Pd-HPW/SiO2 Bi-Functional Catalyst: Sonochemical Synthesis, Characterization, and Effect on Octahydroquinazolinone Synthesis

A Palladium-doped silica-supported heteropoly acid (HPW) (1%Pd-HPW/SiO2) bi-functional catalyst was produced using ultrasonic and conventional procedures. Both forms of catalyst were characterized with distinct analytical approaches in order to access the advantages of each one. The presence of the required functional groups in the catalyst was confirmed using FT-IR. The crystallinity of ultrasonically generated 1%Pd-HPW/SiO2 was confirmed with XRD. The existence of necessary elements in the catalyst was also suggested by XPS and EDX data. BET was used to calculate the surface area of the ultrasonically synthesized catalyst (395 m2 g−1), and it was found to be greater than that of the non-ultrasonic synthesized catalyst (382 m2 g−1). The N2 adsorption-desorption isotherm indicated mesoporous structures. The SEM morphology at a similar magnification exhibited quite different shapes. In comparison to traditional methods, ultrasonic approaches produce higher yields in less time and use less energy. Furthermore, the effect of the preparation method of the 1%Pd-HPW/SiO2 catalyst was extensively studied with respect to the synthesis of octahydroquinazolinones. Excellent product yields, a fast reaction time, and simple work-up methods are some peculiarities associated with the ultrasonically synthesized catalyst. The recycling study was also investigated and found suitable for up to four reaction cycles.

Radiation Graft-Copolymerization of Ultrafine Fully Vulcanized Powdered Natural Rubber: Effects of Styrene and Acrylonitrile Contents on Thermal Stability

Graft copolymers, deproteinized natural rubber-graft-polystyrene (DPNR-g-PS) and deproteinized natural rubber-graft-polyacrylonitrile (DPNR-g-PAN), were prepared by the grafting of styrene (St) or acrylonitrile (AN) monomers onto DPNR latex via emulsion copolymerization. Then, ultrafine fully vulcanized powdered natural rubbers (UFPNRs) were produced by electron beam irradiation of the graft copolymers in the presence of di-trimethylolpropane tetra-acrylate (DTMPTA) as a crosslinking agent and, subsequently, a fast spray drying process. The effects of St or AN monomer contents and the radiation doses on the chemical structure, thermal stability, and physical properties of the graft copolymers and UFPNRs were investigated. The results showed that solvent resistance and grafting efficiency of DPNR-g-PS and DPNR-g-PAN were enhanced with increasing monomer content. SEM morphology of the UFPNRs showed separated and much less agglomerated particles with an average size about 6 μm. Therefore, it is possible that the developed UFPNRs grafted copolymers with good solvent resistance and rather high thermal stability can be used easily as toughening modifiers for polymers and their composites.

Photocatalytic Nanocomposite Polymer-TiO2 Membranes for Pollutant Removal from Wastewater

Photocatalytic TiO2-PVDF/PMMA nano-composites flat sheet membranes were fabricated by phase inversion and then employed in a crossflow filtration pilot to remove model pollutants of various sizes and charge from aqueous solution. The dope solution contained a mixture of PVDF and PMMA as polymers, polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) as additives, triethyl phosphate (TEP) as green solvent and TiO2 as immobilized photo catalyst. After undergoing characterization tests such as SEM morphology thickness, porosity, contact angle and water permeability, the membranes were used to eliminate the model pollutants from synthetic aqueous solution. The impact of the operating conditions (i.e., pH, pressure and initial pollutant concentration) and composition of the doping solution on the performance and photocatalytic and antifouling activity of the membranes was investigated. The results showed that Congo Red and Tartrazine despite their small size were rejected at 99% and 81%, respectively, because of their negative charge, while Ciprofloxacin, which is larger than Tartrazine but of neutral charge, crossed the membrane. The permeability did not decrease with a decline in pollutant concentration but diminished when the pressure increased and was reduced by more than half for wastewater.

