Gravimetric Tests Research Articles

Controlled‐release fertilizer based on poly(butylene succinate)/urea/clay and its effect on lettuce growth

ABSTRACTControlled‐release fertilizer is one of the most critical tools in agribusiness for decreasing environmental impacts. Thus, the development of bio‐based systems able to induce the slow release of fertilizers has become the focus of numerous researchers. In this sense, this work presents a slow‐release fertilizer prepared by melt mixing of poly(butylene succinate) filled with 30 wt % urea and 5 wt % montmorillonite clay. The obtained materials were characterized using FTIR, XRD, and SAXS. Also, the release of urea was investigated using gravimetric and spectrophotometric tests. Finally, a vegetable growth analysis was performed to evaluate the development of lettuce (Lactuca sativa L.). The best composite material can increase the diameter of the lettuce by 67%, whereas the conventional use of urea increased this diameter by 48%. Therefore, the presented materials are useful as fertilizer systems.

Inibidor de corrosão ambientalmente seguro: avaliando extratos de Plectranthus barbatus Andrews

O trabalho apresenta uma avaliação dos extratos etanólico e aquoso de Plectranthus barbatus Andrews (boldo brasileiro) como potenciais inibidores naturais de corrosão para o aço carbono P110 e inoxidável 22Cr-7Ni-3Mo (duplex 22 %Cr), em meio contendo ácido clorídrico 1,0 mol.L-1 e ácido sulfúrico 0,5 mol.L-1. O estudo foi realizado a partir de ensaios gravimétricos com variação na concentração dos extratos e obtenção das eficiências de inibição, e pela análise do perfil químico para identificar metabólitos presentes nos extratos. Os resultados indicaram a ausência de terpenos e a presença de flavonoides, taninos e compostos fenólicos em ambos os extratos. Os ensaios gravimétricos mostraram que os extratos apresentam excelentes resultados para o aço carbono, em ambos os ácidos, com valores de eficiência de inibição superiores a 90 %, revelando o potencial dos extratos como inibidores de corrosão para o aço carbono. Contudo, não apresentam para o aço inoxidável o mesmo desempenho, revelando valores baixos de eficiência de inibição não justificando o uso dos extratos como inibidores para este aço. Os extratos aquoso e etanólico possuem comportamentos diferentes conforme o ácido empregado, com o etanólico proporcionando melhores resultados em ácido sulfúrico e o aquoso em ácido clorídrico.

EVALUATION OF THE INFLUENCE OF THE TIDES ON THE PHYSICALCHEMICAL PARAMETERS PRESENT IN THE WATERS OF THE GUARAGUAÇU RIVER - PR

The GuaraguaçU River is an important Paranaense coastal ecosystem. As this water body approaches the mouth of the river, fresh water is gradually mixed with the salt water of the ocean by the action of the tidal cycle, thus characterizing the estuarine environment. In this study gravimetric tests were carried out to determine the concentration of total solids dissolved in the samples of said river. These values were compared with those of electrical conductivity and the salinity of the samples. Sixteen samples were collected in each of the two sampling periods, with the first period being high tide and the other with low tide. For the homogeneity of the results, the distance between the sampling points was 1100m, making the total of 18km. By evaluating the results obtained, one can notice that in the mixing of the waters three very distinct zones are formed: the first is the one in which there is predominance of continental water; the second is where the mixture of continental and oceanic waters occurs and the third is where there is predominance of oceanic water. In the second sampling zone, the increase in the values of the obtained results is clearly observed, the closer they are to the mouth of the river.

