Addition Of Charcoal Research Articles

Response to Comment on "Fire-Derived Charcoal Causes Loss of Forest Humus"

We find the suggestion that substantial charcoal loss occurred in the humus-charcoal mixtures implausible and discuss why complexing of soluble carbon released from the mixtures by underlying mineral soil should be minor. This exchange highlights our limited knowledge about charcoal effects on native soil carbon, indicating that strong advocacy for charcoal addition to offset CO 2 emissions remains premature.

Possible CO 2 mitigation via addition of charcoal to coking coal blends

Processes involving biomass oxidation are considered to be CO 2 neutral since the replenishing of the biomass by normal growth will remove CO 2 from the atmosphere. Thus the use of charcoal in the production of metallurgical coke, to be used as a reducing agent in the formation of iron, would be a strategy for the reduction of CO 2 in the overall ironmaking process. This paper describes experimental attempts to produce industrial grade coke from coking coal blends to which are added amounts of charcoal up to 10%. Coking experiments were carried out partly in a 30 lb coke oven and partly in a sole heated oven. The influence of blend composition, heating rates and charcoal particle size was investigated. Cokes made using fine charcoal addition (− 60 mesh) were considerably weaker than cokes made from the base blend. This is interpreted to be the effect of the ash constituents in the charcoal which, among other things, contains much higher calcium than the coals used. However, carefully sized fractions of coarse charcoal (− 3/8 + 1/4 in) produced much higher quality coke, possibly the result of a different dispersion of the charcoal mineral components.

Analysis of the C 2H 2 inhibition-based N 2O production curve to characterize the N 2O-reducing activity of denitrifying communities in soil

The characterization of an C 2H 2 inhibition-based N 2O production curve was conducted to estimate the N 2O-reducing activity of denitrifying communities in soil. By normalizing the N 2O production curve and calculating the value of the area under the curve (AUC), visual differences in the time course of N 2O production in the presence and absence of an C 2H 2 treatment were quantified in a series of experiments. The effects of liming and the addition of selected inorganic salts on the N 2O-reducing activity of soil were analyzed. The average N 2O/N 2 + N 2O ratio, which is the ratio of the AUC value in the absence and presence of C 2H 2, indicated that a declining pH and the addition of Cl − and Ca 2+ resulted in the inhibition of the N 2O-reducing activity, whereas liming (pH 6 using calcined lime, dolomite, charcoal, and ash of the charcoal) and SO 4 2− and Mg 2+ addition resulted in enhancing the N 2O-reducing activity. Since the charcoal addition resulted in lowering the average N 2O/N 2 + N 2O ratio despite the fact that charcoal contained larger amounts of Cl − and Ca 2+ than SO 4 2− and Mg 2+, the alkalinity of the charcoal (pH 9.3) rather than the types of anions and cations may be the most significant factor in the stimulation of the N 2O-reducing activity. In addition, we found a non-linear negative relationship between the average N 2O/N 2 + N 2O ratios and the specific increasing rate constant of the N 2O production curve. This result indicated that the application of a growth inhibitor of denitrifying communities into soil decreases the N 2O-reducing activity of soil.

Composição da matriz de encapsulamento na formação e conversão de sementes sintéticas de pimenta-longa

A pimenta-longa (Piper hispidinervium C. DC.) é uma planta nativa caracterizada pela produção de safrol, um metabólito secundário usado na produção de perfumes, cosméticos e inseticidas. Neste trabalho avaliou-se o uso potencial da tecnologia de sementes sintéticas como alternativa à propagação in vitro de pimenta-longa. Foi estudada a influência da constituição da cápsula sobre a formação e conversão in vitrode unidades encapsuláveis. Sementes pré-germinadas de pimenta-longa com 21 dias de cultivo em meio de cultura de MS foram utilizadas como material de encapsulamento. A concentração de alginato de sódio utilizada na matriz de encapsulamento foi de 1,5% (p/v) e a esta consistência se testou na água e o meio de MS nas concentrações plena (100%), 3/4 (75%) e 1/2 (50%) dos sais e vitaminas, associado ou não a carvão ativado (3 g L-1) como elementos da cápsula. Após encapsulamento, os cultivos foram mantidos em sala de crescimento a 25±2ºC, fotoperíodo de 16 horas e intensidade luminosa de 30 mmol m-2 s-1, onde a taxa de conversão e a altura das plantas foram avaliadas quinzenalmente até 30 dias de cultivo. O delineamento utilizado foi inteiramente casualizado, em fatorial 2 x 4, com cinco repetições e dez unidades encapsuláveis por parcela. Verificou-se que o emprego de um endosperma sintético constituído por 3/4 dos sais e vitaminas de MS, acrescido de carvão ativado (3 g L-1) (85,8% de taxa de conversão) ou a utilização de MS pleno, independente do uso de carvão ativado (76,5%) promoveram as melhores taxas de conversão de sementes sintéticas de pimenta-longa. A altura das plantas não foi afetada pelas concentrações de MS e adição de carvão ativado à cápsula.

