Wet Combustion Method Research Articles

Serratula coronata L. Mediated Synthesis of ZnO Nanoparticles and Their Application for the Removal of Alizarin Yellow R by Photocatalytic Degradation and Adsorption.

In this study, the potential of biogenic zinc oxide nanoparticles (ZnO NPs) in the removal of alizarin yellow R (AY) from aqueous solutions by photocatalytic degradation, as well as adsorption, was investigated. The synthesized ZnO NPs were prepared by the simple wet-combustion method using the plant extract of Serratula coronata L. as a reducing and stabilizing agent and characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy. Photocatalytic degradation of AY was monitored by UV–visible spectroscopy and the effects of parameters, such as light source type (UV-, visible- and sunlight), incubation time, pH, catalyst dosage and temperature on degradation were investigated. It was demonstrated that the source of light plays an important role in the efficiency of the reaction and the UV-assisted degradation of AY was the most effective, compared to the others. The degradation reaction of AY was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first-order kinetic model. The degradation kinetics of AY accelerated with increasing temperature, and the lowest activation energy (Ea) was calculated as 3.4 kJ/mol for the UV-light irradiation system, while the Ea values were 4.18 and 7.37 kJ/mol for visible light and sunlight, respectively. The dye removal by the adsorption process was also affected by several parameters, such as pH, sorbent amount and contact time. The data obtained in the kinetics study fit the pseudo-second-order equation best model and the rate constant was calculated as 0.001 g/mg·min. The isotherm analysis indicated that the equilibrium data fit well with the Freundlich isotherm model. The maximum adsorption capacity of AY on biogenic ZnO NPs was 5.34 mg/g.

Microbial responses to doses of cover plant straw in cerrado piauiense oxisol

Carbon and nitrogen from the soil microbial biomass play a significant role in the rotation of C and N, and promote nutrient cycling. Thus, the objective of this study was to evaluate changes in the soil microbial biomass with growing doses of cover plant straw species. The cover plants cultivated in the cerrado biome region were incorporated an Oxisol Ustox. The straw of each cover plant was incorporated at doses of 0; 10; 20 and 30 Mg ha-1. The soil basal respiration was determined by incubating, after 21 days. The microbial biomass carbon and nitrogen were determined by the method the microwave irradiation. The microbial biomass carbon and nitrogen contents in extracts were determined by the wet combustion method and Kjeldahl-N. The metabolic quotient was calculated as the ratio between soil basal respiration rate and microbial biomass C, and the microbial quotient as the ratio between soil microbial biomass C and total carbon of soil. The soil microbial population measured by the attributes of quality responds to the addition of the of grass and legume straws incorporated to the soil; The treatments that cause the greatest stress to the microbial population, at 21 days, mediated by the metabolic quotient, are guandu-anão at a dose of 10 Mg ha-1; Guandu-anão and Guandu fava-larga at 20 Mg ha-1 and Brachiária at a dose of 30 Mg ha-1; The best result regarding microbial attributes of soil quality evaluated was observed with the incorporation of all doses of the straw of Crotalaria-ocroleuca.

Influence of laser excitation power on temperature-dependent luminescence behaviour of Ce- and Tb-incorporated BaMgAl10O17 phosphors

BaMgAl10O17 (BAM) is a highly suitable host lattice for various rare earth ions with excellent luminescence properties in different spectral regions, including a strong photoluminescence (PL) emission from the visible spectral region. A new Ce- and Tb-incorporated BaMgAl10O17 phase was synthesized successfully using a wet combustion method and it was studied as a function of the temperature and laser excitation power. We further characterize the obtained phosphors with X-ray diffraction at room temperature. Different fuel/oxidant (f/o) ratios were introduced to investigate the optimum synthesis conditions for the BAM phosphors and optimum ratio was found out to be 8. The photoluminescence (PL) spectra were collected under the excitation light generated by a Nd:YLF pulse laser at 349 nm as the temperature was increased from 10 K to 300 K. A strong green emission of Tb3+ was observed in the green region of the spectrum due to the 5D4→7FJ transition. We also observed a wide emission band from the Ce3+ ion in the wavelength range of 350–650 nm. The luminescence intensities of all phosphors exhibited different patterns with an increase in the temperature. We also evaluated how the PL spectrum of the rare earth-activated BAM host matrix shifts under various laser excitation powers. The PL intensity of Ce-activated BAM significantly shifted (~30 A) to the blue region of the spectrum with an increase in the laser excitation power, however we did observed no shift forTb3+ activated BAM. The present findings suggest that Tb-incorporated BaMgAl10O17 can be effective as a green phosphor candidate material with a wide range of applications.

