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Infrared Spectra of Inorganic Compounds (3800-45 cm-1)
... The band positions of such glasses are listed in Table (7). The absorption band in (472-493)cm -1 appears in these glasses and corresponds to the absorption band at (500) cm -1 in crystalline P2O5, which is known to be at the fundamental frequency of the (PO4) 3group [24]. The absorption bands at (730-755)cm -1 (1005-1080)cm -1 and (1265-1278) cm -1 could are due to the (P-O-P) range frequency (P-O) stretching frequency and stretching vibration of the (P=O) double band. ...
... Infrared spectra were obtained on glass with CaO concentration varying from (20 to 50) mol % with negligible shifts in band positions. The FTIR spectra of the P2O5-CaO glasses, as shown in Figure (24). Table (8) shows the position bands of the glasses. ...
... It has been shown that most of the absorption bands in the glasses are the same as for crystalline P2O5. The absorption band at (460-470)cm -1, which appears in such glasses corresponding to the absorption at (500)cm -1 in crystalline P2O5, is Known to be al the fundamental frequency of the (PO4) 3group [24]. The absorption bands at (752-779)cm -1 , (1090)cm -1, and (1295-1298)cm -1 can be attributed to the (P-O-P) range frequency, (P-O) stretching frequency, and stretching vibration of the (P=O) double band. ...
... The FTIR data of both the examined dried Co-Mn-Al-K hydrotalcite-like precursors and their calcined analogs are shown in Figure 6. In the FTIR spectra of the dried samples, a band at 1355 cm −1 dominated, which is ascribed, according to literature [27], to characteristic CO3 antisymmetric stretching mode vibration. Its presence in the spectra, together with the presence of the OH stretching mode band at 3435 cm −1 (not shown) confirms the formation of hydrotalcite-like compounds during precipitation. ...
... Its presence in the spectra, together with the presence of the OH stretching mode band at 3435 cm −1 (not shown) confirms the formation of hydrotalcite-like compounds during precipitation. In all dried samples, there was also the vibration at 860 cm −1 , which corresponds, according to literature, also to the K2CO3 out-of-plane bending mode [27]. In the case of sample "1," a band at 822 cm −1 corresponded to KNO3 and/or Al(NO3)3 out-of-plane bending mode. ...
... However, it showed Figure 6. In the FTIR spectra of the dried samples, a band at 1355 cm −1 dominated, which is ascribed, according to literature [27], to characteristic CO 3 antisymmetric stretching mode vibration. Its presence in the spectra, together with the presence of the OH stretching mode band at 3435 cm −1 (not shown) confirms the formation of hydrotalcite-like compounds during precipitation. ...
Direct decomposition of nitric oxide (NO) proceeds over Co-Mn-Al mixed oxides promoted by potassium. In this study, answers to the following questions have been searched: Do the properties of the K-promoted Co-Mn-Al catalysts prepared by different methods differ from each other? The K-precipitated Co-Mn-Al oxide catalysts were prepared by the precipitation of metal nitrates with a solution of K 2 CO 3 /KOH, followed by the washing of the precipitate to different degrees of residual K amounts, and by cthe alcination of the precursors at 500 • C. The properties of the prepared catalysts were compared with those of the best catalyst prepared by the K-impregnation of a wet cake of Co-Mn-Al oxide precursors. The solids were characterized by chemical analysis, DTG, XRD, N 2 physisorption, FTIR, temperature programmed reduction (H 2-TPR), temperature programmed CO 2 desorption (CO 2-TPD), X-ray photoelectron spectrometry (XPS), and the species-resolved thermal alkali desorption method (SR-TAD). The washing of the K-precipitated cake resulted in decreasing the K amount in the solid, which affected the basicity, reducibility, and non-linearly catalytic activity in NO decomposition. The highest activity was found at ca 8 wt.% of K, while that of the best K-impregnated wet cake catalyst was at about 2 wt.% of K. The optimization of the cake washing conditions led to a higher catalytic activity.
... Concretely, the Pmcn (JCPDS PFD 84-1778) or the Pnma (JCPDS PFD 74- 1491) types were observed when LiOH or NaOH were used, respectively. The infrared results correspond well with the XRD analysis, as seen in Fig. 2. In all spectra, the peaks observed in the range of 700-600 cm -1 and 1300-950 cm -1 are characteristic for the ν 1 , ν 3 and ν 4 vibrations of the SrSO 4 sulphate ion [9][10][11]. In the first step (reaction (1)), similar to the XRD results (Fig. 1agroup) peak in the region of 1550-1350 cm -1 [12]. ...
... The distortion of this group may occur due to the (i) presence of structural water in hydrated or hydroxylated-hydrate form [13], (ii) metal itself, which is present in the structure or is used as additive during the synthesis [14], and (iii) due to the distorted crystal structure [15]. As can be seen, the observed bands attributed to the carbonate ion in SrCO 3 [10, 11,[16][17][18] in the range of 1440- 1580 cm -1 were single or split depending on whether NaOH or LiOH was used as an additive. Interestingly, it seems that the alkaline metal has an influence on the structure of SrCO 3 with respect to the type of the space group setting (Pnma or Pmcn) and, consequently, on the type of the main CO 3 2-band in the infrared spectra. ...
Natural celestine (SrSO4) has been succesfully transformed into strontianite (SrCO3) via fast one-step mechanochemical carbonation utilizing gaseous CO2. The process was realized in the environment enriched with LiOH or NaOH additives. The mixtures were milled in a high-energy planetary ball mill for 40 min. The phases formed during the milling were characterized by different characterization techniques, such as X-ray diffraction (XRD) and infrared spectroscopy (FT-IR). The presence or absence of carbon or sulphur in the products was confirmed by a CHNS analysis.
... It is also difficult to judge which carboxyl group ionizes when considering the angles of the two carboxyl groups: ∠C2-C1-O1, 115.13(13) • , ∠ C2-C1-O2, 119.07 (14) • , ∠C7-C8-O3, 118.65(13) • , and ∠C7-C8-O4, 120.11 (13) • . The corresponding angles in KHPhth [4] are: 122.6(2) • , 113.21(17) • , 117.46(16) • , and 117.98(19) • , where the almost equivalent C-C-O angles indicate the ionization of the C8 carboxyl group. ...