PET/PP blend with bamboo charcoal to produce functional composites

Abstract Polymer products belong to petrochemical compounds and uneasily degrade in the natural environment. Besides, the process of extraction and purification of oil consume resources, energy and result in environmental pollution. For recycling of plastic wastes and environmental preservation, this study focused on blending and reprocessing of polyester (PET) and polypropylene (PP) due to their large amount of disposal. In this study, thermoplastic composites were made from blending virgin PET and PP pellets with the bamboo charcoal by melt compounding and then injection molding. The mechanical properties and functions of these composites were investigated. The compositions of blended ratio were also studied in this work. The results show that the mechanical properties of the PET/PP ext (extrusion grade polypropylene) composites were better than that of the PET/PP inj (injection grade polypropylene) composites with 10 and 20% of polyester composition. After three extrusion processes, the tensile strength, impact strength and flexural modulus of the PET/PP ext composites were still, respectively, maintained around 32 MPa, 35 J/m and 2000 MPa. While the content of polyester is 30%, the serious phase separation between PET and PP resulted in poor mechanical properties of the PET/PP ext composites. While the content of polyester was 20%, the mechanical properties of the PET/PP inj composite were not significantly influenced by the addition of bamboo charcoal.

Effects of charcoal addition on N2O emissions from soil resulting from rewetting air-dried soil in short-term laboratory experiments

Laboratory experiments were conducted to examine the effect of charcoal addition on N2O emissions resulting from rewetting of air-dried soil. Rewetting the soil at 73% and 83% of the water-filled pore space (WFPS) caused a N2O emission peak 6 h after the rewetting, and the cumulative N2O emissions throughout the 120-h incubation period were 11 ± 1 and 13 ± 1 mg N m−2, respectively. However, rewetting at 64% WFPS did not cause detectable N2O emissions (−0.016 ± 0.082 mg N m−2), suggesting a severe sensitivity to soil moisture. When the soils were rewetted at 73% and 78% WFPS, the addition of charcoal to soil at 10 wt% supressed the N2O emissions by 89% . In contrast, the addition of the ash from the charcoal did not suppress the N2O emissions from soil rewetted at 73% WFPS. The addition of charcoal also significantly stimulated the N2O emissions from soil rewetted at 83% WFPS compared with the soil without charcoal addition (P < 0.01). Moreover, the addition of KCl and K2SO4 did not show a clear difference in the N2O emission pattern, although Cl− and SO2− 4, which were the major anions in the charcoal, had different effects on N2O-reducing activity. These results indicate that the suppression of N2O emissions by the addition of charcoal may not result in stimulation of the N2O-reducing activity in the soil because of changes in soil chemical properties.

Increasing the Clearance of Protein-Bound Solutes by Addition of a Sorbent to the Dialysate

The capacity of sorbent systems to increase solute clearances above the levels that are provided by hemodialysis has not been well defined. This study assessed the extent to which solute clearances can be increased by addition of a sorbent to the dialysate. Attention was focused on the clearance of protein-bound solutes, which are cleared poorly by conventional hemodialysis. A reservoir that contained test solutes and artificial plasma was dialyzed first with the plasma flow set at 46 +/- 3 ml/min and the dialysate flow (Q(d)) set at 42 +/- 3 ml/min using a hollow fiber kidney with mass transfer area coefficients greater than Q(d) for each of the solutes. Under these conditions, the clearance of urea (Cl(urea)) was 34 +/- 1 ml/min, whereas the clearances of the protein-bound solutes indican (Cl(ind)), p-cresol sulfate (Cl(pcs)), and p-cresol (Cl(pc)) averaged only 5 +/- 1, 4 +/- 1, and 14 +/- 1 ml/min, respectively The effect of addition of activated charcoal to the dialysate then was compared with the effect of increasing Q(d) without addition of any sorbent. Addition of charcoal increased Cl(ind), Cl(pcs), and Cl(pc) to 12 +/- 1, 9 +/- 2, and 35 +/- 4 ml/min without changing Cl(urea). Increasing Q(d) without the addition of sorbent had a similar effect on the clearance of the protein-bound solutes. Mathematical modeling predicted these changes and showed that the maximal effect of addition of a sorbent to the dialysate is equivalent to that of an unlimited increase in Q(d). These results suggest that as an adjunct to conventional hemodialysis, addition of sorbents to the dialysate could increase the clearance of protein-bound solutes without greatly altering the clearance of unbound solutes.