Processing of household waste in the BTLSS using the wet combustion method

The present study discusses physicochemical methods of organic waste processing in closed biotechnical life support systems (BTLSS). Sanitary and household cotton wastes were processed by the method of wet combustion in hydrogen peroxide using an alternating current electric field – a promising physicochemical method for organic waste processing in the BTLSS. The highest efficiency of the process (in terms of power consumption, duration of the process, and oxidation rate) was achieved in experiments with oxidation of a combination of cotton fabrics and urea-containing wastes such as human urine and feces. The reason for this must be that urea is a reactive aqueous solvent of cellulose.

Developing the technology of physicochemical processing of organic waste in closed life support systems for space applications

Closed life support systems for space applications need a technology of processing organic waste produced in the system that would enable incorporating the recycled waste into the mass transfer of the system. Researchers of the Institute of Biophysics SB RAS have developed a method of waste processing that meets these requirements: a physicochemical method of organic waste oxidation in the hydrogen peroxide aqueous solution under application of an alternating current electric field – wet combustion. The mineralized solution produced by this method can be used as a mineral nutrient supplement for higher plants in the life support system. The present study describes technical implementation of the wet combustion method and reports results of developing this method in the last few years. The study addresses problems associated with the design and positions of individual components and different configurations of the wet combustion reactor, showing the way to automate operation of the reactor and reporting optimal parameters of the current applied to the electrodes, which reduce time and power consumption by waste processing.

Soil analytical quality control by traditional and spectroscopy techniques: Constructing the future of a hybrid laboratory for low environmental impact

Soil analysis is an important information in agriculture and environmental monitoring. It is usually performed by wet chemical analysis with high cost and chemical products consumption. In the world, it is estimated that 1.5 billion ha is used as agricultural area. If every 5 ha 2 samples (2 depths) were collected, we would have 600 million soil samples for chemical and granulometric analysis. Considering just the analysis of organic matter (OM) by wet combustion method in the laboratory as an example, we would be utilizing about 840 thousand kg of dichromate and ammonium ferrous sulfate and 3 million L of sulfuric acid. The use of these reagents can have a huge ecological consequence if they do not have an adequate final disposal. An alternative methodology such as proximal sensing can be utilized with low environmental impact. Therefore, the objective of this study was to: i) evaluate the analytical quality of soil attributes via different traditional laboratories and sensors, ii) evaluate the prediction of the models using sensors, iii) assess the uncertainties of lime recommendation analyzed by the laboratories. We applied 96 soil samples at two depths collected in São Paulo State, Brazil. The determination of 15 soil attributes was performed by four different routine laboratories, and they were predicted by 4 sensors (400–2500 nm). Results indicate that the determination of attributes via chemical analysis with low quality led to high error in spectral models. The great predictive performances of clay, OM, cation exchange capacity (CEC), and pH enable the use of sensors in the evaluation of these attributes. Overall, the criteria for classification of analytical results showed that sand, silt, clay, pH, OM, CEC, and base saturation were the attributes that can be determined by the spectroscopy technique with high-quality outcome. The lime recommendation derived from proximal sensor analysis can be used as an efficient method, since it presented a high correlation with the laboratory result. In this sense, a hybrid laboratory analysis can be developed to optimize analysis with better quality control, which is indicated as a great opportunity in the near future.

