High-temperature Combustion Method Research Articles

Quantification and Proxy Indicators of the Carbon Pool in Urban Tree Litterfall: A Case Study of Urban Green Spaces in Beijing

As major carbon (C) pools in cities, urban green spaces play a crucial role in reducing atmospheric carbon. To determine the importance of litterfall C storage in urban green spaces, we selected the leaf area index (LAI) as a proxy indicator for litterfall C density (LCD), and established a log-linear regression model between LCD and LAI to predict the annual litterfall C pool in large-scale urban green spaces using Sentinel-2 satellite remote sensing data. Forty-five sample units were randomly selected in typical urban green spaces in Beijing, China. A high-temperature combustion method was used to measure the LCD of the sampling units, and stepwise linear regression was used to filter the proxy indicator for LCD. The annual litterfall C pool in regions within the Fifth Ring Road was also estimated with inversion using remote sensing data. From 2015 to 2021, the estimated annual litterfall C pool was in the range of 4.5–5.8 × 1010 g, i.e., approximately 18.9% of the total C storage recorded for the urban green space, which was far greater than that observed in forest ecosystems. We concluded that the litterfall C pool in urban green spaces is seriously underestimated, and that urban tree litterfall has the potential to reduce greenhouse gas emissions if used as a carbon-neutral resource.

Spectroscopic Analysis and Dynamics of Dissolved Organic Carbon from an Oil Palm Plantation Peatland

Drainage following conversion of peatlands to oil palm plantations is always associated with carbon (C) loss, one of which is dissolved organic carbon (DOC). Analytical procedure commonly used to determine DOC is the high-temperature combustion (HTC) method, which requires an expensive instrument. An alternative low-cost method has been developed. The objectives of this research were to determine and validate the most suitable UV-Vis spectrophotometer’s wavelength for estimating DOC concentration and evaluating its dynamics from an oil-palm plantation Indonesian-peatland. The DOC concentrations were measured on ground water and canal water samples at wavelengths of 254, 270, and 350 nm and the analytical results were then validated against those reference values resulted from the use of HTC method using Total Organic Carbon Analyzer (TOC Analyzer), based on simple regression analysis. The results showed that the most suitable wavelength for estimating DOC concentration using UV-Vis spectrophotometer was 350 nm. The DOC concentration in groundwater (35.67 ± 8.40 mg L-1) were around two times greater than in canal water (16.26 ± 4.15 mg L-1). The DOC flux from the research area were at the range of 0.66 ˗ 1.15 g C m-2 month-1, with an average of 0.85 g C m-2 month-1.

Europium doped Sr2 YNbO6 double perovskite phosphor for photoluminescence and thermoluminescence properties.

A luminescent double perovskite phosphor Sr2 YNbO6 doped with Eu3+ crystallized to the monoclinic phase and was synthesized successfully via a conventional high-temperature combustion method. The formation of the crystal structure, phase purity, and surface morphology were studied using X-ray diffraction patterns and scanning electron microscopy. The characteristic vibrations between the atoms of the functional groups present in phosphor were studied using Fourier transform infrared spectra analysis. The luminescence properties of the prepared phosphors were investigated in terms of photoluminescence (PL) and thermoluminescence (TL). PL excitation spectra exhibited charge transfer bands and the characteristic 4f6 transitions of Eu3+ . A prominent PL emission was obtained for the phosphor doped with 4 mol% Eu3+ under the 396 nm excitation wavelength. PL emission quenching was observed for the higher doping concentrations due to a multipole-multipole interaction. A highly intense PL emission arose due to the hypersensitive 5 D0 -7 F2 electric dipole transition of Eu3+ that dominated the emission spectra. The thermal stability of the phosphor was examined through temperature-dependent PL. The TL properties of the Sr2 YNbO6 double perovskites irradiated with a 90 Sr beta source at different doses were measured. The double perovskite phosphors under study showed a linear dose-response with increasing beta dose, ranging from 1 Gy to 10 Gy. Trapping parameters of the TL glow curves were determined using Chen's peak shape method and computerized glow curve deconvolution (CGCD). CGCD fitting of the TL glow curves revealed that it was consisted of three major peaks and followed second-order kinetics. The estimated activation energies were determined using different methods and were comparable and significant.