Effect of Charcoal Application on The Early Growth Stage of Acacia mangium and Michelia montana

Charcoal, or black coloured carbon-predominated stuff, is produced during incomplete combustion of woody plant biomass. Charcoal application to the soil can improve chemical and nutritional nature thereby inducing better plant growth and development. However, the utilization of charcoal in forestry sector, especially industrial plantation, has not been introduced due to the absence of available information. Indicator species used in this study are Acacia mangium and Michelia montana . A. mangium is one of the most important species grown in industrial plantations in Indonesia. Meanwhile M. montana is critical endemic species in Gunung Halimun National Park. Glasshouse research was designed to examine the effectiveness of charcoal incorporation into marginal soils on the growth of 6-month-old Acacia mangium and 6-month-old Michelia montana . Charcoal treatments were 0,10, 15 and 20% (v/v) for A. mangium , while 0, 5, 10, 15 and 20 % (v/v) for M. montana . Representative samples of Orthic Acrisol (i.e. Very fine, mixed, semiactive, isohyperthermic, and Typic Paleudult) were collected from B horizon. A completely randomized design with four replications (for A. mangium ) and five replications (for M. montana ) was employed to examine the effect of charcoal application on the plant growth and some important chemical properties of the corresponding soil. Charcoal additions to the soil significantly increased height, diameter, and leaf and stem biomass weight of A. mangium, and significantly increased height, diameter, and total biomass weight of M. montana seedlings in comparison to those of a control. Increasing the amount of charcoal higher than 10% level, however, have little effect on A. mangium growth. On the other hand, increasing the amount of charcoal higher than 10% is still effective on M. montana growth. This study indicated that charcoal application at the rates of 10 % for A. mangium and 15 % for M. montana would be adequate to improve the availability of soil nutrients, and hence significantly induce a better plant growth response.

Effects of natural-resource-based scavengers on the adhesion properties and formaldehyde emission of engineered flooring

In this study we investigated the effects of using four additives, wheat flour (WF), tannin, rice husk (RH) and charcoal, to melamine-formaldehyde (MF) resin for decorative veneer and base plywood in engineered flooring in order to reduce the formaldehyde emission levels and improve the adhesion properties. We determined the effects of variations in hot-press time, temperature and pressure on the bonding strength and formaldehyde emission. Blends of various MF resin/additive compositions were prepared. To determine and compare the effects of the additives, seven MF resin blends were prepared with the four different additives: four with a wt ratio of 8:2 (MF/WF, MF/tannin, MF/RH and MF/charcoal), and three in the wt ratio of 8:1:1 (MF/WF/tannin, MF/WF/RH and MF/WF/charcoal). The desiccator and perforator methods were used to determine the level of formaldehyde emission. The formaldehyde emission level decreased with all additives, except for RH. At a charcoal addition of only 20%, the formaldehyde emission level was reduced to nearly 0.1 mg/l. Curing of the high WF and tannin content in this adhesive system was well processed, as indicated by the increased lap-shear strength. In the case of WF, the lap shear strength was much lower due to the already high temperature of 130°C. The adhesive layer was broken when exposed to high temperature for extended time. In addition, both WF and tannin showed good mechanical properties. With increasing WF or tannin content, the initial adhesion strength increased. The MF resin samples with 20% added tannin or WF showed both good lap shear and initial adhesion strengths compared to the pure MF resin.

