Hydrated lime for metals immobilization and explosives transformation: Treatability study

Fragmentation grenades contain Composition B (RDX and TNT) within a steel shell casing. There is the potential for off-site migration of high explosives and metals from hand grenade training ranges by transport in surface water and subsurface transport in leachate. This treatability study used bench-scale columns and mesocosm-scale laboratory lysimeters to investigate the potential of hydrated lime as a soil amendment for in situ remediation of explosives and metals stabilization in hand grenade range soils. Compared to the unamended soil there was a 26-92% reduction of RDX in the leachate and runoff water from the lime treated soils and a 66-83% reduction of zinc in the leachate and runoff water samples; where the hand grenade range metals of concern were zinc, iron, and manganese. The amended soil was maintained at the target pH of greater than 10.5 for optimum explosives decomposition. The treatability study indicated a high potential of success for scale-up to an in situ field study.

Frequency dependence of the quasi-soft Raman-active modes in rotationally distorted R(3+)B(3+)O3 perovskites (R(3+)-rare earth, B(3+)=Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga)

The structural data and Raman spectra of distorted R(3+)B(3+)O(3) perovskites (R(3+)-rare earth, B(3+)=Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga) with BO(6) octahedral tilts were critically reviewed in order to obtain the frequency (ω) versus BO(6) tilt angle (α) dependence of the quasi-soft vibrational modes. It was found that the relation ω = ϰα is satisfied in a good approximation for each RBO(3) family with fixed B atom, despite the different spatial tilt orientations for compounds of the same series with either orthorhombic Pnma or rhombohedral R ̅3c structure. The dependence of the proportionality coefficient ϰ on the averaged <B-O> octahedral distance can be described using different functions (power, linear and exponential ones). The established dependences can be used for analysis of Raman data and heuristic prediction of structural second-order transitions.

Effects of sintering atmosphere on cement clinkers produced from chromium-bearing sludge

The purpose of this study was to investigate the effects of sintering atmosphere (oxidizing and reducing) on the polymorphs of dicalcium silicates (Ca2SiO4, C2S) and on the chromium leaching of the belite-rich clinkers made from a chromium-bearing sludge. This sludge was generated in an electroplating factory, and in addition to chromium, it contained nickel, copper and zinc. In the clinker production, air was used as the oxidizing atmosphere, and carbon monoxide, which was produced by burning graphite with an insufficient amount of oxygen, was employed as the reducing atmosphere. Dicalcium silicates were substantially formed under both kinds of sintering atmosphere, but there was some nonhydraulic gamma-C2S in the clinkers produced under the oxidizing atmosphere. In addition, the amount of gamma-C2S decreased with the chromium-bearing sludge addition, whereas that of beta-C2S increased. The clinkers produced under the reducing atmosphere had less residual chromium, a finding that shows that more chromium was evaporated. However, the reducing atmosphere can decrease the proportion of hexavalent chromium (Cr(VI)) in the resulting clinkers. For other heavy metals, the residual amounts of nickel and copper generally increased with the sludge addition, but zinc was absent in most of the clinkers produced under the reducing atmosphere. This implies that the evaporation of zinc is much more significant than that of the other heavy metals under a reducing atmosphere. In the leaching tests, the concentrations of nickel, copper, and zinc were below the detection limits in all the leachates. In terms of chromium, the total leaching concentration was highly related to Cr(VI). The clinkers produced under the oxidizing atmosphere had high leaching concentrations of chromium, and thus failed to meet the regulatory limit. In contrast, the reducing atmosphere was effective in decreasing the chromium leaching, and it therefore makes the resulting cement clinkers more environmentally sound.