... The disappearance of the vibration at 1605 cm −1 of the benzene ring framework and the C-H out-of-plane bending vibration at 850 -650 cm −1 indicate that the benzene ring breaks the C-H vibration. However, the vibrations at 1451, 880 and 700 cm −1 of the solid residue prove the existence of K 2 CO 3 [13]. Furthermore, there still exist the asymmetric and symmetric vibrations of RCO 2 K at 1635 and 1383 cm −1 , respectively. ...
Single crystals of potassium hydrogenphthalate monohydrate, KHPhth(H2O), were grown from aqueous solution using a slow cooling method and the structure was determined by X-ray diffraction analysis. The crystals belong to the monoclinic space group P2(1)/c. Its unit cell parameters are as follows: a = 1.1235(1), b = 0.6689(1), c = 1.1998(2) nm, beta = 98.85degrees, V = 0.8909(1) nm(3), D-c = 1.657 g/cm(3), Z = 4, F(000) = 456. The thermal decomposition of the complex was studied using differential scanning calorimetry (DSC), thermogravimetry-derivative thermogravimetry (TGGTG) and FT-IR techniques. With a linear heat rate, the diagrams show three endothermic processes. RCOOK and K2CO3 are produced at 330 and 467degreesC, respectively, according to FT-IR analysis.
... The increasing Li concentration in the catalysts (0.9 and 1.3 wt.%) was reflected by the disappearance of the characteristic Anderson salt bands and the appearance of new broad bands at 840 cm −1 (attributed to lithium molybdate formation) and a not very strong band at 511 cm −1 . It is evident that the original Anderson salt was broken during the preparation of catalyst and new compounds [49]. Bielanski et al. [50] reported on the basis of their FTIR measurements that no Lewis-acid sites are present in the ammonium salts of Keggin type heteropolyacid H 3 P 12 MoO 40 , even after processing at 400 °C. ...
Recently, simultaneous hydrotreatment of various petroleum fractions and plant feedstocks has been in demand. NiMo catalysts can be active in these processes. Therefore, supported NiMo oxide catalysts were prepared by impregnating an alumina support with Anderson’s molybdenum salt (ammonium salt of nickel heteropolymolybdate (NH4)4NiMo6O24H6) and lithium carbonate. The prepared catalysts were tested in hydrodesulfurization (HDS) of thiophene and parallel HDS/HDO (hydrodeoxygenation) of 1-benzothiophene and octanoic acid. Experimental data showed a positive effect of lithium on the parallel HDS/HDO reactions and a negative effect on the HDS of thiophene. A significant effect of lithium on the acidity and reducibility of the NiMo/Al2O3 catalyst as well as the contribution of an Anderson-type heteropolycompound was demonstrated.
Graphical Abstract
... The band at 1634 cm −1 and broad absorption band at 2800-3600 cm −1 , with a maximum at 3424 cm −1 , can be attributed to the OH stretching vibrations of H2O present in the samples [35]. The absorption band at 1643 cm −1 probably corresponds to physically adsorbed water molecules [36][37][38]. Vibration at 1360 cm −1 likely belongs to the rest of the nitrates remaining in the catalysts from the initial components that were precipitated or added to the catalysts by impregnation, which were either not thoroughly washed after precipitation or not fully decomposed during calcination at 500 °C. Similarly, vibrations at 1400 and 1532 cm −1 correspond to CO3 vibrations of the initial sodium carbonate, as it seems that they are connected to each other. ...
Co-Mn-Al mixed oxides promoted by potassium are known as active catalysts for the direct decomposition of nitric oxide (NO). In this study, the answer to the following question has been considered: does the presence of cerium in K-promoted Co-Mn-Al catalysts substantially affect the physical-chemical properties, activity, and stability in direct NO decomposition? The Co-Mn-Al, Co-Mn-Al-Ce, and Co-Mn-Al-Ce-K mixed oxide catalysts were prepared by the precipitation of corresponding metal nitrates with a solution of Na2CO3/NaOH, followed by the washing of the precipitate and calcination. Two other catalysts were prepared by impregnation of the Ce-containing catalysts with Co and Co+K nitrates. After calcination, the solids were characterized by chemical analysis, XRD, N2 physisorption, FTIR, temperature-programmed reduction, CO2 and O2 desorption (H2-TPR, CO2-TPD, O2-TPD), and X-ray photoelectron spectrometry (XPS). Cerium and especially potassium occurring in the catalysts affected the basicity, reducibility, and surface concentration of active components. Adding cerium itself did not contribute to the increase in catalytic activity, whereas the addition of cerium and potassium did. Catalytic activity in direct NO decomposition depended on combinations of both reducibility and the amount of stronger basic sites determined in the catalysts. Therefore, the increase in cobalt concentration itself in the Co-Mn-Al mixed oxide catalyst does not determine the achievement of high catalytic activity in direct NO decomposition.
... Esto va acompañado con un ligero incremento en la intensidad de la banda a 3650 cm -1 . Esta banda está ubicada en el intervalo de frecuencias de las vibraciones de los grupos OH -, localizada en el rango de 3650-3700 cm -1 (Nyquist 1973, Rodríguez-Iznaga y col., 2002 lo que ha sido asociado al incremento de iones OHen la zeolita. ...
Revista Latinoamericana el Ambiente y las Ciencias 6(11): 56-69 2015 56 1 Mordenita natural en el tratamiento de disoluciones alcalinas con cromo hexavalente Natural mordenite in the treatment of alkaline solutions with hexavalent chromium. RESUMEN. En el presente trabajo se estudia la capacidad que posee la zeolita natural del yacimiento Palmarito de Cauto (ZN), Cuba, como un material para el tratamiento de disoluciones alcalinas que contienen especies de cromo hexavalente con diferentes pH y concentraciones de este elemento. Los resultados mostraron que ZN posee la capacidad potencial para neutralizar el pH de las disoluciones alcalinas y remover por adsorción las especies de cromo hexavalente presentes en estas. El marcado efecto neutralizante, manifestado para un amplio intervalo de pH fue asociado a la acción combinada de varios factores tales como la presencia de fases no zeolíticas con acción neutralizante, protones de grupos OH superficiales de la mordenita, adsorción de aniones OH-sobre una doble capa eléctrica y reacción puzolánica. Los estudios por espectroscopia infrarroja no mostraron cambios significativos en la estructura del material, mostrando que la mordenita natural de Palmarito de Cauto tiene gran estabilidad en disoluciones alcalinas. Los resultados son importantes porque sugieren que la zeolita natural del yacimiento Palmarito de Cauto puede ser de interés para el tratamiento de licores básicas residuales industriales que contienen especies de Cr(VI).
