Band 232, Heft 12

A series of γ-MnO 2 -Ce/MMT catalyst materials synthesized by homogeneous precipitation method was investigated for the selective catalytic reduction (SCR) of NO x with NH 3 . X-ray diffraction and specific surface areas were utilized for micro structure and layer spacing investigation. And NH 3 -TPD, Pyridoxine IR, H 2 -TPR and XPS were used to investigate Brønsted acid and Lewis acid, redox properties, atomic concentrations and element chemical state for as-prepared catalysts. The results showed that the γ-MnO 2 -Ce/MMT had superior NO x conversion compared to the bulk particles, among which 6 wt.% γ-MnO 2 -Ce/MMT displayed the best deNO x of 95.3% for the low temperature selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) under the GHSV of 25,000 h −1 , therefore it is a promising catalyst for low temperature NH 3 -SCR.

The oxidative degradation of CV dye in aqueous media has been evaluated using Fenton (Fe 2+ /H 2 O 2 ) and photo-Fenton (Fe 2+ /H 2 O 2 /UV) processes. Various operational parameters like H 2 O 2 dosages, Fe 2+ dosages and [CV] 0 were optimized of both Fenton and photo-Fenton processes for the removal of CV dye from aqueous media. Kinetic results indicated that photo-Fenton process ( k obs =0.0097 min −1 , t 1/2 =71.45 min) is more effective than Fenton process ( k obs =0.0074 min −1 , t 1/2 =93.66 min). Second order rate constant of ˙OH radical with CV dye was calculated to be 3.96×10 9 M −1 s −1 . De-methylated organic intermediates of CV dye detected by LC-MS and some other intermediates like CH 3 COO − , HCOO − , NH 4 + and Cl − were identified by ion-chromatography.

Copper coated steel wires (1–5 numbers) reinforced in LM13 aluminium alloy composites have been prepared using squeeze casting process. Microstructure of composites has been investigated and mechanical properties viz., hardness, tensile strength and ductility have been examined and reported. Dry sliding wear behaviour of composites has been investigated by varying sliding distance and load. Fracture surface of broken tensile specimens and worn surface of wear samples have been investigated using field emission scanning electron microscope (FESEM). The results reveal that copper coated steel wires reinforcement in LM13 aluminium alloy improves the mechanical properties and wear resistance. Average hardness values of 136 BHN and 96 BHN have been observed in steel wire and at the interface of steel wire and aluminium alloy, respectively. Tensile strength of composites increased up to 28% by reinforcing three copper coated steel wires in LM13 aluminium alloy. Dry sliding wear test results reveal that weight loss, wear rate and coefficient of friction decreased with increasing number of copper coated steel wires reinforcement in LM13 matrix. However, weight loss of samples increased with increasing sliding distance and load. LM13 aluminium alloy reinforced with five numbers of copper coated steel wires decreased the weight loss up to 69% as compared to LM13 aluminium alloy tested at 40 N load and a sliding distance of 2500 m. Fracture surface of composites shows broken steel wires and dimples are observed in LM13 matrix. Worn surface of composites shows fine and shallow grooves; whereas delamination is observed in LM13 aluminium alloy. In general, copper coated steel wire reinforcement in LM13 aluminium alloy exhibited better mechanical properties and wear resistance compared to matrix.

Solvent molecules as an important factor can modify the photo-physical behavior of organometallic complexes. For precise investigation, in this paper, the spectral behavior of some groups of copper complexes with different substituents were studied in various solvent media. In this case, the linear solvation energy relationships concept was used for determination of various contribution of media induced specific and non-specific interactions on the photo-physical behavior of various forms of organometallic complexes with azo-containing Schiff-base dyes. Moreover, the calculated dipole moments indicate that samples with different forms tend to have polar structure in the excited state as compared to those in the ground state. By exploiting of calculated dipole moments and obtained quantitative results in the ground and excited states, the dominant solvent induced resonance structures were also estimated. The obtained experimental results can give more information about how these samples can behave in various physical, chemical and biological phenomena.

Aluminium oxide (Al 2 O 3 ) nano particles were synthesized by using both the sol gel technique and solid state reaction (SSR) method. Different proportion of nano carbon cones from 0.5% to 3.5% is doped with aluminium nitrate nano hydrate and annealed subsequently at 1000°C for 3 h to synthesize the nano composite of carbon–alumina. The synthesized samples were characterized by X-ray diffraction to identify the presence of different phases and transitions during this process. The average crystallite size of the nano alumina is found to be 45 nm by sol gel and 43 nm by SSR method respectively by Debye–Scherrer method. Average crystallite size and lattice strain of nano alumina are also estimated from Williamson Hall (WH) plot analysis. It is found to be 69 nm with the strain of 3.3×10 −3 in sol gel, and in SSR method, it is 72 nm with the strain is 3.9×10 −3 . The interplanar distance of various planes of alumina are estimated and compared with JCPDS values. Similar analysis has also been extended for the nano composite of carbon–alumina. The surface morphology of the samples are analyzed using scanning electron microscopy and rough estimate of the crystallites is also given. From the Raman analysis, the presence of alpha phase of alumina has been confirmed. The presence of carbon in the composite has been established through diffuse reflectance spectroscopy. The FTIR spectra of the composite samples ensured the presence of Al–O–Al, O–H and C=O bonds.