Mechanistic investigation on the formation and dehydrogenation of calcium amidoborane ammoniate

Possessing high H(2) capacities and interesting dehydrogenation behavior, metal amidoborane ammoniates were prepared by reacting Ca(NH(2) )(2) , MgNH, and LiNH(2) with ammonia borane to form Ca(NH(2) BH(3) )(2) ⋅2 NH(3) , Mg(NH(2) BH(3) )(2) ⋅NH(3) , and Li(NH(2) BH(3) )(2) ⋅NH(3) (LiAB⋅NH(3) ). Insight into the mechanisms of amidoborane ammoniate formation and dehydrogenation was obtained by using isotopic labeling techniques. Selective (15) N and (2) H labeling showed that the formation of the ammoniate occurs via the transfer of one H(N) from ammonia borane to the [NH(2) ](-) unit in Ca(NH(2) )(2) giving rise to NH(3) and [NH(2) BH(3) ](-) . Supported by theoretical calculations, it is suggested that the improved dehydrogenation properties of metal amidoborane ammoniates compared to metal amidoboranes are a result of the participation of a strong dihydrogen bond between the NH(3) molecule and [NH(2) BH(3) ](-) . Our study elucidates the reaction pathway involved in the synthesis and dehydrogenation of Ca(NH(2) BH(3) )(2) ⋅2 NH(3) , and clarifies our understanding of the role of NH(3) , that is, it is not only involved in stabilizing the structure, but also in improving the dehydrogenation properties of metal amidoboranes.

[Features of calcium crystals and calcium components in 54 plant species in salinized habitats of Tianjin]

Plant calcium (Ca) is composed of dissociated Ca2+ and easily soluble, slightly soluble, and hard soluble combined Ca salts. The hard soluble Ca salts can often engender Ca crystals. To understand the Ca status in different growth form plants in salinized habitats, 54 plant species were sampled from the salinized habitats in Tianjin, with the Ca crystals examined by microscope and the Ca components determined by sequential fractionation procedure. More Ca crystals were found in 38 of the 54 plant species. In 37 of the 38 plant species, drusy and prismatic Ca oxalate crystals dominated, whereas the cystolith of Ca carbonate crystal only appeared in the leaves of Ficus carica of Moraceae. The statistics according to growth form suggested that deciduous arbors and shrubs had more Ca oxalate crystal, liana had lesser Ca oxalate crystal, and herbs and evergreen arbors had no Ca oxalate crystal. From arbor, shrub, liana to herb, the concentration of HCl-soluble Ca decreased gradually, while that of water soluble Ca was in adverse. The concentration of water soluble Ca in herbs was significantly higher than that in arbors and shrubs. This study showed that in salinized habitats, plant Ca crystals and Ca components differed with plant growth form, and the Ca oxalate in deciduous arbors and shrubs played an important role in withstanding salt stress.

Relating reverse and forward solute diffusion to membrane fouling in osmotically driven membrane processes

Osmotically driven membrane processes, such as forward osmosis (FO) and pressure retarded osmosis (PRO), are attracting increasing interest in research and applications in environment and energy related fields. In this study, we systematically investigated the alginate fouling on an osmotic membrane during FO operation using four types of draw solutions (NaCl, MgCl(2), CaCl(2) and Ca(NO(3))(2)) to elucidate the relationships between reverse (from draw solution to feed solution) and forward (from feed solution to draw solution) solute diffusion, and membrane fouling. At the same water flux level (achieved by adjusting the draw solution concentration), the greatest reverse solute diffusion rate was observed for NaCl draw solution, followed by Ca(NO(3))(2) draw solution, and then CaCl(2) draw solution and MgCl(2) draw solution, the order of which was consistent with that of their solute permeability coefficients. Moreover, the reverse solute diffusion of draw solute (especially divalent cation) can change the feed solution chemistry and thus enhance membrane fouling by alginate, the extent of which is related to the rate of the reverse draw solute diffusion and its ability to interact with the foulant. The extent of fouling for the four types of draw solution followed an order of Ca(NO(3))(2) > CaCl(2) >> MgCl(2) > NaCl. On the other hand, the rate of forward diffusion of feed solute (e.g., Na(+)) was in turn promoted under severe membrane fouling in active layer facing draw solution orientation, which may be attributed to the fouling enhanced concentration polarization (pore clogging enhanced ICP and cake enhanced concentration polarization). The enhanced concentration polarization can lead to additional water flux reduction and is an important mechanism governing the water flux behavior during FO membrane fouling. Findings have significant implications for the draw solution selection and membrane fouling control in osmotically driven membrane processes.

