Band 115, Heft 7

A cellulose/activated carbon combined material is prepared and tested for the adsorption of Co(II) from stagnant waters. This material is easily prepared using two different homemade activated carbons as adsorbents and sanitary paper as cellulose source. Cellulose/activated carbon cells so prepared are thoroughly characterized using multiple methods including optical imaging, tensile tests in dry and wet conditions, thermogravimetric analysis and Fourier transform infrared spectroscopy. Afterwards, they are tested for the adsorption of Co(II) from stagnant waters solutions. The results showed that the prepared cells offer good mechanical resistance; the optical microscopy images showed the dispersion of activated carbons grains between cellulose fibres while spectral analysis revealed that the activated carbons keep their chemical properties in the cells. When tested and compared to activated carbons alone for the retention of Co(II) from stagnant waters solutions, the cellulose/activated carbon cells gave better adsorption ratios for both activated carbons (up to double). This study shows an easy way to enhance the efficiency of activated carbons by dispersing their grains within cellulose fibres. Thus the added value of this work is ease of preparation, non-use of harmful chemicals and the economic aspect.

Nanomaterials and their composites have been proven to be effective materials for various energy and environmental applications. In this way, functionalized polymers and their nanocomposites (NCs) are receiving much attention due to their tunable physico-chemical characteristics, cost and ease of availability. As an environmental application, particularly the removal of toxic dyes, photocatalysis has been reported as an emerging technology. The literature survey shows that functionalized polymer nanocomposites (PNCs) as photocatalysts offer an extensive contribution towards the generation of clean, renewable, and practical forms of energy from light-based pollutant removal as environmental remediation. Here, the present concept provides a brief introduction to the field of photocatalysis and environmental remediation, followed by the application of functionalized PNCs. In this view, TiO 2 –NCs are reported to be effective photocatalytic materials. In the present study, CNT-doped TiO 2 NCs samples have been prepared using the sol–gel method and their photocatalytic activity has been investigated through a dye degradation experiment. Compared to the present studies, here the CNT content taken is very low, and it is found to be effective for the dye degradation part of an environmental cleaning application.

The study of six compositions of Cu@N-TiO 2 with different amounts of copper and nitrogen synthesized using a sol–gel method is reported. X-ray diffraction patterns and Raman spectra indicated the formation of a single anatase TiO 2 phase in all materials without evidence of secondary phases including copper or nitrogen. Electron microscopy images showed a homogeneous distribution of the copper particles around a TiO 2 matrix, just as that the insertion of nitrogen did not have a significant effect on the morphology of the particles. X-ray photoelectron spectroscopy analysis confirmed that nitrogen was inserted in the atomic arrangement of titanium dioxide, while copper was presented mainly as metallic element on the TiO 2 surface. Characterization of the optical properties and photoactivity test confirm that band gap strongly depends on the copper and nitrogen content phenomenon attributed to the combined presence of modifiers over the TiO 2 surface and the promotion of a plasmonic effect, which displaced the absorption UV bands to higher wavelengths with respect to un-doped TiO 2 . The catalytic test performed using rhodamine-B as probe molecule, confirm that TiCuN2 and TiCuN3 samples exhibit the best decomposition percentages of 38 and 36 % respectively. Such results confirm the surface plasmon resonance effect associated to Cu particles on the TiO 2 as main cause in the increase in current along synthesized samples and the use of cyclic voltammetry technique to identify these effects between 0.0 and 1.5 V.

A red luminescent coordination polymer has been prepared from a polydentate 8-hydroxyquinoline ligand via mechanochemical synthesis. The obtained coordination polymer is micro/nano spherical and can suspend stably in organic solvents after ultrasonic treatment. Due to the large conjugation of the ligand with a strong polar s -triazine core, the coordination polymer shows a largely red-shifted emission relative to the ligand. The photoluminescence peak of the coordination polymer in organic solvent is at 613 nm, while a largely red-shifted photoluminescence peak at 675 nm and a shoulder peak at 770 nm are found in the photoluminescence spectrum of the coordination polymer in solid due to the strong interchain interaction.

