Polycarboxylic Acids Research Articles

Ensuring Photocatalyst Properties on Cellulosic Fabric by Using Citric Acid Modified with TiO2 Degussa P25 Nanoparticles

Citric acid, which is a type of polycarboxylic acid, is environmentally friendly, and non-harmful and it can be used as a cross-linker. Titanium dioxide (TiO2) nanoparticle is a catalyst that provides many properties for textile products with its large surface area. Present study, a mixture was prepared with different concentrations of citric acid and commercial TiO2 Degussa P25 nanopowder suspensions. Two different curing temperatures (120°C and 140°C) were applied to the cotton fabrics in the pad-dry-cure method. The adhesion of the chemicals to the fiber surface was confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectrophotometer (FT/IR) analysis. The yellowing effect caused by citric acid on cotton fabrics was eliminated with white TiO2 nanoparticles. Methylene blue was used for staining the samples. Color analyses were performed with a spectrophotometer to determine photocatalytic properties of the samples. It was determined that the samples treated with a mixture of 30 g/L citric acid and TiO2 suspensions were the most discolored samples after exposure to solar light. The photocatalyst properties of the samples were further improved by removing the aggregation of TiO2 NPs on the fiber surface with the washing procedure.

Multi-responsive luminescent complex for Fe3+, Cr2O72− and CrO42− species in aqueous solution based on aromatic polycarboxylic acid and imidazole-containing ligand: synthesis, crystal structure and selective detection

One Cadmium(II)-based complex, [Cd(LBIX)(HEA)]n (1), was synthesized using 4,4′-bis((1H-imidazol-1-yl)methyl)-1,1′-biphenyl (LBIX) and 1,2-phenylenediacetic acid (H2HEA) as ligands. The analysis of the single crystal structure reveals that 1 possesses a ladder-like chain structure, which extends into a 3D architecture through π···π interactions. 1 was identified through powder X-ray diffraction analysis (PXRD), elemental analysis (EA), infrared spectroscopy (IR) and thermogravimetric analysis (TGA). It can be seen from the luminescence experiment that 1 has high Ksv value (Cr2O72−: 1.51 × 104 M−1, CrO42−: 1.16 × 104 M−1 and Fe3+: 1.26 × 104 M−1) and lower detection limit (Cr2O72−: 1.14 μM, CrO42−: 1.88 μM and Fe3+: 1.14 μM), it is utilized as a multi-response sensor to recognition Fe3+, CrO42− and Cr2O72− in an aqueous solution. Mechanisms in which fluorescence quenching occurs have been examined using techniques such as PXRD, UV–vis absorption spectra, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Due to its excellent selectivity, high sensitivity and strong stability, it is suitable for detecting Fe3+, CrO42− and Cr2O72− ions as a fluorescent probe.

Mechanisms of permeation of helium, hydrogen, oxygen, and water vapor through silicate-based composite barrier coating layers

When considering coating of flexible films for the packaging of sensitive products, a common goal is to meet all gas barrier requirements in a single process step. One way to achieve this is to improve the barrier performance of polymeric coating layers by incorporating silicate particles. In order to tailor the gas barrier performance of the coatings, understanding the permeation mechanisms through these composite coating layers is required. In this study, polyethylene terephthalate films were coated with composite lacquers comprising montmorillonite particles and a polymer matrix. The compatibility of montmorillonite with polymer matrices of polypropylene, polyacrylate, polycarboxylic acid, and polyvinyl alcohol was tested. The permeation behavior of helium, hydrogen, oxygen, and water vapor in these coatings was investigated. For a composite coating layer comprising montmorillonite and polyvinyl alcohol at a mixing ratio of 1:1 by weight, barrier improvement factors of ▪ compared with the pure polymer coating were found for helium, hydrogen, and oxygen, respectively. It was shown that the permeability coefficients of composite coating layers decrease with increasing permeant kinetic diameter. A comparison of calculated and measured permeability values indicated that the integration of montmorillonite leads to a tortuous permeation path and changes in the free volume and crystallinity of the polymer matrix. The permeation mechanism for water vapor turned out to be completely different from that for non-polar helium, hydrogen, and oxygen and is determined by the so-called polar path effect.

