Band 115, Heft 10

Magnesium oxide-based adsorbents (MGO-A) with different morphologies were synthesized via the hexamethylene tetramine-assisted hydrothermal method. The role of four anions in the reaction system, chloride (Cl ⁻ ), nitrate (NO 3 ⁻ ), sulfate (SO 4 2⁻ ), and acetate (C 2 H 3 O 2 2⁻ ) was systematically investigated to determine the properties of the MgO. Standard characterization techniques were used, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and surface area and pore size interpretations. The kinetics and adsorption isotherm were studied for removal of the dye methyl orange. The dye’s rapid removal led to equilibrium being reached within 5 min. The correlation coefficient values indicate more applicability of pseudo-second-order kinetics than the pseudo-first-order kinetics. Both physisorption and chemisorption can be a pathway towards successfully removing methyl orange. The adsorption isotherm shows that the maximum capacity of the material is very high, 1,062 mg/g for MGO-A. In light of these results, it appears this material holds promise as a dye removal material.

A magnetic and efficient Fe 78 Si 9 B 13 /MnO 2 composite was successfully fabricated by a facile hydrothermal method. This composite was employed as a Fenton-like catalyst for the degradation of methyl orange (MO) under activation of H 2 O 2 . The phase and morphology of the composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The experimental results reveal that the theoretical mass loading of Fe 78 Si 9 B 13 /MnO 2 composite and H 2 O 2 dosage have a significant effect on MO degradation. Fe 78 Si 9 B 13 /MnO 2 composite effectively improved MO oxidation ability and could quickly decolorize the MO to 99.7 %. Decolorization efficiency increased with increasing H 2 O 2 concentration from 0 % to 1.15 %. Additionally, a possible reaction mechanism of the coupling system was proposed.

The effect of two activating agents namely phosphoric acid (H 3 PO 4 ) and iron (III) chloride (FeCl 3 ) is investigated, in activation of carbon obtained from Tinospora cordifolia . The structural and morphological properties of the synthesized activated carbons were investigated using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and Brunauer–Emmett–Teller analysis. A notable yield of ∼60 % of the activated carbons was obtained using a simple and cost-effective approach of chemical activation followed by the thermal activation method. The electrochemical properties of the activated carbons were studied for electric double-layer capacitor application. The electrochemical impedance spectroscopy, galvanostatic charge–discharge and cyclic voltammetry studies revealed superior charge transfer properties of the carbon activated with H 3 PO 4 . The capacitor comprising carbon activated with H 3 PO 4 electrodes shows higher specific capacity of 58 F g −1 at 1 A g −1 than that of carbon activated with FeCl 3 (37.5 F g −1 ). The optimized capacitor delivers superior power density and energy density of 2 kW kg −1 and 28.33 W h kg −1 , respectively.

The aim of this work is to compare the responsive behaviour of titanium, niobium and titanium–niobium alloy during alkaline treatment in forming alkaline titanate layer and their resultant bioactive properties. Titanium and niobium powder mixture with composition in the beta region was pressed at 550 MPa and sintered at 1,200 °C for 2 h. The alloy was soaked in potassium hydroxide aqueous solution at 60 °C for 24 h with different concentrations of 0.5 M and 5 M. The effect of post sintering-heat treatment was investigated by annealing the treated alloy at 600 °C for 2 h. X-ray diffraction analysis and Fourier transform infrared spectroscopy analysis were used to evaluate the chemical composition and the functional group of material on the treated alloy surface respectively. Immersion in Hanks solution for 1 day resulted in traces of calcium and phosphate on alloy surfaces treated in different concentrations of alkali as well as post-heat treatment. The cell viability evaluation using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay on the new beta-Ti alloy with potassium-based titanate layer demonstrated potassium hydroxide treatment with a 5 M concentration after post-heat treatment significantly improved cell proliferation, which is a prerequisite for bone mineral apatite deposition.

