COONa Groups Research Articles

Mechanically robust, transparent, and UV-shielding composite of Na-Alginate and maleic acid-functionalized boron nitride nanosheets with improved antioxidant property

Maleic acid functionalized boron nitride nanosheets (BNNS-MA)/Na-Alginate composite with enhanced mechanical, UV-shielding and antioxidation properties have been fabricated for the first time by solvent evaporation from a homogeneous aqueous dispersion of BNNS-MA/Na-Alginate composite solution. The composite fabrication was driven by homogenous nano-integrations and chemistry of compatibilization of BNNS-MA with Na-Alginate through H-bonding interactions between -COOH functional group of BNNS-MA and -OH, -COONa groups of Na-Alginate. The BNNS-MA/Na-Alginate composites show significant enhancement of mechanical, UV-blocking and antioxidant properties compared to the Na-Alginate. Integrating only 1 wt% BNNS-MA improved the UV-blocking, tensile strength, and antioxidant properties of Na-Alginate film by 99.1%, 73% and 60.3%, respectively. Overall, our findings of BNNS-MA integrated Na-Alginate composite films with improved physical, mechanical, UV shielding, and antioxidant functionalities is very promising to open new insight in the field of transparent UV-protected biopolymer film for consumer products, packaging, cosmetics, and engineering applications.

Soaking pretreatment of hydrogel adsorbent in distilled water to enhance efficiency of adsorption onto low concentration dye

AbstractTo address the poor removal rate of low‐concentration dye adsorption, the soaking pretreatment of hydrogel adsorbent in distilled water was suggested. In contrast to the conventional method of directly adding dried particles into dye solution, the purposed procedure involved adding an adsorbent into distilled water before transferring it into the dye solution. A hydrogel adsorbent based on P(AANa/AM) containing COONa groups was fabricated as an example for the hypothesis. The maximum adsorption capacity of P(AANa/AM) hydrogel adsorbent onto MB was 2455.45 mg/g under an initial MB concentration of 1000 mg/L. After two rounds of soaking pretreatment in distilled water, the clearance rate of 20 mg/L MB increased from 97.79% to 99.40%. Considering the hydrophilicity and ionization of COONa group, a high concentration of Na+ was released into solution. Hydrogel soaked multiple times in fresh distilled water induced the continuous release of Na+ into distilled water, although the swelling equilibrium was already achieved in the first soak. In dye adsorption and desorption experiments, the water absorption behavior was observed. Overall, this work revealed that the soaking pretreatment of hydrogel adsorbent in distilled water can enhance the removal rate of low concentration dye through adsorption.

Contribution Evaluation of Physical Hole Structure, Hydrogen Bond, and Electrostatic Attraction on Dye Adsorption through Individual Experiments

Disagreements over various unanswered questions about contribution of the adsorption process and functional groups on dye adsorption still exist. The main aim of this research was to evaluate the contributions of physical hole structure, hydrogen bond, and electrostatic attraction on dye adsorption. Three ideal representatives, namely, a sponge with porous structure, P(AM) containing -CONH2 groups, and P(AANa/AM) containing -COONa groups, were chosen to evaluate the above contributions. The methylene blue (MB) removal rates of these three products were compared through individual experiments. The results revealed that physical hole structure did not play a role in decreasing dye concentration. Hydrogen bond existed in dye adsorption but did not remarkably reduce dye concentration. The excellent removal results of P(AANa/AM) demonstrated that electrostatic attraction was critical in enriching dye contaminants from the solution into solid adsorbent. The results could provide insights into the dye adsorption mechanisms for further research.

Plasma-Made Graphene Nanostructures with Molecularly Dispersed F and Na Sites for Solar Desalination of Oil-Contaminated Seawater with Complete In-Water and In-Air Oil Rejection.

