Wood Ash Samples Research Articles

The comparative study of using wood ash in lieu of fly ash in South African blended cement paste and mortar

A comparative analysis of the properties of fly ash (FA) and wood ash (WA) blended cement, produced in the controlled environment of a cement factory was examined. Since FA has been adopted in South Africa as a material for blended cement, the possibility of using wood ash in lieu of FA to produce blended cement was investigated. The blended cements were prepared and tested at AfriSam (South Africa) Ltd. Roodepoort, with 10 % and 25 % FA and WA as partial substitution for Ordinary Portland Cement (OPC) clinker (CEM1). The chemical composition of FA and WA, the setting times of the blended cement pastes and the compressive strengths of the blended cement mortars were analyzed and discussed. The results indicated that FA and WA have combined SiO2, Al2O3 and Fe2O3 constituents of 89.29% and 72. 58%, respectively. Also, lower initial and final setting times were observed with 25% WA samples as compared to the control sample and FA samples. WA blended cement showed faster rate of hydration than FA blended cement at early curing age resulting in mortar compressive strength of 26.2 MPa and 25.4 MPa as well as 22.6 MPa and 19.2 MPa for 10% and 25% WA and FA substitution respectively. However, FA blended cement mortar exhibited higher late strength than WA blended cement mortar with 10% FA blended cement mortar resulted in higher compressive strength than control sample at 90 days. The combined synergy of WA and FA in blended cement is envisaged to produce mortar of desirable early and late strengths.

Radiological and Structural Characterization of Raw and Alkali-Activated Wood Ash and Metakaolin Blends

The aim of the presented research was to investigate the application possibility of wood ash and metakaolin to obtain alkali-activated materials as relatively new materials in the building industry. Thus, in order to assess the adequate use of these waste materials, structural and radiological characteristics should be considered. Until now, the focus has been on ash from thermal power plants produced by burning coal, but a large part of households in our country have individual fireplaces in which wood is used as the basic raw material; thus, it is very interesting to measure the activity concentration of radionuclide in wood ash as well as the possibility of reusing that ash for other purposes. All materials were studied, in terms of physical and chemical characteristics, by methods such as X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). XRD measurements of wood ash samples showed that it consists of calcite and larnite. FTIR spectroscopy revealed a polymeric Si–O–Al framework in alkali-activated materials and Si–O bonding bands corresponding to silicon dioxide. Determination of radionuclide content was performed by means of gamma-ray spectrometry. Results showed that the alkaline activation process led to the decrease in the activity concentration of radionuclides detected in the measured samples. External radiation hazard index (Hex) for wood ash was reduced by more than 50% after alkali activation. The results of activity concentration measurements in alkali-activated materials indicate potential for their safe application in building construction.

Using of wood ash as the alternative filler for preparation of rubber mixtures

Processing and material recovery of waste is an important aspect of environmental policy. Ash is waste in terms of legislation, but it is also a material that can be reused. Various works propose that biofuel ash could be used as inorganic fertilizer. The object of this work is based on using of wood ash (WA) from biomass and its modified form as the alternative filler in rubber mixtures. The WA samples with particle size of 25 and 40 µm were modified by silanization and properties of ash samples were characterized by elemental analysis (EDX), Scanning Electron Microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). Model rubber blends were prepared by using modified wood ash as a partial replacement of conventional filler. Furthermore, the influence of the addition of ash on the cure characteristics (minimum torque – ML , maximum torque – MH , optimal cure time – t90 , scorch time ts2 ), mechanical properties (tensile strength at break – TSb , elongation at break – Eb and hardness) and physical properties (cross-link density) in sulfur-cured SBR composites were investigated. Dispersion of the WA filler and its incorporation into vulcanizates were based on observation of the fracture surfaces of vulcanizates by SEM. The results confirmed that the wood ash did not significantly affects the mechanical properties of the vulcanizates and can be used as a partial replacement of carbon black in SBR vulcanizates.