Synthesis, structure, fluorescence and magnetic studies of two oxygen bridged polycarboxylic acid ligands and rare earth metal ion Pr, Gd, and Er complexes

In order to further enrich the research on the synthesis of complexes with polycarboxylic acid ligands and rare earth metal ion. In this study, four rare earth complexes, namely, [Gd(cpia)]n (1), [Er(cpia)]n (2), [Pr(cpna)2·2H2O]n (3) and [Gd(Hcpna)(cpna)•3H2O]n (4) have been synthesized by solvothermal method based on 5-(2-carboxyphenoxy)isophthalic acid (H3cpia) and 5-(4-carboxyphenoxy)nicotinic acid ligand (H2cpna) with rare earth metal ions Pr3+, Gd3+ and Er3+. Single crystal X-ray diffraction analyses reveal that complexes 1, 2 and 3 are two-dimensional network structure, 4 is one-dimensional chain structures. The fluorescence test results show that the fluorescence intensity of complexes 1 and 2 were lower than that of the H3cpia ligand, the fluorescence intensity of complexes 3 and 4 were lower than that of the H2cpna ligand. Magnetic results indicate complex 1 has ferromagentic behavior and weak antiferromagentic behavior in the complexes 2, 3 and 4.

Mechanism study of the effect of superplasticizers in alkali-activated materials containing sludge

To realize the safe disposal of solid waste containing heavy metals, sewage sludge jointly with slag and metakaolin was used to prepare alkali-activated materials (AAMs), and the effect mechanism of polycarboxylate acid superplasticizer (PCE), naphthalene superplasticizer (NS) and aliphatic superplasticizer (AS) in AAMs were studied. The results showed that both the fluidity and strength of AAMs decreased with the addition of sludge. For the NaOH + Na2SiO3 activated mortar specimen, the incorporation of sludge can reduce their fluidity and strength from 206 mm and 80.25 MPa to 193 mm and 42.43 MPa, respectively. However, the addition of superplasticizers into sludge-containing AAMs leads to a reduction of 3–9% of the fluidity. Interestingly, it can enhance the strength of the AAMs, especially the NS and AS, which increase the strength by approximately 25%. This is attributed to the increase of particle dispersion by superplasticizers. However, the free water released in the process is reabsorbed by the sludge, which increases the local alkali concentration and promotes the activation of the activity. The dispersed sludge particles can play the role of physical filling, making the structure denser. HIGHLIGHTS Sludge is adverse effects on both the fluidity and strength of alkali-activated materials (AAMs). The addition of superplasticizers (SPs) increases the strength of AAM with sludge. SPs do not affect improving the fluidity of AAMs with sludge, even slightly bad. The dispersion effect of SPs on the sludge is beneficial to promote its activity in AAMs.

Molecular-level explanation of interactions of random and block polycarboxylic acid dispersants with bituminous coal in coal–water slurry through experiments and simulations

The adsorption conformations of random-structure polycarboxylic acid (PCR) and block-structure polycarboxylic acid (PCB) on coal surfaces were analyzed from a microscopic perspective. This analysis involved a combination of molecular dynamics (MD) simulations and experiments. The saturation adsorption amount of PCB was found to be significantly much larger than that of PCR. Additionally, observations from the contact angle and X-ray photoelectron spectroscopy confirmed that PCB exhibited superior wetting performance on coal compared to PCR and had a greater adsorption layer thickness. The relative concentration changes and the mean square displacement (MSD) of water indicate that the better adsorption of PCB on the coal surface makes the water molecules more evenly distributed, which improves hydration, increases the thickness of the “adsorption layer”, and enhances the mobility of water molecules. The interaction energy suggests the block structure of PCB is more favorable for molecular extension due to its well-defined structure. This provides a theoretical and experimental basis for expanding the molecular sequence structure design of polycarboxylic acid dispersants.

Insight into Relationship between the Products Distribution and Molecular Properties in Carboxylation between Benzene Polycarboxylic Acids and CO2

Insight into Relationship between the Products Distribution and Molecular Properties in Carboxylation between Benzene Polycarboxylic Acids and CO2