... Measured band positions (wavenumbers, cm −1 ) are listed in Tables 5 and 6. The collected patterns are almost identical to those already presented in several previous papers for β-tricalcium phosphate, see for example [39]. Interpretation of the vibrational spectra of β-Ca 3 (PO 4 ) 2 in terms of site-symmetry and factor group analysis have been published by [40,41]. ...
Rare earth elements - doped β-tricalcium phosphates Ca9 RE(PO4)7 (RE = La, Pr, Nd, Eu, Gd, Dy, Tm, Yb) were synthesized by solid-state reaction at T = 1200°C. The obtained RE-doped β-TCP phases were studied by a combination of Scanning Electron Microscopy (SEM) equipped with energy dispersive X-Ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR) and Raman spectroscopies. SEM morphological analyses revealed the presence of sub spherical micro crystalline aggregates, while EDS semi-quantitative analyses confirmed the nominal RE/Ca composition for all the phases. The unit cell and the space group were determined by X-ray powder diffraction data showing that all phases in the series crystallize in the rhombohedral R3c whitlockite-type structure; the unit cell constants are a linear function of the dimension of the substituting rare-earth element, and range from a = b = 10.4695(3)Å, c = 37.500(3)Å and V = 3559.7(2)ų (La) up to a = b = 10.4073(2)Å, c = 37.2725(2)Å, V = 3496.2(2)ų (Yb). The analysis of each compound was completed with the structure model refinement by the Rietveld method and the distribution of RE within the available structural sites is discussed according to the results of the Rietveld refinement. The FTIR and Raman spectra show slight band shifts of the phosphate modes correlated to the evolving size of the RE element.
... A C C E P T E D M A N U S C R I P T assigned to the metal-oxygen bond[29][30][31][32][33][34][35][36]. The first line corresponds to intrinsic stretching vibrations of the metal at the tetrahedral site (Fe tetra-O), whereas the second one is dueThe first peak indicates a loss of water content in the polymer. ...
In this work, we present the spectral investigation of the interactions between the coverage with alginic acid (AA) and nanoparticles for three different composites containing 74, 80, and 88 wt% of magnetite. These results show that the Fe3O4 nanoparticles are coated with the AA and indicate that there is an interaction between them. Moreover, we have investigated the thermal and magnetic properties of all investigated compounds. We show that bonding of alginic acid to the surface of magnetite results in better thermal stability of the polymer and in higher temperature of AA chains degradation. We find that for dense assembly of magnetite nanoparticles, at low temperatures, the intergranular coupling becomes much stronger than between nanoparticles dispersed in composites.
... [24][26]. Sendo assim, todos os picos de vibração analisados no espectro do SnO 2 obtido estão de acordo com os valores reportados, Fig. 3.A Fig. 4) em 659 cm -1 [27, 28]. Após a caracterização do pó, realizou-se o teste catalítico, no qual obteve-se um rendimento mássico de ~ 90% para o processo reacional de transesterificação do óleo. ...
As propriedades físicas e químicas de materiais em escala nanométrica são de imenso interesse e sua importância tem crescido em diversas aplicações tecnológicas. Este trabalho abordou o estudo da influência do método hidrotermal assistido por micro-ondas para obtenção de nanopartículas à base de SnO2, com intuito de utilização como catalisadores. O tratamento térmico em elevadas temperaturas produziu materiais com propriedades catalíticas. O pó obtido foi caracterizado por meio da difração de raios X, espectroscopia Raman e microscopia eletrônica de varredura, a fim de verificar a morfologia, que evidencia a formação de SnO2. Além disso, o pó foi testado na conversão catalítica de óleo vegetal em biodiesel obtendo rendimento de 90%.
... Most oxides examined till date are chemically stable but own low energetic positions of conduction bands and would thus require external assistance for water photo-reduction [7]. In addition, most of these oxides acquire high band gap energies (E g ) and thus prohibiting the energy conversion efficiency [8] . To alleviate such problems, scientists used nanoscale α- Fe 2 O 3 that exhibited high electrons/holes recombination [9]. ...
Graphene oxide (GO):MnFe2O4 (Mn) hybrids synthesized by sol-gel hydrothermal (453 K, 48 h); and annealed at 373 K, were thoroughly characterized using XRD, TEM-SAED, N2 adsorption, XPS, UV–vis diffuse reflectance, and photoluminescence spectroscopy. These hybrids were applied as photoelectrochemical (PEC) materials for water splitting and as photocatalysts for methylene blue (MB) degradation under visible light irradiation. GO1:Mn1 has indicated higher PEC activity towards water splitting with supreme photocurrent density (0.875 mA cm−2) doubling that of GO5:Mn1 (0.350 mA cm−2). High optical absorption and charge transfer rate played key roles in enhancing the PEC activity of the former comparatively; as recorded via chronoamperometric curves. Concurrently, the incident photon to current efficiency (IPCE) of GO1:Mn1 has exceeded the rest of hybrids in the wavelength range of 500–850 nm. Increasing the dispersion of MnFe2O4 between G/GO sheets in GO1:Mn1, lowering the Eg (0.55 eV) value, increasing reduced graphene ratio over oxidized ones as well as increasing the pore radius (76.5 Å) value have all shared in increasing the photocurrent density. More specifically, the residual oxides depicted in GO1:Mn1 (9%); as calculated via XPS, were important in evoking the reactive intermediates OH and O2−; those were responsible for the MB degradation. Increasing the ratio of the reduced graphene (91%) in this particular sample (GO1:Mn1) was chiefly important for lowering the energy gap (Eg) value. In agreement, impedance spectroscopy of the GO1:Mn1 sample has substantiated the charger transfer process; depicted from optical results, via exhibiting the lowest resistance between all the nanohybirds. This latter hybrid of nano-spindle shape and monomodal mesopore type of pores (140 Å) has presented high photocatalytic degradation for MB (10 ppm, 1 g/L, 30 min) with rate constant 0.037 min−1 surpassing the rest of samples.
... Spectra consisted of several overlapping strong absorption bands in the range of 500-1000 cm −1 . These bands can be attributed to the characteristic vibrations of [MoO 4 ] 2− and [Mo 2 O 7 ] 2− groups [22][23][24] . ...