Influence of wood ash pre-treatment on leaching behaviour, liming and fertilising potential

In Denmark, increasing amounts of woody biomass are being used for the production of renewable energy, resulting in more wood ashes being generated. While these materials have been mainly landfilled, wood ashes may also be utilised for fertilizing and liming purposes on top of soils. Pre-treatments involving hardening or granulation may be carried out prior to soil application. In this study, two Danish wood ash samples were hardened and/or granulated. Lab-hardening induced rapid changes in the shape of the acid neutralisation capacity curve of the ashes. Up-flow column tests, assuming local equilibrium conditions, were employed to investigate the leaching from pre-treated ashes. Granules and loose ashes demonstrated similar leaching behaviours, indicating that similar geochemical processes were governing their leaching. In comparison with untreated fresh ashes, the hardened ashes demonstrated reduced leaching of Ca, Ba, Pb and Zn with concentration levels generally below or close to the analytical limits of quantification; to the contrary, the leaching of As, P, Sb, Si, V and Mg was enhanced in the hardened ashes. The release of alkalinity was reduced by hardening. In general, all granules were barely breakable by finger-pinching and they could withstand one month of continuous leaching, preserving their overall shape. The solubility of phosphorous in neutral ammonium citrate indicated that about 30–51% of the total P content in the ash samples was released, suggesting that the ashes could be potentially valuable as P-fertiliser if applied onto soil.

Забруднення 137Cs деревної золи у північних районах Житомирської області

Due to changes in the economic situation in Ukraine, high cost for many segments of the population of natural gas and electricity, residents of different regions are switching to the use of fuel wood of local origin for heating buildings and meeting other economic needs. Today, the process of harvesting fuel wood is often completely spontaneous, that is, the population carries wood harvesting in any accessible places, ignoring the possible negative consequences. The given problem in the absence of state regulation, in addition to the legal aspect, is complicated by the radioactive contamination of forest lands in which uncontrolled harvesting by the population of fuel wood with unknown levels of radionuclide content is carried out. This problem is especially relevant in the Polissya regions of Ukraine, whose forest areas have suffered from the largest radioactive contamination as a result of the Chernobyl accident. Thus, the area of forests with a density of soil contamination with 137 Cs of above 37 kBq / m 2 , in which restrictions on forest use were introduced in Zhytomyr, Rivne, Kyiv oblasts, respectively, accounted for 60%, 56%, 52%, and in the Volyn and Chernihiv oblasts such plantations accounted for about 20% of the total area of the forest fund. Today, the bulk of wood products (fuelwood) does not exceed GNPAR-2005 by 137 Cs (600 Bq / kg) and 90 Sr (60 Bq / kg), but the situation may change for some of the territories contaminated with radionuclides (the northern part of Zhytomyr and Kyiv oblasts) , because in recent years the accumulation dynamics of 137 Cs has negative tendencies for all wood species, an increase in the activity of 137 Cs in the majority of the components of the woodland and the growth of the total content of radionuclides in the wood is observed. As a result of the increase in radioactive contamination of forest stands, the risk of fuel wood harvesting with the levels exceeding GNPAR-2005 by 137 Cs and 90 Sr content has increased recently in the Polissya region of Ukraine, and cases of use of heating fuel for private fuel wood buildings with significant levels of radionuclide contamination are increasing. Wood is a relatively low-salt fuel, the average values of ash content of wood in most of the rocks are in the range of 0.3-1%, therefore, when burning contaminated with radionuclides of wood, because of low ash content of this fuel, the concentration of radionuclides in the mineral part of the waste (ash) is increased with the increase of the specific activity of ash in 50-100 times in comparison with the specific activity of the original wood. Results of the study of contamination level of wood ash with 137 Cs in private farms of settlements in the northern part of Zhytomyr region, performed in 2017, have been analyzed. As a result of the analysis of 154 samples by the gamma spectrometry method, it was found that the 137 Cs specific activity ranged from 170 to 32900 Bq/kg in wood ash, formed during the burning of contaminated wood fuel in wood-fired ovens in private farms of this region. Generalized data on relative distribution of the wood ash samples of the studied settlements by the value of 137 Cs specific activity is presented in the article. According to the Basic Sanitary Rules of Ukraine-2005, using 137 Cs specific activity as a criterion, 9 % of the total number of ash samples, collected in private farms of the monitoring network, can be considered as low-level radioactive waste, in particular: 3.9 % of ash samples, collected in the Bigunsky Village Council; 7.1 % of ash samples, collected in the Mozharovsky Village Council; 7.7 % of ash samples, collected in the Pischanitsky Village Council and 22.7 % of ash samples, collected in Narodychi town. Obtained data indicate that contaminated with radionuclides wood ash is an additional factor of radiation hazard, since it is a potential source of additional external and internal exposure for local population. Key words : wood ash, 137 Cs, specific activity, radioactive waste

