Amounts Of K2O Research Articles

Investigation of potassium transformation characteristics and the influence of additives during biochar briquette combustion

Low energy density and ash fusion problem were problems that limit biomass widespread utilization. To avoid these, maize straw (MS) was blended with two additive –NH4H2PO4 (ADP) and Ca(H2PO4)2 (CPM)-respectively, and the production chain of mixing additive-briquetting-pyrolysis was put forward to produce MS char briquettes (MSC, MSC-ADP and MSC-CPM). Ash fusion characteristics of MS char briquettes after combustion was investigated by XRF, XRD, SEM-EDS and simulation. Results show that the softening temperature increased with the enhanced ratio of P2O5/K2O until 0.2, and CaO/K2O until 0.9. The higher amount of CaO and P2O5, the lower amount of K2O, the better ash fusion characteristics. The P2O5 had larger influence on softening temperature. The surfaces of MSC ashes formed at 1000 °C were fusion and smooth in micro observation, while surfaces of MSC-ADP and MSC-CPM ashes were coarse and the particles were much looser. Both SEM-EDS and XRD results illustrated that phosphorus in additives combined with potassium to produce high melting temperature potassium phosphates rather than low melting temperature potassium silicates. The potassium fixation ability of ADP was better than that of CPM. The calcium silicates and calcium phosphates produced by CPM could improve ash characteristics.

Geochemical characterization of the loess-paleosol sequence in northeast China

Long-term weathering patterns in northeastern China are not well known due to few well-preserved terrestrial paleo-environmental archives in this area. The Chaoyang section is a typical well-preserved loess-paleosol sequence in northeast China with continuous deposition since 423 ka BP; the deposit thus represents an archive of climate change for this region. The sequence was geochemically characterized by major elemental compositions, elemental ratios, a ternary diagram of Al2O3-(CaO* + Na2O)-K2O, improved quantitative reconstruction and elemental distributions with respect to the average for the upper continental crust (AUCC). Another typical loess-paleosol sequence of Lingtai section from the central Chinese Loess Plateau was used for comparison with the loess-paleosol one. The similar AUCC-normalized major elemental distributions and strong correlation of the major elemental compositions between the loess-paleosol sequences indicate that they may have originated predominantly from a similar loess source. Based on the variability in chemical indices corresponding to soil magnetic susceptibility (SUS) and field observations, the loess-paleosol formation period of 423–77 ka BP was separated into eight sub-periods including four periods with greater chemical weathering intensity (paleosols) and four periods characterized by the relative lesser chemical weathering intensity (loess). Relatively intense desilication and fersiallitization primarily occurred in the loess-paleosol sequence from northeast China with greater losses of SiO2 (3.54% in average) and gains of Fe2O3 (0.77%) and Al2O3 (0.33%). Such processes also were reflected in an increase in the amount of K2O (0.41%). Ca and Na leaching was still predominant in the loess-paleosol sequence from the central Chinese Loess Plateau with greater losses of CaO (28.03%) and Na2O (14.03%). The sequence from northeast China records chemical weathering during 423–77 ka BP, which is comparable to the weathering cycles in the sequence from the central Chinese Loess Plateau.

Changes of weed infestation under long-term effect of different soil pH levels and amount of phosphorus:potassium

ABSTRACTThe aim of the present study was to investigate changes of weed species density as a result of long-term (1976–2005) exposure to different soil pH levels, and P2O5:K2O amount in soil created by initial and subsequent periodical liming, and fertilization. As a result of liming during the period 1976–2005, average soil pH levels at the start of the sixth crop rotation (2001–2005) ranged from 4.1 (unlimed) to 6.6. And in each pH plot were four sub-plots with a different amount of mobile phosphorus:potassium. In acid soil (pH 4.1), in spring oilseed rape and in spring barley crops, the dominant weed Spergula arvensis density decreased significantly at a pH of 5.1 or higher. With increasing amount of P2O5:K2O in soil, the abundance of S. arvensis in spring rape and spring barley crops was reduced at all soil pH levels. At pH 5.1, Chenopodium album and Tripleurospermum perforatum were prominent. Elytrigia repens tended to decrease with increased alkalinity and nutrient amount in soil. With reduction of soil acidity from pH 4.1 to 6.6, the total weed infestation consistently declined in all crops. A low amount of P2O5:K2O in soil caused the decline in the abundance of S. arvensis, E. repens and increase in C. album and T. perforatum.

