Range Of Synthesis Conditions Research Articles

Struvite Production from Dairy Processing Waste

Food security depends on sustainable phosphorus (P) fertilisers, which at present are mostly supplied from a finite rock phosphate source. Phosphate (PO43−) and ammonium (NH4+) in dairy processing wastewater can be recovered as struvite (Mg + NH4+ + PO43− 6H20), a nutrient rich mineral for fertiliser application. The objectives of this study were to (1) quantify the effects of, pH, temperature and Mg: PO43− dosing rates on nutrient (PO43− and NH4+) removal and struvite precipitation from post anaerobic digested dairy processing wastewater, and (2) co-blend different dairy processing wastewaters to improve the reactant stoichiometry of NH4+ and PO43− for optimal struvite recovery and NH4+ removal. Phosphate removal (>90%) and struvite production (>60%) was achieved across a range of synthesis conditions, and was significantly impacted by pH as determined by response surface modelling. A combination of disproportionate molar ratios of PO43− and NH4+, presence of calcium and the apparent mineralisation of organic N, resulted in co-precipitation of hydroxyapatite and elevated levels of residual aqueous NH4+. In the second phase of this study, struvite was successfully precipitated and NH4+ removal was improved (~17%) however, higher concentrations of calcium in the wastewater blends resulted in greater hydroxyapatite co-precipitation (up to 30%). While struvite was the desired product in this study the formation of multiple heterogenous P-rich products (struvite and hydroxyapatite) has the potential to improve P recovery from dairy processing wastewaters and produce a fertiliser blend with amenity and value in agricultural systems.

Unique Role of GeO2 as a Noninvasive Promoter of Nano-Sized Zeolite Crystals.

The synthesis of zeolites with nano-sized dimensions is often limited to a narrow design space that conventionally relies upon the design of organics to direct hierarchical materials. Here, it is demonstrated that the addition of an inorganic modifier, germanium oxide (GeO2 ), to a zeolite growth mixture directs the formation of crystals with ultrasmall dimensions. This effect is observed for zeolites ZSM-11and ZSM-5 over a range of synthesis conditions wherein the role of GeO2 in zeolite crystallization deviates from its typical function as a heteroatom. Notably, the final products contain trace amounts of Ge, which indicates the inorganic modifier does not compete for sites in the zeolite framework based on its formation of a discrete phase that enables GeO2 recovery. Catalytic tests using the methanol-to-hydrocarbons reaction reveal significant enhancement in the performance of zeolite catalysts prepared with GeO2 compared to reported examples of nano-sized zeolites. These findings highlight a potentially generalizable and commercially viable synthesis method to reduce mass-transport limitations in zeolites for diverse applications.

Sodium site occupancy and phosphate speciation in natrophosphate are invariant to changes in NaF and Na3PO4 concentration

Analysis of multimodal characterization of Natrophosphate suggests that the crystalline structure is preserved across a range of synthesis conditions.

Characterisation of CVD diamond with high concentrations of nitrogen for magnetic-field sensing applications

Ensembles of nitrogen-vacancy (NV) centres in diamond are a leading platform for practical quantum sensors. Reproducible and scalable fabrication of NV-ensembles with desired properties is crucial, as is an understanding of how those properties influence performance. This work addresses these issues by characterising nitrogen-doped diamond produced by the chemical vapour deposition (CVD) method across a range of synthesis conditions. This is shown to produce material with widely differing absorption characteristics, which is linked to the level of defects other than substitutional nitrogen (NS) and NV. In such material, the achievable concentration of NV− ([NV−]) is found to be influenced by the as-grown properties. At the 10–20 ppm level for [NS], the production of CVD-grown material with strain levels sufficient not to limit achievable device sensitivity is demonstrated and a favourable product of [NV−] and is obtained. Additionally, reproducible properties over a batch of 23 samples from a single synthesis run are achieved, which appears promising for the scalability efforts underway in this area of research.