Variable aging and storage of dissolved black carbon in the ocean

During wildfires and fossil fuel combustion, biomass is converted to black carbon (BC) via incomplete combustion. BC enters the ocean by rivers and atmospheric deposition contributing to the marine dissolved organic carbon (DOC) pool. The fate of BC is considered to reside in the marine DOC pool, where the oldest BC 14C ages have been measured (>20,000 14C y), implying long-term storage. DOC is the largest exchangeable pool of organic carbon in the oceans, yet most DOC (>80%) remains molecularly uncharacterized. Here, we report 14C measurements on size-fractionated dissolved BC (DBC) obtained using benzene polycarboxylic acids as molecular tracers to constrain the sources and cycling of DBC and its contributions to refractory DOC (RDOC) in a site in the North Pacific Ocean. Our results reveal that the cycling of DBC is more dynamic and heterogeneous than previously believed though it does not comprise a single, uniformly "old" 14C age. Instead, both semilabile and refractory DBC components are distributed among size fractions of DOC. We report that DBC cycles within DOC as a component of RDOC, exhibiting turnover in the ocean on millennia timescales. DBC within the low-molecular-weight DOC pool is large, environmentally persistent and constitutes the size fraction that is responsible for long-term DBC storage. We speculate that sea surface processes, including bacterial remineralization (via the coupling of photooxidation of surface DBC and bacterial co-metabolism), sorption onto sinking particles and surface photochemical oxidation, modify DBC composition and turnover, ultimately controlling the fate of DBC and RDOC in the ocean.

Synthesis, structure and electrochemical properties of Co-MOF containing pyridine polycarboxylic acid

Metal-organic frameworks (MOFs) have been widely used in filed of electrochemistry. Compared with traditional inorganic porous materials, the polyvalent pyridinecarboxylic acid ligands have many advantages which contains more active sites, flexible coordination mode, adjustable structure. Therefore, it becomes good choice for constructing MOFs materials with excellent performance. In this paper, a novel MOF was synthesized by pyridine polycarboxylic acid ligand and CoCl2·6H2O using solvothermal method. The physicochemical properties were characterized by FT-IR, powder diffraction and thermogravimetry. Single crystal X-ray diffraction reveal that MOF-1 crystallizes in monoclinic system with P21/C space group. The central Co2+ ions have a dual core structure with 5 and 6 coordination, respectively. The carboxyl groups show two kinds of coordination modes μ2: η1: η1 and μ2: η1: η2, and the pyridine N atoms also coordinate to form a three-dimensional network structure. Electrochemical experiments show that MOF-1 has a lower overpotential (339.4 mV) and Tafel slope (65.3 mV·dec−1) with higher ECSA and better OER kinetics. A large number of exposed active sites indicate that the MOF has higher potential as catalyst for oxygen evolution reaction.

Study on synthesis of temperature-resistant polycarboxylic acid dispersant and its application in oil well cement

Study on synthesis of temperature-resistant polycarboxylic acid dispersant and its application in oil well cement

Dosage- and site-dependent retention of black carbon and polycyclic aromatic hydrocarbons in farmland soils via long-term biochar addition

Biochar, a soil conditioner containing significant amounts of polycyclic aromatic hydrocarbons (PAHs), has gained widespread popularity in agricultural practices due to its advantages in improving soil fertility and carbon sequestration. While biochar may increase soil black carbon (BC) and PAH contents, the quantitative accumulation of BC and PAHs in different soil environments under varying biochar addition dosages remains poorly understood. Here, we investigated the content and composition of black carbon (evaluated using benzene polycarboxylic acids, BPCAs) and PAHs in soils treated with different biochar addition dosages from two long-term experimental farmlands in Ningxia (5-year) and Shandong (7- and 11-year), China. Results showed that increasing cumulative biochar dosage caused elevated contents of black carbon and PAHs, accompanied by decreases in their retention efficiencies. Contrasting retention was observed between sites, with the Shandong site characterized by higher retention efficiencies of BPCAs and lower retention efficiencies of PAHs, possibly owing to its higher temperature, more sandy soil texture, less irrigation, and lower sunlight intensity. Despite both black carbon and PAHs originating from biochar and sharing similar condensed aromatic structures, there was no significant correlation between the contents of black carbon and PAHs, indicating distinct behaviors and fates of these compounds. These findings emphasize the importance of optimizing biochar addition dosages and considering site-specific environmental factors for effective soil black carbon sequestration through biochar application.Graphical

Preparation and performance study of anti mud polycarboxylic acid slump retaining agent

Anti-mud polycarboxylic acid slump retaining agent was prepared by copolymerization of ethylene glycol monovinyl polyethylene glycol ether, diethyl 4-vinylphenyl phosphate, 2-methyl-2-(4-vinylphenyl) propionic acid, unsaturated carboxylic acid (or unsaturated carboxylic anhydride) and unsaturated carboxylic ester under the action of initiator and molecular weight regulator. The effect of the slump retaining agent on the workability of fine aggregate concrete with different mud contents was tested, and the sensitivity of the slump retaining agent to the mud content of machine-made sand was evaluated. At the same time, the viscosity reduction performance of the slump retaining agent was evaluated by using the emptying time of the inverted slump cone and the flow time of V-funnel and L-box. The experimental results show that the synthesized anti-mud polycarboxylic acid slump retaining agent has favourable effects of anti-mud and viscosity reduction.

