Ammonium Fluoride Solution Research Articles

Solvent Extraction of Gallium and Germanium Using a Novel Hydroxamic Acid Extractant

The rare metals gallium and germanium are key strategic metals that are widely used in emerging industries. In this work, a novel hydroxamic acid extractant, BGYW, with low toxicity, was used for the selective solvent extraction of Ga ions and Ge ions from Zn, As, Cu, and Al ions in the solution from zinc smelting. The gallium and germanium ions were extracted efficiently under optimized conditions. Gallium ions were preferentially stripped using sulfuric acid, and germanium ions were stripped using an ammonium fluoride solution. Compared with the commercial extractant YW100, the dissolution loss of BGYW was reduced by 10 times. After 15 cycles, the germanium solvent extraction efficiency of BGYW remained at 100%, and the solvent extraction efficiency of gallium was about 98.7%, while the solvent extraction efficiency of both Ga ions and Ge ions using YW100 decreased to 20% after five cycles. This novel solvent extraction system exhibits considerable promise for application in zinc smelting processes for gallium and germanium solvent extraction.

Increasing the Wear and Corrosion Resistance of a CP-Ti Surface by Plasma Electrolytic Borocarburizing and Polishing

The paper examines the possibility of increasing the wear and corrosion resistance of a CP-Ti surface by duplex plasma electrolytic treatment (borocarburizing and polishing). The structure and composition of diffusion layers, their microhardness, surface morphology and roughness, wear resistance during dry friction and corrosion resistance in Ringer’s solution were studied. The formation of a surface-hardened layer up to 200 μm thick with a microhardness of up to 950 HV, including carbides and a solid solution of boron and carbon, is shown. Subsequent polishing makes it possible to reduce surface roughness and remove weak areas of the porous oxide layer, which are formed during high-temperature oxidation in aqueous electrolyte vapor during borocarburizing. Changing the morphology and structural-phase composition of the CP-Ti surface helps reduce weight wear by a factor of three (the mode of frictional interaction changes from microcutting to oxidative wear) and corrosion current density by a factor of four after borocarburizing in a solution of boric acid, glycerin and ammonium chloride at 950 °C for 5 min and subsequent polishing in an ammonium fluoride solution at a voltage of 250 V for 3 min.

Modification of Silica with Sucrose and Ammonium Fluoride Agents: A Facile Route to Prepare Supports of Iridium Catalysts for Hydrogenation Reaction.

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous silica. The influence of synthesis conditions (pH, temperature, time) on the textural properties of the final materials was determined. Samples obtained in an acidic medium, at pH = 1, and treated at room temperature, yielded products with a large surface area and a narrow pore size distribution in the range of 2-5 nm, while the synthesis at pH = 8 allowed for the formation of mesoporous systems with pores in the range of 14-20 nm. To generate acidity, the silicas were modified with an ammonium fluoride solution and then used as supports for iridium catalysts in a hydrogenation reaction, with toluene as a model hydrocarbon. The influence of parameters such as specific surface area, support acidity, and iridium dispersion on catalytic activity was determined. It was shown that modification with sucrose improved the porous structure, and NH4F modification generated acidity. These parameters favored better reducibility and dispersion of the active phase, resulting in higher activity of the catalysts in the studied hydrogenation reaction.

Study of FZO thin films deposited by ultrasonic spray: influence of precursor milling

In this work, the results of the study of ZnO:F (FZO) films deposited on glass substrates using the ultrasonic chemical spray technique are reported. For the preparation of the films, starting solutions were used at a concentration of 0.2 M of zinc acetate dihydrate [Zn(CH3COO)2.2H2O]) dissolved in a mixture of deionized water:methanol:acetic acid. The precursor was previously ground in a planetary ball mill at 500 rpm at different times. For the addition of the dopant, a 1.6 M solution of ammonium fluoride in deionized water was prepared NH4F. The atomic ratio of [F]/[F + Zn] remained constant at 30 at%. Structural characterizations by X-ray diffraction, morphological by scanning electron microscopy, optical by UV–Vis spectroscopy, and electrical by Hall effect were performed on all deposited films. From the analysis of results, the hexagonal wurtzite phase was confirmed, and a variation of the morphology was observed depending on the deposit conditions. In general, the films presented high optical transmittance in the visible region and the n-type conductivity was confirmed.