Application of High-Temperature Combustion Method for Measuring Content of Organic Carbon in Faecal Pellets and Small-Sized (≤1 mm) Zooplankton

Organic carbon of fecal pellets and small-sized (≤ 1mm) zooplankton was measured using a high- temperature combustion method. The method was adapted for measurements with Shimadzu TOC-VCPH analyzer equipped with a manual injection module. The range of carbon content values was 30–10 000 ng ind–1. The samples for analysis were collected during the cruises of the R/V “Akademik Mstislav Keldysh”in the Kara Sea in 2019-2021. Relationship between body carbon (C, µg ind-1) and prosome length (L, mm) of zooplankton describes by the equation С = 4.24 L1.84, r2 = 0.85, n = 46. Carbon of field collected fecal pellet varied from 9.4 до 102.9 µg С mm–3. The carbon to chlorophyll a ratio of fecal pellets differed by more than two orders of magnitude. The highest values (542 and 736) were obtained in the bays of the Novaya Zemlya archipelago, the lowest (3–6) on the Kara sea shelf in June 2021 soon after ice melting. The perspectives of implication of high temperature combustion method for studies of zooplankton in situ feeding and to estimate the contribution made by pellets to POC vertical flux are discussed.

Evaluating and improving the reliability of the UV-persulfate method for the determination of TOC/DOC in surface waters

The UV-persulfate oxidation method is widely used for determining the total organic carbon concentration of aqueous samples (denoted for convenience as UVP-TOC). However, for some surface water samples, the measurement of TOC by this method can be unreliable, deviating significantly from the true carbon content. In this study, the performance of the UVP-TOC method has been investigated by comparing the results from the analysis of a variety of aqueous samples that included two kinds of surface water samples and related surface water model substances: bovine serum albumin (BSA), sodium alginate (SA), humic acid (HA), tannic acid (TA), benzoic acid (BA) and citric acid (CA), with those from a high-temperature combustion method (elemental analysis); the latter providing the true carbon content value. By comparing the above data, it was found that the UVP-TOC method significantly underestimated the TOC value of the surface water samples, and it was also found that the model components BSA (protein) and HA (humic substances, HS) had a substantial influence on the TOC underestimation, while the SA (polysaccharide), TA (complex organic molecule) and CA/BA (small molecules) had little effect. The results showed that the agglomeration within and between BSA and HA molecules was an important reason for the inaccurate UVP-TOC values of BSA and HA. A further limitation was that for BSA, surfactants (e.g. sodium dodecylbenzene sulfonate, SDBS) and other surfactant-like substances, foam was formed during the CO2 removal purging process by N2 that seriously interfered with the determination of TOC. The study provides new information and insight into the causes of inaccuracies in the UVP-TOC analysis of surface waters and possible approaches to improve the accuracy.

Measurement methods of total organic carbon in seawater

Total organic carbon (TOC) can reflect the total amount of organic matter in water. This paper introduces the common methods of measuring organic carbon, including high temperature combustion method, potassium persulfate oxidation method, spectrometry, ozone oxidation chemiluminescence method, supercritical water oxidation method and so on. At present, high temperature combustion method is the most widely used method for TOC measurement in seawater, because of its high oxidation efficiency. TOC sensor needs to be developed to realize in-situ and long-term monitoring.

Anthelmintic and antibacterial studies of zinc oxide NPs: Synthesized using dragon fruit juice as novel fuel

Present study focus on the dragon fruit as a novel fuel in the field of green synthesis. It is the best-known source to get a variety of natural antioxidants like flavonoids, hydroxycinnamates and betalains. In this context, the High-temperature solution combustion method is used to produce nanoparticles of zinc oxide materials (ZnO-NPs) by zinc nitrate as a starting material and dragon fruit juice used as a fuel. The ZnO-NPs were identified by XRD, Fourier transform infrared spectroscopy (FTIR), SEM & TEM. Wurtzite crystal structure was confirmed by XRD and the average crystallite size was found to be 42 nm. The prepared ZnO.-NPs presented significant anthelmintic property against Indian earthworms in CMC (Carboxymethyl cellulose) solution. Prepared ZnO-NPs from dragon fruit juice exhibited very good antimicrobial property against different bacterial strains such as Bacillus Subtilis ATCC 19659 and Salmonella Typhimurium ATCC 23564.

