Production of bioethanol from waste money bills – A new cellulosic material for biofuels

Waste money bills that are no longer legal tender are non-recyclable and are usually destroyed. In this study, we used this cellulose-rich material for bioethanol fermentation for the first time. Glucose production was enhanced by using diluted H₂SO₄ during pretreatment. Different incubation periods were tested for saccharification and subsequent bioethanol fermentation. The highest yield of glucose (41.90 mg/ml) was shown to increase with 27.20% and 25.90% respectively by increasing the reaction period by 30 min and by increasing the acid concentration by 0.5%. Bioethanol production was enhanced by adding 0.4 mM benzoic acid under anoxic condition. In accordance with three different conditions, the highest amount of bioethanol (22.01 mg/ml) was obtained and bioethanol fermentation was increased by 59.38%, 110.02% and 64.13% respectively with 30 min of reaction periods, 0.5% of acid concentrations and under anoxic condition with benzoic acid. This procedure for the production of bioethanol from a waste material would reduce waste money bill management costs and make a profit from ethanol.     

Bonding of resin adhesives to caries-affected dentin – A systematic review

Minimal invasive dentistry aims at preserving the firm, discolored caries affected dentin (CAD), which is remineralizable. Research studies on resin adhesives are usually performed on sound dentin (SD), though CAD is the substrate routinely encountered for bonding in clinical practice. The aim of this paper was to systematically analyze the published literature on resin-dentin bonding to CAD substrate, in order to answer the question: “Does resin adhesive bonding to CAD produce lower bond strength when compared to SD?”. Three electronic databases (Pubmed, Scopus and ISI web of Science) were searched to identify original laboratory studies that evaluated the bond achieved between resin adhesive and natural CAD by measuring their bond strength. Only articles that met the specific inclusion criteria were included in the review. Among the 29 studies included for this review, majority of the studies had tested the simplified etch-and-rinse or self-etch adhesives. 85% of them showed higher bond strength to SD compared to CAD and the remaining 15% of them showed no difference between these two substrates. Among the studies that used 3-step etch-and-rinse adhesives, 40% showed higher and 60% showed no difference, when bond strength was compared between SD and CAD. Resin adhesives produce lower bond strength to caries-affected dentin than sound dentin. Research studies that reported bond strength of resin adhesives to dentin from sound extracted teeth alone cannot be blindly extrapolated to clinically relevant CAD. Hence, the results from such studies should be dealt with caution.     

Selective adsorption of the gold–cyanide complex from waste rinse water using Dowex 21K XLT resin

The Dowex 21K XLT resin which is a strong basic resin was used to selectively adsorb gold–cyanide complex only, in the actual waste rinse water which coexisted with lead–cyanide complexes. The existence of gold–cyanide complex on the surface of the Dowex 21K XLT resin was proved by SEM and EDX analysis. The maximum removal efficiency value for gold–cyanide complex was about 93% for 10 g/L of resin concentration while adsorption for lead–cyanide complexes did not almost happen at pH 13. The adsorption capacity of Dowex 21K XLT resin for gold and lead–cyanide complexes was about 32 and 0.8 mg/g-dry mass, respectively. Also, most of adsorption process for gold–cyanide complex was completed within 1 h. The exothermic nature of gold–cyanide complex adsorption onto the Dowex 21K XLT resin was revealed because the removal efficiency for gold–cyanide somewhat decreased as temperature increased. It was concluded that the Dowex 21K XLT resin, which has excellent selectivity to gold–cyanide complex, can be applied to the recovery system for gold–cyanide complex in actual waste rinse water.     

