Carbon dioxide adsorption on mesoporous silica surfaces containing amine-like motifs

The postcombustion separation of CO₂ from a flue gas mixture is a unit operation in carbon capture. Today, CO₂ is normally separated with alkanolamines in aqueous solutions. These absorption processes are energy intensive and costly. Increased environmental considerations and the significant footprints of many energy sources warrant the development of new gas separation techniques for the competitive implementation of carbon capture and storage technologies. Improved adsorbent-mediated separation processes are candidates for such new low-energy low-cost processes. In this study, porous silica-based adsorbents with amine-like motifs were synthesized. The temperature- and pressure-dependent adsorption of CO₂ and CO₂/H₂O mixtures were determined and compared for these materials. The experimental uptake capacities of the materials modified with primary propyl amine moieties were significantly higher than those of materials modified with bis-ethanol amine or amidine. The propyl-amine-modified samples also showed good selectivity for CO₂ over nitrogen gas.     

Flow and heat transfer over shallow cavities

The flow over a shallow cavity heated with constant heat flux form the bottom side has been studied experimentally and numerically. In the experimental part, pressure coefficient and Nusselt number have been measured along the cavity floor. In the numerical simulation, the conservation equations of mass, momentum, and energy have been solved. The standard k–? turbulence model is used to account for the turbulent fluctuations. In both experimental and numerical part, the effect of changing cavity aspect ratio and Reynolds number has been studied. It is found that, a single elongated eddy has been formed for aspect ratio lower than 7. As the aspect ratio increases the flow impinges with the cavity floor creating two eddies, one beside the upstream cavity side and the second beside the downstream cavity side. Local Nusselt number along the cavity floor is affected mainly by the flow structure inside the cavity and the average Nusselt number has increased with increasing the aspect ratio up to 10 and with increasing Reynolds number. A correlation for the average Nusselt number, as a function of Reynolds number and cavity aspect ratio, is developed.     

Expected role of nuclear science and technology to support the sustainable supply of energy in Indonesia

Energy resources are available in Indonesia but small per capita. The increase of oil price and its reserve depletion rate dictates to decrease the oil consumption. Therefore, it is imperative to increase the shares of other fossils as well as the new and renewable sources of energy in various energy sectors substituting the oil. The introduction of nuclear power plant becomes more indispensable, although the share is to be small but significantly important for electric generation in Java–Madura–Bali grid. Nuclear technology can have also important role enabling the increase of the shares of renewable, e.g. geothermal, hydro and bio-fuels as well as fossil energies to meet more sustainable energy mix sufficing the energy demand to attain intended economic and population growths while maintaining the environment. The first introduced nuclear power plant is to be the proven ones, but the innovative nuclear energy systems being developed by various countries will eventually also be partially employed to further improve the sustainability. The nuclear science and technology are to be symbiotic and synergistic to other sources of energy to enhance the sustainable supply of energy.     

Yielding behaviour of thermoplastic/elastomer blends cured by gamma irradiation

Mechanical blends of thermoplastic medium density polyethylene (MDPE) and elastomeric ethylene propylene diene monomer (EPDM) have been prepared with a fixed composition of 60/40 wt%. They have been used either in their gum form or loaded with two different reinforcing fillers, high abrasion furnace (HAF) carbon black or precipitated SiO₂ (Hi Sil) of concentration 25–100 phr (parts per hundred parts of resin) with respect to the blend. Curing was achieved by gamma irradiation. Yielding properties (yield stress, yield strain and cold drawing) have been followed as a function of irradiation dose for different blend compositions. Yield stress values increased with irradiation dose and with the content of the reinforcing filler, but yield strain and cold drawing values decreased with irradiation dose and also with the filler content. The data obtained reveal that Hi Sil is more effective as a reinforcing filler, and the prepared blends are suitable for load‐bearing applications. © 2001 Society of Chemical Industry     

Optimization of biohydrogen production by Clostridium butyricum EB6 from palm oil mill effluent using response surface methodology

Clostridium butyricum EB6 successfully produced hydrogen gas from palm oil mill effluent (POME). In this study, central composite design and response surface methodology were applied to determine the optimum conditions for hydrogen production (P_c) and maximum hydrogen production rate (R_max) from POME. Experimental results showed that the pH, temperature and chemical oxygen demand (COD) of POME affected both the hydrogen production and production rate, both individually and interactively. The optimum conditions for hydrogen production (P_c) were pH 5.69, 36 °C, and 92 g COD/l; with an estimated P_c value of 306 ml H₂/g carbohydrate. The optimum conditions for maximum hydrogen production rate (R_max) were pH 6.52, 41 °C and 60 g COD/l; with an estimated R_max value of 914 ml H₂/h. An overlay study was performed to obtain an overall model optimization. The optimized conditions for the overall model were pH 6.05, 36 °C and 94 g COD/l. The hydrogen content in the biogas produced ranged from 60% to 75%.     