The effect of the addition of mangrove wood charcoal to reduce sulfur content in coal

Coal in Sulawesi, especially in South Sulawesi, has several shortcomings since it contains sulfur and produces a high ash content that affects the environment. Desulphurization with High-Temperature Combustion Methods is a sulfur content analysis method using the SC-144DR Dual Range Sulfur Analyzer coal tool, which is one of the methods used to reduce sulfur in coal. Based on the results of the study, it was obtained: a mixture of coal with mangrove wood charcoal with the composition of 25% Sin coal + 75% MWC = 0.067% sulfur content, 50% Sin coal + 50% MWC = 0.089% sulfur content and 75% Sin coal + 25% MWC = 0.107% sulfur content. These results indicate that the more addition of mangrove charcoal, the lower sulfur content in the coal. Decreasing sulfur content can improve the quality of the coal produced, especially in combustion systems that affect the environment.

Impact of silver ions doping and calcination on the physicochemical characteristics of TiO2 nanoparticles with photocatalytic and regeneration potential

Visible light driven Ag+ doped TiO2 photocatalysts were successfully prepared with modified low cost liquid impregnation (LI) method yielding up to 95 % product. The native and newly synthesized photocatalysts were calcined at various temperatures and characterized using diffused reflectance spectroscopy (UV/Vis-DRS), XRD, XPS, TEM, EDX, XRF and pHPZC analyses. The XRD results for all samples revealed that the anatase phase was dominant at all calcination temperatures. The Ag+ doping reduced the band gap energy to 2.88 eV, which significantly enhanced the photocatalytic efficiency towards Methylene Blue (MB) under compact fluorescent light. The photocatalytic efficacy of the nano-catalysts was also tested using a binary solution containing a model dye (MB) and Cd2+ under ordinary compact fluorescent light. The presence of competitive ions i.e. Cd2+ increased the MB degradation up to 4 folds under the ambient conditions whereby the maximum amount of MB adsorbed by nano-catalysts reached to 46 mg/g. The high temperature combustion method was found more effective for the regeneration of TiO2 photocatalysts compared to the chemically regeneration. The reusable character of the regenerated samples posed a significant impact of the current work to be applied in wastewater treatment in bulk.

Visible Light-driven Photocatalytic Performance of Zno Coupled with Up-conversion Phosphors for the Removal of Methylene Blue

In this work it was investigated the photocatalytic activity of ZnO coupled with inorganic “up-conversion” phosphors for the treatment of aqueous solutions polluted with methylene blue (MB), in the presence of visible light irradiation. Specifically, the successfully prepared “up-conversion” phosphors nanoparticles emit, when excited with visible light, UV light with main emission at 365 nm. The photocatalytic tests were carried out in a cylindrical pyrex photoreactor equipped with a magnetic stirrer to ensure the continuous mixing of the physical mixtures of “up-conversion” phosphors and commercial ZnO nanoparticles in the solution and irradiated by visible light instead of UV light normally required to excite ZNO. Experimental results were analysed by evaluating the MB decolourization through spectrophotometric method and the total organic carbon (TOC) through high temperature combustion method. In particular, it was found that the photocatalytic performances obtained using ZnO nanoparticles coupled with “up-conversion” phosphors are strongly increased compared to the use of ZnO alone. These results confirmed the enhancement of photocatalytic performances induced by UV photons emitted by “up-conversion” phosphors nanoparticles, able to activate ZnO, demonstrating how their use in photocatalytic systems can be an alternative to the traditional UV lamps, thus preserving human health, environmental and, at the same time, allows to save the energy in process management.