The effect of organic acids on high-moisture extrusion of soy protein isolate: Comparison between monocarboxylic acid and polycarboxylic acids

This study aimed to explore the potential of organic acids to promote formation of fibrils in plant-based meat analogs during extrusion, as acids were able to induce formation of amyloid-fibrils from protein molecules. Specifically, the effects of acetic acid, tartaric acid, and citric acid with various concentrations (0.05, 0.10, 0.20, and 0.30 mol/kg protein) on the structure and properties of the soy protein isolate (SPI)-based meat analogs from extrusion were investigated. Tartaric acid and citric acid improved the fibrous degree of the meat analogs with the optimal concentration of 0.20 mol/kg SPI, while acetic acid did not have a significant effect. Besides, it was found that citric acid led to a higher fibrous degree than tartaric acid, which might be due to that citric acid was more effective in cross-linking than tartaric acid. Moreover, adding organic acids promoted degradation of SPI, enhancing the flexibility of SPI molecules during extrusion. This, facilitated the rearrangement of protein molecules and the formation of fibrils in meat analogs. Although acetic acid also promoted the hydrolysis of SPI, it hindered the unfolding of SPI during heating and was not able to induce cross-linking of SPI molecules. As a result, acetic acid had no significant impact on the fibrous degree of meat analogs. In conclusion, citric acid and tartaric acid were promising and cost-effective additives to promote production of plant protein-based meat analogs.

Structure and properties study of magnesium oxide porous ceramics prepared by Organic Foam Template Method

Magnesium oxide (MgO) porous ceramics with high porosity, compressive strength and low thermal conductivity were prepared by Organic Foam Template Method. The effects of the sintering temperature, polycarboxylic acid (PCE) dispersant and pore size of organic foam template on the properties of MgO porous ceramics were investigated. The experiment results showed that with the increase of sintering temperature, the MgO porous ceramic shrinkage, skeleton density and compressive strength increased. PCE could increase the fluidity of slurry and make the framework clearer, as well as reduce the cracks formed in the process of drying effectively. When the content of PCE was 0.5 wt-%, the porosity, compressive strength and thermal conductivity of MgO porous ceramics were 88.5%, 1.6 MPa and 0.045 W/(m·K), respectively. In addition, as the pore size of the organic foam template decreased, the porosity decreased, and the resistance increased and the thermal conductivity increased.

Artificial formation of benzene polycarboxylic acids during sample processing of black carbon analysis: the role of organic carbon amount

Black carbon is also known as pyrogenic carbon formed by partial combustion of organic material under limited oxygen supply. It occurs along a continuum from original organic slightly charred material to highly aromatic combustion residues such as charcoal, graphite, and soot. Black carbon is extensively studied in various environments due to its ubiquity. It is also important for the biochar community because it can specifically trace the stable polycondensed part of biochar. Different methods have been adopted for black carbon determination; among them using benzene polycarboxylic acids (BPCA) as molecular markers for the polycondensed aromatic moieties of charred materials. However, different researchers have shown interferences from organic matter during BPCA analysis. Therefore, the aim of this work was to assess if artificial formation of BPCA occurs in soil samples when the organic carbon load exceeds 5–10 mg. For this purpose, we conducted black carbon analysis of different soil samples with varying TOC contents of up to 20 mg. In addition, organic matter-rich plant materials were used as a black carbon-free control (leaves of Ivy and Beech, leaves/needles of Spruce and needles of Thuja). To exclude the high-pressure digestion as source of artificial black carbon formation, a comparison between the conventional and a microwave-assisted extraction (MAE) oxidation process was included. Our results show that for soil samples, no artificial BPCA formation occurred at least up to 20 mg of total organic carbon. Higher sample weights are unrealistic for BPCA analysis of soils using current methodology. Therefore, our results clearly demonstrate that there is no artificial BPCA formation during properly performed black carbon analysis of soil samples. On the contrary, for some samples, BPCA contents tended to decrease with increasing sample weight, and thus increasing amount of TOC. In contrast, for plant samples, artificial BPCA formation of up to 3 g kg−1 occurred when more plant material equivalent to 10 mg total organic carbon was used. However, there was no amount dependence of artificial BPCA formation. The reason for artificial BPCA formation was not the high-pressure digestion, as microwave-assisted digestion showed comparable results. However, for real-world analysis, this artificial BPCA formation is not relevant because such high soil sample weights cannot be used. Nevertheless, when using organic-rich material such as peat and charred materials, the samples should contain less than 10 mg of total organic carbon.Graphical