A study on the recovery of actinide elements from molten LiCl–KCl eutectic salt by an electrochemical separation

Pyroprocessing is a prominent way for the recovery of the long-lived elements from the spent nuclear fuel. Electrorefining is a key technology for pyroprocessing and generally composed of two recovery steps—deposition of uranium onto a solid cathode and the recovery of TRU (TRansUranic) elements. In this study, it was investigated on electrochemical separation of actinides to develop an actinide recovery system in a molten LiCl–KCl eutectic salt. In the electrorefining experiment, uranium was successfully separated from cerium. The effects of the anode material and the surface area were investigated during the electrolysis experiments for a more efficient electrorefining system. Anode potential decreased with an increasing anode surface area, however, an anode effect was observed in case of a complicated anode structure for high surface area. Glassy carbon was found to be the best anode material among the molybdenum, graphite, glassy carbon, and oxide materials. It was found that the solid cathode with a perforated ceramic container could be one of the candidates for a salt clean-up process to remove residual actinide elements in the salt after the recovery step.     

Biohydrogen Production from Organic Waste – A Review

Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency.     

Dewatering sludge by osmotic technique – A comparative experimental study

The present paper aims to introduce a novel and environment-friendly sludge dewatering method based on the osmotic technique, and to examine the efficiency of this method from macro- and micro-points of view. Intact sample, taken from the primary settler of a local wastewater treatment plant in Guangzhou (China), was firstly dewatered by mechanical methods (i.e. vacuum filtration and centrifugation), then by the osmotic technique. Macroscopic experimental results show that: the vacuum filtration and centrifugation can only dewater the sludge from 94.5 to 78.3% and to 78.8%, respectively, whereas, using the osmotic technique, water content of the sludge can be decreased to 44.2% in 12?h and to 35.9% in about two days. The micro-structure, obtained by scanning electron microscope (SEM), shows that: the sludge samples after vacuum filtration and centrifugation have a porous structure and water can be drained either through the cracks that have been developed under the vacuum pressure or by the micro-pores of several micrometers that have been created under the disturbance of the centrifugal force; on the other hand, in the case of the osmotic technique, the samples show a much denser structure, where both the macro- and micro-pores are significantly decreased or even closed at high concentration of the polyethylene glycol (PEG) solution. At last, the future application of the osmotic technique in practice is discussed from the viewpoints of deep dewatering and energy consumption.     

Characterization of gamma irradiated PUREX solvent – A systematic study

ABSTRACT

Radiolysis products were identified in gamma irradiated PUREX solvent under simulated conditions encountered during reprocessing of fast reactor spent nuclear fuel. The irradiated solvent after alkali wash was fractionally distilled for the ease of their analysis. Spectroscopic analysis of various fractions using techniques like Fourier-transform infrared spectroscopy (FT-IR), gas chromatography, gas chromatography-mass spectrometry (GC-MS), and matrix-assisted laser desorption/ionization (MALDI) revealed formation of various classes of compounds which result from fragmentation as well as recombination. 4-Decanol, 4-dodecanol, and oxalic acid were identified as the diluent degradation products. Metal retention behavior suggested the diluent recovered through distillation can be reused as neat diluent.     

Heating rate effects on the crystallization behavior of isotactic polypropylene from mesophase – A de-polarized light transmission study

It was ever reported in a communication of this journal that the large crystal grains having “bamboo leaf-like (BL)” morphology were produced by a rapid heating of isotactic polypropylene (iPP) from the mesophase. In order to optimize the condition to generate the BL crystals, heating rate effects on the crystallization behavior from the mesophase of iPP have been studied by utilizing a de-polarized light transmission (DPLT) method. The DPLT sensitively detected not only the cold crystallization from the mesophase around 100–120 °C but also the crystal grain growth in a narrow temperature region just below the melting temperature. With increasing the heating rate, both the temperature regions of the cold crystallization and the crystal grain growth shifted toward the higher temperatures. When the heating rate is slow (<20 °C/min), the crystal grain growth was not conspicuous. With increasing the heating rate, the rate of the crystal grain growth increased and showed a maximum when the heating rate is approximately 60–80 °C/min. However, excessively fast heating (>100 °C/min) also suppressed the crystal grain growth.     