Magnetic mapping of distribution of wood ash used for fertilization of forest soil

The effect of wood-ash fertilization on forest soils has been assessed mainly through geochemical methods (e.g., content of soil organic matter or nutrients). However, a simple and fast method of determining the distribution of the ash and the extent of affected soil is missing. In this study we present the use of magnetic susceptibility, which is controlled by Fe-oxides, in comparing the fertilized soil in the forest plantation of pine and oak with intact forest soil. Spatial and vertical distribution of magnetic susceptibility was measured in an oak and pine plantation next to stems of young plants, where wood ash was applied as fertilizer. Pattern of the susceptibility distribution was compared with that in non-fertilized part of the plantation as well as with a spot of intact natural forest soil nearby. Our results show that the wood-ash samples contain significant amount of ferrimagnetic magnetite with susceptibility higher than that of typical forest soil. Clear differences were observed between magnetic susceptibility of furrows and ridges. Moreover, the dispersed ash remains practically on the surface, does not penetrate to deeper layers. Finally, our data suggest significant differences in surface values between the pine and oak plants. Based on this study we may conclude that magnetic susceptibility may represent a simple and approximate method of assessing the extent of soil affected by wood-ash.

Long-term leaching of nutrients and contaminants from wood combustion ashes

With increasing amounts of woody biomass being combusted for energy purposes worldwide, more wood ash is being generated and needs management. As an alternative to landfilling, residues may be utilised for liming and fertilising purposes on forest soils. Comprehensive evaluations of long-term leaching from these residues are needed in order to assess potential environmental impacts associated with their utilisation. Two Danish wood ash samples, one fly ash and one mixed ash (a combination of fly ash and bottom ash), were evaluated in long-term percolation column tests (up to L/S ∼2000 L/kg), in order to quantify the release of major, minor and trace metal(loid)s. While columns of three different lengths were used, the leaching of individual elements could be described as a function of the L/S ratio – irrespective of the column length. At L/S 1000 L/kg, the cumulative releases of K, S, Na, Ca and Rb were at 40–100% of their respective solid contents, followed by Ba, Cr, Sb, Sr and V at 15–40% and Al, Mg, Zn, Cd, Co, Fe, Pb, Tl, Mn and P at < 5%. Speciation calculations indicated that (i) the observed concentrations of Ca, Mg, Al, Ba, Si and sulphate from both ash types could be described through the dissolution/precipitation of a limited set of minerals and that (ii) leaching of silicates should be included in long-term assessment of alkalinity release from wood ashes. Non-equilibrium conditions were indicated by flow interruptions. However, the presence of non-equilibrium did not have significant effect on the calculated cumulative releases at high L/S ratios. Based on the assessment of cumulative releases at L/S 10 L/kg and L/S 1000 L/kg it is concluded that low L/S-based data may not provide sufficient background for prediction of long-term release from wood ash, in particular for Ba, Cr, Sb and V, and less critically also for As, Cd, Cu, Mo and Ni.