Tetravalent dysprosium in a perovskite-type oxide

The existence of tetravalent dysprosium in perovskite-type oxide barium zirconate is confirmed in this work. This discovery will stimulate many researchers in diverse fields such as catalysts, solid state ionics, sensors, and fluorescent materials.

Octahedral rotation-induced ferroelectricity in cation ordered perovskites

Electronic structure calculations based on density functional theory have uncovered a novel mechanism for inducing ferroelectric polarizations in cation ordered perovskites. We outline a materials selection strategy for designing this behavior. The guidelines are based on the octahedral rotations found in the two constituent oxides and the way the perovskite building blocks are interwoven to form the superlattice.

Low-field magnetoresistance effect in core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles

Core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles are synthesized and their magnetic and magneto-transport properties are investigated. In these core-shell La(0.7) Sr(0.3) CoO(3) nanoparticles, the cores are single-crystalline and ferromagnetic, whereas the shells are noncrystalline and predominantly paramagnetic. Moreover, the insulating-like shells can serve as a good spin tunneling barrier. Therefore, in such a special core-shell structure, the spin-polarized interparticle tunneling is improved due to the existence of shells, which thus induces an enhanced low-field magnetoresistance effect.

Thermal phase transformations in LaGaO(3) and LaAlO(3) perovskites: an experimental and computational solid-state NMR study

Multinuclear (71)Ga, (69)Ga, (27)Al and (17)O NMR parameters of various polymorphs of LaGaO(3) and LaAlO(3) perovskites were obtained from the combination of solid-state MAS NMR with solid-state DFT calculations. Some of the materials studied are potential candidate electrolyte materials with applications in intermediate temperature solid oxide fuel cells (ITSOFCs). Small variations in the local distortions of the subject phases are experimentally observed by (71)Ga (and (69)Ga) and (27)Al NMR in the LaGaO(3) and LaAlO(3) phases, respectively, with heating to 1400 K. The orthorhombic-to-rhombohedral phase transformation occurring in LaGaO(3) at approximately 416 K is clearly observed in the (71)Ga/(69)Ga NMR spectra and is associated with a significant increase in the quadrupolar coupling constant (QCC). Thereafter a gradual decrease in QCC is observed, consistent with increased motion of the GaO(6) octahedral units and a reduction in the degree of octahedral tilting. The experimental and theoretical (71)Ga, (69)Ga, (27)Al and (17)O NMR parameters (including isotropic and anisotropic chemical shift parameters, quadrupolar coupling constants, and associated asymmetries) of the low and high temperature polymorphs are compared. In general, the calculated values display good agreement with experimental data, although some significant deviations are identified and discussed.

Phosphorus binding to Filtra P in batch tests

Recent guidelines from the Swedish Environmental Protection Agency recommend stricter regulations for phosphorus (P) reduction in small-scale wastewater treatment, which raises the need for additional and novel treatment steps in small-scale facilities. Following a biological pretreatment, filter systems can be a convenient option. In this study, the P binding capacity of the filter material Filtra P was investigated in batch tests. The batch test method was evaluated with respect to the effects of liquid-to-solid ratio and particle size on P binding capacity. For initial concentrations (c(i)) between 3 and 100 mg L(-1), the P in the solution was completely and rapidly bound to the material, indicating that Filtra P was an efficient substrate for this process. The maximum amount of bound P was 4.3 +/- 0.64 g kg(-1) at c(i) = 300 mg L(-1). The P binding capacity and turbidity measured in the supernatant correlated positively. Turbidity was probably caused by calcium-P precipitates, suggesting precipitation was the major removal mechanism. Neither the liquid-to-solid ratio nor the particle size affected P binding capacity significantly (alpha = 0.05) at c(i) = 1000 mg L(-1), confirming that the conditions used in the batch tests were appropriate. In full-scale applications, the precipitate formed may be at risk of being washed out of the filter, leading to low total P reduction and recovery.

