Synergistic inhibition of carbon steel by tertiary butyl phosphonate, zinc ions and citrate

Purpose - To develop a new corrosion inhibitor formulation for carbon steel in low chloride environments. Designlmethodology/approach - Corrosion inhibition efficiencies were evaluated by the weight loss method and by impedance measurement studies. The nature of the inhibition process was evaluated using potentiostatic polarization studies. The nature of the protective film was investigated using X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The concept of synergistic effect was used in the development of the new synergistic inhibitor formulation. Findings - A new corrosion inhibitor formulation, containing tertiary butyl phosphonate (TBP), zinc ions and citrate, has been developed to control the corrosion of carbon steel in low chloride environments. This inhibitor formulation was found to offer a maximum inhibition efficiency of 96 per cent in a neutral pH test environment. It was interesting to observe that the binary system, consisting of higher concentrations of the TBP and zinc ions, offered only 79 per cent inhibition efficiency. The ternary system, consisting of relatively lower concentrations of the phosphonate, zinc ions and citrate offered a higher (96 per cent) efficiency. This ternary inhibitor system also was found to be efficient in acidic as well as basic environments in the pH range 5-8. The inhibitor combination was determined to function as a "mixed8'-type inhibitor, though being predominantly cathodic. A plausible explanation of the mechanism of corrosion inhibition is proposed. Practical implications - The ternary inhibitor formulations based on phosphonate, zinc ions and another environmentally friendly synergists like citrate will be quite useful for corrosion inhibition of carbon steel in cooling water systems as they contain relatively less concentrations of phosphonate and zinc ions. Originalitylvalue - The research paper presents the results of a new synergistic inhibitor formulation and also discusses the mechanistic aspects of corrosion inhibition

Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data

Tropical cyclones (TCs) are deep convective synoptic-scale systems that play an important role in modifying the thermal structure, tropical tropopause parameters and hence also modify stratosphere–troposphere exchange (STE) processes. In the present study, high vertical resolution and high accuracy measurements from COSMIC Global Positioning System (GPS) radio occultation (RO) measurements are used to investigate and quantify the effect of tropical cyclones that occurred over Bay of Bengal and Arabian Sea in the last decade on the tropical tropopause parameters. The tropopause parameters include cold-point tropopause altitude (CPH) and temperature (CPT), lapse-rate tropopause altitude (LRH) and temperature (LRT) and the thickness of the tropical tropopause layer (TTL), that is defined as the layer between convective outflow level (COH) and CPH, obtained from GPS RO data. From all the TC events, we generate the mean cyclone-centred composite structure for the tropopause parameters and removed it from the climatological mean obtained from averaging the GPS RO data from 2002 to 2013. Since the TCs include eye, eye walls and deep convective bands, we obtained the tropopause parameters based on radial distance from the cyclone eye. In general, decrease in the CPH in the eye is noticed as expected. However, as the distance from the cyclone eye increases by 300, 400, and 500 km, an enhancement in CPH (CPT) and LRH (LRT) is observed. Lowering of CPH (0.6 km) and LRH (0.4 km) values with coldest CPT and LRT (2–3 K) within a 500 km radius of the TC centre is noticed. Higher (2 km) COH leading to the lowering of TTL thickness (2–3 km) is clearly observed. There are multiple tropopause structures in the profiles of temperature obtained within 100 km from the centre of the TC. These changes in the tropopause parameters are expected to influence the water vapour transport from the troposphere to the lower stratosphere, and ozone from the lower stratosphere to the upper troposphere, hence influencing STE processes

Free-radical variant for the synthesis of functionalized 1,5-diketones.

International audienceA free-radical approach for the synthesis of functionalized 1,5-diketones has been accomplished through an effective combination play between alkenylacylphosphonates and keto-xanthates as radical surrogates of enolates and enones, respectively