Treatment of Mining and Thermoelectric Waste Through the Geopolymerization Process

Currently, energy and extraction activities generate large amounts of highly polluting waste, so there is a need for sustainable and environmentally friendly technologies. The aim of the study is to treat mining tailings and fly ash through the process of geopolymerization. The samples studied were obtained from the Toquepala mine, Tacna and from the ENGIE-Moquegua hydroelectric plant (Peru). The methodology was based on two stages, the first characterization of Fly Ash (FA) and mine tailings (MT) by EDX chemical characterization, SEM morphology, the second was prepared mixtures of MT and FA in 10 M alkaline solution, cured in 35 days at room temperature and the characterization of the geopolymer by organoleptic analysis, SEM and TCLP. The first stage shows high aluminosilicate content 20.44% Al2O3 and 53.39 % SiO2 for (MT); 22.11% Al2O3 and 51.76% SiO2 for (FA), presents metal and pyrite content. In the second stage, the samples show health and environmental harmlessness, with the formation of tetragonal structures typical of the geopolymer, the samples show a significant reduction of Sr, Ca, Fe, Pb, Ba, Be, and Cu, demonstrating the effectiveness of treatment by means of geopolymerization opening a new field for the environmental passive treatment.

Synthesis and mechanical characterization of Si3N4 reinforced copper-tin matrix composites

The present research reports improvement in mechanical performance of Copper-Tin(Cu-Sn) composites due to the addition of hard Si3N4 particles as reinforcement. Two-step stir casting technique was adopted to prepare Si3N4-reinforced Cu-Sn based composites. The uniform distribution of the reinforcement in the matrix was ensured by SEM morphology and energy-dispersive X-ray (EDAX) spectrum of the developed composites. Brinell hardness test and tension test were used to estimate the hardness and tensile strength of the composite. Si3N4 reinforcing materials added to the extent of 7.5% by wt. to Cu-Sn matrix enhanced hardness by 41% and UTS by 33%, YS by 29% and showed 23% decrement in ductility. Thus a comparison of Si3N4-reinforced Cu-Sn based composites with base metal has shown that considerable improvement in tensile properties such as UTS and YS and hardness if reinforcing material is added to the extent of 7.5%.

Characteristic evaluation of adsorption efficiency of activated wood charcoals in adsorbing acetic acid

Activated wood charcoal (Carbonized) acts as an excellent adsorbent and it finds wide applications. The present study was carried on four different activated wood charcoals Salix (Sac), Pinus (Pac), Anacardium occidentale (AOac) and Calophyllum inophyllum (CIac) found in Karwar district, Karnataka, India. The activated charcoal was prepared by carbonizing in a muffle-furnace at 800 0 C and the yield of carbonized carbon was about 50%. SEM morphology and EDX spectrum indicates the homogeneity and purity of the activated wood charcoals containing 65-86% carbon to that of commercial charcoal (89% C) and hydrogen is absent. Langmuir and Freundlich adsorption isotherms are well-correlated and verified. The regressive coefficient (R2 ) of isotherms recorded a higher value above 0.92 which proves the homogeneous and even adsorption phenomenon by the activated wood charcoals. Sac and AOac recorded highest percentage of removal of acetic acid of about 40-60% and 20-26% with Cac (20-25%) where Pac and CIac recorded 17-23% which is relatively near to the commercially activated charcoal(Cac). On comparison of relative percentage of removal of acetic by activated wood charcoals with commercial charcoal, the activated wood charcoals serve as an efficient adsorbent for acetic acid. The cost and availability of the wood is cheaper.

A facile approach to prepare a flexible and durable electrically driven cotton fabric-based heater

Flexible and durable electrically driven heaters (EDHs) was prepared by using silver nanowire/polydopamine modified cotton fabric (AgNW/PDA-C) as Joule heat generator and polydimethylsiloxane (PDMS) as stretchable matrix.The electric property of the EDHs was investigated, and it can show excellent electrical property and stability. The EDHs can be seen from the SEM morphology that cotton fabric was well protected by the PDMS and has good conductive network. The EDHs also exhibit excellent electrothermal performance under applied voltage. At low-voltages, it can quickly reach satisfactory steady-state temperatures that meet the needs of wearables. By improving the electrothermal model, it can be verified that there is a quadratic function relationship between electric power and steady-state temperature. Under cyclic voltage and bending tests, the EDHs can well maintain steady-state temperature and exhibit excellent dynamic and static electrothermal performance.