Optimisation of Lime-Soda process parameters for reduction of hardness in aqua-hatchery practices using Taguchi methods

This paper presents the optimisation of Lime-Soda process parameters for the reduction of hardness in aqua-hatchery practices in the context of M. rosenbergii. The fresh water in the development of fisheries needs to be of suitable quality. Lack of desirable quality in available fresh water is generally the confronting restraint. On the Indian subcontinent, groundwater is the only source of raw water, having varying degree of hardness and thus is unsuitable for the fresh water prawn hatchery practices (M. rosenbergii). In order to make use of hard water in the context of aqua-hatchery, Lime-Soda process has been recommended. The efficacy of the various process parameters like lime, soda ash and detention time, on the reduction of hardness needs to be examined. This paper proposes to determine the parameter settings for the CIFE well water, which is pretty hard by using Taguchi experimental design method. Orthogonal Arrays of Taguchi, Signal-to-Noise Ratio, the analysis of variance (ANOVA) have been applied to determine their dosage and analysed for their effect on hardness reduction. The tests carried out with optimal levels of Lime-Soda process parameters confirmed the efficacy of the Taguchi optimisation method. Emphasis has been placed on optimisation of chemical doses required to reduce the total hardness using Taguchi method and ANOVA, to suit the available raw water quality for aqua-hatchery practices, especially for fresh water prawn M. rosenbergii.

Reuse of steel slag in bituminous paving mixtures

This paper presents a comprehensive study to evaluate the mechanical properties and environmental suitability of electric arc furnace (EAF) steel slag in bituminous paving mixtures. A variety of tests were executed on samples of EAF slag to characterize the physical, geometrical, mechanical and chemical properties as required by UNI EN specifications, focusing additionally on the volumetric expansion associated with hydration of free CaO and MgO. Five bituminous mixtures of aggregates for flexible road pavement were designed containing up to 40% of EAF slag and were tested to determine Marshall stability and indirect tensile strength. The leaching behaviour of slag samples and bituminous mixtures was evaluated according to the UNI EN leaching test. The tested slag showed satisfactory physical and mechanical properties and a release of pollutants generally below the limits set by the Italian code. Tests on volume stability of fresh materials confirmed that a period of 2-3 months is necessary to reduce effects of oxides hydration. The results of tests performed on bituminous mixtures with EAF slag were comparable with the performance of mixtures containing natural aggregates and the leaching tests provided satisfactory results.

Use of synchrotron XANES and Cr-doped coal to further confirm the vaporization of organically bound Cr and the formation of chromium(VI) during coal oxy-fuel combustion

Through the use of synchrotron XANES and Cr-doped brown coal, extensive efforts have been made to clarify the volatility of organically bound Cr during oxy-fuel combustion and the mode of occurrence and leachability of Cr in resulting fly ashes. As the continuation of our previous study using raw coal, the Cr-doped coal has been tested in this study to improve the signal-to-noise ratio for Cr K-edge XANES spectra, and hence the accuracy for Cr(VI) quantification. As has been confirmed, the abundant CO(2) as a balance gas for oxy-firing has the potential to inhibit the decomposition of organically bound Cr, thereby favoring its retention in solid ash. It also has the potential to promote the oxidation of Cr(III) to Cr(VI) to a minor extent. Increasing the oxygen partial pressure, particularly in the coexistence of HCl in flue gas, favored the oxidation of Cr(III) into gaseous Cr(VI)-bearing species such as CrO(2)Cl(2). Regarding the solid impurities including Na(2)SO(4) and CaO, Na(2)SO(4) has proven to preferentially capture the Cr(III)-bearing species at a low furnace temperature such as 600 °C. Its promoting effect on the oxidation of Cr(III) to Cr(VI), although thermodynamically available at the temperatures examined here, is negligible in a lab-scale drop tube furnace (DTF), where the particle residence time is extremely short. In contrast, CaO has proven facilitating the capture of Cr(VI)-bearing species particularly oxychloride vapors at 1000 °C, forming Ca chromate with the formulas of CaCrO(4) and Ca(3)(CrO(4))(2) via a direction stabilization of Cr(VI) oxychloride vapor by CaO particle or an indirect oxidation of Cr(III) via the initial formation of Ca chromite. The fly ash collected from the combustion of Cr-doped coal alone has a lower water solubility (i.e., 58.7%) for its Cr(VI) species, due to the formation of Ba/Pb chromate and/or the incorporation of Cr(VI) vapor into a slagging phase which is water-insoluble. Adding CaO to coal increased the water-solubility of both Cr(VI) and Cr(III) by forming Ca chromite and chromate, respectively.

