Presence Of Maleic Acid Research Articles

Green superabsorbent hydrogel derived from activated charcoal and glycerol with maleic acid as a cross-linker

Superabsorbent hydrogels characterize a set of polymeric materials with three-dimensional structures capable of absorbing large amounts of water due to their hydrophilic functional groups on their surface. Their application in industries, agriculture, and the environment is of primary significance. This study reports the synthesis and characterization of green superabsorbent hydrogels derived from activated charcoal. The process involved a polymerization reaction between activated charcoal (AC) with glycerol (G) using sodium hydroxide as an initiator in the absence and presence of maleic acid as a crosslinker to synthesize HCG-1 and HCG-2 superabsorbent hydrogel respectively. Characterization of the hydrogels was done using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). Optimization conditions were done by synthesizing hydrogel with varying dosages of both activated carbon and maleic acid as well as swelling time. The FT-IR results showed the appearance of strong sharp peaks at 1591.34 cm-1 and 1400.28 cm-1 in HCG-1 associated with -COO¯ symmetric stretching and asymmetric bending vibrations, indicating interlink between reacting monomers. A new absorption band at 1639.48 cm-1 associated with -COO¯ bending in non-conjugated ester indicates ester-crosslink in HCG-2 hydrogel. XRD analysis showed a phase shift from semi-crystalline to crystalline structure upon crosslinking. SEM analysis showed a crystalline intact, rigid structure without voids and pores on its surface in HCG-1 compared to the smooth irregular pores and lamina structure observed in HCG-2 hydrogel. The dosage ratio of AC: G: maleic acid of 8:5:1 produced hydrogel with an optimal water absorption capacity of 1255.80±0.70%. Maleic acid was found to improve the water absorption capacity of the superabsorbent. The study is an eye opener towards the application of biodegradable hydrogels in agriculture, especially in semi and arid regions.

High-Lignin-Containing Cellulose Nanofibrils from Date Palm Waste Produced by Hydrothermal Treatment in the Presence of Maleic Acid.

Lignin-containing cellulose nanofibrils (LCNFs) have attracted great attention because the presence of lignin brought additional merits to cellulose nanofibrils including hydrophobicity, ultraviolet (UV)-shielding capacity, and reduced water sensitivity. In the present work, LCNFs with lignin content up to 21 wt % were prepared with a high yield exceeding 70 wt %, from neat date palm waste, by a hydrothermal treatment (HTT) at 120-150 °C in the presence of 20-30 wt % maleic acid, followed by high-pressure homogenization. The chemical composition, degree of polymerization, morphology, and colloidal and rheological properties of the LCNFs were investigated to understand how the HTT in the presence of MA affected the properties of the resulting LCNFs. Nanopapers prepared from the LCNF suspensions exhibited mechanical properties lower than those from lignin-free CNF-based nanopapers, yet with decreased hydrophilicity. A mechanism explaining how the HTT in the presence of MA facilitated the disintegration of the biomass into nanoscale material was proposed. Overall, the present work demonstrated a feasible and scalable approach for the sustainable production of LCNF suspensions from neat agricultural residues, with a high yield and a high lignin content, without any need to perform a preliminary partial delignification.

ВПЛИВ МАЛЕЇНОВОЇ КИСЛОТИ НА СКЛАД ТА СТРУКТУРУ МІДЬОРГАНІЧНИХ ДИСПЕРСІЙ, ОТРИМАНИХ ХІМІЧНИМ ТА ЕЛЕКТРОХІМІЧНИМ ВІДНОВЛЕННЯМ Cu2+-ІОНІВ

Using chemical (zinc cementation) and electrochemical (cathodic deposition on titanium nitride) methods, copper microdispersions were obtained in the presence of maleic acid in an acidic solution CuSO4. It was complexonometrically established that electrochemically obtained copper powders are characterized by a high metal content (97.9 wt. %) and a small amount of non-metallic inclusions has been determined. But their dispersion under the action of maleic acid increases by an order of magnitude. The metal content is reduced to 39.7 wt. % in chemically obtained powders. The elemental composition of particles (wt. %) has been determined by energy-dispersive x-ray spectroscopy: C – 9.35, O – 25.76, Cu – 64.90. The presence of complexed water in the organometallic dispersion has been thermogravimetrically proved. These data, combined with the data of IR spectroscopy, led to the conclusion that the main component of the organometallic dispersion is the complex [Cu(C4H3O4)(H2O)2].