“Refractory Metal,RM – Wrap”: A tailorable,pressure-less joining technology

The RM-wrap (RM = Refractory Metal) is a pressure-less, versatile and tailorable joining process: it consists of wrapping Si foils inside a refractory metal wrap (i.e., Mo, Nb, Ta) in order to prevent molten silicon from leaking outside the joined region and infiltrating the facing materials during the joining process.RM-wrap (RM = Mo, Nb, Ta) has been successfully applied to join C/SiC composites in this work: optimized joining treatment consisted of heating to 1450?°C with a heating rate of 1000?°C/h followed by a dwell time of 5?min in a non-reactive environment of Argon flow.The joints were characterized by morphological analysis and lap shear tests at room temperature and 1000?°C.Microscopical analysis revealed an in-situ formed composite joint consisting of a silicon matrix reinforced with silicides of the refractory metals. Joining material exhibited continuous and cracked free bonding with C/SiC irrespective of composite fibre orientation.Joints lap shear strength values at 1000?°C were higher than at room temperature, probably due to the brittle to ductile transition (BTDT) of silicon and silicides.Vickers microhardness on refractory metal disilicides measured inside the joints showed a trend similar to their mechanical strength, with higher lap shear strength and hardness for Mo-Wrap and lower for Ta-wrap joints.     

High temperature gaseous corrosion resistance of MgO-containing refractories – A comparative study

In the work the results of investigations into corrosive resistance to the attack of sulphur oxides of six commercially available basic refractories containing magnesium oxide have been presented. The research was conducted for materials applied in glass furnace regenerators: three types of magnesia-zirconia-forsterite products, one magnesia-forsterite and one magnesia product as well as a magnesia-chromite product to be applied in copper convertors. Investigations were carried out in a semi-flow chemical reactor. Investigations into corrosive resistance were conducted at 600 °C, 800 °C and 1000 °C. The real and equilibrium composition of gaseous phase in the reactor versus temperature was determined. It was assumed that the relative increment of the tested products' mass after a certain time of their staying in the reactor would be and indicator of corrosive resistance. Based on investigations into the phase composition of the products of reaction, it was found that at 600 °C and 800 °C the product's corrosion resulted from the formation of MgSO₄, as the main product of reaction, whereas at 1000 °C – it was the formation of CaMg₂(SO₄)₃. In products with an addition of ZrO₂ destabilisation of the regular structure of c-ZrO₂ was observed as well as its change into the monoclinic variety - m-ZrO₂. The examined refractory materials were ordered according to their corrosive resistance to sulphur oxides at particular temperatures applied in the test. The conducted investigations qualitatively describe the behaviour of refractories exposed to the corrosive attack of sulphur oxides and can be useful in the selection of refractory materials for particular industrial applications.     

Bubbly flow with particle attachment and detachment – A multi-phase CFD study

The available computational fluid dynamics (CFD) models for multi-phase bubble column ignore the effects of attached particles on the dynamics of the bubbles. Bubbles become heavier with the attachment of solid particles which has significant impact on their buoyancy, and hence their flow dynamics. The present paper endeavours to simulate multi-phase slurry bubble column accounting for the effect of bubble–particle aggregate density on the flow dynamics in a multi-phase slurry bubble column. A CFD model was developed and validated against air–paraffin oil data at ambient conditions to understand the hydrodynamics of a three-phase slurry bubble column.     