Vapor diffusion sol-gel synthesis of fluorescent perovskite oxide nanocrystals

A model system consisting of Eu(3+) as the activator ion and BaZrO(3) as the host lattice is employed to demonstrate the potential of the vapor diffusion sol-gel method as a hydrolytic approach to the synthesis of fluorescent alkaline-earth perovskite oxide nanocrystals under ultrabenign conditions. The resulting nanocrystals are suitable precursors for nanostructured red-emitting phosphors.

Arsenic encapsulation using Portland cement with ferrous sulfate/lime and Terra-Bond™ technologies - Microcharacterization and leaching studies

This work reports the results of an investigation on the treatment and encapsulation of arsenic-containing materials by Portland cement with ferrous sulfate and lime (PFL) and Terra-Bond™, a commercially available patented technology. The arsenic materials included: chromated copper arsenate (CCA)-treated wood materials; scorodite-rich mine tailings from the La Trinidad Mine in California; and a soil/smelter dust mixture from the Anaconda Superfund site spiked with monosodium methyl arsenate (MSMA) to simulate an organoarsenic soil material. SEM/EDS and XRD spectra of PFL treated samples showed similarity across all three waste materials while Terra-Bond treated samples showed predominance of elemental sulfur. SEM/EDS of PFL treated samples showed that calcium was imbedded in the structure while micrographs of Terra-Bond treated samples showed the appearance of an epoxy material on the surface. The epoxy material appears to be responsible for encapsulating and reducing the leachability of arsenic. XANES spectra for the PFL treatment of CCA-containing samples showed that arsenic has a predominant pentavalent form (As +5), and the PFL treatment process did not alter the arsenic oxidation state. But, distinct differences were observed for XANES spectra of untreated and PFL treated scorodite-rich mine tailing which changed the arsenic coordination structure from a mixture of As (+3/+5) to exclusively As (+5). Both S/S techniques reduced the amount of arsenic released in the leaching tests. Most cases show lower amounts of arsenic released from wastes treated by the Terra-Bond™ technique when compared to the PFL technique. The pH of the solution significantly affected the leachability, with the amount of arsenic released increasing with pH. Sequential extraction results indicate that sodium hydroxide was favorable in releasing arsenic in the mine tailings. This is due to ligand displacement reactions of hydroxyl ions with arsenic species and high pH conditions that prevent the readsorption of arsenic.

Novel CaO-SiO2 sorbent and bifunctional Ni/Co-CaO/SiO2 complex for selective H2 synthesis from cellulose