Optical characterization of oxyfluoride glasses containing different amounts of K2O additive

In the present study, oxyfluoride glasses containing different amounts of K2O (1.5, 3 and 4.5weight ratio) were prepared by the convenient melting process. The network-modifying role of K2O was proved by differential thermal analysis (DTA) results, which have shown a decreasing trend of crystallization temperature in presence of more K2O. To study structural changes of samples, Fourier transfer infrared (FT-IR) spectroscopy was carried out. According to UV–vis spectra, optical properties were determined. Being a glass modifier agent, K2O shortened the bond chain length and increased the transparency. Direct and indirect band gap energies were increased, which asserts the reduction of semiconducting behavior in presence of K2O. Although creation of none-bridging oxygens by adding K2O resulted in lower degree of order, the Urbach energy (0.32eV) was still lower than other glassy systems.

Glass Forming Ability and Luminescent Properties of P<sub>2</sub>O<sub>5</sub>-ZnO-SrO System Glasses

Glass-forming ability in the P2O5-ZnO-SrO-K2O system was investigated using differential thermal analyzer (DTA). The results showed that adding appropriate amount of K2O could improve the glass-forming ability of phosphate glasses. Meanwhile, the spectroscopic properties of Tm/Tb/Mn co-doped phosphate glasses were studied by photoluminescence (PL) measurements and CIE color coordinate. Blue, green, and reddish orange emission bands were observed in the PL spectra of the phosphate glasses. The combination of these emission bands gave white light by ultraviolet light excitation (360nm). As the Tb4O7 was increased,a gradual shift from white emission to yellow emission was observed in the PL spectra of the glasses. These three ions-doped phosphate glasses are potential candidates for white light-emitting diodes.

Preparation of basic mesoporous molecular sieves K2O/Mg-MCM-41 and its catalytic performance on the cracking of soybean oils

Mesoporous molecular sieves Mg-MCM-41 are prepared in hydrothermal system and characterized by XRD and TEM. By impregnating Mg-MCM-41 with KNO3 solvent, basic K2O/Mg-MCM-41 is prepared. K2O/Mg-MCM-41 is used as catalysts on the cracking of soybean oils, and the cracking products are of the similar acid value as those from Na2CO3 or K2CO3 as catalysts. The performance of cracking oil and the influence of the amount of K2O on catalytic performance are in detail examined.

Characterization of alteration phases on Potash–Lime–Silica glass

Glass with Potash–Lime–Silica (PLS) composition was typically produced for the cathedral windows during the Middle Age in Central and Northern Europe and is known to be very sensitive to the attack of the atmospheric pollutants. PLS glass, containing different amounts of K2O (sample V1=15wt%, V2=20wt%, V3=25wt%), was produced and aged in concentrated boiling H2SO4 and in high temperature-high pressure water, to simulate separately the two alteration processes of leaching (ion exchange) and dissolution, respectively. The aged samples were studied by micro-Raman spectroscopy, by XRPD and by SEM–EDS technique to identify the neo-formed crystalline phases, to get deeper insight into degradation and stability of these systems.The behavior of the glasses as revealed by Raman spectroscopy depends on the K2O content. Gypsum (CaSO4·2H2O), bassanite (CaSO4·1/2H2O) and anhydrite (CaSO4) are found on the alteration layer of the V2 and V3 leached samples. The water aged V1 and V2 glasses show the Raman features of the phyllosilicates gyrolite (Ca16Si24O60(OH)8·14H2O) and reyerite (KCa14Si24O60(OH)5·5H2O) together with hydroxyapatite (Ca5(PO4)3OH). In the alteration layer of the V3 glass, the Raman spectra suggest a mixture of the Ca–K silicate charoite (K5Ca8(Si6O15)2Si2O9(OH)·3(H2O)) and hydroxyapatite.

