Chemical Titration Method Research Articles

Epoxy Value Measurement of E44 Epoxy Resin by Various Chemical Titration Method

AbstractDuring the production of epoxy resins, it is crucial to control or to know the epoxy groups. It is known that epoxy value is the most important analytical index of epoxy resin physical quantity to characterize the number of epoxy groups in epoxy resin. In this paper, two ways for testing the epoxy values of E44 epoxy resin are developed based on chemical titration method: hydrochloric acid‐acetone method and perchloric acid‐tetraethylammonium bromide method. The features of different methods and the influence of approaches on epoxy value are studied systematically. At the significant level of 0.05, for hydrochloric acid‐acetone method, the confidence interval for the mean is (0.454±0.003)eq/100 g, and for perchloric acid‐tetraethylammonium bromide method, the confidence interval for the mean is (0.453±0.003)eq/100 g. It has been proved that the test results of the two methods are basically the same. And the advantages and disadvantages of the two methods have been put forward. In addition, the testing mechanism of hydrochloric acid‐acetone method and perchloric acid‐tetraethylammonium bromide method is illustrated in detail. On the basis of superiority over the two methods, a novel method for testing epoxy resin with rapid and accurate epoxy value can be envisioned.

Phase Composition and Analysis of Surface Micromorphology of Animal Medicine Concha Arcae and Calcined Concha Arcae

The components of concha arcae and calcined concha arcae were analyzed by X-ray powder diffraction and calculated their contents, and their surface morphology was observed by scanning electron microscope. The experimental results showed that the concha arcae was composed of aragonite type and calcite type calcium carbonate, and calcined concha arcae was composed of calcium oxide, calcium hydroxide and calcium carbonate. The surface micromorphology of them were significantly different. Rietveld refinement can accurately and quickly complete the phase identification and quantitative analysis of raw and calcined products of concha arcae by Powder X-ray diffraction, it is more convenient and fast compared with chemical titration method.

Morphology, chemical reaction mechanism, and cross-linking degree of asphalt binder modified by SBS block co-polymer

Recently, the batch production of styrene–butadienestyrene (SBS) modified asphalt has been realized, but quality control is still in the empirical stage. While the chemical reaction position and the cross-linking degree are unclear, affecting the controlling quality of SBS modified asphalt. Therefore, this study investigated the influence of the reaction conditions and the stabilizer content on the performance and morphology of the SBS modified asphalt. And whether the chemical reaction exists and the chemical reaction position were confirmed by preparing the polystyrene (PS) monomer, polybutadiene(PB) monomer, and SBS modified asphalt with and without stabilizer. Finally, the fluorescence microscope (FM) test, Fourier transformation infrared spectroscopy (FTIR) test and the chemical titration method were used to characterize quantitatively the microstructure changes of SBS modified asphalt. The results show that the reaction conditions greatly influence the performance of SBS modified asphalt. After adding the stabilizer, the phase state of the system changed from the SBS phase as a dispersed phase and the asphalt phase as a continuous phase to the double continuous phase, and the network structure was formed. The chemical reaction has taken place in the PB and SBS modified asphalt, and the PB segment of the SBS polymer participates in the chemical reaction. Furthermore, the degree of cross-linking reaction of SBS modified asphalt is low, and the range of the cross-linking percentage is about 12.3%-14.5%.

Elucidating the photodissociation fingerprint and quantifying the determination of organic hydroperoxides in gas-phase autoxidation

Hydroperoxides are formed in the atmospheric oxidation of volatile organic compounds, in the combustion autoxidation of fuel, in the cold environment of the interstellar medium, and also in some catalytic reactions. They play crucial roles in the formation and aging of secondary organic aerosols and in fuel autoignition. However, the concentration of organic hydroperoxides is seldom measured, and typical estimates have large uncertainties. In this work, we developed a mild and environmental-friendly method for the synthesis of alkyl hydroperoxides (ROOH) with various structures, and we systematically measured the absolute photoionization cross-sections (PICSs) of the ROOHs using synchrotron vacuum ultraviolet-photoionization mass spectrometry (SVUV-PIMS). A chemical titration method was combined with an SVUV-PIMS measurement to obtain the PICS of 4-hydroperoxy-2-pentanone, a typical molecule for combustion and atmospheric autoxidation ketohydroperoxides (KHPs). We found that organic hydroperoxide cations are largely dissociated by loss of OOH. This fingerprint was used for the identification and accurate quantification of the organic peroxides, and it can therefore be used to improve models for autoxidation chemistry. The synthesis method and photoionization dataset for organic hydroperoxides are useful for studying the chemistry of hydroperoxides and the reaction kinetics of the hydroperoxy radicals and for developing and evaluating kinetic models for the atmospheric autoxidation and combustion autoxidation of the organic compounds.

