Tobacco stalk lignocellulosic nanofibers characterization for pharmaceutical applications

Lignocellulosic nanofibers derived from tobacco stalk can have countless applications in polymers composites, textile, cosmetics, and pharmaceuticals. Thus, it is important to evaluate biomass characteristics such as the presence of nicotine. In this study, nanofibers were obtained by mechanical fibrillation while cellulose content (0.5 and 2.0%) and drying methods were varied. Nanofibers were characterized by thin layer chromatography, 1H NMR, morphological analysis, α-cellulose content, Fourier transform infrared spectroscopy, X-ray diffraction and thermal analysis. Results demonstrate the absence of nicotine in tobacco stalk. The grinding mill process was efficient to produce by freeze-drying, nanofibers with fiber’s mean diameter of ~30 nm. Solid concentrations can influence the diameter of obtained fibers. Thermal stability increased and crystallinity decreased when alkali treatment was applied. The characterization techniques applied enable the evaluation of tobacco stalk and expanded its application to pharmaceutics.

Performance analysis of erosion resistant Mo2C reinforced WC-CoCr coating for pump impeller with Taguchi’s method

Purpose This study aims to deal with development and performance analysis of high-velocity oxy-fuel (HVOF) thermally sprayed Mo2C-based WC-CoCr (tungsten carbine cobalt chrome) (Co-10% and Cr-4%) cermet coating deposited on the pump impeller steel 316 L. Design/methodology/approach In this work, a study was carried out by modifying the conventional WC-CoCr powder with a small addition of molybdenum carbide (Mo2C). Reinforcement was done by 1–4 wt.% addition of Mo2C feedstocks in WC-CoCr powder by using a jar ball mill process. The design of experiment was implemented for optimization of the percentage of Mo2C feedstock. L16 (4 × 4) orthogonal array was used to design the experiments for erosion output for the input parameters namely velocity, particle size, concentration and Mo2C proportion. Findings Results show that the Mo2C-based WC-CoCr coating provides better microhardness as compared to conventional WC-CoCr coating. The present study also reveals that the deposition of conventional WC-CoCr coating has improved the wear resistance of SS 316 L by 9.98%. However, the slurry erosion performance of conventional WC-CoCr coating was improved as 69.6% by the addition of 3% Mo2C. Practical implications WC-CoCr coatings are universally used for protecting the equipment and machinery from abrasion, erosion and corrosion. So, the 3% Mo2C-based WC-CoCr can be useful in power plants and various industries like mining, chemical, automobile, cementing and food processing industries. Originality/value A new HVOF coating has been developed by the addition of Mo2C feedstock in WC-CoCr powder (Co 10% and Cr 4%) and the percentage of Mo2C feedstock was optimized to improve the tribological behavior of WC-CoCr coating.

On the problem of control over the primary grinding mill ball charging

Considering the fact that the costs related to grinding balls and electric power account for a significant share of operational costs incurred by concentrator plants, this paper highlights the relevance of using an optimized ball charge. The paper considers a conventional approach to ball charging, which involves doing calculations on the basis of a given throughput. The latter serves as a parameter for the specific ball consumption rate approval procedure. At the same time, no consideration is given for the ball wear rate as a parameter defining the grinding performance. It is noted that the ball charge dynamics can be analyzed based on the noise produced by the mill, or the vibroacoustic parameters of the mill. The paper examines some vibro-acoustic ball charge analysis techniques utilized by both domestic and international service providers. It is noted that in all these cases the technique uses just one physical parameter, which is not enough to monitor the total mill load. The VAZM-1M analyzer developed by Soyuztsvetmetavtomatika JSC analyzes and calculates an integral amplitude of the mill vibro-acoustic field. This ensures that all components of the grinding process are taken into account. The paper takes a detailed view of the findings obtained upon analysis of the primary grinding mill ball charge. The work was carried out at the Erdenet concentrator plant as part of contractual scope. A number of different ball charge options was considered, and is it noted that none of the options can resolve this problem completely. The authors describe a possibility to monitor the mill process load with the help of the VAZM-1M analyzer. The authors also analyzed the experiments that aimed at identifying the grinding parameters governed by the mill ball charge. It is shown that the VAZM-1M analyzer gives adequate readings of any ball charge deviations. The mill spectrum registered by the VAZM-1M analyzer contains a resonance peak, which is believed to correlate as a small mill ball charge spectrum. In this regard, a plan of further research was drafted that relies on the use of the VAZM-1M analyzer. The aim is to identify an exact frequency band that would adequately correlate with the mill ball charge.

Thermoelectric and Transport Properties of Permingeatite Cu3SbSe4 Prepared Using Mechanical Alloying and Hot Pressing

Permingeatite (Cu3SbSe4) is a promising thermoelectric material because it has a narrow band gap, large carrier effective mass, and abundant and nontoxic components. Mechanical alloying (MA), which is a high-energy ball mill process, has various advantages, e.g., segregation/evaporation is not required and homogeneous powders can be prepared in a short time. In this study, the effects of MA and hot-pressing (HP) conditions on the synthesis of the Cu3SbSe4 phase and its thermoelectric properties were evaluated. The electrical conductivity decreased with increasing HP temperature, while the Seebeck coefficient increased. The power factor (PF) was 0.38–0.50 mW m−1 K−2 and the thermal conductivity was 0.76–0.78 W m−1 K−1 at 623 K. The dimensionless figure of merit, ZT, increased with increasing temperature, and a reliable and maximum ZT value of 0.39 was obtained at 623 K for Cu3SbSe4 prepared using MA at 350 rpm for 12 h and HP at 573 K for 2 h.