A wrapped nano-flame retardant composed of carbon nanotubes and phosphorus-nitrogen containing polymer: synthesis, properties and flame-retardant mechanism

A nano-flame retardant (PCP-CNT) with the phosphorus-nitrogen containing polymer (PCP) wrapped nanotubes (CNTs) was produced via strong π-π stacking interactions between the walls of CNTs and PCP polymerized with hexachlorocyclotriphosphazene (HCCP) and p-phenylenediamine (p-PDA). The structures and properties of PCP-CNT were characterized by infrared absorption spectrum (FTIR), solid 1H nuclear magnetic resonance spectroscopy (1H NMR), transmission electron microscopy (TEM) and thermal gravimetric analysis tests (TGA). The flame retardancy of the flame-retardant polybutylene terephthalate (FR-PBT) was studied via limited oxygen index (LOI) and cone calorimeter (CONE) tests. The pk-HRR of FR-PBT was significantly reduced by 59.8 and 69.4% with the addition of 10 and 15% PCP-CNT, respectively. In addition, the thermal degradation mechanism of the pristine PBT and FR-PBT were discussed by using Ozawa method.

Predicting Mechanical Strength of In-Use Firefighter Protective Clothing Using Near-Infrared Spectroscopy

The exact lifespan of in-use firefighter protective clothing is difficult to predict due to the large variations in use between individual garments. Furthermore, testing methods used to evaluate new protective clothing are destructive in nature and could not be applied to in-use garments. Various non-destructive techniques have been proposed for the evaluation of in-use clothing, each possessing its own advantages and disadvantages. The ability of near-infrared spectroscopy to predict the tensile strength of thermally aged fabrics used in protective clothing for wildland firefighters and other workers is investigated here. Fabrics were exposed to heat fluxes from 10 kW/m2 to 40 kW/m2 for various durations using the cone calorimeter, after which the tensile strength of the fabrics was measured. Temperatures measured during the exposures and results of thermal gravimetric analysis tests were used to interpret changes in tensile strength. Multivariate linear regression was used to develop correlations between the tensile strength and the reflectance values measured between 1500 nm and 2500 nm for new and thermally aged fabrics. It was found that models based on reflectance measurements made at as few as three wavelengths could be used to estimate the tensile strength of the thermally aged specimens.

Influence of exposure time on morphological and electrochemical properties of corrosion products formed by high temperature sulfidation of aisi/sae-1020 steel

In the present investigation, the influence of exposure time on the morphological and electrochemical properties of corrosion products formed on the surface of AISI/SAE-1020 steel was determined, exposed to conditions of a transfer line that enters the atmospheric distillation unit in the opportunity crude oils processing, applying gravimetry and electrochemical measurements. The exposure times used for gravimetric tests were between 24 and 330 hours. Discontinuous gravimetric tests were carried out in a Parr 4848 dynamic autoclave using a heavy crude oil (HCO) with sulfur content of 2.55 %wt. These results contribute to national and international scientific research and petrochemical industry by using a heavy crude oil contaminant such as sulfur, to reduce the corrosion rate of an AISI/SAE-1020 steel from the formation of iron sulfides on its surface.

Study of AISI/SAE-1020 Steel Corrosion by Sulfidation from Synthetic Sulfur Compounds of Different Molecular Structures

In recent years, the petrochemical industry has been affected by the decrease in global reserves of light crude oil, which has led to increase the processing of heavy crude oils with higher concentration of different contaminants that intensify corrosive phenomena. One of corrosion types that occur most frequently in the processing of heavy crude oils is sulfidation, which is caused by organic sulfur compounds of different molecular structures such as: mercaptans, sulfides, disulfides, polysulfides and thiophenes. These organic sulfur compounds are thermally decomposed at operating conditions of atmospheric distillation towers to generate hydrogen sulfide (H2S), which reacts with the steels used in different refinery equipment, resulting in the formation of iron sulfides layers on the material surface. However, morphological properties of the iron sulfides layers formed depend on the molecular structure of the organic sulfur compounds commonly present in heavy crude oils. For this reason, in the present investigation the effect of molecular structure of different sulfur compounds on the morphological properties of corrosion products obtained by the sulfidation of AISI/SAE-1020 steel is determined. The tests are carried out using three different synthetic crude oils (SCO) prepared from a mineral oil matrix mixed with the corresponding sulfur compound: Dimethyl Sulfide, Dimethyl Disulfide and Ethanethiol. The exposure times used for the gravimetric tests were 24, 36, 48, 60 and 72 h at a constant temperature of 300 °C. Discontinuous gravimetric tests are carried out in a batch static autoclave using synthetic crude oils (SCO) with total sulfur content equal to 1 %wt. Morphological characterization of the corrosion products formed on the surface of AISI/SAE-1020 steel was carried out using the techniques Scanning Electron Microscopy (SEM), in combination with Energy-dispersive X-Ray Spectroscopy (EDS), and X-Ray Diffraction (XRD). The effect of the molecular structure of sulfur compounds on the morphological properties of iron sulfides formed on AISI/SAE-1020 steel is of great interest for the petrochemical industry due to the use of a heavy crude oil contaminant for the formation of an organic coating on the steel surface, which can inhibit corrosion by other contaminants present in the crude oil.