Comparative Study on Effectiveness of Organic Apple Juice Vinegar Over Commercially Available Vinegar Using Chemical Titration Technique for Chicken Quality Analysis

Aim: The purpose of this research is to develop a new apple vinegar based on Podophyllum peltatum and analyze the fermentation process using a new methodology. Materials and Methods: The vinegar-making process began with the addition of Saccharomyces cerevisiae (yeast) and l (acetic bacteria) with apple. Chemical titration method is used to find out the apple juice microbial and compared to the microbial in vinegar. The microorganisms Saccharomyces cerevisiae and Acetobacter pasteurianus were found respectively. Fermentation began with fewer Saccharomyces cerevisiae and Acetobacter pasteurianus, but they were present throughout the alcoholic and acetic phases. Both microbial strains produced ethanol and acetic acid using apple as a substrate. The vinegar also produced acetate, volatile alcohols, and aldehydes. Two groups are taken with 9 sample size per group, G power 80%, coincidence intervals will be 95%. Results and Discussion: The innovative apple vinegars had an acetic acid yield of 8.1%. In the sensory evaluation, apple vinegar was well received. The technology proposed here is innovative in that it employs mixed inocula instead of separate ones (p=0.001). It also uses cell biomass instead of centrifugation at the end of the fermentative process. When compared to commercial vinegar (5%), apple vinegar has a high acetic acid concentration (8.1%). Conclusion: Reduce the working time and also be less expensive. Higher acetic acid concentration in vinegar is helpful to improve the taste of the food.

Chloride ion transport behavior of concrete containing insulating glazed hollow beads exposed to high temperature

• GHBs are beneficial to improve impermeability of concrete after fire. • GHBs have great significance for improving the concrete resistance to thermal damage. • The chloride ion diffusion and remaining service life of GIC after fire was calculated. • A thermal damage permeability model was established. Concrete building structures often suffer serious damage after fire, which poses a great threat to the durability of structures. Due to the high thermal stability and pressure relief mechanism of glazed hollow beads (GHBs), GHBs are of positive significance in improving the concrete’s resistance against high temperature. In this paper, the electric flux test was utilized to investigate the chloride ion transport behaviors of concrete containing insulating GHBs (GIC) after high temperature exposure. The electron probe micro-analysis (EPMA) combined with chemical titration method was adopted as a supplement to carry out a more in-depth analysis on concrete’s permeability. The results show that the anti-chloride ion transport performance of GIC was significantly improved compared to normal concrete. Experimental permeation data were further used to prepare a thermal damage permeability model. That is then used to discuss the impact of including glazed hollow beads on concrete’s residual service life after a fire. These data provide technical guidance for the engineering design and safe operation of undersea tunnels and other structures at risk of fire and subsequent saline water intrusion.

Development of quantitative and concise measurement method of oxygen in fine bubble dispersion.

Fine bubbles (FBs) have attracted significant attention in several research fields. Although some reports have argued that FB dispersion is useful as an oxygen (gas) carrier, only a few reports have examined its properties as an oxygen carrier using experimental data. As one of the reasons for this, there are no standard methods for measuring the oxygen content in FB dispersions. Conventional oxygen measurement methods have certain drawbacks in accuracy or speed; thus, it is difficult to use oxygen content as the primary outcome. In this study, we introduce a Clark-type polarographic oxygen electrode device (OXYG1-PLUS) for oxygen measurement, allowing the dilution of FB dispersion without the influence of ambient air and the adhesion of FBs on the electrode surface due to its special shape. First, the accuracy of our dilution method was evaluated using pure water as a sample, and it was confirmed that our method could measure with an accuracy of ±0.5 mg/L from the results with conventional dissolved oxygen meters. Second, the oxygen content in FB dispersion was evaluated with our method and a chemical titration method (Winkler’s method), and it was found that our method could measure the oxygen content in FB dispersions quantitively. This method satisfies the easiness (4 steps) and quickness (within 8 min) for a wide range of oxygen contents (0 to 332 mg/L, theoretical range) with low coefficient variation (< 4.7%) and requires a small sample volume (50–500 μL); thus, it is a useful method for measuring the oxygen in FB dispersions.