Solar desalination that exploits interfacial evaporation represents a promising solution to global water scarcity. Real-world feedstocks (e.g., natural seawater and contaminated water) include oil contamination issues, raising a compelling need for desalination systems that offer anti-oil-fouling capability; however, it is still challenging to prepare oil-repellent and meanwhile water-attracting surfaces. This work demonstrates a concept of molecularly dispersing functional F and Na sites on plasma-made vertically oriented graphene nanosheets to achieve an in-air and in-water oleophobic, hydrophilic surface. The graphene architecture presents high in-air (138°) and in-water (145°) oil contact angles, with simultaneously high water affinity (0°). Such surface wettability is enabled by oleophobic, hydrophobic -CFx, and hydrophilic -COONa groups of the molecules that disperse on graphene surfaces; low-dispersion (0.439 mJ m-2) and high-polarity (95.199 mJ m-2) components of the solid surface tension; and increased surface roughness produced by graphene edges. The graphene nanostructures pump water upward by capillary action but repel oil from the surface, leading to complete in-water and in-air oil rejection and universal anti-oil-fouling capability for solar desalination. Consequently, stable solar-vapor energy efficiency of more than 85% is achieved regardless of whether the feedstock is pure or oil-contaminated water (e.g., a mixture of oil floating on water, an oil-in-water emulsion), resulting in the efficient production of clean water over several days. This outstanding performance is attributed to the universal (both in-water and in-air) oleophobic wettability, together with high light absorptance contributed by nanotraps, fast interfacial heat transfer enhanced by finlike nanostructures, and accelerated evaporation enabled by sharp graphene edges.

Synthesis, properties, and antianemic activity of new metal complexes of sodium pectinate with iron and calcium

A new water-soluble complex based on sodium pectinate with iron and calcium (P-NaFeCa) was synthesized. The regularities of the complexation of sodium pectinate (with a 35% content of COONa groups) with biogenic metals Ca and Fe were studied. The content of macro- and microelements was determined by atomic emission spectrometry; the product was identified by IR spectroscopy. Using atomic force microscopy, it was found that the average particle size of P-NaFeCa is ~170 nm. The efficiency of P-NaFeCa (per os) was studied for the first time in animals with hemolytic anemia modeled by administration of phenylhydrazine. It was experimentally shown that in vivo P-NaCaFe at a dose of 60 mg kg–1 containing 50% of the recommended therapeutic dose of iron helps to recover the number of erythrocytes and mean concentration hemoglobin in erythrocyte, which indicates the efficiency of P-NaCaFe as an agent restoring the blood parameters after exposure to hemolytic poisons.

Pore size dependent cation adsorption in a nanoporous polymer film derived from a plastic columnar phase.

Self-supporting polymer thin films were obtained by the polymerization of an AB3-type hydrogen-bonded complex in the plastic columnar phase. Porous polymers with pore diameters of ≈1.1 and ≈1.6 nm lined with either -COOH or -COONa groups were fabricated from the polymer thin films. Both the pore size and pore collapse influence the adsorption of cations.

Toward a deeper understanding of the thermal degradation mechanism of nanocellulose

Understanding the thermal degradation process of cellulose-nanofibers (CNF) is necessary for developing high-value added CNF-based materials with e.g. fire retardant properties or high thermal stability. This study compares the thermal degradation behavior of softwood pulp before and after TEMPO-mediated oxidation, and that of the respective CNF and TEMPO-oxidized CNF with either sodium carboxylate (T–CNF COONa) or carboxylic acid surface groups (T–CNF COOH). The cellulose materials were charred under slow pyrolysis (i.e. at 4 °C min−1) from 50 °C to 600 °C using a thermogravimetric analyzer (TGA). The TGA was coupled to a mass spectrometer (MS) to analyze the volatile products evaporated during the heating process. The chemical structure and composition of the resulting chars after heating at different temperatures were assessed by infrared spectroscopy and X–ray diffraction. Fibrillation of the unmodified pulp resulted in a decrease in thermal stability of the obtained CNF, whereas TEMPO-oxidized pulp and T–CNF showed similar thermal behavior. Compared with the starting cellulose pulp, TEMPO-oxidized materials showed a reduced thermal stability. The presence of either sodium carboxylate or carboxylic acid groups influenced in particular the process of thermal degradation of the CNF. While COOH groups enhanced by 14% the thermal stability of CNF, COONa groups promoted the char formation by 27%. Tuning the counterion of T–CNF proved to be a straightforward approach for tailoring the thermal degradation behavior of the materials. The combinations of TG–MS, IR, and XRD finally resulted in the proposal of a degradation pathway for each investigated material.

Tailoring Pore Size and Chemical Interior of near 1 nm Sized Pores in a Nanoporous Polymer Based on a Discotic Liquid Crystal.