Catalysis- and sorption-enhanced biomass gasification is a promising route to high-purity hydrogen (H(2)); however, most CaO-based sorbents for CO(2) capture have poor surface area and mechanical properties, lose carrying capacity over multiple uses, and have insufficient porosity to accommodate extra catalyst sites. We aimed to develop a high-surface-area CaO-SiO(2) framework onto which catalysts could be grafted. The best CaO-SiO(2) sorbent (n(Ca)/n(Si) = 2:1) maintained a CaO conversion of 65% even after 50 carbonation-decarbonation cycles, better than commercial micrometer-sized CaO or tailored CaO, because of stabilization via Ca-O-Si interactions and an ordered porous structure. Bimetallic catalyst grains (Ni/Co alloy, <20 nm) could be evenly loaded onto this structure by impregnation. The resulting bifunctional complex produced H(2) at nearly the same rate as a mixture of catalyst and commercial CaO while using less total sorbent/catalyst. Furthermore, this complex was much more durable due to its higher coking resistance and stable structure. After 25 carbonation-decarbonation cycles, the new catalyst-sorbent complex enhanced the H(2) yield from cellulose far more than a mixture of catalyst and commercial CaO did following the same treatment.

[Effect of different calcium hypochlorite concentrations on the survival of potentially pathogenic microorganisms isolated from Baikal Lake]

The survival rate of bacteria of the genera Pseudomonas and Enterococcus isolated from Baikal Lake, exposed to different concentration of calcium hypochlorite used as a main agent for drinking water disinfection, was studied. Experimental studies have shown that chlorination was imperfect as this method is not always effective against Enterococci.

Long-term field-scale experiment on using lime filters in an agricultural catchment

The River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site lime-sand filters (F1, F2, and F3), established within or on the edge of the buffer zones. The filters contain burnt lime (CaO) or spent lime [CaO, Ca(OH), and CaCO]. Easily soluble lime results in a high pH level (>11) and leads to an efficient precipitation of soluble phosphorus (P) from the runoff. Water samples were taken from the inflow and outflow of each site in different hydrological situations. The length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 significantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. The proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt lime and the other spent lime. Both filter parts removed PTOT and SS efficiently from the water; the burnt-lime part also removed DRP. The mixed-lime part removed DRP for a year, but then the efficiency decreased. The effect of filters on nitrogen compounds varied. We conclude that sand filters incorporating lime can be used together with buffer zones to reduce both P and SS load to watercourses.

Evaluation of a lime-mediated sewage sludge stabilisation process. Product characterisation and technological validation for its use in the cement industry

This paper describes an industrial process for stabilising sewage sludge (SS) with lime and evaluates the viability of the stabilised product, denominated Neutral, as a raw material for the cement industry. Lime not only stabilised the sludge, raised the temperature of the mix to 80-100°C, furthering water evaporation, portlandite formation and the partial oxidation of the organic matter present in the sludge. Process mass and energy balances were determined. Neutral, a white powder consisting of portlandite (49.8%), calcite (16.6%), inorganic oxides (13.4%) and organic matter and moisture (20.2%), proved to be technologically apt for inclusion as a component in cement raw mixes. In this study, it was used instead of limestone in raw mixes clinkerised at 1400, 1450 and 1500°C. These raw meals exhibited greater reactivity at high temperatures than the limestone product and their calcination at 1500°C yielded clinker containing over 75% calcium silicates, the key phases in Portland clinker. Finally, the two types of raw meal (Neutral and limestone) were observed to exhibit similar mineralogy and crystal size and distribution.

A novel method of sludge pretreatment using the combination of alkalis

The present study aims to utilise the advantage of higher sludge solubilisation potential of sodium hydroxide (NaOH) and sludge management properties of lime to achieve sludge pretreatment and its subsequent management. The optimum dosage and time required for sludge pretreatment using NaOH was found to be 1.6 g l(-1) and 3 hr, respectively. At the optimized condition, lime was added at varying concentration (0.3 to 1.6 g l(-1)) to study its effect on capillary suction time, soluble chemical oxygen demand (SCOD) release and total phosphorous (TP) removal. A lime dosage of 0.7g l(-1) was found to be beneficial for soluble chemical oxygen demand (COD) release. When compared to control, the combination of alkalis (NaOH and lime) reduced the TP and capillary suction time (CST) in the supernatant of the sludge. The TP removal was from 100 to 40 mg l(-1) and CST reduction was from 1360 to 350 sec, respectively. The combined alkali pretreatment not only prevent the subsequent TP increase in the effluent, but also decreased the time to filter the sludge, thus makes the digested sludge easier to manage.

