a Supramolecular Fluorescence Switching Probe for Detection of Cationic Surfactant and Metal Ions in Aqueous Media

2014 ◽  
Vol 6 (23) ◽  
pp. 21369-21379 ◽  
Author(s):  
Atul K. Dwivedi ◽  
M. Pandeeswar ◽  
T. Govindaraju
Keyword(s):  
Metal Ions ◽  
Cationic Surfactant ◽  
Aqueous Media ◽  
Fluorescence Switching

scholarly journals Phosphate-Catalyzed Succinimide Formation from an NGR-Containing Cyclic Peptide: A Novel Mechanism for Deammoniation of the Tetrahedral Intermediate

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2217 ◽  
Author(s):  
Ryota Kirikoshi ◽  
Noriyoshi Manabe ◽  
Ohgi Takahashi
Keyword(s):  
Conformational Changes ◽  
Density Functional ◽  
Cyclic Peptide ◽  
Density Functional Theory Method ◽  
Proton Exchange ◽  
Computational Method ◽  
Side Chain ◽  
Tetrahedral Intermediate ◽  
Rate Determining Step ◽  
Proton Source

Spontaneous deamidation in the Asn-Gly-Arg (NGR) motif that yields an isoAsp-Gly-Arg (isoDGR) sequence has recently attracted considerable attention because of the possibility of application to dual tumor targeting. It is well known that Asn deamidation reactions in peptide chains occur via the five-membered ring succinimide intermediate. Recently, we computationally showed by the B3LYP density functional theory method, that inorganic phosphate and the Arg side chain can catalyze the NGR deamidation using a cyclic peptide, c[CH2CO–NGRC]–NH2. In this previous study, the tetrahedral intermediate of the succinimide formation was assumed to be readily protonated at the nitrogen originating from the Asn side chain by the solvent water before the release of an NH3 molecule. In the present study, we found a new mechanism for the decomposition of the tetrahedral intermediate that does not require the protonation by an external proton source. The computational method is the same as in the previous study. In the new mechanism, the release of an NH3 molecule occurs after a proton exchange between the peptide and the phosphate and conformational changes. The rate-determining step of the overall reaction course is the previously reported first step, i.e., the cyclization to form the tetrahedral intermediate.

A single colorimetric sensor for multiple target ions: the simultaneous detection of Fe2+ and Cu2+ in aqueous media

RSC Advances ◽  
2014 ◽  
Vol 4 (43) ◽  
pp. 22463-22469 ◽  
Author(s):  
Hyun Kim ◽  
Yu Jeong Na ◽  
Eun Joo Song ◽  
Kyung Beom Kim ◽  
Jeong Mi Bae ◽  
...  
Keyword(s):  
Metal Ions ◽  
Aqueous Media ◽  
Simultaneous Detection ◽  
Colorimetric Sensor ◽  
Multiple Target ◽  
Novel Approach

The receptor 1 provides a novel approach for the simultaneous colorimetric recognition of two metal ions Fe2+ and Cu2+.

scholarly journals Interactions of atrazine with transition metal ions in aqueous media: experimental and computational approach

3 Biotech ◽  
2015 ◽  
Vol 5 (5) ◽  
pp. 791-798 ◽  
Author(s):  
Vijay Kumar ◽  
Virender Kumar ◽  
Niraj Upadhyay ◽  
Sitansh Sharma
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Aqueous Media ◽  
Transition Metal Ions ◽  
Computational Approach

Measurement of Binding Constants of Poly(ethylenimine) with Metal Ions and Metal Chelates in Aqueous Media by Ultrafiltration

1996 ◽  
Vol 35 (6) ◽  
pp. 1935-1943 ◽  
Author(s):  
Ruey-Shin Juang ◽  
Ming-Nan Chen
Keyword(s):  
Metal Ions ◽  
Aqueous Media ◽  
Binding Constants ◽  
Metal Chelates

Binuclear metal chelate complexes of anthraquinones having a MO4 chromophore. Part 1. Quinizarin

1987 ◽  
Vol 65 (7) ◽  
pp. 1485-1490 ◽  
Author(s):  
M. N. Bakola-Christianopoulou ◽  
P. D. Akrivos ◽  
M. Baumgarten
Keyword(s):  
Metal Ions ◽  
Magnetic Measurements ◽  
Metal Chelate ◽  
Transition Elements ◽  
Chelate Complexes ◽  
Cobalt Nickel ◽  
Oxygen Donor ◽  
Nickel Copper ◽  
Square Planar ◽  
Coordination Spheres

Homobinuclear metal chelate complexes having 1,4-dihydroxy-9,10-anthracenedione (quinizarin) as a bridging unit have been prepared with four bivalent first row transition elements, namely cobalt, nickel, copper, and zinc. The coordination spheres of the metal ions consist of two nearly equivalent six-membered rings with oxygen donor atoms derived from the quinizarin and the terminal ligands which are either β-diketones or salicylic aldehyde. TG, spectroscopic (ir, uv–vis, epr), and magnetic measurements have been applied to an investigation of the geometry adopted by the MO4 chromophores. The results are consistent with varying degrees of distortion from the ideal square planar toward a tetrahedral arrangement around the metal ions, closely related to the specific metal center involved.

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