EVALUATION OF THE FLUORAMMONIUM TECHNOLOGY OF DISCLOSURE OF ILMENITE WITH OBTAINING THE REQUIRED MATEALS FOR INDUSTRY AND MEDICINE

Purpose. Evaluation of the advantages of the innovative direction of obtaining the sought-after titanium and silicon oxides using the technology of hydrofluorination of ilmenite concentrates Research methods. Evaluation of the quality of laboratory samples – products of hydrofluorination of ilmenite with regard to the possibility of integrating the obtained materials into existing production schemes for the production of current titanium and silicon products, as well as in providing raw materials for promising technological processes. Chemical analysis was carried out by the method of atomic spectral analysis. In the laboratory studies, the raw material component was used – ilmenite concentrate from the Malyshev deposit (Vilnohirsky MMC, Ukraine). A fluorine-containing complexing agent – ammonium fluoride (NH4F) was used as a reagent. Laboratory studies of the decomposition of ilmenite in an aqueous solution of ammonium fluoride at temperatures not exceeding 200 °C were performed. Obtained results. Determination of the temperature range and conditions for conducting the ilmenite decomposition process ensures its high productivity and obtaining products that are intermediate and the composition of which determines the content of the subsequent processes of obtaining the target products. Implementation of decomposition of ilmenite using reactions in the solid phase provides a high potential for environmental safety of the technology. Scientific novelty. The obtained data can be used to justify a workable version of the energy-saving technological process of decomposition of ilmenite concentrate. Based on the obtained chemical analyzes of the decomposition products by hydrofluorination of ilmenite, the compliance of the obtained products with the requirements for the starting materials of a number of areas of their use in metallurgy and medicine was established. The possibilities of integration of the obtained materials into the existing production schemes of titanium and silicon products, as well as in providing the raw material needs of promising technological processes are shown. Practical value. The indicators of the purity of the obtained products confirm the prospects of the researched integration of the considered technology into the existing production schemes for obtaining products containing titanium and silicon.

Synthesis of weak cation exchange/C18 bifunctional magnetic polymers for pretreatment and determination of glufosinate and its two metabolites in plasma samples

This study focuses on the purification and detection of glufosinate (GLUF) and its metabolites N-acetyl GLUF and MPP in plasma samples. A Dikma Polyamino HILIC column was used for the effective retention and separation of GLUF and its metabolites, and the innovative addition of a low concentration of ammonium fluoride solution to the mobile phase effectively improved the detection sensitivity of the target analytes. Monodisperse core-shell weak cation exchange (WCX)/C18 bifunctional magnetic polymer composites (Fe3O4@WCX/C18) were prepared in a controllable manner, and their morphology and composition were fully characterized. The Fe3O4@WCX/C18 microspheres were used as a magnetic solid-phase extraction (MSPE) adsorbent for the sample purification and detection of GLUF and its metabolites in plasma samples combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The purification conditions of Fe3O4@WCX/C18 microspheres for GLUF and its metabolites in spiked plasma samples were optimized to achieve the best MSPE efficiency. The purification mechanisms of the target analytes in plasma samples include electrostatic attraction and hydrophobic interactions. Furthermore, the effect of the molar ratio of the two functional monomers 4-VBA and 1-octadecene in the adsorbent was optimized and it shows that the bifunctional components WCX/C18 have a synergistic effect on the determination of GLUF and its metabolites in plasma samples. In addition, the present study compared the purification performance of the Fe3O4@WCX/C18 microsphere-based MSPE method with that of the commercial Oasis WCX SPE method, and the results showed that the Fe3O4@WCX/C18 microsphere-based MSPE method established in this work had a stronger ability to remove matrix interferences. Under optimal purification conditions, the recoveries of GLUF and its metabolites in plasma were 87.6–111 % with relative standard deviations (RSDs) ranging from 0.2 % to 4.8 %. The limits of detection (LODs, S/N≥3) and limits of quantification (LOQs, S/N≥10) were 0.10–0.18 μg/L and 0.30–0.54 μg/L, respectively. The MSPE-LC-MS/MS method developed in this study is fast, simple, accurate and sensitive and can be used to confirm GLUF intoxication based not only on the detection of the GLUF prototype but also on the detection of its two metabolites.