Toward Optical Ceramics Based on Cubic Yb3+ Rare Earth Ion-Doped Mixed Molybdato-Tungstates: Part I - Structural Characterization

Yb3+-doped mixed molybdato-tungstate powders of chemical solution La2–xYbxMoWO9, which crystallize in the cubic system with the space group P213 (No. 198), were studied so that in further research they could serve to the fabrication of transparent optical ceramics. The powders were activated by Yb3+ ions with the concentration of (0.1, 1, 3, 10, 20 mol %) and were prepared by three various techniques: high-temperature solid-state reaction, Pechini, and combustion methods. The main goal of this Part 1 is primarily concerned with the structural characterizations of the cubic structure by XRD analysis, FT-IR, and Raman spectroscopies and of the morphology by SEM and TEM techniques, as well as the calculation of the optical band gap by diffuse reflectance spectroscopy. We have also checked the thermal stability of the samples prepared by combustion and solid-state methods. The TEM images indicated that via combustion method at 600 °C we succeeded to obtain the smallest nanocrystallites with average diameters ...

Small details of big importance: Carbon mass determination in the invasive cladoceran Cercopagis pengoi (Ostroumov, 1891) by the high temperature combustion method

Carbon mass of the non-indigenous predatory fishhook water flea Cercopagis pengoi (Ostroumov, 1891) from the eastern Gulf of Finland, the Baltic Sea, was for the first time measured using the high temperature combustion method. Prior to the analysis, individual dry weight of Cercopagis was determined; altogether ca. 500 organisms were examined. Mean individual dry weight of C. pengoi for July-September was estimated as 34.0 µg; carbon mass averaged 15.8 µg; carbon content, calculated as percent of dry weight, averaged 43.4%. Those values varied over months, mainly because of different population structure of C. pengoi and variation in their diet due to seasonal dynamics of the food objects. However, relations between carbon mass and dry weight for different months did not differ statistically (p<0.001). Therefore, the general polynomial regressions (k=2), describing carbon mass-to-dry weight and carbon content-to-dry weight relationships, were calculated for the entire dataset of individual measurements of C. pengoi body metrics. These data will contribute to adequate evaluation of food web structure and ecosystem alterations in various water bodies invaded by C. pengoi which has got a strong potential to pelagic food web transformations that may impact the overall energy balance and decrease the size of fish stocks.

다양한 환경요인과 난분해성 유기물에 따른 고온산화 및 UV산화방식 총 유기탄소 산화율 변화

This study examined the effects of environmental conditions and the presence of refractory organic matter on oxidation rates of total organic carbon (TOC) measurements based on high temperature combustion and ultraviolet-sulfate methods. Spectroscopic indices for prediction of oxidation rates were also explored using the UV spectra and fluorescence excitation- emission matrix (EEM) of humic acids. Furthermore, optimum TOC instrument conditions were suggested by comparing oxidation rates of a standard TOC material under various conditions. Environmental conditions included salts, reduced ions, and suspended solids. Salts had the greatest influence on oxidation rates in the UV-sulfate method. However, no effect was detected in the high temperature combustion method. The UV-sulfate method showed lower humic substance oxidation rates, refractory natural organic matter, compared to the other methods. TOC oxidation rates for the UV-sulfate method were negatively correlated with higher specific-UV absorbance, humification index, and humic-like EEM peak intensities, suggesting that these spectroscopic indices could be used to predict TOC oxidation rates. TOC signals from instruments using the UV-sulfate method increased with increasing chamber temperature and increasing UV exposure durations. Signals were more sensitive to the former condition, suggesting that chamber temperature is important for improving the TOC oxidation rates of refractory organic matter.

Optimization of luminescence properties of Tb3+-doped α-Sr2P2O7 phosphor synthesized by combustion method

In this paper, thermoluminescence (TL) properties of rare earth Tb3+-doped α-Sr2P2O7 were examined after β-irradiation and photoluminescence (PL) properties of samples were examined for proper excitation. All the samples were synthesized by high-temperature combustion method. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy characterization confirms the formation of pure α-phase with crystallized in orthorhombic structure of samples. The PL emission spectra of all samples exhibit characteristic green emission peaks of Tb3+ where the peak at 545 nm has the highest emission intensity for Tb3+ concentration of 5.0 mol%. The TL glow curves of β-irradiated Tb3+-doped α-Sr2P2O7 phosphors were recorded at different heating rates of 2, 4, and 6 K·s−1. TL curves of all sample exhibit combination of two peaks: peak at 420 K shifts toward higher temperature, while peak at 525 K remains unaffected with the increase in Tb3+ concentration as well as fading effect. The activation energy and kinetic parameters of the samples were evaluated using thermoluminescence peak shape method.

