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1 – 4 of 4Fan Hong‐bo, Wang Hui‐long, Guo Xing‐peng and Zheng Jia‐shen
The effect of sodium N,N‐diethyl dithiocarbamate (SDEDTC) on the corrosion of carbon steel in 0.5mol/L hydrochloric acid (HCl) solution was studied using weight loss…
Abstract
The effect of sodium N,N‐diethyl dithiocarbamate (SDEDTC) on the corrosion of carbon steel in 0.5mol/L hydrochloric acid (HCl) solution was studied using weight loss, potentiodynamic polarisation curves and impedance measurement methods. Experimental results revealed that SDEDTC acted as an inhibitor in acid environments. Moreover, the compound was a mixed‐type inhibitor, acting predominantly as a cathodic inhibitor. Inhibition efficiency increased with increasing SDEDTC concentration at different temperatures. The corrosion inhibition mechanism of SDEDTC for carbon steel in HCl solution was also investigated by impedance techniques.
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Huang Jin‐ying, Zheng Jia‐shen, Fu Chao‐yang, Qu Jun‐e and Liu Jian‐guo
A kind of novel heterocyclic bisquaternary ammonium salt (MBQA) was successfully synthesised with metronidazole as matrix and dichloroethyl ether as the link agent. Weight loss…
Abstract
A kind of novel heterocyclic bisquaternary ammonium salt (MBQA) was successfully synthesised with metronidazole as matrix and dichloroethyl ether as the link agent. Weight loss measurement, potentiodynamic polarisation curves, electrochemical impedance spectroscopy and atomic force microscopy were used to evaluate the corrosion inhibiting performance of MBQA in simulated oilfield water. Experimental data revealed that MBQA acted as an inhibitor in the acidic environment and, furthermore, the compound was a mixed‐type inhibitor. It was found that inhibition efficiency increased with an increase in MBQA concentration at different temperatures. The process of inhibition was attributed to the formation of an adsorbed film on the metal surface, which protected the metal against corrosive agents.
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This study aims to optimize the traffic capacity allocation to solve the problem of low share of public transit in the landside system so as to get rid of the congestion trouble…
Abstract
Purpose
This study aims to optimize the traffic capacity allocation to solve the problem of low share of public transit in the landside system so as to get rid of the congestion trouble in landside traffic. The optimal timetable for airport buses can be searched by changing the departure interval of each line and evaluating the corresponding performance continuously.
Design/methodology/approach
This paper constructs a simulation model based on the real-world situation in Beijing Capital International Airport (BCIA), which simulates the whole process of airport bus schedules and analyzes the connections among multiple steps for transferring. The evaluation system is constructed by considering the benefits of passengers, airports and companies comprehensively. The optimal timetable for airport buses can be searched by changing the departure interval of each line and evaluating the corresponding performance continuously.
Findings
According to the experimental results, an excellent evacuation effect can only be achieved when the majority of departure intervals of airport buses are shortened to 50% of their original values, and some busy routes such as the Beijing Station line are supposed to be reduced to one-third of their original fixed intervals. As the airport bus passenger flow presents an obviously periodic variation over days, the timetable of the airport bus is supposed to be redesigned every day. A flexible bus timetable can not only meet the dynamic passenger flow but also enhance the attractiveness of public transit.
Originality/value
This paper constructs a simulation model based on the real-world situation in BCIA, which can not only model the complex scenes in the whole process of airport bus schedules but also reflect the intricate interaction between transferring passengers and vehicles caused by dense streamlines.
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Maryam Ehteshamzadeh, Taghi Shahrabi and Mirghasem Hosseini
In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N′‐ethylen‐bis and N,N′‐ortho‐phenylen‐bis in 0.5 M sulphuric…
Abstract
Purpose
In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N′‐ethylen‐bis and N,N′‐ortho‐phenylen‐bis in 0.5 M sulphuric acid solutions.
Design/methodology/approach
Measurements were carried out in a three‐electrode cell assembly connected to the corrosion measurement system using software for Tafel polarization. Impedance measurements were carried out at open circuit potential using an electrochemical interface and frequency response analyzer at frequencies from 100 kHz to 10 MHz.
Findings
Results obtained revealed that at high concentrations, each of the investigated Schiff bases and 1‐dodecanethiol (DT) were good inhibitors when added separately to the corrosive media. The decrease in corrosion rate was associated with an increase in their concentrations. It was found that the presence of DT together with Schiff bases in corrosive medium increased inhibition effect, especially at low concentrations. Synergistic effect is discussed from viewpoint of their co‐adsorption. The adsorption of combined inhibitors was found to follow Langmuir isotherm. Thermodynamic calculations revealed that adsorption of combined inhibitors had a physical nature.
Research limitations/implications
In order to improve further the performance of Schiff bases and identifying their synergistic effects with other additives it is suggested that some more researches on other Schiff bases with other alkanethiol molecules must be done.
Practical implications
The results of this paper can be used for acid cleaning of carbon steel in which suitable inhibitor systems with the highest efficiency is required.
Originality/value
This paper reveals that the presence of DT molecules in solution encourage the adsorption of Schiff bases by facilitating the electrostatic co‐adsorption of Schiff base molecules through a synergistic effect.