STIMULATION OF IN VITRO BULBLET GROWTH IN GALANTHUS SPECIES WITH SUCROSE AND ACTIVATED CHARCOAL

We report here a reliable method to stimulate growth of in vitro-produced bulblets of Galanthus species to a size suitable for acclimatization. Proliferating bulblet cultures, from bulb chip explants, were induced and maintained on MS medium supplemented with 30 g/L sucrose, 1 mg/L BA and 0.1 mg/L NAA. The six treatments, prepared in plant growth regulator-free MS medium, were 30 or 60 g/L sucrose in all combinations with 0, 1 or 5 g/L activated charcoal. Fifteen replicates per treatment per plant type (G nivalis, G nivalis 'Flore Pleno' and G. elwesii) were inoculated with bulblet clumps containing 2-4 bulblets. Assessments were made after incubation for 16 weeks at 18°C with 16h photoperiods. Even in the absence of plant growth regulators the cultures continued to form new bulblets in all treatments. Bulblet growth was greatly stimulated by the addition of activated charcoal. In contrast, doubling the amount of sucrose in the medium to 60g/L had only a marginal effect on bulblet growth in the absence of charcoal. Addition of charcoal and sucrose together was found to have a synergistic effect on bulblet growth, in that the benefit of adding the higher rate of charcoal could be seen at only the higher sucrose concentration. Charcoal also induced the formation of large numbers of roots and stimulated root elongation. Bulblets had a normal anatomy in longitudinal section, and, although many of the bulbs sprouted in vitro and lateral bulb units developed in larger bulbs, none formed flowers. Thus it is expected that in vitro-produced bulbs will require either flower initiation treatment(s) or a minimum of one season in field conditions to achieve flowering size.

Charcoal and shrubs modify soil processes in ponderosa pine forests of western Montana

Low-elevation ponderosa pine (Pinus ponderosa Doug. ex. laws) forests of western Montana are naturally fire maintained ecosystems. However, 80–140 years of fire-exclusion has led to the formation of dense, mixed stands of ponderosa pine and Douglas-fir (Pseudotsuga menzesii (Mirbel) Franco), an understory co-dominated by graminoids and ericaceous shrubs, and low N availability. Ericaceous shrubs in particular have been found to influence soil processes in boreal ecosystems and potentially exacerbate N limiting conditions. In this set of studies, we investigated the influence of graminoid and ericoid litter chemistry on soil processes and evaluated the influence of charcoal as a sorbant of C compounds and depositional product of fire. A series of experiments were performed with two common understory plants of this ecosystem, elk sedge (Carex geyeri Boott) and kinnikinnick (Arctostaphylos uva-ursi (L.) Spreng.), an ericaceous shrub. Charcoal (100 g m−2) and glycine (5 g m−2) were applied in factorial combination to intact litter microcosms of these species. Non-ionic resin capsules were used to monitor mobile C compounds and ionic resins were used to monitor net N mineralization and nitrification in-situ. Greenhouse studies revealed that the addition of glycine and charcoal leads to a significant increase in net nitrification in shrub litter microcosms, but not sedge litter microcosms, as measured by NO3− sorption to ionic resin capsules. Charcoal and glycine also resulted in a significant increase of anthrone reactive C (soluble hexose sugars, an index of bioavailable C) in shrub litter microcosms. Analysis of leaf litter leachate from these two plant communities indicated similar nutrient concentrations, but almost 20 times more phenolic compounds in shrub leaf leachates. Charcoal was shown to be extremely effective at sorbing phenols, removing over 80% of phenolic compounds from solution. These results suggest that charcoal deposition after fire may modify a nitrification interference mechanism by sorbing plant secondary metabolites. After time, charcoal loses its ability to sorb C compounds and ericaceous litter decomposition, and subsequent release of phenolics, may interfere with nitrification once again.

Charcoal effects on soil solution chemistry and growth of Koeleria macrantha in the ponderosa pine/Douglas-fir ecosystem

We conducted laboratory and greenhouse experi- ments to determine whether charcoal derived from the ponderosa pine/Douglas-fir ecosystem may influence soil solution chemistry and growth of Koeleria macrantha ,a perennial grass that thrives after fire. In our first experi- ment, we incubated forest soils with a factorial combination of Douglas-fir wood charcoal generated at 350°C and extracts of Arctostaphylos uva-ursi with and without the addition of glycine as a labile N source. These results showed that charcoal increased N mineralization and nitrification when glycine was added, but reduced N mineralization and nitrification without the addition of glycine. Charcoal significantly reduced the solution con- centration of soluble phenols from litter extracts, but may have contributed bioavailable C to the soil that resulted in N immobilization in the no-glycine trial. In our second experiment, we grew K. macrantha in soil amended with charcoal made at 350°C from ponderosa pine and Douglas- fir bark. Growth of K. macrantha was significantly diminished by both of these charcoal types relative to the control. In our third experiment, we grew K. macrantha in soil amended with six concentrations (0, 0.5, 1, 2, 5, and 10%) of charcoal collected from a wildfire. The data showed increasing growth of K. macrantha with charcoal addition, suggesting some fundamental differences between laboratory-generated charcoal and wildfire-produced char- coal. Furthermore, they suggest a need for a better understanding of how temperature and substrate influence the chemical properties of charcoal.