Postponement growth and antioxidative response of Brassica nigra on CuO and ZnO nanoparticles exposure under soil conditions

Due to unique physiochemical properties, nanoparticles (NPs) have acquired substantial attention in the field of research. However, threats of ecotoxicity and phytotoxicity have limited their biological applications. In this study in vivo experiments were performed to determine the effect of CuO (12.5, 25 and 50 mg/kg) and ZnO (200, 400 and 600 mg/kg) NPs on growth, and antioxidant activities of Brassica nigra. The results showed that CuO NPs did not affect the seed germination while presence of ZnO NPs in the soil generated an inhibitory effect. Both CuO and ZnO NPs positively influenced the growth of stem and other physiological parameters i.e. stem height increased (23%) at 50 mg/kg CuO while root length decreased (up to 44%) with an increase in the concentration of NPs. Phytochemical screening of apical, middle and basal leaves showed elevated phenolic and flavonoid contents in the range of 15.3–59 μg Gallic Acid Equivalent (GAE)/mg Dry Weight (DW) and 10–35 μg Querceitin Equivalent (QE)/mg DW, respectively, in NPs‐treated plants. Antioxidant activity was higher in CuO NPs‐treated plants as compared to ZnO and control plants. Results conclude that CuO and ZnO NPs at low concentrations can be exploited as nanofertilisers in agriculture fields.Inspec keywords: biochemistry, enzymes, renewable materials, crops, nanoparticles, soil, nanofabrication, zinc compounds, organic compounds, agricultural products, toxicology, nanobiotechnologyOther keywords: antioxidative response, ZnO nanoparticles exposure, soil conditions, unique physiochemical properties, germination, antioxidant activities, brassica nigra plant, antioxidant activity, CuO NP‐treated plants, control plants, ZnO NPs effect, mass 15.3 mug to 59.0 mug, mass 10.0 mug to 35.0 mug, CuO, ZnO     

Bezier surface/surface intersection

The computational requirements and accuracy of two methods for finding the intersection of Bezier surfaces are examined. In both methods, the existence of an intersection curve is confirmed by using the convex hull property of such surfaces. The first method evaluates the intersection by recursive subdivision of two patches with overlapping hulls. The second method detects a point on the intersection curve and then incrementally traces the intersection in the parametric spaces of the two surfaces. With both methods, the intersection of a pair of first-order planar patches must be solved analytically. The intersection is approximated by first-order Bezier patches in the first case and by planar triangles in the second. Overall, the method of incremental tracing is shown to give more accurate results than the method of recursive subdivision     

Biologically‐synthesised ZnO/CuO/Ag nanocomposite using propolis extract and coated on the gauze for wound healing applications

Wound healing has long been recognised as a major clinical challenge for which stablishing more effective wound therapies is necessary. The generation of metallic nanocomposites using biological compounds is emerging as a new promising strategy for this purpose. In this study, four metallic nanoparticles (NPs) with propolis extract (Ext) and one without propolis including ZnO/Ext, ZnO/Ag/Ext, ZnO/CuO/Ext, ZnO/Ag/CuO/Ext and ZnO/W were prepared by microwave method and assessed for their wound healing activity on excision experimental model of wounds in rats. The developed nanocomposites have been characterised by physico‐chemical methods such as X‐ray diffraction, scanning electron microscopy, diffuse reflectance UV–vis spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and Brunauer–Emmett–Teller analyses. The wounded animals treated with the NPs/Ext in five groups for 18 days. Every 6 days, for measuring wound closure rate, three samples of each group were examined for histopathological analysis. The prepared tissue sections were investigated by haematoxylin and Eosin stainings for the formation of epidermis, dermis and muscular and Masson''s trichrome staining for the formation of collagen fibres. These findings toughly support the probability of using this new ZnO/Ag/Ext materials dressing for a wound care performance with significant effect compared to other NPs.Inspec keywords: nanomedicine, X‐ray diffraction, II‐VI semiconductors, visible spectra, ultraviolet spectra, nanocomposites, biomedical materials, proteins, wounds, nanoparticles, scanning electron microscopy, nanofabrication, skin, zinc compounds, silver, antibacterial activity, Fourier transform infrared spectra, copper compounds, molecular biophysicsOther keywords: propolis, wound healing applications, effective wound, metallic nanocomposites, biological compounds, metallic nanoparticles, microwave method, wound healing activity, physico‐chemical methods, Fourier transform infrared spectroscopy, diffuse reflectance UV‐vis spectroscopy, Brunauer‐Emmett‐Teller analyses, wounded animals, wound closure rate, wound care performance, histopathological analysis, scanning electron microscopy, X‐ray diffraction, thermogravimetric analysis, haematoxylin, Eosin stainings, Masson trichrome, epidermis, muscular trichrome, collagen fibres, time 18.0 d, time 6.0 d, ZnO‐CuO‐Ag     

Recovery and reutilisation of copper from metal hydroxide sludges

Sludges generated from electroplating wastewaters contain high concentrations of metals. Studies have confirmed that the concentrations of several metals in the sludge exceed that of those found in natural ores. A very good example is in the case of copper. The natural copper ore contains less than 1% of copper, whereas copper precipitate sludges from the electroplating industry may have an average of 5–10% of copper. Thus, they are one of the largest sources of untapped metal-bearing secondary materials amenable to metals recovery. In Malaysia, most of these metal-bearing sludges are disposed in specially engineering landfills, as many of them do not have the proper incentives and recovery technology. Very less metal recovery is being carried out, and there seems to be a huge waste in these valuable metal resources. With regards to that, an experimental study was carried out to develop and optimise a method of copper recovery from metal hydroxide sludges. Sludge samples containing high concentrations of copper were obtained from a local electroplating plant for the study. A procedure based upon mineral acid leaching or solubilisation was carried out. Two different types of acids, hydrochloric acid (HCl) and sulphuric acid (H₂SO₄) were used to compare the extractability of copper. Experiments were conducted at various acid concentrations and temperatures to determine the maximum amount of copper recoverable. From the results obtained, maximum copper (95%) was solubilised using H₂SO₄ of 10 M at temperature 110°C, for a leaching period of 4 h. These copper concentrated solutions were then heated and crystallised to form CuSO₄ crystals. These crystals were then washed with water and purified. They can be then further treated and reutilised in the metallurgical industry. This study introduces a sustainable method of utilising an electroplating sludge containing valuable metals.