Recirculation of biomass ashes onto forest soils: ash composition, mineralogy and leaching properties

In Denmark, increasing amounts of wood ashes are generated from biomass combustion for energy production. The utilisation of ashes on top of forest soil for liming purposes has been proposed asan alternative to landfilling. Danish wood ash samples were collected and characterised with respect to chemical composition, mineralogy and leaching properties (batch leaching at L/S 2 and 10L/kg, and pH-dependent leaching at 10L/kg). Large variations in the ash liming properties were observed (ANC7.5: 1.8–6.4meqH+/g), indicating that similar soil application dosages may result in different liming effects. High contents of Ca, Si, P, K and Mg were observed in all samples, while the highest contents of S and N were found in fly ashes and mixed ashes (combination of fly and bottom ashes). Similarly, the highest contents of some trace metals, e.g. Cd, Mo and Se, were observed for fly ash. Releases of major, minor and trace elements were affected significantly by pH: high releases of PO43−, Mg, Zn, Cu and Cd were found for acidic conditions relevant to forest soils, while the highest releases of Mo and Cr were observed in alkaline conditions. Mineral phases were selected based on XRD analyses and the existing literature, and they were applied as inputs for the geochemical modelling of pH-dependent leaching. Mineral dissolution was found adequate for a wide range of major elements and nutrients, while the description of trace elements could be done only for parts of the pH-range. Content and leaching of PAHs were observed below detection limits. The source-term release of Ca, K, Mg, Mn, and P in acidic conditions relevant to forest soils was higher than ten years of atmospheric deposition, in contrast to the relatively low release of Al, Fe and Na. The potential release of Cd was found to be the most critical element compared with soil quality criteria, whereas the maximum theoretical loads of Ba, Cd, Cr, Sr, Mo, Ni, Pb, Sb, Se, Sn and V were relatively low.

Evaluation of the Biotoxicity of Tree Wood Ashes in Zebrafish Embryos.

Ashes derived from biomass combustion and used as soil fertilizers can generate negative environmental and human health risks, related to leaching of heavy metals and other putative toxic elements. Tree wood ash composition may vary depending on geographical location and surrounding industrial processes. In this study, we evaluated the biotoxicity of lixiviated tree wood ash samples from trees of the Ash (Fraxinus), Cherry (Pronus), Hazel (Corylus), and Black locust (Robinia) genus collected in an industrialized region in Northern Italy. Elemental chemical analysis of the samples was performed by total reflection X-ray fluorescence technique and their biotoxicity was assessed in zebrafish (Danio rerio) embryos. Ashes from Ash, Cherry, and Hazel trees, but not Black locust trees, had a high concentration of heavy metals and other putative toxic elements. Accordingly, a dose-dependent increase in mortality rate and morphological and teratogenic defects was observed in zebrafish embryos treated with lixiviated Ash, Cherry, and Hazel tree wood samples, whereas the toxicity of Black locust tree wood ashes was negligible. In conclusion, lixiviated wood ashes from different plants show a different content of toxic elements that correlate with their biotoxic effects on zebrafish embryos. Tree wood ashes derived from biomass combustion may represent a potential risk for the environment and human health.

Biodiesel production using heterogeneous catalysts including wood ash and the importance of enhancing byproduct glycerol purity

Transesterification of vegetable oils or animal fats with methanol in the presence of catalysts produces fatty acid methyl esters (FAME) and glycerol as a co-product. This study was focused on a comparative study of the transesterification of refined, bleached and deodorized palm oil (RBD palm oil) using a heterogeneous catalysts CaO with and without γ-alumina (γ-Al2O3) as a support. The results were also compared to that using sodium hydroxide (NaOH), which is a homogenous catalyst. Parameters like the amount of catalyst, the molar ratio of methanol to oil, reaction time and reaction temperature that affect methyl ester and glycerol formation were analyzed and the optimum conditions were determined. The FAME and glycerol content (96.75% and 92.73% respectively) obtained using CaO were lower in purity compared to that using CaO/Al2O3 (97.66% and 96.36% respectively). In the second phase of our work, wood ash from two different sources (birch bark & flyash from a biomass based power plant), which were calcined at 800°C were studied for their potential use as a cheap renewable alternative heterogeneous catalyst. Both the wood ash samples were found to have good potential for use in such production process, but needs to be optimized further to obtain biodiesel which meets fuel biodiesel specifications. Both CaO and CaO supported on alumina produces FAME to levels that meet the fuel specifications required for blending with diesel. However, the latter produces a purer form of byproduct glycerol that can be easily converted to value added products, without the need for purification. On this basis the supported catalyst is recommended for use in industry as it can add to profits in integrated plants which produces biodiesel and simultaneously uses the byproduct glycerol for value added products.