숯 첨가 콘크리트벽돌의 물성특성과 친환경 성능에 관한 연구

After the new house symptoms recently, room environment pollution problem of building syndrome and so on is becoming research about ways to solve this being risen. Is taking advantage of nature data by building materials by one of this way, but Friendly Environmental performance examination for structure material is insufficient misgovernment being real condition that put emphasis in ability as most embellishment and in finish. Environmental examination is insufficient misgovernment on factor itself as structure material. Also, being real condition that radon that is responsible for lung cancer occurrence next to smoke in building materials such as concrete and so on is happened, the danger is reported much through mass communications and research paper etc. Therefore, this research measured radon release amount and the carbon dioxide adsorption rate for physical special quality measuring and Friendly Environment Efficiency that follow to 'KS F 4004 Concrete bricks' regulation after manufacture Concrete Bricks utilizing charcoal that is nature material by sand. This study finding carbon dioxide density appeared and displayed effect that charcoal Controls radon release that happen in Concrete Bricks to maximum 74% that decrease to best 95% though decreased the charcoal addition rate increases.

Estabelecimento de um protocolo para a propagação &lt;em&gt;in vitro&lt;/em&gt; de rainha-do-abismo, &lt;em&gt;Sinningia leucotricha&lt;/em&gt; (Hoehne) Moore- (Gesneriaceae)

Sinningia leucotricha is a native plant of Parana (Brazil), which is considered endangered. The objective of this work was to establish a protocol for in vitro propagation of Sinningia leucotricha. The treatments were: (T1) MS, (T2) MS 50%, (T3) MS 200%, (T4) MS 100% + 1.0 gL -1 of activated charcoal, (T5) MS 50% + 1.0 gL -1 of activated charcoal and (T6) MS 200% + 1.0 gL -1 of activated charcoal. The experimental design was entirely casualized with 10 replications per treatment, and 5 plants per replication. Plant height, root length, total fresh weight and number of shoots were evaluated 120 days after cultivation. After thirty days of seedling acclimatization, the germination/sticking proportion was evaluated. The higher averages for all analyzed features was the MS 50% without activated charcoal addition (T2), and the germination/ sticking proportion was 100% for all treatments.

Weed composition and cover after three years of soil fertility management in the central Brazilian Amazon: Compost, fertilizer, manure and charcoal applications

Soils of the lowland tropics in the central Brazilian Amazon are generally highly leached, acidic and nutrient‐poor. Charcoal, combined with other soil amendments, might improve fertility but this, in turn, could lead to increased weed problems for agricultural production. This experiment was conducted to assess weed pressure and species composition on plots receiving various inorganic and organic soil amendments, including charcoal. Additions of inorganic fertilizer, compost and chicken manure resulted in increases in weed ground cover of 40, 22 and 53%, respectively, and increases in species richness of 20, 48, and 63%, respectively. When chicken manure was applied, dominance by a few weed species was reduced, such that different species were more evenly represented. Although charcoal additions alone did not significantly affect weed ground cover or species richness, a synergistic effect occurred when both charcoal and inorganic fertilizers were applied. The percentage ground cover of weeds was 45% within plots receiving inorganic fertilizer, 2% within plots receiving charcoal and 66% within plots receiving both amendments. Improvements in the fertility of nutrient‐poor soils of the tropics might increase weed pressure and make the development of effective weed management strategies more critical. These effects on weed populations were observed nearly 2.5 years after the addition of charcoal, chicken manure and compost, and &gt; 1 year after the last application of inorganic fertilizer.