Aluminum matrix/aluminum-iron intermetallic composite materials pose challenges in plastic processing due to the susceptibility of hard intermetallic compound particles to fracture. This study introduces a novel fabrication method involving pure iron mesh, hot-dip aluminum plating, and solidification. Through ten consecutive folding, forging, and intermediate annealing cycles, aluminum matrix and iron undergo diffusion, leading to the formation of Fe 2 Al 5 and FeAl 3 interface reaction layers, as confirmed by X-ray diffraction analysis. Subsequent forging cycles cause the breakage or detachment of Fe 2 Al 5 and FeAl 3 particles from the interface, resulting in the formation of large-sized Fe 2 Al 5 and small-sized Fe 2 Al 5 intermetallic particles. FeAl 3 intermetallic particles are observed via microscopic examination. These particles can be uniformly dispersed within the aluminum matrix through plastic flow, enabling the successful fabrication of A1100/Fe 2 Al 5 and AlFe 3 composite sheets. Furthermore, the study investigates the impact of intermetallic compound content, sliding speed, and forward load on the dry sliding wear of A1100/FeAl composites. It is found that Fe 2 Al 5 and AlFe 3 intermetallic compound particles effectively mitigate adhesive wear, plowing, and oxidative wear of the composites. With an AlFe intermetallic compound content of 4.3 wt.%, the volume wear rate remains low under conditions corresponding to PV = 56.652 (equivalent to a normal load of 19.6 kPa and a sliding speed of 2.87 m s −1 ).

This paper aims to investigate the effect of laser ablation on the mechanical performance of graphene-filled glass fibre reinforced polymer (GFRP) repaired lap joints. The performance characteristics of repaired laminates were measured in terms of surface roughness, tensile strength and flexural strength according to ASTM standards. While the surface morphology was examined using a confocal microscope, scanning electron microscopy was adopted to analyse the laser ablated fibre–matrix interface. The average surface roughness significantly increased with an increase in laser power from 4 to 10 W which was attributed to the presence of graphene and burnt fibres. The laser ablation conditions corresponding to 10 W laser power, 300 mm s −1 scanning speed, 20 kHz of pulse frequency, 0.05 mm line spacing and 5 laser passes lead to the highest tensile strength (36.033 MPa) and bending strength (30.972 MPa) of GFRP laminates. The laser ablated microstructure was characterised by fibre pull-out, epoxy residue, burnt, clean fibres as evidenced by scanning electron microscopy.

Human hip failure remains a significant issue, and constructing artificial joints is imperative for affected individuals. This study examined the mechanical and wear behavior of polyether ether ketone (PEEK) polymers, including bare PEEK (BP), HA (Hydroxyapatite)-infused PEEK (HA-PEEK), and GO (Graphene oxide)-infused HA-PEEK (GO-HA-PEEK). The samples were prepared using compression molding, and wear characteristics were evaluated using a linear reciprocating tribo-tester against a stainless-steel counterface under a load 50 N, frequency 5 Hz, stroke length 20 mm, and time 30 min. The 10 % w/w HA inclusions slightly elevate the PEEK’s tensile strength from 29.85 ± 1.11 MPa (BP) to 34.23 ± 1.09 MPa, and the 0.5 % w/w GO with 10 % w/w HA encapsulations have significantly improved tensile properties (65.10 ± 1.12 MPa), which is 2.2 fold higher than the BP. However, the attained impact properties fall below the satisfactory level. Coefficient of friction and wear rate are significantly reduced. The wear rate reduced from 3.39 × 10 −6  mm 3  N −1  m −1 (BP) to 2.54 × 10 −6  mm 3  N −1  m −1 on HA-PEEK, and more than two times reduction (1.69 × 10 −6  mm 3  N −1  m −1 ) with 0.5 % w/w GO incorporating HA-PEEK. The results show that the reinforcements significantly reduced wear and improved the mechanical strength of PEEK polymers. Unlike BP and HA with lowered impact resistance, GO integrated HA-PEEK exhibited outstanding mechanical and wear performance. Therefore, HA and GO-infused PEEKs are suitable alternatives for hip repair applications.