Search results for "Hydrochloric acid"
showing 10 items of 76 documents
Direct perturbation theory in terms of energy derivatives: scalar-relativistic treatment up to sixth order.
2011
A formulation of sixth-order direct perturbation theory (DPT) to treat relativistic effects in quantum-chemical calculations is presented in the framework of derivative theory. Detailed expressions for DPT6 are given at the Hartree-Fock level in terms of the third derivative of the energy with respect to the relativistic perturbation parameter defined as λ(rel)=c(-2). They were implemented for the computation of scalar-relativistic energy corrections. The convergence of the scalar-relativistic DPT expansion is studied for energies and first-order properties such as dipole moment and electric-field gradient within the series of the hydrogen halides (HX, X = F, Cl, Br, I, and At). Comparison …
Self-Organization Pathways and Spatial Heterogeneity in Insulin Amyloid Fibril Formation
2009
At high temperature and low pH, the protein hormone insulin is highly prone to form amyloid fibrils, and for this reason it is widely used as a model system to study fibril formation mechanisms. In this work, we focused on insulin aggregation mechanisms occurring in HCl solutions (pH 1.6) at 60 degrees C. By means of in situ Thioflavin T (ThT) staining, the kinetics profiles were characterized as a function of the protein concentration, and two concurrent aggregation pathways were pointed out, being concentration dependent. In correspondence to these pathways, different morphologies of self-assembled protein molecules were detected by atomic force microscopy images also evidencing the prese…
Fourier transform infrared determination of CO 2 evolved from carbonate in carbonated apatites
2000
A quantitative method based on FTIR has been developed to determine carbonate in synthetic apatites. The method measures the evolved CO2 after reaction of 50 mg apatite with 2 mL of hydrochloric acid (0.5 M) in a reaction vessel, heated to 40 degrees C. The CO2 evolved was swept by a carrier of nitrogen to a laboratory-made infrared gas cell of 39 mm pathlength and 490 microL volume. The signals were recorded as a function of time and the areas of the chemigram peaks obtained from the measurements in the wavenumber range of 2,500-2,150 cm(-1), were interpolated using a calibration curve. The method can be used to study apatites with carbonate contents below 0.2% with a sampling frequency of…
Lawrencium chemistry: no evidence for oxidation states lower than 3+ in aqueous solution
1988
Lawrencium (3-min 260Lr) together with other actinides, was produced in the bombardment of a 249Bk target with 18O ions. There was no sign of a reduction of Lr3+ in dilute hydrochloric acid by V2+ or Cr2+, although in the same experiments, Md3+ was reduced to Md2+ (E°=−0.2 V). The resulting limit for the reduction potential of the Lr3+/Lr1(2)+ couple is E° < −0.44 V.
Assessment of the influence of counter ions on biosorption of copper cations in brewer's spent grain - Waste product generated during beer brewing pr…
2019
Abstract The influence that conditioning leached ground barley grain (known as “brewer's spent grain” (BSG)) has on the effectiveness of copper cation sorption was analysed. Saturation with counter ions of functional groups present on the grain surface was carried out in hydrochloric acid, sodium hydroxide, sodium and calcium chloride solutions. For comparison, BSG was also conditioned in demineralised water. Spent barley grain is a by-product of the brewing industry which can be used as a biosorbent in the removal of heavy metals from waste water. Emphasis is placed on the effect of competitive sorption of copper and hydrogen cations and the negative influence of a solution alkalinisation …
Towards a deeper understanding of the inhibition mechanism of a new 1,2,3-triazole derivative for mild steel corrosion in the hydrochloric acid solut…
2020
Abstract The corrosion inhibition effect of a new synthesized heterocycle 1,2,3-triazole, namely(1-p-tolyl-1H-1,2,3-triazol-4-yl) methanol (TTM) was studied in 1 M hydrochloric acid solution by using both experimental and theoretical techniques. The inhibitory action of the TTM was investigated by potentiodynamic polarization (PDP) at various temperatures (298–333 K). PDP experiments revealed that the TTM behaved as mixed type inhibitor by decreasing both anodic and cathodic corrosion densities. Electrochemical impedance spectroscopy (EIS) measurements confirmed that the studied inhibitor can suppress mild steel corrosion effectively in acidic solution with an inhibition efficiency of 90% a…
Design, synthesis and stimuli responsive gelation of novel stigmasterol-amino acid conjugates.
2020
Abstract An efficient synthesis of three novel stigmasterol-amino acid (glycine, l -leucine and l -phenylalanine) conjugates as stimuli responsive gelators is reported. The gelation properties of the prepared compounds were investigated in a variety of organic as well as aqueous solvents. The most striking finding of our investigation was that the hydrochloride salts of the prepared conjugates acted as gelators, whereas the neutral conjugates were either non-gelators or formed only a weak gel in anisole. The hydrochloride salts of stigmasteryl glycinate and l -leucinate form gels in n-alcohols (n = 4–10) and in ethane-1,2-diol, and that of stigmasteryl l -phenylalaninate forms gels in aroma…
A tensiostatic study of the anodic behaviour of tungsten in acid solutions
1975
Abstract Tensiostatic anodization of tungsten has been studied in 1 N solutions of H 2 SO 4 , HClO 42 , HNH 2 SO 3 and HCl at 25 °C. For several voltage values, the curves of current vs . time and open-circuit voltage vs . time have been obtained. All results indicate that the oxide films produced during the polarization are slowly dissolved in the acid solutions. The HCl, and to a lesser extent the HNH 2 SO 3 solutions, show a more aggressive behaviour. For values of the applied voltage above about 50 V, gas evolution begins. In the case of HCl solutions, the gas is Cl 2 and the electrode is rapidly corroded.
Burner backflow reduction in regeneration furnace
2011
In the present case from the steel industry, waste hydrochloric acid from the pickling process is regenerated using spray roasting. The process is driven by four burners placed symmetrically along the periphery of the cylindrical main section of the reactor. Severe problems with gas backflow and sintering of iron oxide inside the burner chamber have led to a complete shut down of the process 1-2 times every week, which is a frequency which significantly affects the productivity. In this study the influence of a kick-out on the gas flow in the vicinity of the burner chamber is investigated numerically. It is shown that the kick-out geometry creates a vortical low pressure region preventing t…
A combined computational and experimental study on the mild steel corrosion inhibition in hydrochloric acid by new multifunctional phosphonic acid co…
2020
Two triazole derivatives with phosphonic acid as pendent group, namely [3-(4-phenyl-[1–3]triazol-1-yl)-propyl]-phosphonicaciddiethylester (PTP) and [3-[4-(4-dimethylamino-phenyl)-[1–3]triazol-1-yl]-propyl]-phosphonic acid diethylester (DMPTP) were synthesized and fully characterized using NMR spectroscopy, Mass spectrometry, Infra-Red (FT-IR) spectroscopy and elemental analysis. The synthesized multifunctional heterocycles were investigated to inhibit the corrosion of mild steel in acidic solution HCl (1 M) by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and weight loss measurements. The results of the different corrosion measurement techniques are in goo…