Agrobacterium-mediated transformation of the wetland monocot Typha latifolia L. (Broadleaf cattail)

An Agrobacterium-mediated model transformation system was standardized for the wetland monocot Typha latifolia L. to achieve the long-term objective of introducing candidate genes for phytoremediation. Two binary plasmid vectors, pCAMBIA1301/EHA105 and pTOK233/LBA4404, both containing the gus (beta-glucuronidase) and hptII (hygromycin phosphotransferase II) genes, were used for transformation. Fifty-day-old 5 mg/l picloram-derived calli were cocultivated and selected on medium containing 20 mg/l or 40 mg/l hygromycin. Resistant calli were regenerated on medium supplemented with 5 mg/l 6-benzylaminopurine, with or without 20 mg/l or 40 mg/l hygromycin and with or without charcoal (10 g/l). Transient GUS activity in explants ranged between 28% and 36%. Hygromycin-resistant calli, selected after 3 months, showed stable GUS expression. A total of 46 plants were regenerated and established in the greenhouse; 13 showed stable GUS expression. Cocultivation of dark culture-derived calli, directly selected on regeneration medium containing 20 mg/l hygromycin and rooted on medium with 20 mg/l hygromycin was the best protocol. The addition of charcoal did not have any effect on regeneration. PCR and Southern analyses of transgenic calli and transgenic plants confirmed the presence of the introduced genes. In conclusion, T. latifolia could be genetically transformed by Agrobacterium tumefaciens.

Rooting Medium Composition and In Vitro Rooting and Greenhouse Survival of Five Raspberry Cultivars

In vitro rooting and subsequent greenhouse survival of `Autumn Britten', `Boyne', `Comet',`Nova' and `Qualicum' raspberry (Rubus idaeus L.) plantlets were compared following four weeks on a rooting medium with and without activated charcoal, and with 0.1, 0.5, 1.0, 2.0 or 3.0 milligrams per litre IBA. The addition of charcoal significantly increased the percentage of plantlets that produced roots in vitro for the hard-to-root cultivars. Percent rooting in vitro was highest with the three lower levels of IBA. Root number was influenced only by the cultivar, while root diameter and length were affected by all the factors investigated. Greenhouse survival was affected by the cultivar, the presence or absence of charcoal and the IBA level in the in vitro rooting medium, with significant interactions. Provided charcoal was present in the rooting medium, the level of IBA didn`t alter survival. The addition of charcoal to the rooting medium improved greenhouse survival of the three hardest-to-root cultivars. Plug plant stem length; internode length and dry weight were increased by the presence of charcoal in the in vitro rooting medium for all but the easiest to establish cultivar. Chemical names used: 3-indolebutyric acid (IBA).

Microwave heating behaviour of nickeliferous limonitic laterite ores

The nickeliferous laterite ores, in which the nickel occurs in oxide form, represent a significant potential resource of metallic nickel. However, in comparison to the nickel-containing sulfide ores, the extraction costs are relatively high and thus it will be necessary to develop new processing techniques, which are both technically and economically viable. In the present research, the potential application of microwaves for the heating of a nickeliferous limonitic laterite ore ((Fe,Ni)O(OH) · nH2O) was investigated. Firstly, since the nickeliferous limonitic laterite ore contains considerable moisture, both free and combined, then thermogravimetric analysis (TGA) was performed in order to characterize the changes, which result from the dehydration processes. Derivative thermogravimetric analysis (DTGA) curves were calculated from the TGA data. Secondly, the real (ε′) and imaginary (ε″) permittivities of the ore were measured at frequencies of 912 and 2460 MHz at temperatures up to about 1000 °C using the cavity perturbation technique and these results were related to the DTGA curves. Also, the loss tangent (tanδ=ε″/ε′) was calculated from the permittivity data. Finally, the microwave heating behaviour of the nickeliferous limonitic laterite ore was determined at 2460 MHz. The results show that the both the real (ε′) and imaginary permittivities (ε″) and the loss tangent (tanδ) increase with temperature and change as both the free and the combined moisture are removed. The permittivities (ε′ and ε″) increased with increasing slope of the TGA curve and vice versa during the goethite to hematite dehydroxylation reaction, where there was a maximum in the permittivities (ε′ and ε″). It is proposed that these changes, which occur during the dehydroxylation reaction, are a result of the liberation of hydroxyl units from the goethite structure. Furthermore, some hydroxyl units were retained in the hematite structure (i.e. hydrohematite (α-Fe2−x/3O3−xOHx)) even after the goethite to hematite transition and thus the permittivities of the dehydroxylated ore were higher than that of normal hematite. With regards, to their microwave heating behaviour, it is shown that despite the relatively low permittivities (ε′ and ε″) of these materials at low temperatures, they can be heated using microwaves. The microwave heating process can be improved by conventional preheating of the sample or by the addition of charcoal as a susceptor or by selecting a crucible material, which acts as a susceptor. There is a rapid increase in the permittivities over the temperature range of about 600–800 °C and this combined with the low thermal conductivities of these oxides, can result in rapid internal heating of the sample and thermal runaway.