A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu3+ doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu3+ phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour.
... Various methods have been developed to make the supercapacitor. The examples are double-layer thin filmmethod [5,6] and the doctor blademethod [7], the method of double-layer thin film which produces the electrode is too thick, the microstructure is not homogeneous, so that the capacitance is still low and doctor blade methods which fragile and easilybroke [8]. Thosevarious methods are not able to make a lightweight, tightly bound to the substrateelectrode, and the method is complicated / difficult to implement. ...
Energy crisis that occured in Indonesia suggests that energy supply could not offset the high rate request and needs an electric energy saving device which can save high voltage, safety, and unlimited lifetime. The weakness of batteries is durable but has a low power density while the capacitor has a high power density but it doesn’t durable. The renewal of this study is CNT-MnO2 thin film fabrication method using electrophoretic
deposition.
Electrophoretic
deposition is a newest method to deposited CNT using power supply with cheap, and make a good result. The result of FTIR analysis showed that the best CNT-MnO2 composition is 75:25 and C-C bond is detected in fingerprint area. The result is electrode thin film homogen and characterized by X-ray diffraction
(XRD) peaks 2θ=26,63° is characterization of graphite, and 2θ=43,97° is characterization of diamond Carbon type and measured by Scherrer formula results 52,3 nm material average size .EIS test results its capacitance about 7,86 F. from the data it can be concluded that CNT-MnO2 potential electrode very promising for further study and has a potential to be a high capacitance, and fast charge supercapacitor which can be applied for electronic devices, energy converter, even electric car.
... The Raman bands for rutile are quite similar to that of reported ones in the literature [26] and the Raman features of the rutile phase are far less characterized, a red shift is attributed to the nonstoichiometric effects for the E g rutile type mode. FTIR spectra of nano TiO 2 show peaks corresponding to the fundamental as overtones stretching vibrations of OeH and bending vibrations of adsorbed water molecules around 3350e3450 cm À1 and 1620e1635 cm À1 , respectively [27]. The low intensity of these peaks with increase in the calcinations temperature is indicates the removal of large portion of adsorbed water from TiO 2 .Fig. 3 shows a broad intense band below 1200 cm À1 that may be is due to TieOeTi vibration [28]. ...
Catalytic systems by which nitrogen oxides (NOx) in automotive emissions may be reduced to nitrogen are highly efficient when used with rich-burn engines, but are far less effective when excess oxygen is present in the exhaust gases produced, for example, by energy-efficient lean-burn engines. Herein, we describe the synthesis of Sr1-xNixSnO3 (x = 0 to 0.2) perovskite-type by a modified Pechini method and their capacities to catalyze the reduction of nitric oxide (NO) with carbon monoxide (CO) in the presence carbon dioxide, water vapor and excess oxygen. The materials showed a selectivity of NO reduction rather CO. The highest conversions of NO into nitrogen were observed at temperatures within the range 450–500 °C, with a maximum conversion of 40% attained for the 10% of nickel containing sample. Spectroscopic analyses of the perovskites prior to and following the reduction process revealed changes in the local SnO6 symmetry of the structure followed the formation of strontium carbonate during catalysis. The results also indicate that AO12 and SnO6 sites are both active in the catalytic process, besides being favored by the presence of oxygen vacancies, which adsorbs and activates NO molecules and increase the mobility of lattice oxygen.
Nonlinear optical (NLO) materials have been applied in many high technology fields. In this work, the first principles high-throughput screening pipeline (FHSP) has been used for searching NLO materials from...
The center-radial channels throughout dendritic mesoporous silica nanospheres (DMSNs) give rise to easily approachable internal spaces, high specific surface area, large pore volumes, etc. Some other substances with matchable sizes could be decorated into DMSNs’ channels. As a result, DMSNs are very fascinating platforms for catalysis, tumor therapy, drug delivery, and so on. In this study, we demonstrate a facile approach of introducing black TiO2-x nanoparticles into DMSNs’ center-radial channels. Dendritic mesoporous silica&titania nanospheres (DMSTNs) were initially manufactured by coating DMSNs with tetrabutyl orthotitanate precursor and calcination in air. Black dendritic mesoporous silica&titania nanospheres (b-DMSTNs) with TiO2-x particles dispersed in DMSTNs channels were then developed by reducing DMSTNs with NaBH4 under Ar atmosphere. There exist abundant Ti³⁺ and oxygen vacancies in TiO2-x bulks. Even though the as-prepared structured material cannot work as cathode materials for lithium-ion battery, they can satisfactorily serve as photocatalysts for H2 production and CO2 reduction under simulated sunlight. The b-DMSTNs can yield ca. (i) 11,939 μmol·g⁻¹ H2 with a 2387 μmol·g⁻¹·h⁻¹ rate in 5 h with the assistance of chloroplatinic acid, greater than that of white DMSTNs which produce about 9578 μmol·g⁻¹ H2 with a 1915 μmol·g⁻¹·h⁻¹ rate; (ii) 14.78 μmol·g⁻¹ CO (74.43%) and 5.07 μmol·g⁻¹ CH4 (25.57%) with its specific selectivity.
Graphical Abstract
Rice industrialization worldwide generates significant amounts of rice husk as a by-product. When rice husk is burned to obtain energy, a relatively common practice, a substantial portion of the husk turns into ash, and both constitute environmental liabilities. Using rice husk and ash as starting materials to produce high-value products could help in mitigating the environmental impact while providing economic revenue. Rice husk and rice husk ash as produced in a local cogeneration plant without any pretreatments were evaluated as feasible sources for silicon nitride (Si 3 N 4 ) and silicon oxynitride (Si 2 N 2 O) whiskers by carbothermal reduction and nitridation. Rice husk and the ash were held at temperatures between 1200 and 1400 °C for 3 h under flowing nitrogen. Increasing soaking temperature values led to higher whisker development for both starting materials, with the best results observed at 1400 °C. Whereas α-silicon nitride whiskers were obtained when rice husk was employed, the graphite surface-to-ash ratio dictated whisker composition for the ash. Treatment of the ash at the soaking temperature value of 1400 °C led to silicon oxynitride for lower graphite surface-to-ash ratios, but when this ratio was increased, α-silicon nitride predominated. α-silicon nitride whiskers had cross sections ranging from about 100 nm to 1 µm in width, whereas the silicon oxynitride whiskers had cross sections ranging from approx. 100 to 500 nm in diameter. Both types of whiskers were observed to be in the millimeter length range.