Montmorillonite as corrosion protective pigment

Different types of montmorilonites (MMTs) were studied for a survey of properties which may contribute for corrosion control, while they are employed as pigments in corrosion protective organic coatings. Experimental methodology involves epoxy novolac paints specially formulated with iron oxide plus 1 or 5 wt.% MMTs, long term corrosion tests, gravimetric tests, titrations of MMTs filtrates and suspensions. The emphasis in literature is that MMTs improve barrier properties. Nevertheless, results revealed that MMTs are not inert pigments. They have two important properties hardly considered: active corrosion inhibition and control of H+ permeation which depend on MMTs affinity by water.

High temperature corrosion behavior on molten nitrate salt-based nanofluids for CSP plants

Recently, a number of theoretical and experimental studies have been performed to understand the effect of nanoparticles on thermal properties and heat transfer performance but there is a lack regarding their corrosion properties. In this work, an extended corrosion characterization (at central tower plant storage temperature (565 °C)) has been carried out in two different grades of solar salt (industrial and refined purity) doped with the addition of 1 wt% Al2O3 nanoparticles or 1 wt% SiO2 nanoparticles. Corrosion rates were determined in commercial stainless steel commonly used in CSP technology (347SS) by gravimetric tests, measuring the weight gain during 1000 h, identifying the corrosion products by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The lowest corrosion rate (0.007 mm/year) was obtained in the refined solar salt with the addition of 1 wt% Al2O3 nanoparticles. A protective layer was formed in the steel-salt interphase, identified through XRD as Al2O3. Additionally, hematite (Fe2O3) and magnetite (Fe3O4) were obtained as unprotective corrosion products throughout the test carried out with or without nanoparticles. In addition, the presence of impurities on the salts generated some stable compounds, as magnesium ferrite (MgFe2O4).

PROTECTIVE PROPERTIES OF «SOLING» SERIES INHIBITORS IN ACIDIC MEDIA CONTAINING HYDROGEN SULPHIDE

The work presents the results of the study of a number of inhibitory compositions of the “Soling” series based on acetylenic alcohols and their mixtures with nitrogen-containing compounds of various types in a hydrochloric acid (0.1 M HCl) containing 100 ppm of hydrogen sulphide. Gravimetric tests and electrochemical studies were performed on mild steel St3 at ambient temperature. The exposure time of the samples was 24 h. Polarization curves were obtained in a three-electrode cell, using the SOLARTRON 1280 C electrochemical measuring complex. The following protective compositions were studied: Soling IK-1 on the basis of unsaturated alcohol in a mixture with sulfur-containing amide in an aqueous medium; Soling IK-2 on the basis of unsaturated alcohol with additions of quaternary ammonium salt and complexone; Soling IK-3 on the basis of unsaturated alcohol in the system of organic solvents, as well as Soling IK-4(A) on the basis of a high-molecular nitrogen-containing surfactant (molecular weight from 300 to 400) with additions of unsaturated alcohol in a system of organic solvents and Soling IR-4(B) based on a high-molecular nitrogen-containing surfactant with a molecular weight of up to 300. It has been obtained that the use of unsaturated alcohols without additives in the presence of hydrogen sulphide is possible only at sufficiently high concentrations. At low concentrations, the corrosion process is markedly stimulated (composition IK-3). In a mixture with nitrogen-containing compounds (compositions IK-1, IK-2, IK-4(A)) it is possible to achieve high protective effect allowing the use of these compositions for hydrogen sulfide-containing media. The most effective are the compositions IK-2 and IK-4(A), for which the protective effect reaches the values of 97 and 90%, respectively, and also these compositions in the whole range of concentrations studied eliminate the appearance of hydrogen blistering. In most cases, the studied compositions are characterized by effective inhibition of the partial cathodic process. For SolIng IK-2 inhibition of the partial anodic reaction is clearly expressed.Forcitation:Menshikov I.A., Shein A.B. Protective properties of «Soling» series inhibitors in acidic media containing hydrogen sulphide. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 7. P. 90-97