A Global Ocean Oxygen Database and Atlas for Assessing and Predicting Deoxygenation and Ocean Health in the Open and Coastal Ocean

In this paper, we outline the need for a coordinated international effort toward the building of an open-access Global Ocean Oxygen Database and ATlas (GO2DAT) complying with the FAIR principles (Findable, Accessible, Interoperable, and Reusable). GO2DAT will combine data from the coastal and open ocean, as measured by the chemical Winkler titration method or by sensors (e.g., optodes, electrodes) from Eulerian and Lagrangian platforms (e.g., ships, moorings, profiling floats, gliders, ships of opportunities, marine mammals, cabled observatories). GO2DAT will further adopt a community-agreed, fully documented metadata format and a consistent quality control (QC) procedure and quality flagging (QF) system. GO2DAT will serve to support the development of advanced data analysis and biogeochemical models for improving our mapping, understanding and forecasting capabilities for ocean O2 changes and deoxygenation trends. It will offer the opportunity to develop quality-controlled data synthesis products with unprecedented spatial (vertical and horizontal) and temporal (sub-seasonal to multi-decadal) resolution. These products will support model assessment, improvement and evaluation as well as the development of climate and ocean health indicators. They will further support the decision-making processes associated with the emerging blue economy, the conservation of marine resources and their associated ecosystem services and the development of management tools required by a diverse community of users (e.g., environmental agencies, aquaculture, and fishing sectors). A better knowledge base of the spatial and temporal variations of marine O2 will improve our understanding of the ocean O2 budget, and allow better quantification of the Earth’s carbon and heat budgets. With the ever-increasing need to protect and sustainably manage ocean services, GO2DAT will allow scientists to fully harness the increasing volumes of O2 data already delivered by the expanding global ocean observing system and enable smooth incorporation of much higher quantities of data from autonomous platforms in the open ocean and coastal areas into comprehensive data products in the years to come. This paper aims at engaging the community (e.g., scientists, data managers, policy makers, service users) toward the development of GO2DAT within the framework of the UN Global Ocean Oxygen Decade (GOOD) program recently endorsed by IOC-UNESCO. A roadmap toward GO2DAT is proposed highlighting the efforts needed (e.g., in terms of human resources).

The Effect of the Calcination Temperature on the Physical, Chemical and Mineralogical Characteristics of Sugar Cane Bagasse Ash (SCBA) for Use As Pozzolan

Statement of Novelty: This study analyzes the influence of the washing process and the calcination temperature on the morphological, physical, chemical and mineralogical characteristics of SCBA. The objective of the present study is to evaluate the morphological, physical, chemical and mineralogical characteristics of sugar cane bagasse ash (SCBA). The ashes were obtained by calcination of sugarcane bagasse (SCB), a waste product generated by the sugar and alcohol industry, at temperatures of 500°C, 600° C and 700°C, and the influence of this calcination on the pozzolanic activity of SCBA. The techniques used to characterize these ashes include helium gas picnometry, sedigraphy, scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffractometry (XRD) and Fourier transform infrared spectrometry (FTIR). The evaluation of the pozzolanicity of these ashes was carried according to chemical titration method as proposed by Fratini, modified Chapelle method and finally using the pozzolanic activity index (PAI) with cement. The results showed that the SCBA presented high pozzolanicity, regardless of the calcination temperature.

