Papers by Keyword: HCl

Abstract: Corrosion is a change in the properties of a material, mainly metal, due to a reaction with the surrounding environment. One of The ways to inhibit corrosion is by adding inhibitors. Organic inhibitors are inhibitors that are considered environmentally friendly. In this study, the guava leaf extract of Psidium guajava was used as an organic inhibitor. Materials used are API 5L Grade B steel in 1M HCl solution as corrosive media with the concentration of the extract used in this study 1188ppm with a temperature variation of 30, 35, 40, 45, and 50 Celcius degrees. The types of tests carried out in this study were Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization. The results of the potentiodynamic polarization test of organic inhibitors obtained an efficiency of 96.7550% with a corrosion rate of 1,04460 mm/year at a temperature of 30 degrees Celsius. In the electrochemical impedance spectroscopy test, the efficiency was 96,8546%, at a temperature of 30 degrees Celsius. The results of this study showed that the inhibitor of organic Psidium Guajava extract was The higher the temperature given to the inhibitor, it does not significantly affect the efficiency of the inhibitor, which acts the corrosion rate.

Abstract: The inhibition performance of Arachis hypogaea (AH) surfactant-based oil on 316L steel in 5 M HCl solution was studied by weight loss method. Result showed that AH shielded 316L steel from the severe corrosion effect of of Cl^- anions responsible for 316L corrosion in HCl at 0% AH concentration. The optimum inhibition efficiency occurred as 89.72% at 504 h as AH retarded the redox reaction for all other samples of inhibited AH inhibitor concentration. Adsorption of AH onto 316L surface was effective as the regression values moved close to unity with 0.9458, obeying Langmuir isotherm adsorption principle.

Abstract: The pitting corrosion resilience and passivation behaviour of 434 ferritic stainless steel was studied in 1 M H₂SO₄ solution at 0% to 2% NaCl concentration by potentiostatic technique and optical illustration characterization. Data showed 434 steel underwent metastable pitting activity at the lowest metastable pitting potential and current by reason of the effect of SO₄^2- anions within the electrolyte. Addition and increase in Cl^- anion concentration decreased the potential while simultaneously increasing the current value at which metastable pitting occurs till 1% NaCl concentration. The presence of chlorides decreased the passivation range of the steel with regards to Cl^- anion concentration compared to the electrolyte without chlorides till 0.5% NaCl concentration. Beyond this concentration no further decrease in the steel’s passivation range was observed despite increase in chloride concentration. Beyond 1% NaCl concentration passivation of the steel completely collapsed signifying threshold chloride concentration for optimal steel utilization on astringent conditions. Potentiostatic data showed variation in chloride concentration from 0.25% to 1% had strong effect on the pitting resistance of 434 steel. Optical images of 434 steel morphology at 0%, 0.25% and 2% NaCl concentration in 1 M H₂SO₄ solution showed important details. At 0% and 0.25% NaCl concentration, corrosion pits were clearly visible though the dimension and depth of the pits from the electrolyte with 0.25% NaCl concentration were more defined and deeper. At 2% NaCl concentration, corrosion pits were larger and the surface morphology showed severe morphological deterioration by reason of the synergistic action of SO₄^2- and excess Cl^- anions.

Abstract: The protection performance of admixed Lavandula latifolia and Ricinus communis (LLRC) oil distillates on low carbon steel in 0.5 M H₂SO₄ and HCl was performed by gravimetric measurement. Data output shows LLRC distillate effectively stifled the corrosion of the carbon steel with peak protection performance of 96.35% at 1% LLRC concentration in H₂SO₄ solution and 88.72% at 6% LLRC concentration in HCl solution. LLRC performed more effectively in H₂SO₄ solution than in HCl. The performance of LLRC in H₂SO₄ exhibited significant non dependence on observation time while LLRC concentration strongly influenced its performance. In HCl solution observation time and LLRC concentration influenced the performance output of LLRC distillate in different proportions. Statistical evaluation rated the influence of LLRC concentration the protection performance of LLRC at 90.66% compared to 2.22% for observation time, while the corresponding values in HCl are 55.37% for LLRC concentration and 21.04% for observation time. Calculated data for standard deviation shows relatively minimal variation from mean values with respect to LLRC concentration and observation time at lower LLRC concentration in H₂SO₄ solution. At higher LLRC concentration, the degree of variation increases due to relative instability with respect to exposure time. The standard deviation values in HCl are significantly and relatively higher than the values obtained in H₂SO₄ solution due to significant deviation from mean values which signifies extensive instability with respect to exposure time. The margin of error shows 91.7% and 93.3% of LLRC protection performance data in H₂SO₄ and HCl solution are greater than 80% inhibition efficiency at margin of error of +6.99% and +6.31%.

Abstract: The corrosion mitigation effect of aminophen (an organic fluid derivative) on 1070 aluminum alloy was studied in 1 M HCl solution by potentiodynamic polarization and weight loss analysis. Data obtained showed aminophen performed poorly at low concentrations (2.5%, 5% and 7.5%) with optimal value of 49.9% and 30% (potentiodynamic polarization and weight loss analysis) at 7.5% aminophen concentration. At 10% concentration, significant improvement in inhibition efficiency value was observed (53% and 61.33%), but the value is below the threshold minimum for effective inhibition. Effective inhibition efficiency occurred at 12.5% and 15% aminophen concentration with values of 71% and 81.67% at 12.5% concentration, and 89% and 70.77% at 15% concentration. Plots from weight loss indicated stable thermodynamic behavior throughout the exposure hours. Aminophen demonstrated anodic-cathodic type inhibition characteristics with dominant cathodic inhibition action. Corrosion inhibition behavior of aminophen aligned with Frumkin and Freundlich adsorption isotherm models. However, thermodynamic calculations show adsorption did not occur. Inhibition behavior of aminophen on 1070 aluminum occurred through modification of the corrosive media.