Terahertz imaging has been applied as a new nondestructive observation method in the heritage science research field. In particular, the preparation layer that is important for conservation, has not been observed nondestructively with other measures using electromagnetic waves. In this paper, the advantage of terahertz waves and examples of terahertz imaging of wall paintings and Japanese panel screens are introduced.
Two types of titania-containing dendritic mesoporous silica nanospheres (DMSNs) have been successfully fabricated for organic dyes removal, water splitting, and carbon dioxide reduction by their adsorptive or photocatalytic performances. Hybrid dendritic mesoporous silica&titania nanospheres (DMSTNs) were initially prepared by grafting tetrabutyl orthotitanate (TBOT) onto DMSNs. Then, hollow dendritic mesoporous silica&titania nanospheres (HDMSTNs) were realized merely by etching the solid DMSTNs with alkaline solution. The surprising structural evolution from the solid state to the hollow was thoroughly revealed by scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM) for the first time. DMSTNs maintain the dendritic morphology with spherical TiO2 nanoparticles uniformly dispersed. HDMSTNs not only keep the dendritic topology, but also possess the hollow texture with TiO2 nanoparticles unevenly dispersed and aggregated. DMSTNs and HDMSTNs exhibit excellent adsorption capacities for methylene blue, while the latter shows improved adsorption capacity. DMSTNs and HDMSTNs can hardly adsorb methyl orange (MO), nevertheless, the two materials can photodegrade MO with outstanding abilities. Amazingly, the latter exhibits decreased degradation capacity despite of its hollow architecture and higher content of titanium oxide. Furthermore, DMSTNs and HDMSTNs display higher photocatalytic activities over hydrogen generation than that of carbon dioxide reduction under visible light. However, DMSTNs and HDMSTNs show various photocatalytic selectivities and activities for the production of carbon monoxide (CO) and methane (CH4). In short, DMSTNs and HDMSTNs have distinct structural superiorities as adsorbents or photocatalysts for different photocatalytic reactions, respectively.
By the combination of the isolated P2O7 dimers and MgO4 tetrahedra, α- and β-Rb2Mg3(P2O7)2 polymorphs were synthesized by a high-temperature solution method. α-Rb2Mg3(P2O7)2 crystallizes in non-centrosymmetric space group P212121, while β-Rb2Mg3(P2O7)2 crystallizes in centrosymmetric P21/c. Both structures contain a three dimensional [Mg3P4O14]²⁻ anionic framework, while Rb⁺ cations are in the space. Structure analyses show that the isolated P2O7 dimers can easily adjust their variable configurations and orientations to fit the different coordination environments of the cations, which is conducive to the formation of polymorphs. The phase transformation process from α- to β-Rb2Mg3(P2O7)2 was further investigated by powder X-ray diffraction and thermal gravimetric/differential scanning calorimetry measurements. In addition, UV-vis-NIR diffusion spectra indicate both materials have deep-ultraviolet cut-off edges (below 190 nm). α-Rb2Mg3(P2O7)2 is second-harmonic generation (SHG)-active and the origin of SHG response was investigated by the SHG density calculations. The first-principle calculations were also carried out to illuminate their structure-property relationships.
Selective and controllable cataluminescence (CTL) sensors for volatile organic compounds (VOCs) are significant for chemical safety, environmental monitoring, health effects on human beings, and so forth. Most of the exploited CTL-based sensors suffer relatively low response and poor selectivity because of their high sensitivities to interferential substances. In this investigation, dendritic fibrous nano-silica & titania (DFNST) spheres have been synthesized as novel sensing materials and the corresponding DFNST-based CTL sensor has been fabricated to detect diethyl ether with high selectivity via a method of utilizing one 440 nm bandpass filter. The as-prepared DFNST hybrids not only keep the excellent dendritic fibrous morphology but also bear ca. 21 wt% catalytic titanium oxide of anatase crystalline structure. The DFNST-based sensor exhibits extremely strong CTL emission at 440 nm toward diethyl ether against other VOCs like acetone, ethyl acetate, butanol, and so forth. The high response can be attributed to the unique architectural texture of DFNST. Under the optimum parameters, ether could be easily detected in a wide range from 2.0 to 40.0 mM with a fine detection limit of 1.55 mM (S/N = 3). Furthermore, the working life of this CTL sensor is satisfactory with outstanding stability and durability, far from damaging the morphology and activity of the DFNST sensing material. In conclusion, it is expected that this novel sensing material, the relevant CTL sensor, and the approach of employing the bandpass filter will be significant for the detection of diethyl ether in actual applications.
Dies ist ein Kapitel der 12. Auflage des VDI-Wärmeatlas.
In this study, the kinetics of the photodegradation of tartrazine (TA) and sunset yellow (SY) was systematically evaluated at different pH values in the presence of α-Fe2O3 nanostructures as a cost-effective and efficient photocatalyst. For each dye, time-spectral data was recorded in the pH range 8–12, then the whole data was resolved by hard soft-modelling parallel factor analysis to obtain the kinetic profiles of the components existing during simultaneous kinetic and equilibria processes. Then, the rate constants of degradation processes together with their uncertainties were computed. The results revealed that pH strongly affects the mechanism and the rate constants of the dyes photoreactivity due to changing the structure of the analytes. In fact, those protonated/deprotonated structures with resonance forms were less degradable because of their stability and then showed lower rate constant(s).
In the present study, ZnO/ZnS composite powders were synthesized by one-step solution combustion method. Thiourea was used both as the combustion fuel and sulphur source. Oxidizer-to-fuel (O:F) ratios between 0.5 and 1 were chosen as the main synthesis parameter. Structure, microstructure, chemical composition, and photoluminescence properties of the powders were also investigated. X-ray diffraction patterns showed simultaneous functions of thiourea as combustion fuel and sulphur source. The relative concentration of ZnS to ZnO increased by O:F ratio. Fourier-transform infra-red spectroscopy spectra demonstrated some bands associated with the unwanted organic compounds in the final product in addition to Zn–O and Zn–S bonds. Furthermore, scanning electron microscope micrographs showed the presence of some gel-like regions located around highly agglomerated particles. Photoluminescence spectra also indicated strong emission peaks for O:F ratio of 0.5 due to significant crystal defects and lower crystallinity.