A novel protocol for rapid identification of anisotropic diffusion properties of polymer matrix composite materials with complex texture

The paper focuses on a proposal for a novel protocol for the rapid identification of anisotropic diffusion properties of composite materials with complex texture. The method consists in performing small time gravimetric tests on composites samples and measuring the initial slope of their mass uptake curve with respect to t. The identification is performed by employing the analytical expression of the slope of the curve in the anisotropic case, an extension of the Shen and Springer slope method for isotropic and orthotropic diffusion. Analysis and discussion are dealt within a planar anisotropic diffusion test case issued from the literature.

Biofilm Formation and Corrosion on Carbon Steel API 5LX60 in Clayey Soil

Corrosion of buried pipelines is a matter of concern to the oil and gas industry since the time when carbon steel began to be widely used in these pipelines for the transportation of fluids. The microbial communities associated with biofilms promote modification in the surrounding environment and may accentuate the degradation of oil and gas pipelines causing leaks or even accidents. This work aimed to evaluate corrosion and biofilm formation in carbon steel API 5LX60 coupons buried in clayey soil from an industrial region in north-eastern Brazil. The average corrosion rates were determined by gravimetric test and the quantification of bacteria and fungi were using the Most Probable Number (MPN) and Colony Forming Units (CFU) techniques respectively. The results showed a great influence of clayey soil on corrosion rates and time of adherence for microorganisms on metal surfaces.

Corrosion Protection of Pipeline Interior Surface By Sacrificial Metal Coatings in a Natural Gas Environment

While corrosion protection of the exterior of natural gas pipeline has developed to be a routine process, including use of coatings and cathodic impressed current systems; the protection of the inside of the pipe is not as straightforward. This work explores the use of sacrificial metal coatings to protect the pipes inner surface. Coatings, applied by techniques including hot dip, electroplated, and thermally spray, were applied to one side of low carbon steel plates which were similar in composition to an API 5L pipeline steel. Coatings evaluated included Zn, alloys of Zn (95 Zn-5 Al, 85 Zn- 15 Al), Al, and an alloy of 95 Al- 5 Mg. Existing models suggest that any residual water, which often contains chlorides and CO2 from the gas, will be the primary contributors to any corrosion. Gravimetric corrosion tests were conducted in autoclaves to simulate the partial pressure of CO2 found in a natural gas pipeline. A test condition of; immersed samples in a 3 ½ wt. % NaCl brine, with a pressure of 300 kPa (45 psig) of CO2, and a temperature of 40 °C; was used. Tests of 168 h duration with, and without, a nonconductive masking of the steel substrate were conducted. For the tests where the steel surfaces were exposed, on the back side of the coated side of the steel test coupons, did not show significant corrosion after the tests with any of the sacrificial coatings. For the Zn, or Zn alloy, samples; a layer of ZnCO3 formed on coated and uncoated steel surfaces. The results indicated that for these conditions, the thermally sprayed coatings showed less weight loss than the hot dipped or electroplated coatings, and the Zn alloy with 15% Al had less weight loss than either the pure Zn or the Zn with 5 % Al. Visual examination indicated that while AlMg alloy successfully protected the uncoated steel from corrosion, it showed heavy corrosion including pitting in these conditions.