Natural composites possess good qualities like light weight, harmlessness, cheapness and ease of processing. However, their performance is limited compared to conventional material. Hence, it is required to improve the performance of natural composites to extend their usage in various industrial applications. In this research, an attempt has been made to improve the performance of epoxy–jute natural composite using different natural fillers made of neem seed and groundnut shell particles. Initially, the epoxy–jute composite [N:G (0:0)] was prepared and the properties of the composite were investigated. Additionally, natural-fillers were incorporated into the N:G (0:0) composite, and a variety of composites were produced. These included N:G (1:0), N:G (3:1), N:G (1:1), N:G (1:3), and N:G (0:1), with the weight fractions of neem and groundnut shell particles adjusted accordingly. The properties of the aforementioned composites were compared with the properties of N:G (0:0) composite. Results revealed that the particle reinforced composite exhibited significant improvement in the properties of the composites. Moreover, in comparison to the other composites, the N:G (0:1) composite exhibited superior tensile strength (43.28 MPa), flexural strength (46.08 MPa), impact resistance (13.93 kJ m −2 ), and hardness (24.7 HV). This could be due to the fibrous structure of groundnut shell compared to neem seed which was fragile in nature. Furthermore, the same composite displayed less water absorption (2.8 % at 6 days time period). Moreover, the N:G (1:0) composite exhibited the least thermal conductivity (0.31 W m −1  K −1 ). Based on results, it was concluded that the bio-fillers such as neem seed and groundnut shell particles assisted improvement the properties of epoxy–jute composite.

B 4 C/TiB 2 /Mo ceramic nozzles were obtained by uniaxial hot-pressing. The mechanical properties and erosion behaviour of B 4 C/TiB 2 /Mo ceramic nozzles were investigated. Volume erosion rate was used to rank the erosion behaviour of the B 4 C/TiB 2 /Mo ceramic nozzles. The relationship between mechanical properties and the volume erosion rate of the nozzles was discussed. X-ray diffraction analysis showed that in-situ reaction to form TiB 2 happened during sintering. Scanning electron microscopy was employed to observe the fracture surfaces and eroded surfaces of B 4 C/TiB 2 /Mo ceramic nozzles. A model of erodent particles and nozzle during the erosion test was established using the JH2 model. The maximum von Mises stresses on the entry, middle and exit surfaces of the nozzle were calculated. The result showed that the hardness played a key role in influencing the erosion behaviour of B 4 C/TiB 2 /Mo ceramic nozzles. Erosion mechanisms of B 4 C/TiB 2 /Mo ceramic nozzles at the entry, middle and exit bore area were mainly brittle fracture, fracture & plowing and micro-plowing, respectively.

A superhydrophobic copper coating was prepared by combining ionic liquid copper electrodeposition and a brief stearic acid modification process. After modification, the copper stearic acid was well formed and flower-like clusters were present on the surface of the superhydrophobic coating. Finally, the surface of the sample exhibits a good superhydrophobic performance with a contact angle of 158° and obvious self-cleaning behavior. The results of potentiodynamic polarization and electrochemical impedance measurements revealed that the presence of a superhydrophobic surface could improve the anti-corrosion property of the samples.

Diffusion bonding of oxide dispersion strengthened ferritic steel PM2000 1.2 mm thickness plates sandwiched by aluminium foils was carried out. This joining was achieved under laboratory air at temperatures less than 660 °C by simultaneously applying heat and sufficient compression of about 210 MPa to give a high level of plastic deformation to the Al interlayer. The resulting microstructures and phases at the interface were characterised using scanning and transmission electron microscopy and microanalyses. The formation of intermetallic phase type FeAl was detected close to the interface and the FeAl 3 further away on the aluminium side. The bonded samples were heat treated under a special regime and bend tested. In the treated samples Fe–Cr compounds were noticed. The corrosion study of the heat-treated samples in laboratory air at 950 °C demonstrated a high temperature corrosion resistance.

This study investigated the effects of pulsed current frequency and shielding gas composition on the weld metal geometry and nitrogen content. Austenitic stainless-steel sheets were welded by gas tungsten arc welding using 0, 0.5, 1, 2, 5, and 10 vol.% of nitrogen gas in argon shielding gas and pulse frequencies of 40, 80, 120, 160, and 200 Hz. Weld sections were recorded using a stereomicroscope. Weld depth and cross-section of the weld metal were measured by ImageJ ® software and their changes were recorded. Nitrogen analysis tests were performed on the weld metal and, the results were analyzed. Investigations revealed that by increasing the nitrogen content of the shielding gas up to 10 vol.%, the nitrogen content of the weld metal almost doubles at the maximum nitrogen level. This increase was more considerable at higher current frequencies. Also, by increasing the pulsed current frequency, the weld pool and the weld metal depth-to-width ratio increased to 37 % and 44 %, respectively, at the maximum level of shielding gas nitrogen. In addition, at the frequency of 200 Hz, increasing nitrogen led to an 86 % and 72 % increase in the weld pool and the weld aspect ratio, respectively.