A triazine based disc shaped molecule with two hydrolyzable units, imine and ester groups, was polymerized via acyclic diene metathesis in the columnar hexagonal (Colhex) LC phase. Fabrication of a cationic nanoporous polymer (pore diameter ∼1.3 nm) lined with ammonium groups at the pore surface was achieved by hydrolysis of the imine linkage. Size selective aldehyde uptake by the cationic porous polymer was demonstrated. The anilinium groups in the pores were converted to azide as well as phenyl groups by further chemical treatment, leading to porous polymers with neutral functional groups in the pores. The pores were enlarged by further hydrolysis of the ester groups to create ∼2.6 nm pores lined with −COONa surface groups. The same pores could be obtained in a single step without first hydrolyzing the imine linkage. XRD studies demonstrated that the Colhex order of the monomer was preserved after polymerization as well as in both the nanoporous polymers. The porous anionic polymer lined with −COOH groups was further converted to the −COOLi, −COONa, −COOK, −COOCs, and −COONH4 salts. The porous polymer lined with −COONa groups selectively adsorbs a cationic dye, methylene blue, over an anionic dye.

A Dendrimer-Based Forward Osmosis Draw Solute for Seawater Desalination

A dendrimer-based forward osmosis (FO) draw solute, poly(amidoamine) terminated with sodium carboxylate groups (PAMAM-COONa), was investigated for seawater desalination. Compared with existing FO draw solutes, PAMAM-COONa offers unique advantages: (1) Its aqueous solution can generate high osmotic pressure because of the large number of −COONa groups. (2) The low viscosity of PAMAM-COONa solution can reduce internal concentration polarization (ICP), which adversely affects FO water flux. (3) PAMAM-COONa has a relatively large molecular size, favoring reduced reverse solute flux. In our FO tests using 2.5-generation (2.5G) PAMAM-COONa draw solution (33.3 wt %) and seawater (Singapore coast) feed solution, a relatively high water flux of 9 L m–2 h–1 was achieved with commercial HTI FO membrane. In addition, a considerably reduced reverse solute flux of PAMAM-COONa compared to that of NaCl was attained. After FO testing, the diluted PAMAM-COONa solution was reconcentrated to its original osmotic pressure wit...

Synthesis and characterization of a novel fibrous antibacterial fiber with organophorsphor functional groups

ABSTRACTA novel antibacterial fiber named ethyltriphenylphosphonium bromide‐polyacrylonitrile fiber (ETPB‐PANF) was synthesized by chemical modification of PANF reacted with ETPB. The PANF was first immersed in NaOH solution to get Na‐PANF with COONa groups. Na‐PANF was then reacted with ETPB to get the final fiber. During the process of synthesis, this article investigated on the initial concentration of ETPB, the contact time, the reaction temperature, and the pH of the solution that may have effect on the properties of ETPB‐PANF. ETPB‐PANF was characterized by Fourier transform infrared spectroscopy, thermo gravimetric analyzer, scanning electron microscope, and X‐ray photoelectron spectroscopy, and the releasing amount of ETPB from ETPB‐PANF was examined by inductively coupled plasma atomic emission spectrometry. The antibacterial activity of ETPB‐PANF was examined against Escherichia coli and Staphylococci aureus by improved shake flask method in sterile saline. The results showed that organophorsphor functional groups have been successfully grafted on PANF, and ETPB‐PANF showed good antibacterial abilities for E. coli and S. aureus. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40935.

Property variation of ionic liquid [Bmim][AuCl4] immobilized on carboxylated polystyrene submicrospheres with a small surface area

In order to understand the effect of surface chemical groups on the immobilized species, Au-containing imidazolium-based ionic liquid (IL) [Bmim][AuCl4] was intentionally immobilized on polystyrene (PS) submicrospheres (d ∼300 nm) with a very small surface area (4–10 m2/g), which possess carboxyl-moiety (COONa or COOH) on the surface. The behavior of immobilized [Bmim][AuCl4] on the two types of submicrospheres was investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and powder X-ray diffraction (XRD). It was revealed that the melting points (T m) of [Bmim][AuCl4] that had been immobilized on PS-COONa and PS-COOH submicrospheres were decreased by 2.7 and 4.1°C, respectively. The interaction mechanism between the IL and submicrosphere surface moieties was further analyzed by X-ray absorption fine structure (XAFS) analysis. The data indicated that the coordination environment of Au species changed markedly when [Bmim] [AuCl4] was immobilized on the surfaces of PS-COONa and PS-COOH submicrospheres, as illustrated by the decrease in white line peak intensity. The effect of surface COOH groups on T m depression and the white line peak intensity of the XANES spectrum is more pronounced than that of COONa groups, most likely due to the possible hydrogen bond formation between the COOH group and [Bmim]+.