Electroplating solution concentration detection based on interference principle and balanced detector

In this research work a noble approach towards measurement of solution concentration in electroplating process has been exercised by inducting laser interferometer and balanced detector. The research design of this study has been fragmented into three parts. In the first part, an experimental set up constituting of DFB laser, Michelson interferometer, reflector, balanced detector, oscilloscope and high performance industrial control computer was established for detection of electroplating solution concentration. In the second part, by taking the quantitative observations of solution concentration, light intensity, refractive index and voltage, a mathematical model was established. The model parameters were identified and verified by the common liquids. In the third part of the study, experiments were carried out on single solution and mixed solution during nickel plating of punched steel strip. The experiment revealed that the concentration detection of single solution, the error found was within 1.32%. In the concentration detection of mixed electroplating solution, the error was within 2.03%. The error is less than the detection error of chemical titration method (3%), which meets the requirements of the enterprise. It is indicated that the proposed method can detect the refractive index and liquid concentration quickly and accurately, which lays the foundation for the optimization control of the solution concentration in the process of nickel plating in punched steel strip.

Online real time determination of free formaldehyde content during polymerization process of phenolic resin by NIR spectra and a modeling-free method

Real time detection of free formaldehyde content during synthesis process of phenolic resins is of great significance for controlling the quality of resin products. In this paper, we proposed a method of near infrared (NIR) spectroscopy combined with multivariate curve resolution-alternating least squares (MCR-ALS) to online real time detect free formaldehyde content during the synthesis process of phenolic resins. The absorption band of CH bonds in formaldehyde was extracted by MCR-ALS from the overlapped absorption bands of CH bonds in phenol, formaldehyde and intermediate products, and is directly utilized to monitor free formaldehyde content during polymerization process. The calculated results of MCR-ALS are highly consistent with those obtained by the chemical titration method, which indicates this method is accurate. Compared with multivariate calibration commonly used for NIR, this method does not require modeling, and is more labor-saving and easier to spread in industrial production.

Synthesis and Characterization of Cationic Waterborne Epoxy Acrylic Resin

In this work, a cationic waterborne epoxy acrylic resin (WCEA) was synthesized from bisphenol an epoxy resin, acrylic acid, acrylic acid, hydroquinone as an inhibitor, and N, N-dimethylbenzylamine (DMBA) as a catalyst. The changes of NCO groups and acid value during the synthesis process were measured by chemical titration method, and its Fourier Transform Infrared (FTIR) spectra were investigated. The results indicate that the acidified waterborne resin has great water solubility and storage stability after grafting the half-blocked isocyanate.

Recognition of the Enzymatically Active and Inhibitive Oxygenous Groups on WO3-x Quantum Dots by Chemical Deactivation and Density Functional Theory Calculations.

The design and construction of efficient nanozymes are vital for bio/chemo-sensing applications, while the systematic catalytic mechanism study is the prerequisite. Tungsten oxide (WO3-x) quantum dots (QDs), an alternative to conventional heavy metal-containing semiconductor QDs, possess peroxidase-like activity but limited catalytic efficiency. Therefore, the functions of the typical oxygenous groups in determining the enzymatic activity of the WO3-x QDs by target-specifically shielding the carboxyl (-COOH), hydroxyl (-OH), or carbonyl (-C═O) groups, respectively, using a chemical titration method. The results show that the -C═O groups could accelerate the nanozymatic catalysis kinetically, while the -OH ones were the catalytically inhibitive sites, which were further corroborated by the density functional theory (DFT) computations. The application potential of the WO3-x derivatives with an enhanced catalytic ability was verified via the colorimetric cholesterol sensing. The proposed method based on the benzoic anhydride (BA)-modified WO3-x QDs with deactivated -OH groups showed a wider linear range and higher sensitivity than those based on the unmodified ones.

Synthesis of waterborne polyurethane acrylate–modified epoxy resin

This study aimed to synthesize a cationic waterborne polyurethane acrylate–modified epoxy acrylic resin (CWEA) from bisphenol A epoxy resin, acrylic acid, 2,4-toluene diisocyanate, polyethylene glycol 400 (PEG-400), 2-hydroxyethyl acrylate, and hydroquinone as inhibitors and N,N-dimethylbenzylamine as a catalyst. The changes in the NCO groups and the acid value during the synthesis process were measured using the chemical titration method. This method was considered as the best method for synthesizing epoxy acrylate monoesters, with optimal reaction conditions for polyurethane acrylate–modified epoxy resin.