Leaching studies of potash–lime–silica glass with medieval composition by IRRAS

Potash–lime–silica glasses were extensively used during medieval times for several art objects and stained glass windows which are considered as a fundamental part of the decorative plan of churches and cathedrals in Northern Europe. The high potash content of this particular type of glass is the reason for its low chemical durability and hence accelerated deterioration, which entails the formation of leached layers and corrosion products, especially when exposed to atmospheric agents and to air pollutants.In order to preserve the value and to avoid the degradation of these artistic glasses, it is important to understand the chemical processes occurring on the glass surfaces by studying the role of glass composition and corrosion agents. For this purpose the leaching progress of two types of potash–lime–silica glasses (glass M1 with a silica content lower than 50% and high amounts of K2O and CaO, and glass M3 with 60% SiO2, 25% CaO and 15% K2O) was studied by using Infrared Reflection Absorption Spectroscopy (IRRAS) and the dependency of the corrosion rate on the nature of the acids (sulphuric, nitric and hydrochloric acids) was tested. The corrosion rate during the early stages of corrosion is different, depending on the type of acid used during the experiments: The results showed that glass M1 presents a high corrosion rate when leached in sulphuric acid in comparison to nitric and hydrochloric acids; in contrast to this result glass M3 is more resistant to the attack of sulphuric acid compared to the other acidic solutions and has a much higher chemical stability in comparison to glass M1.Furthermore the applicability of a self-built unit for IRRAS measurements was tested monitoring the progression of the leaching processes, in order to continue with further in-situ aging studies on the weathering mechanisms occurring on the glass surfaces.

Raman study of model glass with medieval compositions: artificial weathering and comparison with ancient samples

Potassium‐rich ash‐based glass is typical of medieval glass windows used in the Central Europe since 1000 A. D.. Glasses with medieval‐like composition were prepared with different amounts of K2O (15–20–25 K2O weight%) using recipes deduced from archaeometric literature. Raman data of these samples were interpreted on the basis of the Qn units model and of the polymerization index Ip and confirm a close dependence of glass depolymerization on the potassium content. Generally, K‐based glasses have high alteration sensitivity to pollutants conveyed by liquid or vapour water (rain, humidity and fog). In this work, the glass alteration processes were studied in terms of structural modifications related to the glass K content. Leaching and network dissolution were investigated by attack with boiling concentrated sulfuric acid and by exposure to high temperature and high pressure bidistilled water, respectively. The weight loss and alteration layer thickness were measured. The structural changes in the glass network and the presence of neoformation crystallized products were determined through linear Raman maps on altered glass cross sections. The more the glass network structure is depolymerized, the more the surface chemical attack is facilitated. The results obtained for the model glasses are compared with those for a set of ancient K‐rich glass fragments. Copyright © 2012 John Wiley & Sons, Ltd.

Algunas consideraciones mineralógicas y geoquímicas sobre la amazonita del estado de Chihuahua, México

This work characterizes the distinctive features that influence the geological setting of amazonite, as well as the relationship between their deposits and specific genetic types of granitoids. Mineralogical and geochemical conditions of the amazonite formation as well as the typomorphic attributes are described. New information about finding and geochemical features of the Mexican amazonite is here presented (deposit Hills Bahues, Coronado municipality). There is a chemical evolution of the amazonite from granites to pegmatites, characterized by increasing amounts of K2O, Rb2O, Cs2O, PbO, Sr, U y Th, and by decreasing amounts of Al2O3, Na2O, Fe2O3 and Ba. The amazonite characterized by a high degree of Al/Si order. All the parameters obtained from X-ray diffraction (∆>0.90) and infrared reflection spectroscopy show that the studied amazonite belong to the maximum ordered microcline. The colorimetric parameters of the Mexican amazonite are: λ=495–503 nm, P=10–12%, Y=34.7–35.3%. The typomorphic features and color for different amazonite generations from Hills Bahues deposit are close to the amazonites from