Nanostructural evolution in mesoporous networks using in situ High-Speed Temperature Scanner

Mesoporous networks with a special distribution of functional centers are an important class of high performance materials for catalysts, bioscaffolds, energy conversion and storage systems. Methods of fabrication allowing to control over special distribution of the functional sites of required phases and designed morphology are still of a great challenge. Here, we report a wet-combustion method for functionalization of the mesoporous network of alumina nanofibers with a single fiber diameter of 7 ± 2 nm by Ni-based nanoparticles. The second-scale duration of the combustion process developing high flame temperature (>1000 °C) allows fabrication of mesoporous functional networks with tailored size, morphology and homogeneity of the dopants in a single-stage. The mechanism of the combustion process are studied by in situ high-speed temperature scanner, which continuously records the temperature history and applied power during the process. It readily allows quenching of the samples at a specified point, demonstrates the critical effect of a fuel on the decomposition temperature, combustion enthalpy, functional group, and pH. As a result of the wet-combustion synthesis, aligned double core-shell NiO-NiAl2O4-Al2O3 fibers or NiO nanoparticles deposited onto alumina nanofibers can be formed.

The template-assisted wet-combustion synthesis of copper oxide nanoparticles on mesoporous network of alumina nanofibers

A novel wet-combustion method is developed to functionalize mesoporous network of alumina nanofibers. The wet-combustion method includes coating the nanofibers with the solution of the precursors of dopants mixed with fuels, followed by dissociation/oxidation of the precursors in a combustion mode. Due to the high temperature of the flame and short duration of the combustion process, this approach possesses such unique feature as control over the size, morphology and homogeneity of the deposited nanostructures as well as ability to avoid additional procedures of calcination.In this study, urea and glycine as the basic fuels and copper nitrate as the precursor of copper and oxidant as well as mesoporous network of alumina nanofibers (with single fiber diameter of 7 ± 2 nm) as the template are used. As a result, a mesoporous network of highly oriented copper oxide – alumina composite nanofibers are produced. It is shown that the fuel type and the ratio of fuel-to-oxidizer do not evidently influence on the chemical composition of the product, while the morphology of the deposited copper oxide is controlled by the initial composition of reagents. The average crystallite size of the deposited CuO is 16 and 19 nm for the systems containing stoichiometric amount of glycine and urea, respectively.

Determination of Heavy Metals Contents of Some Monofloral Honey Produced in Turkey

In the present work, some element contents (Cd, Se, Cr, Pb, Cu, Mn, Ni, Zn, Fe) of 23 different monofloral honey samples from different regions of Turkey were assessed. Origins of monofloral honey research materials are as follows; Pimpinella sp., Castanea sp., Astragalus sp., Onobrychis sp., Mentha sp., Coridothymus capitatus, Robinia pseudoacacia, Cedrus libani, Gossypium sp., Thymus sp., Euphorbia sp., Tilia sp., Eucalyptus sp., Ferula sp., Centaurea solstitialis, Petroselinum sp., Vitex agnus-castus, Helianthus annuus, Citrus sp., Pinus sp., Rhododendron sp., Arbutus sp., Ceratonia siliqua. Metal contents of samples were determined by wet combustion method in ASS machine. As a result of the study, heavy metal contents of honey samples were as follows; Cd

Methods of soil organic carbon determination in Brazilian savannah soils

Several methods exist for determining soil organic carbon, and each one has its own advantages and limitations. Consequently, a comparison of the experimental results obtained when these methods are employed is hampered, causing problems in the comparison of carbon stocks in soils. This study aimed at evaluating the analytical procedures used in the determination of carbon and their relationships with soil mineralogy and texture. Wet combustion methods, including Walkley-Black, Mebius and Colorimetric determination as well as dry combustion methods, such as Elemental and Gravimetric Analysis were used. Quantitative textural and mineralogical (kaolinite, goethite and gibbsite) analyses were also carried out. The wet digestion methods underestimated the concentration of organic carbon, while the gravimetric method overestimated. Soil mineralogy interfered with the determination of carbon, with emphasis on the gravimetric method that was greatly influenced by gibbsite.

Numerical Simulation of the Multi-Component Slurry Gasification with the Non-Premixed Combustion Model

Considering the volumetric reactions and particle surface reactions in an entrained flow gasifier, the non-premixed combustion model based on the wet particles combustion method is adopted to simulate the multi-component slurry gasification process with FLUENT software. The velocity, temperature and concentration profiles of the gas products in the gasifier are obtained. Simulated results agree well with the commercial data, which verified the validity and applicability of the present model. Simultaneously, the reaction subarea in the gasifier has turned out to be obvious, the water evaporation, volatiles cracking and combustion reactions mainly appear in the jet region of the gasifier, the char gasification mainly appear in the freeboard region, but few reactions appear in the recirculation region. Moreover, with the increase of the mass fraction of the multi-component slurry, the content of the syngas at the gasifier outlet increases, while with the oxygen carbon atom ratio increasing, the syngas yield is rising early but declining later.