Microwave heating behaviour of nickeliferous limonitic laterite ores

The nickeliferous laterite ores, in which the nickel occurs in oxide form, represent a significant potential resource of metallic nickel. However, in comparison to the nickel-containing sulfide ores, the extraction costs are relatively high and thus it will be necessary to develop new processing techniques, which are both technically and economically viable. In the present research, the potential application of microwaves for the heating of a nickeliferous limonitic laterite ore ((Fe,Ni)O(OH) · nH 2O) was investigated. Firstly, since the nickeliferous limonitic laterite ore contains considerable moisture, both free and combined, then thermogravimetric analysis (TGA) was performed in order to characterize the changes, which result from the dehydration processes. Derivative thermogravimetric analysis (DTGA) curves were calculated from the TGA data. Secondly, the real ( ε ′) and imaginary ( ε ″) permittivities of the ore were measured at frequencies of 912 and 2460 MHz at temperatures up to about 1000 °C using the cavity perturbation technique and these results were related to the DTGA curves. Also, the loss tangent (tan δ= ε ″/ ε ′) was calculated from the permittivity data. Finally, the microwave heating behaviour of the nickeliferous limonitic laterite ore was determined at 2460 MHz. The results show that the both the real ( ε ′) and imaginary permittivities ( ε ″) and the loss tangent (tan δ) increase with temperature and change as both the free and the combined moisture are removed. The permittivities ( ε ′ and ε ″) increased with increasing slope of the TGA curve and vice versa during the goethite to hematite dehydroxylation reaction, where there was a maximum in the permittivities ( ε ′ and ε ″). It is proposed that these changes, which occur during the dehydroxylation reaction, are a result of the liberation of hydroxyl units from the goethite structure. Furthermore, some hydroxyl units were retained in the hematite structure (i.e. hydrohematite (α-Fe 2− x/3 O 3− x OH x )) even after the goethite to hematite transition and thus the permittivities of the dehydroxylated ore were higher than that of normal hematite. With regards, to their microwave heating behaviour, it is shown that despite the relatively low permittivities ( ε ′ and ε ″) of these materials at low temperatures, they can be heated using microwaves. The microwave heating process can be improved by conventional preheating of the sample or by the addition of charcoal as a susceptor or by selecting a crucible material, which acts as a susceptor. There is a rapid increase in the permittivities over the temperature range of about 600–800 °C and this combined with the low thermal conductivities of these oxides, can result in rapid internal heating of the sample and thermal runaway.

Environmental manipulation treatment effects on the reactivity of water-soluble phenolics in a subalpine tundra ecosystem

Subalpine tundra ecosystems are characterised by a multitude of ecological stresses such as nutrient poor conditions and low pH, and are dominated by plants producing high levels of phenolic compounds. The aim of this study was to assess how alleviation of those stresses affects the reactivity (oxidation and complexation) of water-soluble phenolics in plant tissue, humus and mineral soil. We used a field manipulation experiment that was set up in 1989 in which plots dominated by the ericacious dwarf shrub Empetrum hermaphroditum Hagerup have been subjected to additions of inorganic and organic nitrogen (N), charcoal, and lime. From these plots we collected senescent leaves of E. hermaphroditum, humus, and mineral soil and determined the levels of redox-active phenolics and complexation activity (e.g., complexation towards phenol, L-tryptophan, and proteins) in water extracts of those samples. Addition of charcoal to the soil increased redox-active phenolics in E. hermaphroditum senescent leaves while the other treatments had no significant effect. Most of the treatments did not significantly affect the levels of redox-active phenolics in the humus and mineral soil water extracts. However, inorganic N amendments slightly increased the concentration of redox-active phenolics in humus. There were strong positive effects of addition of inorganic and organic N on the complexation activity towards phenol, L-tryptophan and proteins in humus water extracts. In addition, charcoal amendments increased complexation towards proteins (measured as lipase activity). In general, our results show that environmental manipulation treatments can have differential effects on redox-active phenolics and complexation activity of phenolics present in senescent leaves and humus. This is important knowledge for a better understanding of how environmental changes can affect humification processes and N cycling.