La dégradation thermique en milieu aqueux d'une résine échangeuse d'ions cationique forte (l'ARC 9351) a été étudiée. La résine est un copolymère sulfone du polystytène réticule avec du divinylbenzène. Cette résine, après avoir été caractérisée notamment par spectrométrie de masse à impact laser et par analyse thermique par calorimétrie à balayage différentielle (DSC), est dégradée selon deux méthodes de pyrolyse. La première consiste en une hydropyrolyse en autoclave à 300°C pendant 24 heures, et l'autre a été conduite en ampoule scellée sous pression réduite de 200°C à 400°C pendant des temps variables. Dans chaque cas, les produits de dégradation, qu'ils soient organiques ou minéraux ont été analysés par un ensemble des techniques spectroscopiques et chromatographiques complémentaires entre elles. Certaines nous ont permis de suivre les processus de dégradation. Dans ce contexte, l'analyse directe des résines dégradés ou non, par microsonde a impact laser s'est avérée être une technique particulièrement efficace et rapide pour évaluer le degré de dégradation thermique de la résine. Cette nouvelle approche expérimentale a pu être étendue aux autres résines échangeuses d'ions ou à d'autres polymères fonctionnalisés. Ce travail propose également un mécanisme plus complet de la dégradation des résines cationiques fortes sulfonées, qui explique la formation de certains composes de dégradation, notamment soufres, lesquels n'avaient pas été jusqu'à présent mis en évidence
The temperature dependences of the electrical conductivity of nanocomposites based on low-density polyethylene (LDPE) and Cu2S nanoparticles are studied. It is shown that, starting from a certain temperature, the temperature dependence of the electrical conductivity is described by the following Arrhenius equation: σ = σ0exp(–E/kT); the logσ = f(10³/T) dependence has several linear portions with different activation energy values. The observed behavior of the logρ = f(1/T) dependence of the LDPE/Cu2S nanocomposites suggests that an increase in temperature is accompanied by an increase in the mobility of the structural units of the polymer matrix in the bulk and on the surface of the sample. The polymer–filler interfacial interactions decrease the electrical resistance of the boundary layer and thereby lead to a decrease in the activation energy of the charge carriers and an increase in the electrical conductivity of the nanocomposite.
Technological approaches have been developed to the preparation of single-phase lithium niobate batches doped with magnesium, zinc, iron, and rarer-earth elements (TR = La, Pr, Nd, Sm, Gd, Dy, or Er) from high-purity niobium-containing solutions to avoid niobium pentoxide separation, its mixing with lithium carbonate, and LiNbO3 preparation from this mixture by a solid-phase reaction. Two process flowsheets have been proposed, being applicable over the entire ranges of the studied dopant concentrations. Optimal parameters for preparing single-phase LiNbO3 batches of tailored compositions have been determined. The batches prepared by the developed technology are intended for growing doped optical-quality lithium niobate single crystals.
A mesoporous nanoplate network of two-dimensional (2D) layered nickel hydroxide Ni(OH)2 intercalated with polyoxovanadate anions (Ni(OH)2−POV) was built using a chemical solution deposition method. This approach will provide high flexibility in controlling the chemical composition and the pore structure of the resulting Ni(OH)2−POV nanohybrids. The layer-by-layer ordered growth of the Ni(OH)2−POV is demonstrated by powder X-ray diffraction and cross-sectional high-resolution transmission electron microscopy. The random growth of the intercalated Ni(OH)2−POV nanohybrids leads to the formation of an interconnected network morphology with a highly porous stacking structure whose porosity is controlled by changing the ratio of Ni(OH)2 and POV. The lateral size and thickness of the Ni(OH)2−POV nanoplates are ~ 400 nm and from ~ 5 nm to 7 nm, respectively. The obtained thin films are highly active electrochemical capacitor electrodes with a maximum specific capacity of 1440 Fg─1 at a current density of 1 Ag─1, and they withstand up to 2000 cycles with a capacity retention of 85%. The superior electrochemical performance of the Ni(OH)2−POV nanohybrids is attributed to the expanded mesoporous surface area and the intercalation of the POV anions. The experimental findings highlight the outstanding electrochemical functionality of the 2D Ni(OH)2−POV nanoplate network that will provide a facile route for the synthesis of low-dimensional hybrid nanomaterials for highly-active supercapacitor electrode.
Polymeric carbon nitride quantum dots (CNQDs) with an average size of approximately 2.5 nm were prepared directly from melamine via a one-step molten salt method. The formation mechanism and photoluminescence (PL) properties of resulting CNQDs were investigated by means of TEM, XRD and PL spectroscopy. The CNQDs can be dispersed in water to form transparent colloidal solution and emit blue PL with excellent photostability. Interestingly, upon addition of CuCl2 and NaHCO3 in turn, the PL of CNQDs can be turned off and on accordingly. Taking advantage of on-off-on PL response, the CNQDs can be used as fluorescent security ink for information coding, encryption and decryption, indicating their promising application in data security and high-level anti-counterfeiting field.
Generally, sulfur is inclined to combine with oxygen to form sulfate ions in the solid-state reaction. Interestingly, an extraordinary sulfide silicate, Na6Si3S8O, was successfully obtained in vacuum-sealed silica tube for the first time. Its crystal structure features novel 1D straight chains composed by the interconnection of tri-polymerized [Si3S8O]6– and [Na4S5O]11– units, demonstrating the first sulfide silicate exhibiting S–Na–O and S–Si–O connections without the S−O bonds. Moreover, Na6Si3S8O is also verified as a promising birefringent material owing to its large birefringence (Δn = 0.215−0.094 from 0.3 to 4.0 μm).
For the purpose of clarifying the water quality effect on the corrosion of galvanized piping used in fresh waters, the chemical identification of zinc corrosion products and corrosion test of galvanized steel pipes were carried out. Analyses of zinc corrosion products were made on pipes which had been in actual service as a water pipe at several cities in Japan, using chemical methods, X-ray diffraction, and infrared spectroscopy. In low alkalinity (<50mg/l as CaCO3) and relatively high silica (>10mg/l) waters, the main constituent of zinc products was amorphous zinc silicate, while in less frequent cases, hemimorphite, Zn4(OH)2Si2O7·H2O, was identified. In high alkalinity (148mg/l as CaCO3) water, which is less common in Japan, basic zinc carbonate was observed. The corrosion rate of galvanized pipes was measured in flowing Tokyo municipal water in a once-through test assembly, in which several chemicals at different levels were added to the water. The most influential factor to the zinc corrosion was pH; the decrease of pH value markedly increased the corrosion rate. The addition of chloride or sulfate did not affect the corrosion rate of galvanized steel pipes. The results were interpreted on the basis of the solubility of zinc silicate or carbonate scales which showed minimum solubility at pH 8 to 10.
