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Inhibition Efficiency (inhibition + efficiency)

Distribution by Scientific Domains

Polymers and Materials Science	53%
Chemistry	46%

Selected Abstracts

Synergistic effect of halide ions and polyethylene glycol on the corrosion inhibition of aluminium in alkaline medium

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009
S.A. Umoren
Abstract The corrosion inhibition of aluminium in alkaline medium was studied at 30 and 40°C in the presence of polyethylene glycol (PEG) using gravimetric (weight loss) and thermometric techniques. The effect of halides (KCl, KBr, and KI) on the inhibitory action of PEG was also studied. It was found that PEG acted as inhibitor for aluminium corrosion in the alkaline medium. Inhibition efficiency increased with increasing inhibitor concentration. An increase in temperature led to increase in both the corrosion rate and inhibition efficiency in the absence and presence of inhibitor and halides. Phenomenon of chemical adsorption mechanism is proposed from the values of Ea, Qads, and ,G obtained. The adsorption of PEG on the surface of aluminium was found to obey Flory,Huggins and Temkin adsorption isotherms. The synergism parameter, S1 evaluated was found to be greater than unity indicating that the enhanced inhibition efficiency caused by the addition of halides is synergistic in nature. The inhibition efficiency, surface coverage and synergism parameter increased in the order; I,> Br,> Cl, showing that a joint adsorption of PEG and halide ions on aluminium plays a significant role in the adsorption process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 14 2010
Eno E. Ebenso
Abstract Density functional theory (DFT) at the B3LYP/6-31G (d,p) and BP86/CEP-31G* basis set levels and ab initio calculations using the RHF/6-31G (d,p) methods were performed on four sulfonamides (namely sulfaacetamide (SAM), sulfapyridine (SPY), sulfamerazine (SMR), and sulfathiazole (STI)) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies (%IE). The order of inhibition efficiency obtained was SMR > SPY > STI > SAM which corresponded with the order of most of the calculated quantum chemical parameters namely EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), the energy gap (,E), the Mulliken charges on the C, O, N, S atoms, hardness (,), softness (S), polarizability (,), dipole moment (,), total energy change (,ET), electrophilicity (,), electron affinity (A), ionization potential (I), the absolute electronegativity (,), and the fraction of electrons transferred (,N). Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the sulfonamides studied. The results showed that the %IE of the sulfonamides was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the sulfonamides studied was found to be close to their experimental corrosion inhibition efficiencies. The experimental data obtained fits the Langmuir adsorption isotherm. The negative sign of the EHOMO values and other thermodynamic parameters obtained indicates that the data obtained supports physical adsorption mechanism. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source]

Molecular Dynamics Simulation of Interaction between Calcite Crystal and Phosphonic Acid Molecules

CHINESE JOURNAL OF CHEMISTRY, Issue 3 2010
Jianping Zeng
Abstract The interactions between calcite crystal and seven kinds of phosphonic acids, nitrilotris(methylphosphonic acid) (NTMP), nitrilo-methyl-bis(methylphosphonic acid) (NMBMP), N,N -glycine-bis(methylphosphonic acid) (GBMP), 1- hydroxy-1,1-ethylenebis(phosphonic acid) (HEBP), 1-amino-1,1-ethylenebis(phosphonic acid) (AEBP), 1,2-ethylenediamine- N,N,N,,N, -tetrakis(methylphosphonic acid) (EDATMP), and 1,6-hexylenediamine- N,N,N,,N, -tetrakis- (methylphosphonic acid) (HDATMP) have been simulated by a molecular dynamics method. The results showed that the binding energy of each scale inhibitor with the (1l,0) (1l,0) face of calcite crystal was higher than that with (104) face, which has been approved by the analysis of pair correlation functions. The sequence of scale inhibition efficiencies for phosphonic acids against calcite scale is as follows: EDATMP>HDATMP>HEBP>NTMP>GBMP>HEBP>NMBMP, and the growth inhibition on the (1l,0) face of calcite was at the leading status. Phosphonic acids deformed during the binding process, and electrovalent bonds formed between the phosphoryl oxygen atoms in phosphonic acids and the calcium ions on calcite crystal. [source]

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Synergistic effect of halide ions and polyethylene glycol on the corrosion inhibition of aluminium in alkaline medium

Synthesis of poly(p -phenylene diamine) and its corrosion inhibition effect on iron in 1M HCl

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008
P. Manivel
Abstract Water-soluble poly(p -phenylene diamine) was chemically synthesized. Its corrosion inhibition performance was evaluated for iron corrosion in 1M HCl at various concentrations, and the results were compared with that of the monomer. The corrosion inhibition properties were evaluated by polarization techniques and electrochemical impedance spectroscopy. The results showed that poly(p -phenylene diamine) was a more efficient corrosion inhibitor than the monomer and gave an 85% inhibition efficiency at a concentration of 50 ppm, whereas the monomer gave an efficiency of 73% at 5000 ppm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Polyethylene glycol and polyvinyl alcohol as corrosion inhibitors for aluminium in acidic medium

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007
S. A. Umoren
Abstract The corrosion inhibition of aluminum in H2SO4 in the presence of polyethylene glycol (PEG) and polyvinyl alcohol (PVA) as inhibitors at 30,60 °C was studied using gravimetric, gasometric, and thermometric techniques. The inhibition efficiency (%I) increased with increase in concentration of the inhibitors. Increase in temperature increased the corrosion rate in the absence and presence of inhibitors but decreased the inhibition efficiency. Both PEG and PVA were found to obey Temkin adsorption isotherm at all concentrations and temperatures studied. Phenomenon of physical adsorption is proposed from the activation parameters obtained. Thermodynamic parameters reveal that the adsorption process is spontaneous. PEG was found to be a better inhibitor than PVA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source]