Methods for the determination of carbon in Ultisol in eastern Amazon

Soil carbon (C) content is a sensitive indicator of agricultural management impact. Different methods are usually adopted to determine soil C content, which can lead to variable results and therefore hinder the correct interpretation of management impacts. In this study, we tested three commonly used soil C determination methods (dry combustion with elemental analysis, dry combustion with loss-on-ignition, and wet combustion) with soil samples from agricultural sites under different management conditions (fire and fire-free land preparation) and forest. The wet combustion method underestimated soil C content in relation to the standard method (dry combustion with elemental analysis). We found high determination coefficients of predictive equations of total C (dry combustion with elemental analysis) based on concentration values determined either through wet combustion or loss-on-ignition. Thus, we recommend the use of the loss-on-ignition method, which is cheap, fast, and of low environmental impact, to predict total soil C concentration under the studied management conditions.

Carbon storage, structure and composition of miombo woodlands in Tanzania’s Eastern Arc Mountains

AbstractWe determine the aboveground biomass and carbon storage (ABGC) of trees and the herbaceous layer in miombo woodland in the Eastern Arc Mountains (EAM) of Tanzania. In four 1‐ha sample plots in Nyanganje and Kitonga Forests, we measured all trees ≥10 cm diameter alongside height and wood mass density. The plots contained an average of 20 tree species ha−1 (range 11–29) and 344 stems ha−1 (range 281–382) with Shannon diversity values of 1.05 and 1.25, respectively. We weighted nine previously published woody savannah allometric models based on whether: (i) the model was derived from the same geographical region; (ii) the model included tree height/wood mass density in addition to stem diameter; and (iii) sample size was used to fit the model. The weighted mean ABGC storage from the nine models range from 13.5 ± 2 to 29.8 ± 5 Mg ha−1. Measured ABGC storage in the herbaceous layer, using the wet combustion method, adds 0.55 ± 0.02 Mg C ha−1. Estimates suggest that EAM miombo woodlands store a range of 13–30 Mg ha−1 of carbon. Although the estimates suggest that miombo woodlands store significant quantities of carbon, caution is required as this is the first estimate based on in situ data.

Optimizing the weight loss-on-ignition methodology to quantify organic and carbonate carbon of sediments from diverse sources

The sequential weight loss-on-ignition (WLOI) method for determination of organic and carbonate or inorganic carbon (C) content was evaluated on sediments from diverse sources with a great range of C contents. The sediments were collected from canal, wetland, river, estuary, lake, and marine sites. The organic and inorganic C contents of these samples ranged from 1 to 430 g kg( -1) and from 4 to 97 g kg( -1), respectively. Combinations of the combustion time and temperature and optimal weight ranges of representative samples were tested, and comparisons of the WLOI method with other methods, including dry combustion and wet combustion, were made. These methods were (1) use of the carbon-nitrogen-sulfur (CNS) autoanalyzer with normal and reduced temperatures for total and organic C, (2) thermogravimetry for both organic and inorganic C, (3) use of the CNS autoanalyzer after removal of inorganic (carbonate) C by fumigating samples with concentrated HCl for organic C, (4) Walkley-Black wet combustion method for organic C, and (5) pressure-calcimeter associated with subtraction method (total C minus inorganic C) for organic C determinations. The results of analyzing samples of sediments of diverse origins showed that the optimal combination of temperature and time of WLOI depended mostly on the sources of the analyzed sediment. The WLOI analysis of sediment samples for organic C from wetlands, canal, estuary, or river sites needed a relatively low temperature but that of sediment samples from lake and marine sites required a relatively high temperature. Overall, to obtain reliable analysis results of samples from widely varied sediment sources except marine sediments, 500°C for 12 h was optimal for organic C content determination, and 800°C for yet another 12 h was optimal for inorganic C content determination. The temperature could even be reduced to 475°C if only wetland and stream sediments were included, but for marine sediments, 550°C for 12 h was necessary. Precise C content determinations for most sediment sources could be obtained by WLOI when sample quantities ranged from 2.0 to 4.0 g. The WLOI method, when conducted properly, resulted in precise measurements of C contents in "standard samples" used for calibration, and these values were closely comparable to results obtained with other dry combustion methods (R (2) ≥ 0.96). We conclude that WLOI, which has advantages of simplicity, cost-effectiveness, and no waste disposal over other methods, can provide precise measurements of organic and inorganic C contents in sediments from a wide range of sources, but the selection of heating temperature and exposure time should be carefully considered based on sediment sources.