Bonding Pretreatment of Aesthetic Dental CAD-CAM Materials through Surface Etching with a Mixed Aqueous Solution of Ammonium Fluoride and Ammonium Hydrogen Sulfate.

Hydrofluoric acid (HF) is commonly used as an etchant for the pretreatment of dental computer-aided design/computer-aided manufacturing (CAD-CAM) materials, such as glass-ceramics and resin composites. Despite its effectiveness, the harmful and hazardous nature of HF has raised significant safety concerns. In contrast, ammonium fluoride (AF) is known for its relatively low toxicity but has limited etching capability. This study explored the potential of ammonium hydrogen sulfate (AHS), a low-toxicity and weak acid, to enhance the etching ability of aqueous AF solutions for the bonding pretreatment of CAD-CAM materials. This study investigated five types of aesthetic CAD-CAM materials: lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, resin composites, and zirconia. Seven experimental etchants were prepared by varying the amount of AHS added to aqueous AF solutions, with each etchant used to etch the surfaces of the respective CAD-CAM materials. The treated surfaces were analyzed using scanning electron microscopy and confocal laser scanning microscopy. Additionally, the shear bond strength (SBS) of the CAD-CAM materials treated with a luting agent (resin cement) was evaluated. The results indicated that the AF1/AHS3 (weight ratio AF:AHS = 1:3) etchant had the most substantial etching effect on the surfaces of silica-containing materials (lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, and resin composites) but not on zirconia. The SBS of the materials treated with the AF1/AHS3 etchant was comparable to that of the commercial HF etchant. Hence, an AF/AHS mixed solution could effectively etch silica-containing CAD-CAM materials, thereby enhancing their bonding capabilities.

Determination of 26 bisphenols in dust by ultra performance liquid chromatography-tandem mass spectrometry

Bisphenol A (BPA) is one of the most widely produced compounds in the world and was listed as a substance of very high concern by the European Chemicals Agency in 2016. Because of its toxicity, many countries and regions, including China, have banned BPA addition in feeding-bottles. And the European Union (EU) has banned BPA use in other food contact materials and thermal paper. Restrictions on BPA have contributed to the widespread use of alternatives. As the toxicity of BPA alternatives continues to be revealed, the alternatives of BPA alternatives are being developing. As the most extensive alternative for BPA, bisphenol S (BPS) was proven to have estrogen-disrupting effects and developmental toxicity of the neuroendocrine system. Therefore, BPS alternatives are used in thermal paper. In this study, alternatives to both BPA and BPS are collectively referred to as bisphenols (BPs). As a pooling matrix of many indoor chemicals, dust is an important pathway for human exposure to BPs. BPA and its alternatives are routinely detected in dust. As BPS alternatives have been detected in recycled paper and sludge, it is also very important to detected in dust. However, common analytical methods for BPs have low sensitivity and contain few BPS alternatives. Therefore, a high-throughput, high-accuracy, and high-sensitivity method must be established for the determination of BPs in dust; this will lay the foundation for subsequent studies on the environmental behavior and exposure risk of BPs. In this study, an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of 26 variations of BPs in dust. UPLC-MS/MS parameters of the variations were optimized to compare the separation effect and response intensity in different columns and mobile phases. The influence of the extraction solvent and solid phase extraction (SPE) on the extraction efficiency and purification effect of target compounds were optimized by using the isotopic internal standard method, and the 26 variations of BPs in dust was quantitatively analyzed. Finally, the dust samples were extracted by using 3 mL of acetonitrile and 3 mL of a 50% methanol aqueous solution in an ultrasound bath. The combined extract was further purified by using an Oasis HLB cartridge (60 mg/3 mL). The cartridge was then washed with a 40% methanol aqueous solution (0.5 mL) and eluted with methanol (2 mL). The target compounds were separated on a CORTECS® UPLC® C18 column (100 mm×2.1 mm, 1.6 μm), with methanol and 1 mmol/L ammonium fluoride solution as mobile phases and a flow rate of 0.3 mL/min. Electrospray ionization (ESI) was applied in the positive, negative, and multiple reaction monitoring (MRM) modes for the mass scan. Under optimized conditions, the linear ranges of the 26 targets behaved well linearly in their respective ranges with correlation coefficients (r2)>0.999. The limits of detection (LODs) and limits of quantification (LOQs) were assessed using signal-to-noise (S/N) ratios of 3 and 10, respectively. The LODs and LOQs of the method were 0.01-0.75 μg/kg and 0.02-2.50 μg/kg, respectively. The accuracy of the method was evaluated by conducting a recovery test at three spiked levels: LOQ, two times the LOQ, and 10 times the LOQ, with the average recoveries ranging from 83.7% to 114.9%. The precision of the method was evaluated by using the relative standard deviation (RSD). The intra-day RSDs and inter-day RSDs were 0.86%-9.79% (n=6) and 5.16%-19.5% (n=6), respectively. The established method was used to determine 11 dust samples. Fifteen BPs were detected at a detection rate of 9.1%-100.0%. The detection rate for BPA, BPS, bisphenol F (BPF), 4-hydroxy-4'-isopropoxydiphenylsulfone (BPSIP), and diphenyl sulfone (DPS) was 100.0%. BPSIP, 4-allyloxy-4'-hydroxydiphenyl sulfone (BPS-MAE), and bis-(3-allyl-4-hydroxyphenyl) sulfone (TGSA) were first detected in Chinese dust, whereas 4-benzyloxy-4'-hydroxydiphenyl sulfone (BPS-MPE), 4-hydroxybenzoic acid benzyl (PHBB), and DPS were first detected in dust samples worldwide. This method is simple, rapid, and sensitive, and is suitable for the qualitative screening and quantitative analysis of the 26 BPs in dust samples.