Study on Synthesis and Surface Activities of Silk Peptide-Based Surfactants

Silk peptide-based surfactants were synthesized from fatty acyl chloride and silk peptide using Schotten-Baumana method. The structure of the product was characterized by IR and amino acid analysis, and the surface activity of the product was tested. The IR spectra showed the characteristic bands corresponding to the stretching vibration of C=O, N-H, C-N and -COONa groups. The amino acid analysis indicated that there were many kinds of amino acid in the products, and the most ones were glycine and alanine, which made up nearly 95% of the total content of amino acid. The surface activity experiment results showed these surfactants had excellent surface activity. In the homologous compounds of surfactants, the critical micelle concentration (cmc) reduced and the trend of micelles formation increased with the hydrocarbon chain length increasing.

Factors affecting the adsorption of cationic dyes on polymeric hydrogels prepared by gamma irradiation

AbstractThe adsorption of the cationic dyes Rhodamine B (RB) and Crystal Violet (CV) on polyacrylamide/poly(acrylic acid) (poly(AAm/AAc), 25:25 % weightwise) and polyacrylamide/poly(sodium acrylate) (poly(AAm/AAcNa), 25:25 % weightwise) hydrogels was studied, employing the Langmuir and Freundlich isotherms. The results of swelling tests at pH 5.5 indicate that poly(AAm/AAcNa) hydrogel shows maximum percentage swelling (%S) was 4400 %. Moreover, the results show that the adsorption capacity is pH‐ and concentration‐dependent. At pH >5 adsorption of RB and CV increases due to ionization of COOH and COONa groups of (poly(AAm/AAc) and (poly(AAm/AAcNa) and interactions with the cationic groups of the dyes. However, at pH lower than 5, adsorption is still high, which can be explained by considering the formation of hydrogen bonds between the amino groups of the dyes and the COOH groups of the polymeric hydrogels. Moreover, the kinetics of adsorption follows a first‐order equation. Furthermore, scanning electron microscopy (SEM) micrographs of polymeric hydrogels doped with CV and RB have morphological differences from the pure form. Our data show that Rhodamine B adsorbs more efficiently on both polyacrylamide/poly(acrylic acid) and polyacrylamide/poly(sodium acrylate) hydrogels than CV. Copyright © 2004 Society of Chemical Industry

New route to the preparation of carboxymethylchitosan hydrogels

A new method to prepare CM–chitosan hydrogels was introduced with the use of steam. The procedure was simple and economical, with no toxic chemicals involved. The steam-induced crosslinking of CM–chitosan sodium salt involved the –NH2 and –COONa groups, forming amide linkages (–CONH–), evidently supported by FTIR spectroscopy and other techniques. The hydrogels instantly imbibed a great deal of water. The degree of swelling (DS) of the hydrogels was found to be up to 36, depending on the harshness of steaming conditions used. Likewise, the coloration of the samples increased from light beige to brown with increasing temperature and duration of steam exposure. The overall efficiency of the steam method for the crosslinking of CM–chitosan sodium salt was quite high. The percentage weight loss was found to be less than 10 to obtain hydrogels with DS values around 20. No weight loss in the dry weight of the fractionated hydrogels was observed when the samples were steamed at 115°C or higher for 15 min or longer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4016–4020, 2003

Chemical Modification of the Diamond Surface Using Benzoyl Peroxide and Dicarboxylic Acids

We report a new method for introducing carboxylic groups onto the diamond surface. Hydrogenated diamond surfaces were treated in a solvent containing benzoyl peroxide and dicarboxylic acid. Surface characterization was performed by diffuse reflectance infrared Fourier transform spectroscopy. After the reaction, a CO peak appeared, and the shape of the CH peak at 2780−2960 cm-1 depended on the kind of dicarboxylic acid. When deuterium-labeled diamond powders were treated in the same manner, aliphatic CH peaks were observed in the range 2780−2960 cm-1. The CH peaks were assigned to the (CH2)n groups of the dicarboxylic acids bonding to the diamond surface. When the modified diamond surfaces were treated with NaOH(aq), peaks assigned to the CO bond of the COONa groups appeared at 1578 cm-1, which indicated that carboxylic groups were present on the diamond surface. The presence of HOOC(CH2)nOCO groups on the diamond surface has been demonstrated.