A structure/function study of polyaminoamide dendrimers as silica scale growth inhibitors

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2005
Konstantinos D Demadis
Abstract Dendrimers have attracted immense attention during the last decade due to their interesting properties both from a basic and an applied research viewpoint. Encapsulation of metal nanoparticles for catalysis, drug delivery and light harvesting are only some applications of dendrimers that are breaking new ground. A novel application of dendrimer technology is described in the present paper that relates to industrial water treatment. Industrial water systems often suffer from undesirable inorganic deposits. These can form either in the bulk or on metallic surfaces, such as heat exchangers or pipelines. Silica (SiO2) scale formation and deposition is a major problem in high-silica-containing cooling waters. Scale prevention rather than removal is highly desired. In this paper, benchtop screening tests on various silica inhibition chemistries are reported, with emphasis on materials with a dendrimeric structure. Specifically, the inhibition properties of commercially available STARBURST® polyaminoamide (PAMAM) dendrimers generations 0.5, 1, 1.5, 2, and 2.5 are investigated in detail together with other commonly-used scale inhibitors. Experimental results show that inhibition efficiency largely depends on structural features of PAMAM dendrimers such as generation number and nature of the end groups. PAMAM dendrimers are effective inhibitors of silica scale growth at 40 ppm dosage levels. PAMAM dendrimers also act as silica nucleators, forming SiO2,PAMAM composites. This occurs because the SiO2 formed by incomplete inhibition interacts with cationic PAMAM-1 and -2. The general scope of silica formation and inhibition in industrial waters is also discussed. Copyright © 2005 Society of Chemical Industry [source]

Inhibition of 304 stainless steel corrosion in acidic solution by Ferula gumosa (galbanum) extract

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2009
M. Behpour
Abstract The inhibition effect of the extract of galbanum (Ferula gummosa Boiss.) on the corrosion of 304 stainless steel in 2 M HCl solution was studied by weight loss measurements, Tafel polarization, and electrochemical impedance spectroscopy (EIS) methods. It was found that the inhibition efficiency (IE) increases as the extract concentration is increased. Tafel polarization method revealed the mixed mode inhibition of galbanum extract (GE) with predominant control of anodic reaction. The effect of temperature on the corrosion behavior of steel indicates that inhibition efficiency of the natural substance increases with the rise in temperature. At all temperatures, the adsorption of the extract components onto the steel surface was found to follow the Temkin adsorption isotherm. [source]

Inhibition of corrosion of AZ91 magnesium alloy in ethylene glycol solution in presence of chloride anions

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2005
E. Slavcheva
Abstract The influence of chloride ions on the corrosion of AZ91 magnesium alloy in water/ethylene glycol solutions and the inhibiting effect of lactobiono-tallowamide (LTA) were investigated using electrochemical and surface analysis methods. Potentiodynamic polarization curves in aqueous solution of ethylene glycol (50:50w%) containing 0.1 g.L,1 chloride and up to 0.5 g.L,1 LBT were obtained at room and at elevated temperatures. The chloride anions showed a distinct deteriorating effect as they caused pit initiation and accelerated the dissolution of the tested alloy. The selected organic compound demonstrated good protective properties against corrosion of AZ91 magnesium alloy and behaved as inhibitor of mixed type hindering both the cathodic and the anodic partial reactions. It showed inhibition efficiency of 77% at relatively low concentration of 0.2 g.L,1 and was considered as a promising corrosion inhibitor. The mechanism of inhibition was discussed on the basis of the electrochemical impedance spectroscopy (EIS) and XRD analysis of the surface. [source]

Specific critical concentrations of low dosage hydrate inhibitors in a THF,NaCl hydrate formation solution

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2010
Ailin Ding
Abstract Hydrate formation and its attendant problems are well known in the oil and gas industry. The desire to reduce the costs and environmental impact of traditional hydrate inhibitors has led to a focus on the design, development and evaluation of novel and environmentally friendly low dosage hydrate inhibitors (LDHIs). In this study, two LDHIs, namely Luvicap® EG and Gaffix® VC-713, were tested using tetrahydrofuran (THF) as a hydrate promoter and a ball-stop rig. The ball stop-time was used to determine the inhibition efficiency. The concentration effect of inhibitors, salts and solvents on the ball-stop time was investigated. Results indicated that the inhibition efficiency of an inhibitor is sensitive to the micro-environment of the THF-hydrates activities which includes the concentration and types of these additives. The reproducibility and consistency of the test results were also largely dependent on the concentration of inhibitors. Reliable information was provided only if the concentration of the inhibitor was above a critical concentration, below which the testing results scattered drastically and were inconsistent. As the critical concentration was inhibitor-dependent, a specific critical concentration (SCC) was proposed which is the first reported in such investigations. We concluded that the inhibition efficiency of an LDHI should be determined by both the ball-stop time and its SCC. Comparison of ball-stop times between two inhibitors should be made above their SCCs. Salt and solvent concentrations and other additives present in the operating systems should also be considered when a suitable LDHI concentration is determined for a particular field application. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd. [source]