Increasing the Hardness and Corrosion Resistance of the Surface of CP-Ti by Plasma Electrolytic Nitrocarburising and Polishing.

The possibility of increasing the hardness to 1420 HV and the corrosion resistance of the CP-Ti surface using a combined plasma electrolytic treatment consisting in anodic plasma electrolytic nitrocarburising in a solution of ammonia, acetone and ammonium chloride at 900 °C and subsequent plasma electrolytic polishing is shown. The morphology, surface roughness, phase composition, structure and microhardness of the modified layer were studied. The corrosion characteristics of the treated surface were studied through potentiodynamic tests and electrochemical impedance spectroscopy. It has been shown that an increase in the surface roughness has a negative effect on the corrosion resistance. The proposed plasma electrolytic polishing makes it possible to remove the outer porous oxide layer, providing increased corrosion resistance. The highest reduction in the corrosion current density, by 13 times compared to CP-Ti and by two orders compared to a plasma electrolytic nitrocarburising sample, is achieved after plasma electrolytic polishing in a solution of ammonium fluoride (4%) at 300 V for 3 min.

Low-temperature desiliconization of activated zircon concentrate by NH4HF2 solution

The demand for zirconia concentrates significantly exceeds the supply, which causes a significant difference in their cost, which raises the question of removing silicon from zircon to obtain a zirconium dioxide concentrate. The article presents the development of a low-temperature technology for processing activated zircon concentrates with the production of a baddeleyite concentrate used for the manufacture of high-temperature ceramics, including the possibility of regenerating the main reagent. The optimal conditions for desiliconization were established as follows: concentration of NH4HF2 solution – 30 %, duration – 60 min, temperature – 90 °C; the ratio of solid to liquid – 1:5. Under these conditions, more than 99 % of silicon goes into solution. During the leaching process, zirconia partially reacts with the leaching agent to form ammonium heptafluorozirconate, which has lower water solubility than ammonium fluorides and ammonium hexafluorosilicate. Subsequent calcination allows the heptafluorozirconate to be converted back into zirconia. The resulting solution of ammonium hexafluorosilicate can be used to obtain amorphous silicon dioxide and ammonium fluoride solution, which serves as a raw material in the process of regeneration of the leaching solution with its reuse for processing a new batch of raw materials. Based on the work results, it was possible to achieve more than 99 % degree of desiliconization of zircon concentrate. The appropriate waste-free technological scheme for obtaining baddeleyite concentrate was proposed.