Influence of the COOH and COONa groups and crosslink density of poly(acrylic acid)/montmorillonite superabsorbent composite on water absorbency

AbstractA novel poly(acrylic acid)/montmorillonite superabsorbent composite with a water absorbency of 1100 times its own weight was synthesized by the graft copolymerization of acrylic acid with a cross‐linking agent in the presence of montmorillonite ultrafine powder. The influence of the amount of crosslinker and montmorillonite on water absorbency has been investigated. It was found that a crosslinker concentration of 0.03 wt% and 30 wt% montmorillonite gave the best results. The collaborative absorbent effect of sodium carboxylate and carboxylic acid groups was superior to that of sodium carboxylate or carboxylic acid groups alone, and the composite with a ratio of about 2/3 for sodium carboxylate to carboxyl acid groups possessed the highest water absorbence.© 2001 Society of Chemical Industry

Investigation of Microphase Separation and Thermal Properties of Noncrystalline Ethylene Ionomers. 2. IR, DSC, and Dielectric Characterization

The microphase structure of noncrystalline poly(ethylene-co-13.3 mol % methacrylic acid) (E-0.133MAA) ionomers was investigated by using infrared (IR) spectroscopic, X-ray scattering, differential scanning calorimetric (DSC), and dielectric measurements. The noncrystallinity was confirmed by small-angle X-ray scattering (SAXS) and DSC studies, which has enabled a quantitative analysis of the SAXS ionic peak associated with ionic aggregates without being perturbed by the polyethylene lamellae peak. In 60% neutralized Na ionomer, it was revealed that almost 100% of MAA side groups including unneutralized COOH are incorporated into the ionic aggregates with an average ionic core radius (R 1 ) of ∼6 A. The dielectric relaxation studies showed that the ionic aggregates form a microphase-separated ionic cluster. Analysis of dielectric strengths indicated the most (∼90%) of the COONa groups are present in the ionic cluster. On the other hand, in the 60% neutralized Zn ionomer, both SAXS and dielectric studies indicated that the ionic aggregates with R 1 ∼ 4 A are almost isolated and dispersed in the matrix; the formation of ionic cluster was not recognized. Similarly to partly crystalline E-MAA ionomers, all noncrystalline E-0.133MAA ionomers exhibited an endothermic peak at 320-330 K (labeled T i ) on the first heating, depending on the aging time at room temperature. Several factors that would be critical for the DSC T i peak were discussed. It was concluded that the DSC T i peak is certainly associated with changes of the state of ionic aggregate region.

Alkaline hydrolysis of polyacrylonitrile, 1. Structure of the reaction products

The alkaline hydrolysis of a polyacrylonitrile suspension was carried out in a water/ethanol mixture at 75°C. The product structure was studied by means of solid state 13C NMR spectroscopy. The hydrolyzed samples contain up to 20% of amidines, which are formed in the nearest neighborhood of the COONa groups. Amidines are relatively stable under the given reaction conditions up to almost complete conversion of the nitrile groups, then being hydrolyzed gradually into amides. After complete hydrolysis of the amidines, the resulting poly[(acryl amide)-co-(sodium acrylate)] exhibits a Bernoulli triad distribution of the comonomer units. The data obtained might be useful in elucidating the reaction mechanism.

The neutralization reaction of nitro-H-carboxymethylcellulose

The interaction of nitro-H-carboxymethylcellulose with a solution of sodium hydroxide has been investigated. Three reactions take place in parallel: neutralization of the −COOH groups, denitration, and degradation of the main chain at the β-glucosidic bonds. Conditions permitting these reactions to be regulated have been found. It has been established that when not less than 80 mole-% of −COONa groups and not more than 130 mole-% of −ONO2 groups are present the product of the neutralization reaction (nitro-Na-CMC) is soluble in water.

Apparent molar heat capacities of aqueous solutions of propylamine, 1,4-butanediamine, 1,6-hexanediamine, propylamine hydrochloride, propionamide, pyridine, and sodium benzenesulfonate at temperatures from 300 K to 525 K and a pressure of 28 MPa

The apparent molar heat capacities of dilute aqueous solutions of propylamine, 1,4-butanediamine, 1,6-hexanediamine, propylamine hydrochloride, propionamide, pyridine, and sodium benzenesulfonate were measured at 300 K<T<525 K andp=28 MPa. Corrections for hydrolysis or dissociation reactions and relaxation effects were applied where necessary, and the results were extrapolated to infinite dilution to obtainCp,2∞. After subtracting the heat capacity of a point mass, the remaining heat capacity was successfully divided into functional group contributions at all temperatures. Including the results of our previous papers on alcohols and diols and carboxylic acids and sodium carboxylates, the heat capacity contributions of the CH2, CH3, OH, COOH, (COOH)2, NH2, CONH2, COONa, and NH3Cl groups are now available, and these allow reasonably accurate predictions of the heat capacities of all aqueous compounds composed of these groups in this temperature range.