The role of K2O on sintering and crystallization of glass powder compacts in the Li2O–K2O–Al2O3–SiO2 system

The effects of K2O content on sintering and crystallization of glass powder compacts in the Li2O–K2O–Al2O3–SiO2 system were investigated. Glasses featuring SiO2/Li2O molar ratios of 2.69–3.13, far beyond the lithium disilicate (LD-Li2Si2O5) stoichiometry, were produced by conventional melt-quenching technique. The sintering and crystallization behaviour of glass powders was explored using hot stage microscopy (HSM), scanning electron microscopy (SEM), differential thermal (DTA) and X-ray diffraction (XRD) analyses. Increasing K2O content at the expense of SiO2 was shown to lower the temperature of maximum shrinkage, eventually resulting in early densification of the glass-powder compacts. Lithium metasilicate was the main crystalline phase formed upon heat treating the glass powders with higher amounts of K2O. In contrast, lithium disilicate predominantly crystallized from the compositions with lower K2O contents resulting in strong glass–ceramics with high chemical and electrical resistance. The total content of K2O should be kept below 4.63 mol% for obtaining LD-based glass–ceramics.

Deactivation mechanism of potassium additives on Ti0.8Zr0.2Ce0.2O2.4 for NH3-SCR of NO

Potassium additives slightly decreased catalytic activity for NH3-SCR of NO when the mass amount of K2O was less than 1.0%, but dramatically decreased the catalytic activity when the mass amount of K2O was more than 3.0%. The deactivation mechanism was that potassium additives directly decreased the specific surface area, the total acid amount and the acid strength of the strong acid sites, and induced the KCl-rich crystallization and the formation of non-active K2ZrO3, K2TiO3 and K2CeO3.

The effects of promoters of K and Zr on the mesoporous carbon supported cobalt catalysts for Fischer–Tropsch synthesis

The mesoporous carbon supported cobalt catalyst (15%Co/MC) was found to be more active and selective to C5+ than the traditionally activated carbon supported one (15%Co/AC) for the Fischer–Tropsch synthesis (FTS). The addition of small amount of K2O and ZrO2 significantly affected the FTS behavior of 15%Co/MC. The addition of 1% K inhibited the FTS activity dramatically, while the addition of 3% Zr increased the FTS activity significantly. The addition of K2O decreased the surface acidity while increased the surface basicity of 15%Co/MC, resulting in the increased heat of adsorption of CO and substantially decreased heat of adsorption of H2 on Co. In contrast, the addition of ZrO2 increased the surface acidity and heat of adsorption of H2 on Co. The FTS activity was found to be related to the ratio of heats for the adsorption of CO and H2 on the catalysts 15%Co/MC, 15%Co–1%K/MC and 15%Co–3%Zr/MC. The highest FTS activity was obtained on the catalyst with the heat ratio of 1.2.

Soil chemical properties as affected by plant derived ash to replace potassium fertilizer and its conversion value

Potassium chloride (KCl) presently used as main source of K, tends to become more expensive, therefore, there is a need for a breakthrough in finding alternative materials to replace KCl. The aim of this paper is to present recent research on the use of plant derived ash to replace KCl fertilizer, especially in relation with soil chemical characteristics and its conversion value. Plant derived ash coming from palm sugar processing unit which use farm waste as main fuel was used in this experiment. Treatments investigated were no K2O application (control), applied with K2O in forms of both KCl and plant derived ash in dosages of 100, 200, 300, 400, 500 and 600 mg kg-1 air dry soil. The mixture of soil with those treatments were then incubated for one year. After incubation period, the soil in pots were divided into two parts, first part was added with 2g urea, while other part was added with 2 g SP 36. Both parts were incubated for two months. Results of this experiment showed that plant derived ash can be used to replaced KCl. To obtain similar soil K content, the amount of K2O in form of plant derived ash needed to be added or its conversion value is 1.44 times the amount of K2O in form of KCl. Use of plant derived ash also increased the content of soil Ca, available P, ratio of Ca/Mg and pH. Plant derived ash did not caused nitrogen loss. Key words: Potassium, fertilizer, plant derived ash, pH, soil.