Formation of smooth anodic nanoporous iron oxide film for enhancing photocathodic protection on plain carbon steel

It is essential to fabricate smooth nanoporous iron oxide film with fewer defects on plain carbon steel (CS) to improve photocathodic protection of the film in corrosive media. For that, high temperature annealing heat treatment was chosen to manipulate the metallographic structure of CS in the muffle furnace at 900 °C with the duration of 30 min. Following that, the annealed CS was anodized in a mixture of aqueous ammonium fluoride solution and ethylene glycol to fabricate smooth nanoporous oxide film on CS. Finally, as-anodized oxide film was calcinated at 450 °C for 4 h in nitrogen atmosphere to form crystalline iron oxide film. Several electrochemical techniques were applied to analyze the photoelectron property and photocathodic protection performance of nanoporous iron oxide films. On the contrary, rough nanoporous iron oxide film with more striking defects was fabricated on untreated (no annealed) CS by using the same anodization and calcination processes. The results show that the metallographic structure of annealed CS behaved more uniform ferrite grains and fewer pearlite precipitate than untreated CS. Thereby, a smooth nanoporous iron oxide film with fewer defects formed on annealed CS. On the contrary, a rough nanoporous iron oxide film with more defects, such as dimples and cracks were fabricated on untreated CS. Both of iron oxide films were composed of hematite as the main phase and magnetite as the secondary phase. Therefore, the smooth iron oxide film displayed comparatively better conductivity and higher donor density under the condition of illumination than the rough film. On account of those, smooth film exhibits comparatively higher anodic and cathodic reaction activities and more excellent and stable photocathodic protection to the counter.

Structure of two NH4BiF4 polymorph modifications. Ionic motion in NH4BiF4 and cubic products of its partial thermal decomposition

The conditions for the synthesis of two polymorph modifications of ammonium tetrafluorobismutate (III) from the heated water solution of ammonium fluoride (bifluoride) were studied with different BiF3:NH4HF2(NH4F) reagent concentrations. The crystal structure of monoclinic β–NH4BiF4 (a ​= ​8.1014(3), b ​= ​6.6208(2), c ​= ​8.1045(3) Å, β ​= ​111.003(1)°, sp.gr. P21/c) was determined for the first time. The structure of α–NH4BiF4 (a ​= ​8.3185(6), b ​= ​7.5902(6), c ​= ​6.4866(5) Å, β ​= ​93.687(1)°, sp.gr. P21/c) was refined. Both polymorph modifications have layered structures with a single nine-coordinated bismuth site. The thermal decomposition of NH4BiF4 was studied and two products of the decomposition having a cubic structure were isolated. The fluorine and ammonium mobility in obtained phases was probed with 1H, 19F NMR.

Flexible TiO2 nanograss array film decorated with oxygen vacancies introduced by facile chemical reduction and their photocatalytic activity

Flexible TiO 2 nanograss array film was prepared by simple chemical oxidation of Ti wire mesh at a low temperature of 353 K. To improve its visible-light-driven photocatalytic activity, we further carried out a low-temperature chemical reduction to introduce oxygen vacancies in the solution of ethylene glycol (EG) and ammonium fluoride (NH4F). The results of XPS and EPR confirmed the formation of surface and bulk oxygen vacancies was confirmed, and their concentrations increased as the reduction time increased. Compared with the as-annealed TiO 2 film, the as-reduced specimens exhibited higher visible-light-driven photocatalytic activity. When reduction time was 48h, the photocatalytic activity was increased by 15.8 times compared to the as-annealed sample. The remarkable improvement in photocatalytic activity should be ascribed to the oxygen vacancies’ introduction. The most excellent photocatalytic performance was obtained when a suitable concentration ratio of surface oxygen vacancies to bulk oxygen vacancies was reached. Low-temperature chemical reduction in the solution of EG + NH4F is very efficient and convenient for introducing defects such as oxygen vacancies and Ti3+.