Spektrensammlungen Rechnerunterstützte Recherchen Interpretative Systeme Qualitative Gemischanalyse Literatur
Germanophosphates, in comparison with other metal phosphates, are less studied but potentially exhibit more diverse structural chemistry with wide applications. Herein we applied a hydro-/solvo-fluorothermal route to make use of both the “tailor effect” of fluoride for the formation of low dimensional anionic clusters and the presence of alkali cations of different sizes to align the anionic clusters to control the overall crystal symmetries of germanophosphates. The synergetic effects of fluoride and alkali cations led to structural changes from chain-like structures to layered structures in a series of five novel fluorogermanophosphates: A2[GeF2(HPO4)2] (A = Na, K, Rb, NH4, and Cs, denoted as Na, K, Rb, NH4, and Cs). Although these fluorogermanophosphates have stoichiometrically equivalent formulas, they feature different anionic clusters, diverse structural dimensionalities, and contrasting crystal symmetries. Chain-like structures were observed for the compounds with the smaller sized alkali ions (Na+, K+, and Rb+), whereas layered structures were found for those containing the larger sized cations ((NH4)+ and Cs+). Specifically, monoclinic space groups were observed for the Na, K, Rb, and NH4 compounds, whereas a tetragonal space group P4/mbm was found for the Cs compound. These compounds provide new insights into the effects of cation sizes on the anionic clusters built from GeO4F2 octahedra and HPO4 tetrahedra as well as their influences on the overall structural symmetries in germanophosphates. Further characterizations including IR spectroscopy and thermal analyses for all five compounds are also presented.
Zinc deficiency and excess can result in adverse health outcomes. There is conflicting evidence regarding whether excess or deficient zinc in the diet can contribute to carcinogenicity. The objective of this study was to characterize zinc carbonate basic for use as a source of dietary zinc in a rodent toxicity and carcinogenicity study investigating the effects of zinc deficiency and excess. Because of the complex chemistries of zinc carbonate basic compounds, inconsistent nomenclature, and literature and reference spectra gaps, it was necessary to employ multiple analytical techniques, including Karl Fischer titration, combustion analysis, inductively coupled plasma–optical emission spectrometry, X-ray diffraction, infrared spectroscopy, X-ray fluorescence spectrometry, and thermogravimetric analysis to characterize the test article. Based on the collective evidence and through the process of elimination, the test article was found to be composed mainly of zinc carbonate basic with zinc oxide as a minor component. The zinc content was determined to be 56.6% (w/w) with heavy metals such as arsenic, cadmium, mercury and lead below the limit of quantitation of less than or equal to 0.01%. The test material was stable at ambient temperature. Based on the work described in this manuscript, the test article was suitable for use as a source of zinc in studies of deficiency and excess in the diet.
The synthesis of transition metal (Me = Ni and Zn) containing SAPO-34 nanoparticles was conducted by applying insonation as the precrystallization treatment. The effects of synthesis parameters on the properties of SAPO-34 products and their derivatives in terms of the crystallinity, size and morphology of particles, structure and hydroxyl functional groups, and stereochemistry of metal ions were investigated to elucidate how the isomorphous substitution or the mere presence of transition metal ions was influenced by the crystallization treatment, mixing method, or the amount and type of metal species. The physicochemical properties of the prepared samples were characterized by various techniques including XRD, SEM, TEM, EDX, UV-Vis DRS, FTIR, and TGA. The results indicated that sonochemically prepared SAPO-34 samples possessed higher crystallinity and uniform crystals with narrow particle size distribution. The nature of the metal species could affect the physicochemical properties of the synthesized samples and Zn-doped SAPO-34 samples showed a lower crystallinity, larger unit cell parameters, and more uniform crystals. Also, it was found that the significant variations in the morphology, size, and uniformity of the metal-doped SAPO-34 crystals were acquired based on the different mixing methods. Meanwhile, the mixing methods played a key role in the incorporation of metal ions into the SAPO-34 framework, and mixing method (II), in which the metal sources were added to the precursor gel prior to the addition of the phosphoric acid, had prominent capability to locate the metal ions, in particular nickel ions, in the SAPO-34 skeleton.
An amorphous graphene-like CuB23 alloy with a sheet height of 1.033 nm and a high specific surface area of 674.88 m² g⁻¹ was prepared via a solution plasma technique with the assistance of polyvinylpyrrolidone. It exhibited a fast, stable and highly selective response to H2S at room temperature with a 1 ppb detection limit.
Additives to MgB2 can improve the superconducting functional characteristics, such as critical current density (Jc) and irreversibility field (Hirr). Recently, we have shown that repagermanium (C6H10Ge2O7) is an effective additive, enhancing both Jc and Hirr. To look into details of the processes taking place during the reactive sintering, a thermal analysis study (0.167 K s−1, in Ar) is reported. We used differential scanning calorimetry between 298 and 863 K and simultaneous thermogravimetric—differential thermal analysis between 298 and 1233 K. Samples were mixtures of powders with composition 97 mol% MgB2 and 3 mol% C6H10Ge2O7. Up to 863 K, repagermanium decomposes by multiple steps and forms amorphous phases. A reaction with MgB2 is not observed. Above this temperature, partial decomposition of MgB2 occurs. Crystalline Ge and MgO are detected before formation of Mg2Ge and MgB4, when temperature approaches the melting point of Ge (1211 K). Carbon substitution for boron in the crystal lattice of MgB2 is observed for samples heated above 863 K. The amount of substitutional C does not significantly change with temperature.