Prevention of struvite scaling in digesters combined with phosphorus removal and recovery--the FIX-Phos process

The fixation of phosphorus (FIX-Phos) combines struvite prevention and phosphorus recovery by the addition of calciumsilicatehydrate (CSH) particles into the anaerobic digester. The CSH fixates phosphorus as calcium phosphate and reduces the phosphorus concentration in the sludge water that allows for control of struvite formation. The phosphorus-containing recovery product can be separated and recovered from the digested sludge. In pilot plant experiments, 21% to 31% of phosphorus contained in digested sludge could be recovered when CSH was added at concentrations of 2 g/L to 3.5 g/L to a mixture of primary sludge and waste activated sludge (WAS) from enhanced biological phosphorus removal. The recovery product contained few heavy metals and a phosphorus content of 18 wt % P2O5, which allows for recycling as fertilizer. The fixation of phosphorus within the digester may increase wastewater sludge dewaterability. The phosphorus recycle stream to the headworks of the wastewater treatment plant is reduced.

Gold nanoparticles on the surface of soda-lime glass: morphological, linear and nonlinear optical characterization

Materials presenting high optical nonlinearity, such as materials containing metal nanoparticles (NPs), can be used in various applications in photonics. This motivated the research presented in this paper, where morphological, linear and nonlinear optical characteristics of gold NPs on the surface of bulk soda-lime glass substrates were investigated as a function of nanoparticle height. The NPs were obtained by annealing gold (Au) thin films previously deposited on the substrates. Pixel intensity histogram fitting on Atomic Force Microscopy (AFM) images was performed to obtain the thickness of the deposited film. Image analysis was employed to obtain the statistical distribution of the average height of the NPs. In addition, absorbance spectra of the samples before and after annealing were measured. Finally, the nonlinear refractive index (n2) and the nonlinear absorption index (α2) at 800 nm were obtained before and after annealing by using the thermally managed eclipse Z-scan (TM-EZ) technique with a Ti:Sapphire laser (150 fs pulses). Results show that both n2 and α2 at this wavelength change signs after the annealing and that the samples presented a high nonlinear refractive index.

Fabrication of CaO-based sorbents for CO₂ capture by a mixing method

Three types of sorbent were fabricated using various calcium and support precursors via a simple mixing method, in order to develop highly effective, durable, and cheap CaO-based sorbents suitable for CO(2) capture. The sorption performance and morphology of the sorbents were measured in a thermogravimetric analyzer and a scanning electron microscopy, respectively. The experimental results indicate that cement is a promising low-cost support precursor for contributing to the enhancement of cyclic CO(2) sorption capacity, especially when organometallic calcium precursors were used. A sorbent (with 75% CaO content) made from calcium l-lactate hydrate and cement showed the highest CO(2) sorption capacity of 0.36 g of CO(2)/g of sorbent and its capacity decreased only slightly after 70 cycles of carbonation and calcination.

Transesterification of sunflower oil on single step sol-gel made Al2O3 supported CaO catalysts: effect of basic strength and basicity on turnover frequency

The activities of single step sol-gel made calcium oxide on alumina catalysts were studied as a function of CaO loading, methanol/oil molar ratio and the amount of the catalyst in the transesterification of sunflower oil at 50°C. Also, the turnover frequency (TOF) of the catalysts was calculated to better understand the relationship between the basicity/basic strength and the catalytic activity. From volcano curve (TOF vs. basic strength), it was found that under 50°C and methanol/oil molar ratio of 9, 60% CaO/Al(2)O(3) had the highest turnover frequency, 0.028s(-1), whereas 85% CaO/Al(2)O(3) showed the highest biodiesel yield, ∼96.6%, but TOF obtained on it was 0.012s(-1). It seemed that 60% CaO catalyst had the proper basic strength to obtain the highest TOF.