DEVELOPMENT OF A LOW-TEMPERATURE DESILICONIZATION METHOD FORTHE POLYMETALLIC SLAGS WITH A SOLUTION OF AMMONIUM HYDROGEN FLUORIDE

This paper considers a method for removingsilicon dioxide from the polymetallic slags of the Nerchinsk silver smelters, which operated from the 17th to the 19th centuries. The main com-ponents are presented both in the oxygen-containing form (iron, silicon, etc.) and in the form of sulfides (lead,zinc). It was found that during the process, silicon passes into solution in the form of ammonium hexafluorosilicate. Iron, aluminum and a number of other components react with NH4HF2, but stay in the solid phase due to their low solubility in the resulting system. After remov-ing silicon, the solid residue is subjected to pyrohydrolysis to obtain a product that can be subjected to magnetic separation to obtain a magnetic iron concentrate and a non-ferrous metal concentrate, which can later be used to extract zinc, lead, silver, etc. Fluorine is removed from the cycle with the pyrohydrolysis product in the form of calcium fluoride. Productive solution is directed to the silicon dioxide production. The final solution of ammonium fluoride is used for ammonium hydrodifluo-ride by means of the water evaporation. In the process of evaporation of the ammonium fluoride solution, the ammonia molecule is split off with the formation of ammonium hydrodifluoride. The whole process of desiliconization is shown in the technological scheme. Main stages of the method demand typical equipment, so it allows us to speak about the applicability of this method in industry for both mineral and artificial raw materials with a high content of silicon dioxide or silicates of various compositions.

Growth of porous anodic TiO2 in silver nitrate solution without fluoride: Evidence against the field-assisted dissolution reactions of fluoride ions

Al, Ti, Zr and other metals can be anodized to form metal oxides with a porous structure or a nanotube structure. However, the mechanism of formation of oxide nanopores is still controversial. Anodic TiO2 nanotubes are usually obtained in an electrolyte containing fluoride ions, so a field-assisted dissolution reaction involving fluoride ions is considered to be the main reason for the formation of nanopores. In this paper, titanium was anodized at high current in a silver nitrate solution without fluoride, and a porous titanium oxide structure was obtained, which proves that a field-assisted dissolution reaction involving fluoride ions is not essential for the formation of nanopores. The electronic current leads to oxygen evolution, and the oxygen bubble mold effect is the real reason for the formation of nanopores. These interesting results show that the mechanism of formation of anodized TiO2 nanotubes is the same as that of porous oxide structures. Moreover, the growth rate of nanotubes in an aqueous solution of silver nitrate was much higher than that in a glycol solution of ammonium fluoride at the same voltage.

Solar photocatalysts based on titanium dioxide nanotubes for hydrogen evolution from aqueous solutions of ethanol

Titanium foil was anodized to grow titanium dioxide nanotubes (TiO2 NT) by using an original technique. A solution of ethylene glycol and ammonium fluoride with a concentration of 0.5 wt% was employed as electrolyte, corrosion-resistant steel was chosen as the cathode material. Anodic oxidation was carried out potentiostatically at a voltage of 60 V at ambient temperature for 90 min. Modification of as prepared TiO2 NT were modified by calcination in air at 350°C for 4 h. Platinization of TiO2 NT was carried out by chemical reduction of platinum from H2PtCl6 solution by NaBH4 solution. Photocatalyst characterization was performed by using XRD, BET, SEM, XPS techniques. It was found that the calcination of as-prepared TiO2 NT leads to 6-fold increase of the photocatalytic activity under UV-irradiation. The enhanced activity of TiO2 NT is associated with the developed specific surface area and unique morphology of TiO2 NT. This results in high rate of separation of photogenerated excited electrons and holes. Due to high separation rate the catalytic activity increases substantially.

Fabrication of titanium dioxide nanotubes by difference the anodization voltage and time

In this paper, Titanium dioxide nanotube arrays (TNAs) were obtained by electrochemical anodization in the electrolyte containing 0.3 wt% solution of ammonium fluoride in 90 ml of ethylene glycol and 10 ml of deionized water. Following this the different conditions of voltage (5–50 V) and time (30 min − 2 h) at room temperature. The morphology, composition, and crystalline phases of the TNAs were examined by Field Emission Electron Microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction technique (XRD), respectively. The results of the experiment show that anodizing time and anodizing potential affected the formation of TNAs. When anodizing potential increased anodizing time decreased but when anodizing potential decreased anodizing time increased. Moreover, the formation of titanium dioxide starts becoming tubes at 10 V. Also, the diameter of the TNAs were about 10–100 nm.