Comparaçao de métodos de determinação do carbono orgânico em solos cultivados com eucalipto

A determinação de C orgânico do solo tem sido realizada, principalmente, por métodos baseados na oxidação química. Contudo, recentemente, o C tem sido determinado por métodos de combustão seca, como o CHNS/O. Este trabalho teve como objetivo comparar três métodos para determinação do C de solos cultivados com eucalipto em regiões com diferentes características edafoclimáticas. Foram comparados os métodos: Walkley-Black, Yeomans & Bremner e combustão seca (CHNS/O), utilizando amostras de diferentes classes de solos obtidas nas seguintes profundidades: 0-20, 20-80 e 80-130 cm nos Cambissolos; 0-25, 25-70 e 70-110 cm nos Latossolos; e 0-18, 18-50 e 50-110 cm nos Neossolos. Amostras de TFSA foram trituradas em almofariz, passadas em peneira de malha de 0,2 mm e submetidas aos três métodos de determinação de C. Os teores de C obtidos correlacionaram-se positiva e significativamente entre si. Os métodos Walkley-Black e Yeomans & Bremner tenderam a subestimar os teores de C em relação ao método de referência, CHNS/O, tanto no que se refere às camadas superficiais quanto àquelas mais profundas, com menores teores de C. Equações de regressão linear com elevados valores de R² permitiram transformar os teores de C obtidos por Walkley-Black e Yeomans & Bremner em C por combustão seca.

Avaliação do método de perda de peso por ignição na análise de matéria orgânica em solos da Serra Gaúcha do Rio Grande do Sul

A matéria orgânica do solo nos laboratórios de rotina de análise de solo, em geral, é determinada por métodos de combustão úmida. Entretanto, esses métodos contaminam com cromo os efluentes laboratoriais. Assim, surge a necessidade de avaliar métodos alternativos de determinação da matéria orgânica do solo. O presente trabalho teve como objetivo avaliar o desempenho do método de perda de peso por ignição como método alternativo e que não possui o contaminante cromo na análise de matéria orgânica do solo, tendo sido realizado no Laboratório de Análise de Solo e Tecido Vegetal da Embrapa Uva e Vinho, no município de Bento Gonçalves, RS. Amostras de dezenove solos não-cultivados e cobertos com pastagem natural da região fisiográfica da Serra Gaúcha do RS, com argila variando de 210 a 530g kg-1 foram coletadas na camada de 0-20cm. Os solos foram secodos ao ar, passados em peneira com malha de 2mm, retirados, manualmente, resíduos de vegetais remanescentes no solo, macerados, novamente passados em peneira com malha de 1mm e preparados para a análise de C orgânico pelos métodos de perda de peso por ignição, Walkley-Black e solução sulfocrômica. Os dados mostraram que o método de perda de peso por ignição e o método de combustão úmida Walkey-Black, em geral, estimaram percentagens de matéria orgânica menores que os determinados pela solução sulfocrômica. Assim, a adoção do método de perda de peso por ignição, que não possui o contaminante cromo, necessita de calibração para as correções das diferenças, desde que se admita o método Walkey-Black e de solução sulfocrômica como métodos de referência e que estimem com maior precisão os teores de matéria orgânica em solos.