Farmers' perceptions and management of soil organic matter – a case study from West Africa

A farm survey was carried out in 155 Ghanaian villages covering parts of the forest and savanna zones of West Africa to assess farmers' views on ‘soil organic matter’ (SOM) and its management. The results of a closed questionnaire accompanied by open discussions showed that most farmers are well aware of SOM and its importance for crop yields. In southern Ghana, farmers perceive SOM generally by its colour, while in northern Ghana, it is mostly assessed by the density and kind of vegetation. Farmers' perception of the properties of SOM was directed at its main functions as a primary provider of plant nutrients and its ability to conserve water. Other properties mentioned were the improvement of soil aeration and drainage, the loosening of soil structure as well as its impact on soil temperature. The major strategies farmers used in maintaining or augmenting SOM levels were: manure application, mulching with crop residues, slashing weeds without burning, composting, and shifting cultivation (natural fallow). Promoted technologies, such as green manuring, no tillage, or agroforestry were used only by a few of the farmers interviewed. The differences between farmers' views and strategies in the two zones as well as farmers' constraints in SOM management are discussed. It appears that the level of farmers' commitment to excellent soil management can vary with biophysical as well as socio-economic conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

A screening study on the activation energy of vanadate‐based catalysts for diesel soot combustion

The activation energy of carbon combustion catalysed by alkali vanadates or alkali vanadates/chlorides mixtures is assessed by the Ozawa method. The most active catalyst, Cs₄V₂O₇, entails more than 50% decrease of the activation energy compared to non‐catalytic combustion (from 157 down to 75 kJ/mol). The catalyst performance is enhanced when the catalyst is dissolved in a eutectic liquid (e.g., AgCl + CsCl), which likely improves the catalyst/carbon contact conditions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mathematical modelling of Aspergillus ochraceus inactivation with supercritical carbon dioxide – A kinetic study

The aim of this research was to analyze and model the combined effect of pressure and temperature upon Aspergillus ochraceus spores exposed to high pressure carbon dioxide (HPCD) treatment and to estimate the kinetic parameters. Lately, many empirical or semi-empirical mathematical models were presented and discussed for different microorganisms, mainly bacteria, demonstrating an increased need for tools able to quantify the parameters of the microbial inactivation. A. ocharaceus HPCD inactivation was adequately described by first order reaction kinetics and a synergic effect of pressure and temperature was noticed for the experimental range where pressure varied from 5.4 to 7.0 MPa and temperature varied from 30 to 50 °C. The decimal reduction time (D) ranged from 47.07 min at 5.4 MPa and 30 °C to 5.04 min at 7.0 MPa and 50 °C. In this study three mathematical models were evaluated in order to find the best one that describes accurately the influence of pressure and temperature on the studied microbial response. An empirical exponential equation, that described pressure and temperature influence in the form of a polynomial equation, was found to best describe the dependence of A. ochraceus HPCD inactivation in the range 5.4–7.0 MPa and 30–50 °C.This work adds insight to moulds inactivation at the already existing body of knowledge on bacteria inactivation with HPCD and provides support to potential industrial applications of the minimal–thermal methods that combine high pressure and mild temperature with carbon dioxide for different food matrixes.     

Comprehensive management of mineral scale deposition in carbonate oil fields – A case study

The majority of oilfields, especially those under water injection suffer from scale deposition. The common method of addressing the scale issue is to deploy the integrated scale risk management, by which the data from all available disciplines such as Chemistry, Field Engineering, Completion Engineering, etc. are integrated to make the most suitable decision. The main aim of this study is to perform integrated scale risk management in the A carbonate oil field, under water injection.     

Effects of surface initial condition on aqueous corrosion of glass—A study with a model nuclear waste glass

Being a nonequilibrium material, the structure of glass varies with the sample history. Thus, the initial surface condition of a glass can vary with the preparation condition and have a large impact on its reactivity. This paper shows that the aqueous corrosion behavior of international simple glass (ISG) varies depending on the initial surface state. The ISG glass samples were prepared as-polished-only and polished-then-annealed and they were immersed in aqueous solution saturated with soluble SiO₂ at 30°C (modeling a mild condition) and at 90°C (modeling a severe condition). Molecular dynamics simulations were performed to obtain coordination numbers of network formers of ISG to assist oxygen speciation calculations. The surface structures of as-prepared and corroded ISG samples were analyzed using various imaging and spectroscopic techniques. Among these analyses, only the oxygen speciation with x-ray photoelectron spectroscopy showed discernable differences between two uncorroded surfaces with different preparation histories; all other methods could not differentiate the surface preparation history before aqueous corrosion. Such minor difference in chemical structures was found to have a profound impact on corrosion behaviors in the mild condition. In the harsh condition, the surface history dependence was not as drastic as the corrosion in the mild condition. The analysis results of the corroded surfaces suggested that the thickness and structure of the alteration layer formed on ISG in aqueous corrosion can vary with the initial surface state.     