INVESTIGATION OF HIGH-ALLOY CHROME-NICKEL STEELS CORROSION RESISTANCE

Background Oil and gas equipment is subjected to intense internal corrosion throughout the entire process of oil and gas production and treatment. Corrosive aggressiveness of the environment is provided by dissolved gases present in the formation and waste waters: oxygen, hydrogen sulphide, carbon dioxide, as well as the vital activity of bacteria and high mineralization. The most dangerous consequence of these factors is the development of local corrosion on the metal. Highly significant equipment in the oil and gas fields are the tubing and casing pipes. One of the ways to improve their durability is to use corrosion-resistant steels that are highly resistant to acidic and alkaline environments, as well as aggressive salt solutions. High-alloy chromium-nickel steels of 08Kh18N10T and 10X17N13M2T grades are often used for these purposes. Aims and Objectives Study of 08Х18Н10Т and 10Х17Н13М2Т steels to pitting corrodibility. Investigation of the of inhibitor protection influence on the change in corrosion rate of underground equipment and pipelines of producing wells at the fields of Samotlorneftegaz JSC using the simples of 08Х18Н10Т and 10Х17Н13М2Т steels. Metods Gravimetric tests of the steels under investigation were carried out in accordance with State Standard 9.502-82 «Unified system for protection against corrosion and aging. Metal corrosion inhibitors for water systems. Methods of corrosion testing». Tests on pitting corrodibility were carried out in accordance with State Standard 9.912-89 «Steels and alloys are corrosion-resistant. Methods of accelerated tests for resistance to pitting corrosion». Polarization studies were performed on the Field Machine potentiostat in a three-electrode clamp electrochemical cell. Corrosive media for polarization studies was a model fluid simulating the composition of the reservoir water of the Samotlor field. Results As a result of gravimetric tests, it is established that in highly aggressive chlorine-containing media steels 08Х18Н10Т and 10Х17Н13М2Т are subjected to local pitting corrosion, and the corrosion resistance of steel 10Х17Н13М2Т is higher than that of 08Х18Н10Т steel. Based on the results of polarization studies, it has been established that the application of the corrosion inhibitor SONKOR-9011 at a concentration of 30 ppm provides a shift in the corrosion potential of the steels to be investigated in the positive range, with a protective effect of 66 %.

Protective Performance of Polyaniline-Sulfosalicylic Acid/Epoxy Coating for 5083 Aluminum.

Epoxy coatings incorporating different content of sulfosalicylic acid doped polyaniline (PANI-SSA) have been investigated for corrosion protection of 5083 aluminum alloy in 3.5% NaCl solution. The performance of the coatings is studied using a combination of electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), gravimetric tests, adhesion tests, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the content of PANI-SSA not only affects the coating compactness and the transportation of aggressive medium, but also has a significant influence on the-based aluminum. The coating with 2 wt. % PANI-SSA exhibits the best corrosion inhibition due to its good protective properties and the formation of a complete PANI-SSA induced oxide layer.

A much cheaper method to separate ethanol after solid-state fermentation process in renewable energy production

Abstract Planar Thermal Source (PTS) was used to separate ethanol from Solid-State Fermented crushed straw Material (SSFM) instead of the traditional separation method of water steam in Advanced Solid-State Fermentation technology (ASSF). Complete thermo gravimetric test was done on prepared material to study the mass change rules under heating of PTS. Factors considered were temperature of PTS (T, 20–100 °C), wet content of material (θ, 0.1–0.9), ethanol concentration in wet of material (ω, 0.03–0.11). The weight order of factors on material mass change speed V was T > θ > ω, and ω can be ignored for that was an order of magnitude less important than θ and T. V linearly increases with higher T, increases by power function with higher θ. V model with T and θ was regressed. As ethanol separating from SSFM can be considered as ethanol evaporating from ethanol solution, ethanol solution evaporation model was derived. Above all, model of ethanol separation from SSFM by PTS was derived. The cost model was added. Software was programmed to calculate the separation process and its cost. The method will promote the ASSF technology to produce fuel ethanol. The study can also be reference on drying process of other crushed plant material.