Luminescence study and dosimetry approach of Ce on an α-Sr2 P2 O7 phosphor synthesized by a high-temperature combustion method.

We report synthesis of a cerium-activated strontium pyrophosphate (Sr2 P2 O7 ) phosphor using a high-temperature combustion method. Samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and thermoluminescence (TL). The XRD pattern reveals that Sr2 P2 O7 has an α-phase with crystallization in the orthorhombic space group of Pnam. The IR spectrum of α-Sr2 P2 O7 displays characteristic bands at 746 and 1190 cm(-1) corresponding to the absorption of (P2 O7 )(-4) . PL emission spectra exhibit a broad emission band around 376 nm in the near-UV region due to the allowed 5d-4f transition of cerium and suggest its applications in a UV light-emitting diode (LED) source. PL also reveals that the emission originates from 5d-4f transition of Ce(3+) and intensity increases with doping concentration. TL measurements made after X-ray irradiation, manifest a single intense glow peak at around 192°C, which suggests that this is an outstanding candidate for dosimetry applications. The kinetic parameters, activation energy and frequency factor of the glow curve were calculated using different analysis methods.

Phase composition and luminescent properties of strontium aluminate long persistence phosphor synthesized by combustion synthesis method with different Sr/Al ratios

Strontium aluminate long persistence phosphors are synthesized by combustion method. By controlling the raw material ratio (Sr/Al), the effects of phase composition on subsequent spectroscopic properties of phosphors are studied. Results show that the phase composition changes from strontium-rich phase to aluminum-rich phase with the decrease of Sr/Al: when the rate of Al/Sr changes from 3:1 to 1:1, the main crystal phase of samples is Sr3Al2O6, and it exhibits the characteristic fluorescence of Eu3+ in the lattice of Sr3Al2O6; when the rate of Al/Sr is between 1:2 and 2:7, phase composition is the mixture of SrAl2O4 and SrAl4O7, and it emits the characteristic fluorescence of Eu2+ in SrAl2O4 but not in SrAl4O7; when Al/Sr decreases to 1:4 or even 1:12, the main crystal phase of samples transform into SrAl12O19, and the characteristic emission peak is about 470 nm, which corresponds to the characteristic emission of Eu2+ in SrAl12O19. At the end of the article, the influence laws of two different synthesis methods on phase composition of samples between high-temperature solid method and combustion method are compared. Compared with the high-temperature solid method, the rule of influence is similar, but the mole ratio of Al/Sr in products is always higher than the initial ratio of the raw material, and compounds like Sr4Al14O25 are not obtained by combustion method.

Ti<sub>2</sub>AlN Prepared by Self-Propagating High-Temperature Combustion Method Using TiN as Additive

Ti2AlN ceramic have been prepared by self-propagating high-temperature synthesis method using Ti, Al and TiN mixture as raw materials under different N2 pressures. X-ray diffraction (XRD) and scanning electron microscope (SEM) have been used to determine the phase composition and micro morphology of the products. XRD analysis indicates that the main phase of the products is layered ternary compound Ti2AlN, but there are TiN and AlTi3 impurities in the products. With increasing N2 pressure, the relative content of TiN and AlTi3 decreases. SEM imagines exhibits that the grains of the products become larger with increasing N2 pressures.

Current Wet Persulfate Digestion Method Considerably Underestimates Total Phosphorus Content in Natural Waters