Applications of the Biosorption Process for Nickel Removal from Aqueous Solutions – A Review

Wastewaters and contaminants released to the aqueous environment increase due to developing industrialization and technology. These wastewaters should be treated before being discharged to water bodies. Also, reusable materials in wastewaters must be recovered by appropriate techniques. Discharge limits required by the authorities become more stringent with updated legislations. Nickel ions can be reusable by recovering it after the biosorption process. So, this will prevent the loss of raw materials in industries and it also affects the economy in a positive way. Conventional heavy metal removal processes may be costly and inadequate to meet the desired discharge limits and they exhibit low efficiencies. Eco-friendly and economical treatment technologies gain great importance in the removal and recovery of nickel from wastewaters. In this study, biosorption which is the subject of numerous studies and one of the heavy metal removal methods will be investigated, and nickel removal by this technique and the biosorption mechanism will also be elaborated with data from literature studies.     

A density functional theory insight into the extraction mechanism of lithium recovery from alkaline brine by β-diketones

In this study, the mechanism of lithium extraction with β-diketones was investigated by resolving the reaction mechanism, thermodynamic property, and molecular interaction through density functional theory approach. Before the selective extraction of lithium, the β-diketones had tautomerism with the product of enol. The enol structure was unsteady in alkaline environment so that Li⁺ can be selectively extracted by taking the place of hydroxyl hydrogen. Meanwhile, the synergistic effect of TOPO intensified the extraction ability by the generation of strong electrostatic. Based on the calculated Gibbs energy changes, the parameters of extraction efficiency and separation factor were analyzed and they had qualitative consistence with the experimental results. Meanwhile, it was determined that the electron-withdrawing effect of the subsistent group in the β-diketones had a critical influence on the extraction separation performance. Besides, the theoretical model predicted successfully the transition of extraction complex from hydrophilicity to lipophilicity after the combination with synergistic reagent.     

Formation of hexagonal plate shaped ZnO microparticles – A study on antibacterial and magnetic properties

The focus of this work is to realize ZnO microparticles with simultaneously enhanced antibacterial and magnetic properties through a double cationic (Mg+Co) doping. Undoped and magnesium (Mg)+ cobalt (Co) doped ZnO microparticles were synthesized using a cost-effective simple soft chemical route. Their surface morphological, magnetic, antibacterial and structural properties were investigated. Antibacterial studies of the prepared samples were carried out against a Gram Positive and Gram Negative bacteria. From the antibacterial studies, it is found that the double cationic doped ZnO microparticles exhibit superior antibacterial efficiency compared with undoped and single cationic doped ZnO microparticles. The FESEM images show that the undoped and single cationic (Mg/Co) doped ZnO particles have hexagonal block structures of micro scale dimensions whereas the double cationic doping causes the formation of hexagonal plate structures having near nanoscale thickness (~150 nm), thereby increasing the effective reactive surface area. The magnetization curves show that the coexistence of Mg²⁺ and Co²⁺ ions in the ZnO lattice causes a pronounced increase in the ferromagnetic behavior, already present in the undoped and single cationic doped ZnO material. The XRD, FTIR and PL results support the discussion on the antibacterial and magnetic results. The EDAX profiles and the compositional mapping images confirm the presence of expected proportions of the constituent elements and their uniform distribution in the final product. Structural studies show that the products exhibit hexagonal wurtzite structure of ZnO without any secondary phases.