The Composition and Use Value of Tree Biomass Ash

Abstract Wood-based ash landfilling is increasing issue not only in Latvia but in the whole world as more biomass is used for energy production. Utilization of wood burning waste as fertilizer is already used worldwide, but there is lack of information about chemical composition of wood ash obtained from Latvia plants, so the aim of this study was to determine chemical composition and analyse possible utilization options of wood-based ash from Latvia plants. Therefore wood ash samples from 53 companies were collected, sieved and chemical composition of samples was determined. It was concluded that within higher capacity of furnace more coarse fraction of wood ash was observed which is less valuable as fertilizer. Wood ash is good liming material consisting alkali compounds and other biogenic elements but also heavy metals, which are pollutants and could cause environmental problems.

CO2 capture and sorbent regeneration performances of some wood ash materials

Wood ash, which is recognized as an environmental pollutant, is tried as a new material for CO2 capture in this work. Five wood ash samples obtained from different raw materials were chosen, and an experimental demonstration of the CO2 capture performances of these wood ash samples was present in detail in a modified fixed bed reactor system. The CO2 capture and the sorbent regeneration performances of wood ash were investigated under different conditions by changing the temperature, H2O concentration, gas flow rate and the heating rate. The CO2 capture capacities are in the range of 0.35–0.54mmol CO2/g for different wood ash samples under the condition of 60°C, 10% CO2+12% H2O. The CO2 capture processes contain two parts for these samples. One is the physical adsorption process, and another is the chemical reaction of K2CO3 with CO2 and H2O to form KHCO3, K2CO3·1.5H2O and K4H2(CO3)3·1.5H2O. The desired wood ash is proved to be regenerable and stable during 10-cycle CO2 sorption–desorption tests. The deactivation model and the Avrami–Erofeyev model are adopted to evaluate the CO2 sorption and desorption kinetics of this sample respectively. Considering the low cost, and the recycling of environmental pollutants, wood ash is a nice choice for CO2 capture.

The application of wood ash as a reagent in acid mine drainage treatment

The paper deals with a possible utilisation of wood ash as a reagent in treating acid mine drainage (AMD) from opencast mining of brown coal. Wood ash samples were obtained having combusted deciduous and coniferous tree wood in a household furnace. The dominant mineral phases in wood ash are calcite, quartz, lime and periclase. The used AMD is characteristic of high contents of sulphates, iron, manganese, heavy metals and low pH. The AMD treatment process included dosing of wood ash to adjust pH values about 8.3 (a dose of 0.5gl−1) or calcium hydroxide (a dose of 0.2gl−1) for comparison. The reaction time was 20min. Dosing of wood ash in AMD resulted in an increase of pH in solution from 3.5 to 8.3, which caused the removal of metal ions mainly by precipitation, co-precipitation and adsorption. Comparing the application of Ca(OH)2 in AMD treatment, at an almost identical pH value the concentrations fell in both cases for Fe, Mn, As, Co, Cu, Ni, Zn, Mg, Al and Mo. Applying wood ash the drop was even more distinct in Mn, Zn and Mg. The results of sedimentation tests in an Imhoff cone confirm that the settling capacities of sludge using wood ash are significantly better than when using calcium hydroxide in acid mine drainage treatment.

Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating

Ash is formed when plant calcium oxalate crystals (CaC2O4) decompose to form calcite (CaCO3). We found that ash does retain the original calcium oxalate radiocarbon concentration, but in addition, there is another minor 14C source. This is shown by the presence of a consistent small shift in the pMC and δ13C levels when comparing cellulose and ash from modern and archaeological woods. Possible mechanisms for 14C exchange during combustion or due to diagenesis are considered in order to define parameters for identifying better-preserved wood ash samples.