Telechelic Carboxyl‐Terminated Polynorbornenes and Copolym‐ers via Chain‐Transfer Ring‐Opening Metathesis Polymerization

AbstractCarboxyl‐terminated polynorbornenes (CTPNB) have been prepared via ring‐opening metathesis polymerization (ROMP) catalyzed by Grubbs II catalyst (G2) in the presence of maleic acid (MA) as a chain transfer agent (CTA). The influences of reaction conditions on the molecular weight of products, including molar ratios of C=C/G2, C=C/CTA and amount of solvent were investigated. The results indicated that the molecular weight of CTPNBs could be controlled by varying the molar ratio of C=C/G2 or C=C/CTA. In addition, norbornene (NB) was copolymerized with cyclooctene (COE) in order to obtain carboxyl‐terminated copolymers via chain‐transfer ROMP. The unsaturated carboxyl‐terminated (co)polymers were further hydrogenated by using p‐toluenesulfonyl hydrazide/tri‐n‐propylamine reagents. The structures of polymers were characterized by FT‐IR, NMR and MALDI‐TOF mass spectroscopy, and their thermal properties were determined by DSC and TGA.

Kinetics and morphological characteristics of struvite (MgNH4PO4.6H2O) under the influence of maleic acid.

This work reports a stirred-batch lab crystallization to examine the influence of maleic acid (HO2CCHCHCO2H), and temperatures (30 and 40 °C) on crystallization kinetics and morphology of struvite. The crystallization was followed by measuring the pH change up to 70 min. The pH decreased drastically for the first 5 min of the run, then started to tail off. It was found that the crystallization rate constants range from 1.608 to 6.534 per hour, which agrees with the most published value. Higher maleic acid concentrations resulted in greater growth retardation; the highest retardation was 74.21%, which was achieved for 30 °C with 20.00 ppm maleic acid. SEM imaging of the obtained precipitates showed irregular prismatic morphology, and the associated EDX confirmed that the precipitates were struvite (MgNH4PO4⋅6H2O). As checked through XRD, the crystalline nature of the struvite was further confirmed, and that co-precipitation of struvite with struvite-K was observed. The co-precipitation was the result of K+ adsorption onto the crystal surface. Temperatures had less influence on struvite crystallization. At 40oC and 20.00 ppm the rate constant was 1.332 per hour; whereas at 30oC and 0.00 ppm) the corresponding was 1.776 per hour, indicating the retardation of about 25%. Thus, the temperature effect is only 1/3 of the maleic acid effect. The current findings suggest that the presence of maleic acid can be used to elucidate the mechanism of crystallization as well as the crystalline phase transformation of struvite. In practical terms, maleic acid could be potential as a scale inhibitor.

Facile access to carboxyl‐terminated polybutadiene and polyethylene fromcis‐polybutadiene rubber

ABSTRACTCarboxyl‐terminated polybutadiene (CTPB) is a widely used telechelic liquid rubber, which is mainly prepared by anionic or free‐radical polymerization of 1,3‐butadiene. It is known that the microstructure of liquid polybutadiene rubber largely affects its processability and mechanical properties. However, it is hard to control its microstructure in the free radical or anionic polymerization. In this study, a series of CTPB with highcis‐1,4 content has been prepared for the first time via the oxidolysis and selective oxidation ofcis‐polybutadiene rubber (BR). Hydrogenation of their CC double bonds withp‐toluenesulfonyl hydrazide/tri‐n‐propylamine (TSH/TPA) reagents afforded carboxyl‐terminated polyethylenes (CTPE). For comparison, commercial CTPB (FCTPB), prepared by free‐radical polymerization of 1,3‐butadiene, was also hydrogenated and gave FCTPE with more ethyl branches. Linear CTPE (L‐CTPE) was synthesized by ring‐opening metathesis polymerization of 1,5‐cyclooctadiene in the presence of maleic acid and subsequent hydrogenation. The microstructure of the polymers was established by FT‐IR,1H NMR,13C NMR, and GPC and their thermal properties were determined by DSC and TGA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2019,136, 46934.