Characteristics of the reduction behavior of zinc ferrite and ammonia leaching after roasting

A novel method for recovering zinc from zinc ferrite by reduction roasting-ammonia leaching was studied in this paper. The reduction thermodynamic of zinc ferrite by CO was analyzed. The effects of roasting parameters on the phase transformation and conversion rate of zinc ferrite, and the leaching behavior of zinc from the reductive roasted samples by ammonia leaching, were experimentally investigated. The mineralogical phase compositions and chemical compositions of the samples were characterized by X-ray diffraction and chemical titration methods, respectively. The results showed that most of the zinc ferrite was transformed to zinc oxide and magnetite after weak reduction roasting. 86.43% of the zinc ferrite was transformed to zinc oxide under the optimum conditions: CO partial pressure of 25%, roasting temperature of 750°C, and roasting duration of 45 min. Finally, under the optimal leaching conditions, 78.12% of zinc was leached into the solution from the roasted zinc ferrite while all iron-bearing materials were kept in the leaching residue. The leaching conditions are listed as follows: leaching duration of 90 min, ammonia solution with 6 mol/L concentration, leaching temperature of 50°C, solid-to-liquid ratio of 40 g/L, and stirring speed of 200 r/min.

Cu(II) Sorption Performance of Novel Chitosan/Ter-(vinyl pivalate-maleic anhydride-N-tert-butylacrylamide) Microcapsules

In this study, first, the ter-polymerization reaction between vinyl pivalate (VP), maleic anhydride (MA), and N-tert-butylacrylamide (NTBA) was done in inert atmosphere (N2). FT-IR and 1HNMR spectroscopy was applied to study the chemical composition of the obtained ter-polymers. MA content of the ter-polymers was determined by following the chemical titration method. Second, novel chitosan/ter-(vinyl-pivalate-maleic-anhydride-N-tert-butylacrylamide) microcapsules were synthesized. In microcapsule production, chitosan polymer served as a matrix for acrylamide ter-polymers with four different molar ratios. The microcapsules were characterized by FT-IR and SEM analyses. Cu(II) sorption efficiency of the microcapsules were tested at different pH levels, temperature, sorbent dosage, and metal ion concentration. Comparison with blank chitosan microbeads revealed that incorporation of acrylamide ter-polymers into the cross-linked chitosan matrix increased the metal sorption. Sorption capacities of the sorbents were recorded; blank chitosan microbeads: 67.03 mg g−1, and chitosan/acrylamide ter-polymer microcapsules: in range of 75.39–98.64 mg g−1. The findings demonstrated chitosan/acrylamide ter-polymer microcapsules can be utilized in sorption of Cu(II) ions in water treatment

Transformation of functional groups during lignite heat-treatment and its effects on moisture re-adsorption properties

The surface functional groups of lignite are thought to be the significant factor influencing the moisture re-adsorption behavior of dried coal. Several lignite samples with different surface functional groups were prepared by thermal treatment from 160 °C to 240 °C in N2 and air. In situ FTIR and chemical titration methods were carried out to measure the functional groups of the raw coal and dried samples, and the results from these two methods were compared. FTIR spectra were deconvoluted to reveal the transformation of different functional groups, e.g. CH3, CH2, CH, anhydrides, esters, aldehydes, carboxylic acid, quinones, and ketones. The moisture re-adsorption behaviors of the heat-treated coals under relative humidity of 75% at 25 °C were measured, and the effect of functional groups on moisture re-adsorption property was investigated. The results showed that CHx functional groups decreased dramatically, especially in air, when heat-treating temperature was higher than 200 °C. For the CH, CH2, and CH3 functional groups, their decomposition activation energies are 29.6, 44.2 and 19.3 kJ·mol−1, and their oxidation activation energies are 65.9, 36.1 and 36.5 kJ·mol−1, respectively. In air, when the heat-treating temperature raised to 240 °C, aromatic esters, aliphatic esters and anhydrides all sharply increased. The quinones were probably produced from the transformation of phenolic hydroxyl (Ar-OH) at 240 °C in air. Moreover, coal samples heat-treated in N2 and air showed different equilibrium moisture capacity, which can be attributed to the different contents of hydrophilic groups. The contents of ketones, aldehydes, COOH and Ar-OH had a good linear relationship with equilibrium moisture capacity. The hydrophilic abilities of ketones, aldehydes, COOH and Ar-OH in lignite are higher than that of quinones, esters and anhydrides.