An on-line aerosol laser mass spectrometer with three, easily interchangeable laser based ionisation methods for characterisation of inorganic and aromatic compounds on particles

An aerosol mass spectrometric set-up is presented comprising three different laser based techniques for on-line analysis of particles. The implemented methods are one-step laser desorption/ionisation (LDI), two-step laser desorption/photoionisation (LDPI) and thermal desorption/photoionisation (TDPI). Photoionisation processes for the latter two methods are based on resonance enhanced multiphoton ionisation (REMPI), which is highly selective and sensitive for polyaromatic hydrocarbons (PAH). LDI is especially suitable for the detection of inorganic compounds and the determination of sum values such as elemental carbon content. Investigated samples were particles from spruce wood ash generated by an oxygen-controlled residential heating system and exhaust gases from a gasoline driven passenger car. In the positive LDI mass spectra several metal cations such as potassium and iron are detectable, whereas carbon clusters can be observed with the negative mode. With LD-REMPI and TD-REMPI various PAH such as phenanthrene and derivatives, pyrene, etc., become visible. In the wood ash samples relatively high yields of retene were found, which could be used as tracer compound for coniferous wood combustion. All three modes can be applied with only slight modifications of the instrument. Thus, it allows characterising single particles on a real time basis and, depending on the application, the most convenient technique can be selected.

Reduction of soluble chromate in wood ash by formaldehyde

The wood-working industry produces large amounts of wood residues. A considerable part of these is subjected to thermal utilization, and the wood ash obtained is usually disposed of. Owing to the severe regulations in several countries, disposal of wood ash has become problematic. These regulations restrict especially the water-solubility of heavy metals and organic compounds of wastes. Leachates of wood ash samples in many cases exceed the limit value for Cr-VI. To allow disposal of wood ash in future, the content of soluble Cr-VI must be lowered. In addition to a previously described procedure for the treatment of leachates containing up to 2 mg/ l Cr-VI, this study presents a method of treating leachates with higher Cr-VI concentrations up to 10 mg/ l . The treatment includes mixing the wood ash with aqueous formaldehyde solutions of appropriate concentration.

Treatment of wood ash containing soluble chromate

The “TA Siedlungsabfall” issued in Germany in May 1993 will entail severe problems concerning the disposal of wood ash. One particular problem is associated with the occurrence of soluble chromium compounds in the leachates of wood ash. During combustion of wood, wood residues or waste wood, Cr-III which is generally found in wood is partly oxidized to Cr-VI. Under the conditions of the leaching test DIN 38 414 part 4, which is the compulsory test procedure according to the “TA Siedlungsabfall”, Cr-VI is partly soluble. Thus, the comparatively low limit value for the leachates is exceeded by many wood ash samples. To achieve significant reduction of the soluble Cr-VI content of wood ash, a procedure termed wet ash removal was applied. Investigations were carried out both under industrial conditions and in the laboratory. It is shown that wood ash leachates with Cr-VI concentrations of up to about 2 mg/l can be treated effectively with this procedure.

Titrimetric determination of calcium carbonate equivalence of wood ash

Wood ash is a residual material produced during the process of biomass burning for energy. Spreading this material on the land is used as a means of its disposal. Wood ash contains carbonates which react to raise soil pH, and its regulation is based on ash calcium carbonate equivalence (CCE). The procedure suggested by the Association of Official Analytical Chemists (AOAC) for the determination of the CCE of agricultural limestone is routinely used for the determination of the CCE of wood ash samples. This procedure involves heating a weighed amount of sample with HCI and then back-titration of the remaining acid with NaOH. Unlike agricultural limestones, which are largely carbonates, some wood ash samples contain significant amounts of contaminants such as alumino-silicate clays which may consume acidity when heated with HCl. Significant consumption of acidity by alumino-silicates during CCE analysis would cause the determination of artificially high CCE values, as these alumino-silicates would not be expected to neutralize acidity under field conditions. This study investigated whether the AOAC method of CCE determination resulted in reproducible, accurate CCE values when applied to wood ash samples with various amounts of alumino-silicate contaminants. The accuracy of the method was calculated by comparing the CCE values with those obtained from a soil incubation method. Time of heating had little effect on the CCE value obtained. The back-titration step was reproducible from operator-to-operator despite the formation of a white precipitate before the end-point. The CCE values obtained from the titrimetric method were similar to those obtained from a soil incubation method.