Telah dilakukan fabrikasi material nanokomposit CNT/MnO2 sebagai material elektroda superkapasitor dengan reaksi redox antara CNT dan KMnO4. Variasi komposisi dari kedua bahan tersebut dilakukan untuk mengetahui sifat struktur, morfologi dan kelistrikannya dengan perbandingan massa CNT/MnO2 sebesar 0, 25, 50 dan 75%. Pola struktur kristal dan morfologi dari material serbuk nanokomposit CNT/MnO2 dikarakterisasi dengan X-ray diffraction (XRD), scanning electron microscope (SEM) dan transmission electron microscope (TEM), sedangkan pola ikatannya dikarakterisasi dengan FTIR. Serbuk nanokomposit CNT/MnO2 ini selanjutnya dibuat pellet berbentuk silinder berukuran diameter 1 cm dan ketebalan 2 mm dengan variasi penambahan pengikat polyvinylidene difluoride (PVDF) sebesar 10, 20 dan 30% dari campuran CNT/MnO2. Pellet dari material CNT/MnO2 ini selanjutnya dipanaskan pada temperatur 70 oC selama 1 jam. Hasil pengukuran resistansinya menunjukkan bahwa material CNT/MnO2 dengan perbandingan massa CNT/MnO2 sebesar 75% dan penambahan pengikat PVDF sebesar 20% menunjukkan nilai resistansi yang paling rendah. Selanjutnya prototip superkapasitor CNT/MnO2 dengan menggunakan PVDF sebesar 20% diukur dengan metode electrochemical impedance spectroscopy menghasilkan nilai kapasitansi spesifik sebesar 7,86 F/gr. Nanocomposite materials CNT/MnO2 have been fabricated as candidate of supercapacitor electrode material with a redox reaction between CNT and KMnO4. Variations in the composition of the two materials were carried out to determine the structure, morphology and electrical properties of CNT/MnO2 with mass ratio of 0, 25, 50 and 75 %. Pattern of the crystal structure and morphology of the CNT/MnO2 nanocomposite powder were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), while the bond pattern was characterized by FTIR. CNT/MnO2 nanocomposite powder was managed to make cylindrical pellets with diameter of 1 cm and thickness of 2 mm with variations addition of binder polyvinylidene difluoride (PVDF) of 10, 20 and 30%. Pellets of the material were then heated at a temperature of 70 oC for 1 hour. Resistance measurement results showed that the ratio of the mass of material CNT/MnO2 by 75% and additions by 20% PVDF binder showed the lowest resistance value. Furthermore, CNT/MnO2 supercapacitor prototype using PVDF of 20% measured with electrochemical impedance spectroscopy method showed specific capacitance of 7.86 F/gr.
Combining unique fiber morphologies with self-decontamination technologies can enhance degradation of toxic compounds on fibrous substrates. Co-continuous electrospinning was used to fabricate nanofibrous cellulose acetate membranes with unique, grooved fiber morphology due to the selective dissolution of polyethylene oxide. The grooved cellulose acetate membranes were deacetylated to form grooved cellulose membranes. A self-decontaminating polyoxometalate (POM) (H5PV2Mo10O40) was synthesized and used to functionalize the grooved nanofibrous membranes as well as non-grooved nanofibrous membranes, pure cotton, 65/35 polyester/cotton fabrics and Tencel® peachskin fabric. The POM-treated substrates were exposed to methyl parathion, a simulant of the chemical warfare agent (CWA) VX, to evaluate the decontamination performance. It was found that the POM grafted, grooved nanofibrous cellulose membrane has significantly improved self-decontamination, owing to increased amount of POM grafted as a result of increased surface area. This work contributes to the use of novel fiber morphologies in breathable chemical protective apparel to achieve better CWA decontamination and comfort.
The frequency band below the mid-infrared region was studied actively in the 1960s and 1970s during the development of FTIR spectroscopy. While researchers explored the use of this “far-infrared” region for spectroscopy at that time, only the mid-infrared region has become commonly used in FTIR methods. Spectra of typical art materials, such as pigments and binders, are introduced, and factors which affect the spectra are discussed.
This paper describes the single crystals of Tb3+ doped KCl grown by the Bridgeman–Stockbarger method. The grown crystal was subjected to Fourier transform infrared (FTIR), X-ray diffraction method (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), Vickers’s micro hardness and photoluminescence (PL). The presence of various functional groups has been identified from FTIR studies with their vibrating frequency range from 400 to 4000 cm−1. The structural studies on the grown crystals were carried out by X-ray diffraction analysis technique and found that the grown crystal crystallizes in a cubic structure. The lattice cell parameters of Tb3+-doped KCl crystals are a = b = c = 3.14260 Å and α = β = γ = 90°. The optical properties were studied by PL spectra. The excitation spectrum shows the peak at 237, 262 and 345 nm. Upon excitation at 261 nm, the emission spectrum exhibits a broad band at 377, 410 and 490 nm corresponding to 5d → 4f transition. EPR measurements showed fine structure spreading over a wide field region and the calculated g-factor value for more intense resonance signal is 2.3 and 2.2. The mechanical strength of the grown crystal was estimated by the Vicker’s micro hardness test. It confirms that the grown material is found to be a hard material. SEM shows that the particles have irregular shapes with various sizes (ranging from few microns to 20 μm) and it seem to be a cloudy like features. Owing to the high luminescence with the advantage of micrometer dimension, it can be suggested that these materials will find more applications in the field of display and lighting.
Die Oberflächen von strahlungsundurchlässigen Körpern emittieren und absorbieren bei Temperaturen T≠0 K Energie durch Wärmestrahlung, deren Ausbreitung nicht an ein Trägermedium gebunden ist. Als Folge der Emission und Absorption findet zwischen verschieden temperierten Oberflächen eine durch Strahlung hervorgerufene Wärmeübertragung statt, die thermodynamisch die Bedeutung eines Wärmeflusses hat. Im Temperaturgleichgewicht ist der resultierende Wärmestrom null.
A new process is optimized and presented for the recovery and regeneration of LiFePO4 from spent lithium-ion batteries (LIBs). The recycling process reduces the cost and secondary pollution caused by complicated separation and purification processes in spent LIB recycling. Amorphous FePO4·2H2O was recovered by a dissolution-precipitation method from spent LiFePO4 batteries. The effects of different surfactants (i.e. CTAB, SDS and PEG), which were added to the solution on the recovered FePO4·2H2O, were investigated. Li2CO3 was precipitated by adding Na2CO3 to the filtrate. Then the LiFePO4/C material was synthesized by a carbon thermal reduction method using recycled FePO4·2H2O and Li2CO3 as the Fe, P, and Li sources. The as-prepared LiFePO4/C shows comparable electrochemical performance to that of commercial equivalents.
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