Filler-Reinforced Elastomers Based on Functional Polyolefin Prepolymers

Carboxy-telechelic polyolefin prepolymers were synthesized via ring-opening metathesis polymerization of 3-ethyl-1-cyclooctene in the presence of maleic acid. Following hydrogenation these difunctional prepolymers were cross-linked with a trifunctional aziridine in the presence of fumed silica or carbon black fillers to yield polyolefin elastomers with significantly enhanced mechanical properties as compared to the unfilled versions. The tensile strength, modulus, and tear strength of the elastomers can be tuned by changing the filler type and the total filler content. Further study on the reinforcing mechanism suggests that both the polymer–filler interactions and the filler–filler interactions play key roles in the mechanical property enhancements.

Kinetics of Maleic Acid and Aluminum Chloride Catalyzed Dehydration and Degradation of Glucose

We report the positive effect of maleic acid, a dicarboxylic acid, on the selectivity of hexose dehydration to 5-hydroxymethyfurfural (HMF) and subsequent hydrolysis to levulinic and formic acids. We also describe the kinetic analysis of a Lewis acid (AlCl3) alone and in combination with HCl or maleic acid to catalyze the isomerization of glucose to fructose, dehydration of fructose to HMF, hydration of HMF to levulinic and formic acids, and degradation of these compounds to humins. The results show that AlCl3 significantly enhances the rate of glucose conversion to HMF and levulinic acid in the presence of both maleic acid and HCl. In addition, the degradation of HMF to humins, rather than levulinic and formic acids, is reduced by 50% in the presence of maleic acid and AlCl3 compared to HCl combined with AlCl3. The results suggest different reaction mechanisms for the dehydration of glucose and rehydration of HMF between maleic acid and HCl.

Carboxy-Telechelic Polyolefins in Cross-Linked Elastomers

We demonstrate that ring-opening metathesis copolymerization of 3-hexyl-cis-cyclooctene and cis-cyclooctene in the presence of maleic acid as a chain transfer agent leads to precise control over the molar mass, branching and crystallinity of the resulting carboxy-telechelic polyalkenamers. Subsequent hydrogenation using a silica-supported platinum catalyst had a negligible effect on the carboxy functionality and led to telechelic polyolefins with high thermal resistance, low glass transition temperatures (<−57 °C), little to no crystallinity, and viscosities similar to those of liquid silicon rubber prior to cross-linking. These properties are ideal for easily processable reactive polyolefin prepolymers that can be readily cured to form elastomers. We demonstrate that a fast and controlled curing process can be achieved in the presence of polyfunctional aziridines. The properties of the thermoset elastomer products were evaluated by tensile, differential scanning calorimetry, and dynamic mechanical analyses.

Incorporation of Ceramic Particles into Nickel and Cobalt Electroless Deposits

Abstract- The aim of this work was to elucidate factors affecting electroless codeposition of metals with ceramic particles. Codeposition of SiC, SiO 2 and Al 2 O 3 particles with Ni-P and Co-P matrixes in citrate-malonate alkaline solutions was compared. The positive surface charge of SiC particles corresponded to increased adsorption of hypophosphite anions, while negatively charged SiO 2 and Al 2 O 3 particles showed high adsorption of metal ions. It resulted in high incorporation of the carbide into the metal layers and low percentages of oxides in the coatings. Adsorption of nickel ions on SiC particles was promoted by the presence of maleic acid in the bath, however it did not improve incorporation of the particles into the Ni-P matrix. Equilibrium distribution of the species in the plating baths was also calculated. Keywords- Electroless Deposition; Nickel; Cobalt; Composite; Surface Charge; Adsorption I. INTRODUCTION Composite coatings are produced usually by incorporation of solid particles into a metallic matrix in electrolytic or electroless processes

Fabrication of nano Delafossite LiCo0.5Fe0.5O2 as the new adsorbent in efficient removal of reactive blue 5 from aqueous solutions

In this paper, nanoparticles of delafossite-type LiCo0.5Fe0.5O2 were prepared by sol–gel method in the presence of maleic acid as a chelating agent. The nanoparticles were characterized using differential thermal analysis, X-ray powder diffraction, Fourier infrared spectroscopy, transmission electron microscope, scanning electron microscopy and scanning tunneling microscopy. The nanoparticles showed the excellent adsorption properties towards reactive dye, reactive blue 5 (RB5). The adsorption studies were carried out at different pH values, various adsorbent dosages and contact time in a batch experiments. The kinetic studies indicate that the removal process obeys the second-order kinetic equation. Also, the isotherm evaluations reveal that the adsorption of RB5 by the nanoparticles follows the Freundlich model.