A chemical titration method for quantification of carbenes in Mo- or W-containing catalysts for metathesis of ethylene with 2-butenes: verification and application potential

We introduce and experimentally validate a simple titration method for quantifying the number of carbenes acting as active sites in the metathesis of ethylene with 2-butenes over Mo- or W-containing catalysts.

Influence of nano-dimensionality on magnetotransport, magnetic and electrical properties of Nd1-xSrxMnO3-δ (0.3 ≤ x ≤ 0.7)

Magneto-electric and electronic properties of Nd1-xSrxMnO3-δ (0.3 ≤ x ≤ 0.7) (NSMO) nanoparticles are investigated. NSMO nanoparticles are synthesized by glycine assisted auto combustion method. The structural and morphological properties are probed using X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). NSMO crystallizes in orthorhombic structure and nearly spherical agglomerated morphology is observed. Resistivity of the order of few MOhm-cm is recorded for all the compositions and the transport mechanism is interpreted by using Mott variable range hopping (VRH) model. In absence of magnetic field all samples show insulating nature over the studied temperature region (300- 5 K), while Metal to Insulator transition is observed in the presence of magnetic field (8T). Large Colossal Magnetoresistance (CMR) is noticed below 50 K for NSMO.Observed Curie temperature is in the range of 102–115 K and it is found to be independent of Strontium doping concentration. Bifurcation in FC-ZFC, for all the samples, is at higher temperature than blocking temperature (∼72 K) indicates glassy state. We have calculated thickness of magnetic dead layer by two different ways and it lies between 1.6 and 2.9 nm. Concentration of divalent element and oxygen non-stoichiometry affects the relative fraction of Mn3+/Mn4+ ions. Mn3+/Mn4+ in our samples is determined from areas under the deconvoluted X-Ray Photoelectron Spectra (XPS) of Mn core level. The Mn3+/Mn4+ ratio is higher than the value expected from nominal composition, which indicates oxygen non-stoichiometry. Oxygen non-stoichiometry is also confirmed by chemical titration method.

Spectrophotometric methods for lignin and cellulose in forest soils as predictors for humic substances

SummaryThe origin and fate of humus, a soil organic matter fraction that is most resistant to decomposition, are not yet completely understood. Humus derives mainly from plant structural components; that is, lignin and cellulose, together with several other primary and secondary compounds. There are several methods to estimate lignin and cellulose in plant material; however, the applications to soil are limited and usually complicated and expensive. Conversely, humus can be estimated in soil by chemical titration methods, which estimate the carbon linked to humic and fulvic acids (HAC and FAC). Therefore, we carried out analyses that aimed to compare, within beech forest soils, spectrophotometric data for lignin and cellulose with those of HAC and FAC. We used soil samples from six different beech woods in Italy, sampling in four layers from 0–5 to 30–40 cm. The relations between spectrophotometric cellulose and lignin and HAC and FAC were tested by linear mixed models. Our results showed that both lignin and cellulose were significant predictors for HAC and FAC, even if cellulose had a larger conditional coefficient of determination (R2c). The best fit was between cellulose and the sum of HAC and FAC (R2c = 0.675). Our novel approach proved that spectrophotometric lignin and cellulose provide reliable results in both organic and mineral beech forest soils, even though lignin had a greater random variation than cellulose. Thus, spectrophotometric lignin and cellulose provide reliable and rapidly obtained predictors of humic substances in beech forest soils, with appropriate conversion factors to estimate HAC and FAC.Highlights Humic substances are of pivotal importance in the global carbon cycle. There is a need for simple and rapid methods to estimate humic substances. Spectrophotometric methods provide fast results for cellulose and lignin in soils. Lignin and cellulose function as good predictors for humic substances in forest soils.