Evaluating Methods of In‐Field Soil Organic Matter Analysis

The actual content of the soil organic carbon (SOC) has to be periodically measured for soil classification and nutrient management purposes. Traditional SOC tests are relatively time consuming and costly. A rapid field test would be valuable to delineate soil map units with similar SOC to simplify the process of land evaluation while increasing precision. The objectives of this study were to develop and evaluate a new field measurement technique for the quick assessment of SOC. The new method measures the emitted CO2 concentration 3 min after treatment of the soil sample with acidic potassium (K) permanganate solution. The inorganic carbonate content of the soil is measured separately with the addition of sulphuric acid only. Carbon dioxide concentration from both procedures is measured with a portable infrared gas analyzer. The difference between the concentrations measured after the two separate reactions provide an estimate of SOC. Samples from brown forest soils (ca Hapludalf) (0.19–5.53% SOC) were used for the method development. The correlation coefficient between the SOC determined by the new method and laboratory wet combustion method content was 0.76 for the full range of SOC and 0.81 for the soil samples with less than 20% carbonate.

Rapid Combustion Synthesis of Light-Storing-Emitting Material SrAl2O4 : Eu2 + , Dy3 + and Its Spectral Characteristics

Light-storing-emitting materials composed of are synthesized via the wet combustion method, and the fluffy resultants obtained are easily pulverized into powder samples. The fluorescent spectra of the sample show the same characteristics as those samples fabricated by the dry method. But the phosphorescent spectrum shows uniquely two peaks at 506 and 535 nm, with the intensity at 506 nm stronger than that at 535 nm, which is presumably ascribed to the splitting of the orbitals of into two groups, and . The lower-energy level has two equal orbitals and , while the higher-energy level has three equal orbitals , and . More photons are stored and released from the higher orbitals, resulting in a higher intensity at the 506 nm peak than that at the 535 nm peak in the phosphorescent spectrum.

Recovery rate of organic c in organic matter fractions of Grantsburg soils

Walkley‐Black method is a simple and rapid method for organic carbon analysis. Because of incomplete oxidation of organic carbon (C), the recovery of organic C is low with this method. Assuming the 77% recovery of organic C with Walkley‐Black method, the results are corrected with a correction factor of 1.30. The objective of this study is to determine the soil organic C recovery rate and appropriate correction factor for Walkley‐Black (wet combustion) method for tilled soils in southern Illinois. Soil samples were collected in 1995 and 1996 from a trial established in southern Illinois on a moderately well drained, Grantsburg (fine‐silty, mixed, mesic Oxyaquic Fragiudalf) soil. Organic C contents with the Leco analyzer (dry combustion) were significantly higher as compared to the Walkley‐Black method in different tillage systems (no‐till, chisel plow and moldboard plow), soil organic matter fractions (whole soil and mineral fraction) and soil depths (0–5 and 5–15 cm). The recovery percentage of organic C was lower than the assumed percentage with the Walkley‐Black method. No significant differences in organic C recovery percentage were found due to differences in tillage systems and depths, whereas the recovery percentage was lower in mineral fraction as compared to the whole soil. The lower organic C recovery percentage was due to the more stable organic C compounds in the mineral fraction. On the basis of these findings, correction factors of 1.35 and 1.41 are proposed for whole soil and mineral organic C analysis with Walkley‐Black method, respectively for tilled Grantsburg and other similar soils in southern Illinois.

Evaluation of organic carbon oxidation efficiencies of a modified wet combustion and Walkley‐black procedures in Nigerian soils

The organic carbon (C) oxidation efficiencies of the Walkley‐Black and modified wet combustion procedures were evaluated in soil samples taken from different ecological zones and diverse parent materials in Nigeria. Dry combustion using a C analyzer was the standard to evaluate the efficiency of the modified wet combustion method. The efficiency of the Walkley‐Black method was later compared to that of the modified wet combustion procedure. The results indicated that the modified wet combustion and the dry combustion procedures were highly correlated (r=0.99**)‐Significant correlation (r=0.96**) was also found between the Walkley‐Black and the modified wet combustion procedures. There was no correlation between the C data obtained using the modified wet digestion method and the % DCB‐Fe2O3. These results suggest the absence of strong organo‐mineral complexes in these soils. Organic C recoveries by the Walkley‐black method were not affected by fine‐grinding (<0.5 mm) of the soil samples. It is suggested that both the modified wet combustion and the Walkley‐Black methods may be used without a correction factor in Nigerian soils. The modified wet combustion procedure was also found to be an adequate substitute for the dry combustion procedure.