Preparation and properties of modified POD membranes by polycarboxylic acids copolymerization

A series of X-POD polymers were prepared by condensation reaction of terephthalic dihydrazide and four different polycarboxylic acids in polyphosphoric acid (PPA) as solvent, and the corresponding membranes were formed by phase inversion method. The modified X-POD polymer structures have changed from linear structure to multidimensional network structure, which has great influence on the quality and performance of the membranes. The membrane structures were characterized by FTIR, and the thermal stability of the samples was determined by Thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The ultraviolet transmittance and fluorescence properties of membranes were tested by ultraviolet spectrophotometer. The crystallinity and orientation of the samples were observed by X-ray diffraction (XRD). The surface and cross-sectional morphology of the membranes were evaluated by scanning electron microscope (SEM). Additionally, the oxidation and water absorption properties of the membranes were collected, and the mechanical properties of the membranes were tested. Overall, X-POD membranes show good mechanical properties, chemical inertness and thermal stability. The quality and mechanical properties of X-POD membranes demonstrated varying degrees of improvement. Notably, the mechanical properties of II-POD and III-POD membranes were enhanced by 244.52% and 203.66%, respectively. X-POD membranes exhibit high strength and excellent toughness, rendering them a highly promising material for membrane applications in the market.

Cd(ii) coordination polymers constructed from tris-pyridyl-tris-amide and polycarboxylic acid: synthesis, structures and sensing properties

Reactions of a C3-symmetrical ligand and Cd(ii) salts with various polycarboxylic acids afforded three new coordination polymers, demonstrating that the length and shape of the polycarboxylate ligands govern the structural diversity.

A thermosensitive luminescence halloysite-based nanocomposite enabling encryptable thermal printing.

In situ formation of carbon dots on halloysite nanotubes is demonstrated by treating polyacrylamide-grafted halloysite nanotubes with polycarboxylic acid without the recourse to extremely high temperatures or solvents. Thermosensitive luminescence and phosphorescence properties are carefully investigated. The polyacrylamide-grafted halloysite nanotubes are further processed as composite films for encryptable thermal printing.

Effect of flame‐retardant melamine and dispersants on the mechanical, thermal, and foaming properties of flexible polyurethane foam

AbstractThe objective of this study was to investigate the effect of adding flame‐retardant melamine and five different dispersants on the precipitation, foaming, mechanical, and thermal properties of flexible polyurethane foam (FPUF). Precipitation experiments were conducted to analyze the effect of dispersant on the separation of flame retardant and polyol, and the foaming characteristics of polyurethane (PU) foam after adding dispersant were analyzed. The effect of adding a dispersant on mechanical strength was characterized by measuring tensile strength, tearing strength, and hardness, and scanning electron microscopy analysis was performed to analyze morphological characteristics. Thermogravimetric analysis (TGA) was performed to analyze the thermal properties of PU foam. A horizontal flame test, limiting oxygen index test, and cone calorimeter tests were conducted to examine the flame retardancy of PU foam with flame retardant melamine and dispersant added. The dispersant ANTI‐TERRA‐U is a solution of a salt of unsaturated polyamine amides and low‐molecular acidic polyesters. And, the dispersant BYK‐220S is a solution of a low molecular weight, unsaturated acidic polycarboxylic acid polyester with a polysiloxane copolymer. The dispersants ANTI‐TERRA‐U and BYK‐220S improved the density, tensile strength, tear strength, and hardness of FPUF. TGA of the top and bottom portions of the foam showed less weight difference for samples containing dispersants, indicating better homogeneity due to improved dispersibility. Therefore, we conclude that dispersants are beneficial additives to improve the mechanical properties and dispersibility of PU foam.

Occurrence of Benzene Polycarboxylic Acids in Ash and Streamwater after the Cameron Peak Fire

Occurrence of Benzene Polycarboxylic Acids in Ash and Streamwater after the Cameron Peak Fire