T phosphorus (TP) in river and lake water is an important environmental variable that can be used as an indicator of nutrient status and water quality. TP was recently selected as an environmental stressor and numeric criteria have been developed based on its background concentration in a given environment. To minimize the eutrophication risk in aquatic ecosystems, U.S. Environmental Protection Agency water quality criteria require that TP is not exceed 10−128 μg/L for river and streams. Following EPA method 365.1, TP in surface waters is routinely determined on unfiltered water samples that are digested by autoclave in the presence of persulfate. Recent studies, however, indicated this method suffers low recovery of particulate phosphorus (PP) and we suggest reliable high temperature combustion method be used for PP determination. Raw water samples contain both suspended particles and dissolved constituents. In EPA TP method 365.1, unfiltered water sample is used for persulfate digestion but no attention was given on how to keep sample homogeneous and representative to the field condition. Due to rapid settling of large particles in water sample containers, it is difficult to keep sample homogeneous during subsampling and analysis. For example, it is practically impossible to avoid particle settling when samples are seating in an autosampler during automated online digestion and analysis. TP consists of particulate phosphorus and total dissolved phosphorus (TP = PP + TDP). Because most TP resides in particulate phase loss of particles during sampling and analysis can result in a significantly underestimated TP. To obtain representative particulate samples, filtration through 0.45 μm pore size filters has been used to separate PP from TDP (it might require a large volume of water if water turbidity is low). Particles collected on the filters are used to determine the PP. The filtrates are used to determine dissolved inorganic phosphorus (DIP) and TDP. The difference between TDP and DIP is operationally defined as dissolved organic P (DOP). The sum of PP and TDP can provide an accurate estimate of TP in natural waters. DOP and PP are usually converted to DIP which can then be measured by the molybdenum blue method. Wet persulfate digestion has been widely used for digesting TDP samples with variable conversion efficiency for different DOP compounds, ranging from 66% for inositol phosphate to 100% for ADP. On the other hand, high temperature combustion is needed for PP determination. High temperature combustion at above 550 °C can decompose all organic matters and inorganic minerals to simple inorganic compounds. With commercial CHN elemental analyzer available, it has become a conventional technique for measuring carbon, hydrogen and nitrogen content of particulate samples. In PP determination, high temperature combustion in the presence of oxidizing reagent Mg(NO3)2 was followed by acid extraction to recover DIP. This method has been used for analysis of PP in sediment and TDP in water samples and achieved a close to 100% conversion efficiency. However, no commercial P elemental analyzer is available and manual analysis of PP by high temperature combustion remains time-consuming and labor-intensive. It is worth to note that the first persulfate digestion method developed by Menzel and Corwin in 1965 was for measuring seawater TP. In that study, only a few DOP compounds were tested for recovery. A dried zooplankton tissue was suspended in distilled water and then the filtrate from the suspension was analyzed by persulfate digestion method. This extracted, filtered sample contained only DOP and no PP sample was tested. Ironically, this seawater method become obsolete in marine community has since been widely adapted for TP measurement in freshwater where particulate matter, dominated by clay minerals, is much more abundant than oceanic waters. Recently, Suzumura pointed out the limitation of this method for determination of TP in natural waters. He compared wet persulfate digestion with high temperature combustion on sediment, plankton and mineral samples. While

The different luminescent characteristics of MgAl 2O 4:Mn 2+ between phosphor powder and nanoparticles

Mn 2+ doped bulk and nano-sized MgAl 2O 4 phosphors are synthesized by high-temperature solid-state reaction and combustion method, respectively. The bulk phosphor exhibits bright green fluorescence and phosphorescence, while the nanophosphor however exhibits only red fluorescence without phosphorescence. The different luminescence properties are studied based on the analysis of excitation and emission spectra as well as phosphorescence decay curves. The enhancement of the green and red luminescence with doping Mn 2+ is discussed.

Acid Mine Drainage Potential of the Coral Snake Waste Dump, Anglogold Ashanti, Obuasi Mine

This paper assessed the Acid Mine Drainage (AMD) potential of the Coral Snake Waste Dump located close to the Enkansu and Kaw streams in Obuasi. Ten water and fifty rock samples were analysed for physico-chemical parameters. Acid Base Accounting (ABA) determinations using static methods were employed to ascertain AMD potential of the dump. The modified ABA and the High Temperature Combustion methods were used to determine the Neutralisation Potential (NP) and the Maximum Potential Acidity (MPA) of the various rocks at the dump. The Net Neutralisation Potential (NNP) and Neutralisation Potential Ratio (NPR) of the rocks were calculated from the values of the NP and MPA. The pH of the streams ranges between 7.09 and 7.81. As and Pb concentrations in the streams were above WHO limits for drinking water. The major constituents of the waste dump; phyllites and greywacke constituting about 75.0 % of rocks are not acid generating. The schist and oxide minerals have negative NNP and MPA implying that they are acid generating. However, quartzite analysis indicates they lie in the uncertainty zone. The results show that the Coral Snake Waste dump is not acid generating, although As and Pb levels in streams are issues of major concern.