2,5-Bis(4-pyridyl)-1,3,4-oxadiazole as Efficient Organic Corrosion Inhibitor for Carbon Steel in Normal Hydrochloric Acid Medium: Influence of the Temperature on the Inhibition Process

2,5-Bis(4-pyridyl)-1,3,4-oxadiazole (4-POX) has been synthesized and studied as organic corrosion inhibitor for carbon steel (CS) in 1M HCl solution using the weight loss technique in the temperature range from 303 to 333 K. The obtained results confirmed the excellent anticorrosion properties of 4-POX and the inhibition efficiency increased with increasing inhibitor concentration and decreased with increasing temperature medium. A mixture of physisorption and chemisorption is proposed for the corrosion inhibition mechanism and the process followed the kinetic/thermodynamic model of Langmuir in the temperature range from 303 to 343 K. The adsorption and kinetic parameters for CS/4-POX/1 M HCl system were calculated from experimental gravimetric data and the interpretation of the results are given

Diameter controlled growth of SWCNTs using Ru as catalyst precursors coupled with atomic hydrogen treatment

In this work, we present a practical approach for controlling single walled carbon nanotubes (SWCNTs) diameter distribution through thin film Ru catalyst, coupled with hydrogen pre-treatment. Uniform and stable Ru nanoclusters were obtained after dewetting the Ru thin films under atomic hydrogen pre-treatment. SWCNTs were synthetized by double hot filament chemical vapor deposition (d-HFCVD) on SiO2/Si substrates at different temperatures. We found that the temperature is an important synthesis parameter that in fluences the diameter distribution of the final SWCNTs. Statistical analysis of the Raman radial breathing modes evidences the growth of highly enriched semi-conducting SWCNTs (about 90%) with narrow diameter distribution that correlates directly with the catalyst particle size distribution. Electrical measurement results on as-grown SWCNTs show good thin-film transistor characteristics

Structural and mechanical properties of radiofrequency N

C38 carbon steel has been nitrided by radiofrequency cold plasma discharge with the aim to study the effect of gas composition on structural and mechanical properties of nitrided substrates. The plasma nitriding was carried out on unheated substrates, using two different gas mixtures (75% N2/25% H2 and 25% N2/75% H2) for 8 h of plasma treatment. Electron Probe Microanalysis (EPMA) showed that the nitrogen content and the nitride layer thickness mainly depend on the hydrogen content in the plasma. For 75% N2/25% H2 mixtures, nitrided samples showed the formation of thicker nitride layer with high content of nitrogen compared to those formed in the case of 25% N2/75% H2 or pure N2 . The thickness of the nitride layer formed is approximately 15 μm for 8 h of plasma with 75% N2/25% H2 . X-ray photoelectron spectroscopy (XPS) was employed to obtain chemical-state information of the plasma- nitrided steel surfaces. The mechanical properties of plasma-nitrided C38 steel were investigated by Vickers microhardness measurements. The micromechanical results show the formation of a new hard layer on the surface after N2/H2 treatment plasma and it reaches a maximum value of more than 2242 HV0.005 for 75% N2/25% H2 plasma-nitrided samples. However, a decrease in the hardness values with the applied load has been evidenced

Understanding the adsorption of 4 H -1,2,4-triazole derivatives on mild steel surface in molar hydrochloric acid

International audienceThis study examines the use of some 4H-triazole derivatives, namely 3,5-diphenyl-4H-1,2,4-triazole (DHT), 3,5-bis(4-pyridyl)-4H-1,2,4-triazole (4-PHT) and 3,5-bis(4-methyltiophenyl)-4H-1,2,4-triazole (4-MTHT) for corrosion and dissolution protection of mild steel in normal hydrochloric acid solution. The inhibiting efficiency of the different additives is evaluated by means of weight loss and electrochemical techniques such as ac impedance measurements and polarisation curves. The experimental results obtained reveal that 4-MTHT is the best effective inhibitor and the inhibition efficiency is found to be in the following order: 4-MTHT > 4-PHT > DHT. The variation in inhibitive efficiency mainly depends on the type and nature of the substituents present in the inhibitor molecule. Polarisation curves show that theses triazoles are mixed-type inhibitors in 1 M HCl. The inhibition efficiency increases with 4H-triazole derivatives concentration and attains the maximum value of 99.6% in the case of 4-MTHT at 5 × 10−4 M. The results obtained from weight loss electrochemical studies were in reasonable agreement. The adsorption of 4H-triazole derivatives on the steel surface obeys to the Langmuir isotherm model. The thermodynamic data of adsorption and activation are determined and discussed. The fundamental thermodynamic functions were used to glean important information about the 4H-triazoles inhibitory behaviour. Molecular modeling was used to get better insight, about structural and electronic effects in relation to the inhibition efficiencies

A microfluidic chip enables fast analysis of water microplastics by optical spectroscopy

Microplastics contaminating drinking water is a growing issue that has been the focus of a few recent studies, where a major bottleneck is the time-consuming analysis. In this work, a micro-optofluidic platform is proposed for fast quantification of microplastic particles, the identification of their chemical nature and size, especially in the 1-100 µm size range. Micro-reservoirs ahead of micro-filters are designed to accumulate all trapped solid particles in an ultra-compact area, which enables fast imaging and optical spectroscopy to determine the plastic nature and type. Furthermore, passive size sorting is implemented for splitting the particles according to their size range in different reservoirs. Besides, flow cytometry is used as a reference method for retrieving the size distribution of samples, where chemical nature information is lost. The proof of concept of the micro-optofluidic platform is validated using model samples where standard plastic particles of different size and chemical nature are mixed