Preparation of Rutile Titanium Dioxide White Pigment by a Novel NaOH Molten‐Salt Process: Influence of Doping and Calcination

AbstractRutile titanium dioxide (TiO2) white pigment is prepared by a novel NaOH molten‐salt process. Titanium slag is decomposited by NaOH molten salt to obtain sodium titanate which is then converted into hydrate titanium dioxide (H2TiO3) through acid dissolution and hydrolysis. Finally, TiO2 white pigment is prepared by H2TiO3 doping and calcinations. H2TiO3 prepared by this innovative method is characterized and the influencing factors of doping and calcination of H2TiO3 on pigmentary properties of TiO2 are investigated. H2TiO3 with certain characteristics could be prepared through the controlled hydrolysis step in the NaOH molten‐salt process. Good pigmentary properties of rutile TiO2 white pigment are achieved by doping with suitable amounts of K2O, P2O5, Al2O3, and rutile nuclei, thereby approaching the quality of the commercial TiO2 pigment standards.

Spectral characterization and prediction of nutrient content in winter leaves of litchi during flower bud differentiation in southern China

Nutrient availability can affect the cracking rate of the litchi fruit tree, and the nutrient content of the canopy can be used to monitor availability and fertilizer needs of the litchi orchard. In this study, we analyzed the correlation between calcium (Ca), magnesium (Mg) and potassium (K) in canopy leaves and four indices of in situ spectral data of litchi canopy. These were reflectance (R), reciprocal-logarithm-transformed reflectance (log(1/R)), the first-order derivative of reflectance (dR) and the first-order derivative of reciprocal-logarithm-transformed reflectance (dlog(1/R)). The results showed that the spectra of the litchi canopy have common spectral characteristics. The correlation between the selected nutrients of the litchi canopy and R or log(1/R) was weak, that between the nutrients and dR was significant and with dlog(1/R) it was the most significant. The 1262 nm wavelength for dR and 1018 nm one for dlog(1/R) had the most significant correlation with Ca. The 1293 nm wavelength for dR and 1601 nm one for dlog(1/R) had the most significant correlation with Mg. The 1686 nm wavelength for dR and 1337 nm one for dlog(1/R) had the most significant correlation with K. Therefore, those wavelengths were chosen to create the regression equations for prediction. The linear regression equations performed the best when predicting canopy nutrient content of litchi for Ca at 1018 nm, Mg at 1601 nm and K at 1337 nm. Further, the formulated application of K2O played an important role in reducing the amount of K2O applied (50.6 g/plant on average) and in increasing the yield of the litchi tree by 4.4 kg/plant on average. These results are relevant for implementing a precision agriculture approach for litchi production and for environmental protection in South China or in other litchi production areas of the world. Other nutrients that affect litchi growth need to be studied in the future.

In situsynchrotron powder diffraction study of active belite clinkers

The clinkerization processes to form belite clinkers, with theoretical compositions close to 60 wt% of Ca2SiO4, have been studiedin situby high-resolution high-energy (λ = 0.30 Å) synchrotron X-ray powder diffraction. In order to obtain active belite cements, different amounts of K2O, Na2O and SO3have been added. The existence range of the high-temperature phases has been established and, furthermore, Rietveld quantitative phase analyses at high temperature have been performed for all patterns. The following high-temperature reactions have been investigated: (i) polymorphic transformations of dicalcium silicate, \alpha_{\rm L}'-Ca2SiO4↔ \alpha_{\rm H}'-Ca2SiO4from 1170 to 1230 K, and \alpha_{\rm H}'-Ca2SiO4↔ α-Ca2SiO4from 1500 to 1600 K; (ii) melting of the aluminates phases, Ca3Al2O6and Ca4(Al2Fe2)O10, above ∼1570 K; and (iii) reaction of Ca2SiO4with CaO to yield Ca3SiO5above ∼1550 K. Moreover, in all the studied compositions the temperature of the polymorphic transformation \alpha_{\rm H}'-Ca2SiO4↔ α-Ca2SiO4has decreased with the addition of activators. Finally, active belite clinkers were produced as the final samples contained α-belite phases.