DEVELOPMENT OF TECHNOLOGY OF SYNTHESIS CORROSION INHIBITOR FOR DRILLING AGENTS

Background Metal equipment used in drilling wells may be exposed to corrosion. Dissolved gases in the drilling fluid, such as oxygen, carbon dioxide and hydrogen sulfide, can lead to serious corrosion damage to equipment, both on the surface and inside the well. Aims and Objectives The aim is to develop the production of corrosion inhibitor technology for drilling agents. Results The technological scheme for production a new corrosion inhibitor prepared by reacting triethylenetetraamine and 1,2-dichloroethane is worked out. The optimum synthesis conditions are identified. We investigated the physicochemical properties of the compound. To test the protective properties, the received inhibitor was subjected to electrochemical and gravimetric tests on the corrosion rate of steel specimens. According to the results of tests inhibitor at low concentrations showed a high degree of protection - 98,5 % in hydrochloric acid so that it can be recommended for industrial applications to protect equipment in drilling agents. The most optimal concentration of the inhibitor was determined by efficiency and cost.

Polymer-Ceramic Composite Scaffolds: The Effect of Hydroxyapatite and β-tri-Calcium Phosphate.

The design of bioactive scaffolds with improved mechanical and biological properties is an important topic of research. This paper investigates the use of polymer-ceramic composite scaffolds for bone tissue engineering. Different ceramic materials (hydroxyapatite (HA) and β-tri-calcium phosphate (TCP)) were mixed with poly-ε-caprolactone (PCL). Scaffolds with different material compositions were produced using an extrusion-based additive manufacturing system. The produced scaffolds were physically and chemically assessed, considering mechanical, wettability, scanning electron microscopy and thermal gravimetric tests. Cell viability, attachment and proliferation tests were performed using human adipose derived stem cells (hADSCs). Results show that scaffolds containing HA present better biological properties and TCP scaffolds present improved mechanical properties. It was also possible to observe that the addition of ceramic particles had no effect on the wettability of the scaffolds.

Influence of submicron-sheet zinc phosphate synthesised by sol–gel method on anticorrosion of epoxy coating

Abstract Submicron-sheet zinc phosphate (SZP) was synthesised by sol–gel method. Anticorrosion behaviour of epoxy coating with SZP was investigated by electrochemical impedance spectroscopy, gravimetric test, adhesion test and scanning electron microscopy. Results showed that the submicron-sheet structure of SZP pigment can reduce defects in the coating, improve consistency of pigment/resin interface and lengthen diffusion pathways. SZP pigments in coating had more contact area with permeating water, ensuring PO 4 3− quickly attained the specific density to inhibit corrosion on the steel surface. Thus, SZP pigment can enhance the barrier properties of coatings and effectively inhibit the corrosion reactions at coating/metal interface.

Anticorrosion behaviour of amorphous silicon-based coatings prepared by remote cold plasma-assisted chemical vapour deposition process

Organosilicon films were deposited on carbon steel samples using remote microwave nitrogen plasma-assisted chemical vapour deposition. The deposits were obtained using TetraMethyDisoloxane monomer mixed with oxygen. The formed films were characterised using electron microprobe analysis, Fourier transformed infrared spectroscopy, contact angle measurements, scanning electron microscopy and atomic force microscopy. The electrochemical properties of the organosilicon coatings were evaluated using gravimetric experiments next to electrochemical tests. A significant increase in the corrosion resistance behaviour of the organosilicon coated carbon steel specimen was found when the samples were immersed in 3% aqueous sodium chloride solutions. Also, the surface pre-treatment process of carbon steel had an important influence on the morphological and electrochemical behaviour. Argon pre-treatment improves significantly the corrosion resistance or organosilicon coated steel samples. Gravimetric tests in particular showed that samples pre-treated with argon result in lower weight loss and decreased corrosion rates compared to interfaces pre-treated with nitrogen plasma. Keywords: PACVD, carbon steel, organ silicon, corrosion, pre-treatment, electrochemical impedance spectroscopy.