Effect of Precursor Fluorine Concentration Optical and Electrical Properties of Fluorine Doped Tin Oxide thin Films

We have studied effects of Fluorine (F) concentration on the structural, optical and electrical properties of Fluorine Doped Tin Oxide (FTO) thin films. The FTO films were fabricated with homemade spray pyrolysis setup and calcinated for twenty minutes at air environments. The homogeneous solution of Stannous Chloride (SnCl2.2H2O) and Ammonium Fluoride (NH4F) in distilled water was used as a precursor solution. Both the substrate and oven temperature was set to ca. (550 ± 5)℃ during the film synthesis and calcination processes. The films’ optical and electrical properties were investigated from transmittance, reflectance and resistance measurements. The transmittance of FTO film is found to be decreased for increasing F concentration from 0.28 M to1.14 M and increased for 1.14 M to 11.37 M. Also reflectance found to be significantly modulated with varying molar concentration of F. The maximum and minimum of the reflectance (Rmax and Rmin) found to vary from 49 % and 7 %, respectively). However, there was no clear dependency on the dopant F concentration; slightly enhancement may be true which is probably due to the increase in fundamental absorption as photon striking increases. Electrical measurement showed the decrease of resistance of 0.85M FTO film from 138 Ω to 17 Ω.

Fluoride etching of AlZSM-5 and GaZSM-5 zeolites

The post-synthesis treatment of AlZSM-5 and GaZSM-5 zeolites by etching with buffer solution of ammonium fluoride and 0.25 M HF acid was carried out. The treatment is applied in order to obtain secondary pores in crystals and to provide easier access to the catalytically active zeolite centers. Hydrothermal synthesis of these zeolites was performed from systems containing tetrapropylammonium bromide as a template. The reaction parameters of synthesis conditions for both zeolites were optimized in order to obtain pure crystalline phases. The zeolites obtained were characterized by X-ray diffraction, IR spectroscopy, scanning electron microscopy, physical adsorption–desorption of nitrogen and solid-state NMR spectroscopy. It has been found that the result materials remain with high crystallinity while new mesoporous are created in their structure. The volume due to the presence of mesopores increases by up to 67% from the total volume, which is a drastic increase compared with the parent solids. The investigations with FTIR spectroscopy of low-temperature CO adsorption and solid-state NMR spectroscopy show that the treatment is slightly selective toward dissolution of heteroatom (aluminum or gallium). This phenomenon is observed for the first time for gallium-substituted zeolites. In order to study the influence of the metal atom in zeolite structure and the efficacy of the acid attack on the catalytic activity, the samples obtained were tested in reaction of m-xylene and toluene transformation.

Characterizing phosphorus availability in waste products by chemical extractions and plant uptake

AbstractBackground: The fertilizer value of phosphorus (P) in waste products relies heavily on its availability to the subsequent crop.Aim: We studied the link between extractable P in waste products and apparent P recovery (APR, i.e., difference in plant P uptake between P amended and un‐amended soils divided by the amount of P added) using spring barley grown on three sandy soils.Methods: The products included sewage sludge, biomass ash, struvite, compost, meat and bone meal, biochar from sewage sludge, and industrial sludge. Soft rock phosphate and triple‐superphosphate (TSP) were included for comparison. Availability of P was characterized by extraction with water and solutions of sodium bicarbonate, citric acid, oxalic acid, hydrochloric acid, ammonium acetate, ammonium fluoride and anion exchange resin membranes. TSP was used to establish mineral‐fertilizer‐equivalents (MFE). Water and bicarbonate extractions were also applied to products incubated with soil before extraction.Results: The APR ranged 26 to 31% for TSP and 0 to 30% for waste products. APR correlated most strongly with bicarbonate extractable P. The correlation increased when products were incubated with soil before extraction.Conclusions: We conclude that bicarbonate extraction is a good indicator of potential P availability. However, interactions between waste products and soil properties modify P availability.