The Purity of Methacrylic Acid Crystals under the Presence of Maleic Acid and Methanol in Melt Crystallization

The Purity of Methacrylic Acid Crystals under the Presence of Maleic Acid and Methanol in Melt Crystallization

The influence of a small amount of maleic acid on crystal deposition phenomena of methacrylic acid in melt crystallization

Crystal deposition phenomena were investigated in the suspension melt crystallization of an organic acid. Methacrylic acid was used as the target substance, a certain amount of methanol was used as the solvent, and the effect of a small amount of maleic acid by-produced in methacrylic acid synthesis was focused on. Batch crystallizations were carried out on a laboratory scale using various concentrations of maleic acid. In the presence of maleic acid, a certain deviation from equilibrium of the pure binary system was observed in the final composition of mother liquor. Moreover, nevertheless the final temperature in the crystallizer was same, the amount of crystal deposition in the presence of maleic acid was smaller than in the absence of maleic acid. It was suggested that the final amount of crystal deposition decreased in the presence of maleic acid. Additionally, it was observed that the obtained crystal size was smaller in the presence of maleic acid. Hence, a simplified kinetic analysis of crystal deposition rates was carried out to make the effect of maleic acid clear. Consequently, it was suggested that the cause of the above-mentioned phenomena was the existence of the maleic acid concentration dependent pseudo-liquidus line.

MECHANICAL PROPERTIES AND CURE TEST OF A NATURAL RUBBER/POLY(VINYL ALCOHOL) BLEND

Abstract Properties and antibacterial activity of polymer blend films prepared from polyvinyl alcohol (PVA) and natural rubber (NR) blends, in the presence of maleic acid as a cross-linking agent were studied. The effect of the maleic acid content, curing temperature, and curing time on the properties of the polymer blend was investigated. Cross-linking between PVA and maleic acid was observed by attenuated total reflection mode–Fourier transform infrared spectroscopy at 1152 cm−1. The swelling ratio of the polymer blend decreased as a function of the increase of the maleic acid content. The tensile strength of the polymer blend increased with an increase of both the maleic acid and the curing time. The highest tensile strength of the samples was observed with 40% w/w maleic acid after a 24 h curing time at 120 °C. The elongation at the break of 60/40 NR/PVA was ∼500% at 120 °C for 1 h. In addition, the polymer blend showed good antibacterial activity with Staphylococcus aureus ATCC25923, Escherichia coli ATCC25922, and Acinetobacter baumannii JVC 1053 and could find many applications.

Crystal Growth Phenomena of Methacrylic Acid under the Presence of Maleic Acid in Melt Crystallization

Crystal Growth Phenomena of Methacrylic Acid under the Presence of Maleic Acid in Melt Crystallization

Sorption studies of neutral red dye onto poly(acrylamide‐co‐maleic acid)‐kaolinite/montmorillonite composites

AbstractIn this study, a procedure for preparation of organic–inorganic composite was established. The procedure was based on gamma irradiation polymerization of polyacrylamide (PAAm) in presence of maleic acid (MA), clay minerals [kaolinite (K)], or [montmorillonite (M)] and methylenebisacrylamide (NMBA) as a crosslinker. The functionality of the produced adsorbents were assayed using FTIR spectroscopy, SEM, and XRD and were evaluated for sorption of neutral red (NR) dye from aqueous solutions via batch sorption experiments. Various factors influencing the sorption behavior (e.g., pH, sorbent dose, and dye concentration) were studied. The sorption data fitted well with Langmuir isotherm model. Batch kinetic experiments showed that the adsorption followed pseudosecond‐order kinetic model with correlation coefficients greater than 0.999. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Structural, dielectric, optical and ferroelectric property of urea succinic acid crystals grown in aqueous solution containing maleic acid

Urea-succinic acid crystals have been grown at room temperature from aqueous solution in the presence of maleic acid by a slow evaporation technique. The structural parameters were determined using powder X-ray diffraction (XRD) and found to have monoclinic symmetry (space group P2 1/ m) with a=9.902, b=17.510, c=5.555 Å and α= γ=90°, β=96.46°. The transparency and optical analysis were carried out using UV–vis analysis. The optical band gap is found to be 4.71 eV. The presence of various functional groups was confirmed by FTIR analysis. The samples have shown piezoelectric behavior with a fairly good piezoelectric charge coefficient ( d 33) of 5 pC/N, when it is poled at 7 kV/cm. The hysteresis loop was plotted and the remnant polarization and coercive field were found to be 2.8 μC/cm 2 and 4 kV/cm, respectively. The dielectric analysis was carried out as a function of temperature at various frequencies and the results were also discussed.