Características de produção de frutos de melancia sem sementes em função de fontes e doses de potássio

O experimento foi conduzido em uma propriedade rural, próxima à cidade de Borborema - SP, no período de fevereiro a abril de 2002, com o objetivo de avaliar a produtividade de frutos de melancia sem sementes, híbrido Shadow, em função de fontes e doses de potássio. O delineamento experimental utilizado foi blocos casualizados em esquema fatorial 3 x 4, com três repetições, sendo avaliadas as fontes cloreto, nitrato e sulfato de potássio e as doses 50, 100, 200 e 300 kg ha-1 de K2O, em Argissolo Vermelho Amarelo Distrófico. O maior número de frutos por planta (1,7) foi obtido com as fontes KNO3 e KCl, respectivamente nas doses de 172 e 182 kg ha-1 de K2O. A massa do fruto foi influenciada somente pela dose de potássio e a maior massa foi obtida com 158 kg ha-1 K2O. As produtividades máximas foram obtidas com 94,1; 183 e 193,4 kg ha-1 de K2O, respectivamente, nas fontes K2SO4, KCl e KNO3. Para cada 1 kg de K2O utilizado na fonte K2SO4, obteve-se 201,6 kg de frutos, enquanto a mesma quantidade de K2O nas fontes KCl e KNO3 proporcionou a produção de 111,5 e 109,6 kg ha-1 de frutos.

Potential Use of Olive-Waste Ash from Cogeneration Plants as a Soil Amendment

A greenhouse study was conducted to evaluate the potential use of olive-cake ash as a soil amendment, using pepper (Capsicum annuum, L. cv Italian sweet). Three soils of different pH (acidic, neutral and calcareous) were used. Treatments included a control (no fertilizer application), NPK fertilizer, and two ash-application rates that provided a complete dose (equivalent to the K2O amount in the fertilizer) and a half dose (equivalent to half the K2O amount in the fertilizer), respectively. The ash was effective in raising soil pH. Ash treatments increased the pepper (stems and leaves) dry matter yield over control; although these increases were lower than treatment including NPK. Application of ash significantly increased leaf P concentration and AB-DTPA extractable P in soil, especially in the acidic and neutral soils. Leaf K concentrations and readily and slowly available K forms in soils were affected positively by the addition of the ash. These results demonstrate that ash from the combustion of wet olive cake can be used as a beneficial organic soil amendment.

Effect of K2O on Crystallization of Li2O-SiO2 Glass

The effect of a small amount of K2O on the crystallization behavior of the system of Li2O-SiO2 glass was investigated. Lithium disilicate (Li2O•2SiO2; L•2S) and lithium metasilicate (Li2O•SiO2; L•S) crystals precipitate simultaneously, but only L•2S crystals grow upon further heat treatment in the glass without K2O (Li glass). In the glass containing K2O (K3 glass), only L•S crystals precipitate and grow. The stable crystalline phases are L•2S and SiO2 crystals in both glasses. Phase separation was observed before crystallization; a Li2O-rich phase formed an isolated droplet phase in Li glass and the continuous phase in K3 glass. The Li+-K+ ion exchange test confirmed these structures. [SEM-EDX] analysis confirmed that K2O exists in the Li2O rich phase after phase separation in K3 glass. Thus, K3 glass separates into two phases, one of which is a continuous phase rich in Li2O and containing considerable amount of K2O. The L•S crystal precipitates and grows in this phase upon further heat treatment. Consequently, K2O suppresses the crystallization of L•2S and promotes the precipitation of L•S crystals.