Abstract: Retracted article: Neem leaf oil distillates (NLD) was evaluated for its corrosion inhibition properties on low carbon steel in 0.5 M HCl, 1 M HCl, 3.74 M NH₄Cl and 5.61 M NH₄Cl solutions. Weight loss analysis shows NLD performed effectively at all concentrations studied in HCl media with optimal inhibition efficiencies of 97.54% and 97.56% at 5% NLD concentrations. NLD performed poorly at 1-4% NLD concentration in 3.74 M and 5.61 M NH₄Cl solutions with protection performance values below 50%. At 5% NLD concentration the protection performance values increased sharply to 78.53% and 79.0% at 312 h of exposure. Standard deviation values for NLD protection performance output in 0.5 M HCl solution were significantly high indicating highly unstable inhibition behavior and thermodynamic tendency to corrode with respect to exposure time. At 5% NLD concentration the standard deviation value decreased significantly. In 1 M HCl, 3.74 M NH₄Cl and 5.61 M NH₄Cl solutions the standard deviation values were relatively low due to improved stability of protonated NLD molecules in interaction with the steel surface. Experimental data showed 92.44%, 100%, 30.77% and 20% of NLD protection performance data from 0.5 M HCl, 1 M HCl, 3.74 M NH₄Cl and 5.61 M NH₄Cl solutions are above 70% inhibition value with margin of error of +7.99, +0, +11.22 and +9.72. Statistical data from analysis of variance showed exposure time dominates the performance output of NLD distillate on low carbon steel from 0.5 M HCl and 1 M HCl at values of 81.76% and 82.03% compared to the effect of NLD concentration which were negligible. In NH₄Cl solution, NLD concentration dominates the protection performance output of NLD on the carbon steel compared to exposure time with values of 96.42% and 96.95%.

Abstract: Adsorption isotherms of Ni (II) and Cu (II) ions by alumino-silicates, modified with N, N'-bis (3-triethoxysilylpropyl) thiocarbamide (BTM-3), and HCl, were obtained. The adsorption kinetics of heavy metal ions is studied, using the kinetic pseudo-first and pseudo-second order models. It is shown that, when alumino-silicates are modified, the rate and energy of adsorption increase. It is established that the kinetics of the adsorption of the studied ions is best described by a pseudo-second order model. The maximum value of the adsorption rate constant of 33.7∙10^-5 g/ (mmol min) corresponds to nickel (II) ions for alumino-silicates, modified with HCl. The maximum value of the adsorption rate constant value of 2.91∙10^-5 g/ (mmol min) for alumino-silicates, modified with BTM-3, corresponds to Cu (II) ions.

Abstract: Corrosion behavior of the alloys 1.7386 (P9), 1.4462, 1.4841, 1.4959 (Alloy 800HT) and 2.4816 (Alloy 600) was tested for 24, 72 and 240 h between 480 – 680 °C. The testing gas atmosphere contained 3.8 vol. % HCl, 200 ppm H₂S and CO, CO₂ and N₂. It simulated conditions present in a thermal cracking process for post-consumer plastics. Samples were analyzed by metallography, SEM/EDX and XRD after corrosion experiments. Additionally, their mass loss during the test was evaluated. A multilayered structure of corrosion products grew on the samples during the corrosion experiments. The composition of the corrosion products depended not on the material, but on the testing temperature. At 680 °C chromium sulphide formed the outer layer, followed by a chromium oxide layer. Below these two layers a chlorine containing layer was observed. At 480 °C mainly nickel sulphide was detected, besides chromium oxide and iron- and chromium chloride. Especially at higher testing temperatures FeCl₂ was not observed directly on the samples, but as colorless crystals at the colder parts of the testing equipment. At 680 °C the mass loss of the samples decreased with increasing nickel content. However, this effect changed entirely at lower testing temperatures. At 480 °C 1.7386 and 2.4816 showed nearly the same mass losses.

Abstract: In this paper, acrylic acid was grafted to chitosan in order to change the structure; polymer was obtained from modified chitosan. A series of novel toughened composite NF memebranes were prepared by over-coating the polysulfone ultrafiltration membrane with the polymer of modified chitosan. The chitosan derivatives and the polymer were characterised by infrared spectrophotometer (IR); the structure of the membrane was characrerised by scanning electron microscopy (SEM) and atomic force microscope (AFM). The composite NF membrane’s performances were strictly related to the structure of polymer. The rejection of the membrane was 96.3% with flux as high as 386.46 L m^-2 h^-1 with the 1000 mg/L of NaCl. Tensile strength of membrane increased 46%. The HCl (5%) resistance increased from 20.3 to 36.8h. The NaOH (5%) resistance increased from 18.3 to 31.6h. These results indicated the prepared toughened composite NF memebrane was excellent NF membrane, which had a wide application prospect.

Abstract: By inspecting the CVD growth parameters, such as the flow rates of HCl and H₂ carrier gases, the pressure and the C/Si ratio, the trench filling in a high-rate mode with a high growth rate on the bottom and a relatively low growth rate on the mesa top was carried out. 4H-SiC trenches with the depths of 48 and 55 μm have been completely filled at the rates of 6.2 and 5.5 μm/h, respectively.