ChemInform Abstract: One-Pot Synthesis of Novel Spiro-Annelated Pyrrole-Containing Heterocyclic Systems from Suitable Synthons.

New tetracyclic systems containing a pyrrolobenzodiazepine 5 or a pyrrolobenzotriazepine 6 moiety bounded by a spiro linkage to the piperidine nucleus are described. They have been synthesized by a simple reaction involving the interaction between proper aromatic amines and 4-oxopiperidines substituted or not at the 1-position in the presence of maleic acid as a catalyst. The synthesis of spiropyrrolo[1,2-a]quinoxaline-2,4′-piperidine 7 and its 1′-acyl derivatives by the same procedure is also reported.

Rheological Behavior, Tensile Properties, Morphology, and Thermal Stability of Recycled Poly(vinyl chloride)/Acrylonitrile Butadiene Rubber (PVCr/NBR) Blends: The Effect of Maleic Acid

Blends of recycled poly(vinyl chloride) (PVCr) and acrylonitrile butadiene rubber (NBR) modified by addition of maleic acid (MAc) are prepared by using a Haake Rheomix. The effect of MAc on melt Rheological behavior, tensile properties, morphology, and thermal stability of PVCr/NBR blends are investigated. The recorded data obtained from the Haake Rheomix are converted into values of apparent shear rate, apparent shear stress, and apparent viscosity. The apparent viscosity of the blends is found to decrease with increase in the shear rate and follow the pseudoplasticity behavior. At a similar shear rate, the presence of MAc in PVCr/NBR blends exhibits higher apparent viscosity than PVCr/NBR blends without MAc. Activation energy, Ea decreases with increasing shear rate, obviously due to the strong non-Newtonian behavior of PVCr/NBR blends. The addition of MAc in PVCr/NBR blends exhibits higher stress at peak and stress at 100% elongation but lower elongation at break and thermal stability than PVCr/NBR blends without the addition of MAc. Scanning electron microscopic (SEM) examination of extracted surfaces of PVCr/NBR+MAc blends indicates the increase of the interfacial interaction between PVCr and NBR phases with the presence of Mac.

Biomimetic Catalysis for Hemicellulose Hydrolysis in Corn Stover

Efficient and economical hydrolysis of plant cell wall polysaccharides into monomeric sugars is a significant technical hurdle in biomass processing for renewable fuels and chemicals. One possible approach to overcoming this hurdle is a biomimetic approach with dicarboxylic acid catalyst mimicking the catalytic core microenvironment in natural enzymes. This paper reports developments in the use of a dicarboxylic acid catalyst, maleic acid, for hemicellulose hydrolysis in corn stover. Hemicellulose hydrolysis and xylose degradation kinetics in the presence of maleic acid was compared to sulfuric acid. At optimized reaction conditions for each acid, maleic acid hydrolysis results in minimal xylose degradation, whereas sulfuric acid causes 3-10 times more xylose degradation. These results formed the basis for optimizing the hydrolysis of hemicellulose from corn stover using maleic acid. At 40 g/L dry corn stover solid-loading, both acid catalysts can achieve near-quantitative monomeric xylose yield. At higher solids loadings (150-200 g dry stover per liter), sulfuric acid catalyzed hydrolysis results in more than 30% degradation of the xylose, even under the previously reported optimal condition. However, as a result of minimized xylose degradation, optimized biomimetic hydrolysis of hemicellulose by maleic acid can reach approximately 95% monomeric xylose yields with trace amounts of furfural. Fermentation of the resulting unconditioned hydrolysate by recombinant S. cerevisiae results in 87% of theoretical ethanol yield. Enzyme digestibility experiments on the residual corn stover solids show that >90% yields of glucose can be produced in 160 h from the remaining cellulose with cellulases (15 FPU/g-glucan).