Shear strength measurements of hafnium diboride thin solid films

Micromechanical and microscratch properties of chemical vapor deposition synthesized hafnium diboride thin solid films were measured. A range of synthesis conditions was explored by varying the substrate temperature, precursor pressure, and ex situ annealing conditions. Adhesion and shear strength measurements were performed using indentation and scratch techniques, respectively. The hardness of the as-deposited and annealed films was found to be in the 7–22GPa and 6–32GPa range, respectively. Scratch studies revealed a coefficient of friction of 0.13–0.21 depending on the deposition and annealing conditions with the as-deposited films exhibiting lower coefficient of friction. The adhesion strength was found to increase twofold to threefold with annealing, while annealing has no impact on the shear strength of the films.

Preparation and Characterization of PMMA and its Derivative via RAFT Technique in the Presence of Disulfide as a Source of Chain Transfer Agent

Poly(methyl methacrylate) (PMMA) were synthesized by using chain transfer agents(CTA), S-1-Dodecyl-S′-(α,α′-dimethyl-α-acetic acid) trithiocarbonate (MTTCD), S,S′-bis (2-hydroxyethyl-2′-dimethylacrylate) trithiocarbonate (BDATC), 2-cyanoprop-2-yl dithiobenzoate (CPDB) respectively, through the reversible addition fragmentation chain transfer (RAFT) polymerization under a range of synthesis conditions. The results indicated that the structure of the end-group of RAFT agents had significant effects on the ability to control polymerization. Compared with MTTCD and CPDB, BDATC can provide better control over the relative molecular mass, distribution and polymerization of PMMA. The derived well-controlled block copolymer PMMA-b-PDMAEMA and PMMA-b-PDMAEA were also successfully prepared by using N, N-dimethylaminoethy acrylate (DMAEA) or N, N-dimethylaminoethyl methacrylate (DMAEMA) as the second monomer. The chemical composition and structure of the products were characterized by FTIR, 1HNMR, XRD and DSC. CO2 and N2 permeation performance of the PMMA-b-PDMAEA/PS composite membranes were tested at different pressure. The results showed that the resulted composited membrane had a CO2 permeation rate of 3.68×10-5cm3 (STP) cm-2s-1cmHg-1, a N2 permeation rate of 1.78×10-7 cm3 (STP) cm-2s-1cmHg-1 and an ideal CO2/ N2 selectivity of 206.6 at a feed gas pressure of 7.6 cmHg and 30 oC.

Abstract 5746: ARC-P HS+: A versatile radiosynthesizer for the production of PET tracers

Abstract Objective: Positron Emission Tomography (PET) has seen dramatic growth in research over the last 20 years, and is now a standard in the diagnosis, staging, and treatment monitoring of cancer. PET uses molecular probes in trace amounts to examine specific biochemical, biological, and pharmaceutical processes noninvasively with high sensitivity, and has the advantage that the same probe can be used across cell cultures, mouse models, and patients. Although the majority of clinical PET studies are performed with 2-[F-18]fluoro-2-deoxy-D-glucose ([F-18]FDG), FDG-PET does not identify the specific biochemical pathways through which disease is occurring nor can it provide a companion diagnostic for the discovery, development, and use of molecular therapeutics. New technologies are needed to accelerate the development, production, and distribution of novel PET probes to increase the sophistication of cancer care through personalized medicine. Methods: The ARC-P HS+ radiosynthesizer was developed to address limitations in other synthesizers that restrict the diversity of probes they can produce. The ARC-P HS+ contains three reaction vessels that are moved among dedicated stations for reagent addition, sealed reaction, evaporation, and transfer, eliminating exposure of tubing and valves to high pressures, the root cause of limitations in other systems. It was designed to handle a wide range of synthesis conditions, including multiple reaction vessels, reagents that are corrosive or sensitive to the environment and reaction steps performed at high temperatures (e.g., up to 165C) and pressures (e.g. >100 psig [690 kPag]). To ensure ease of setup and diversity of probes, reagents are installed via a disposable cassette, which contains all wetted paths. Each cassette comprises reagent storage vials, gaskets for sealing the reaction vial, purification cartridges, and disposable valves. Results: Compared to our first generation synthesizer, the cassette-based approach of ARC-P HS+ reduced the number of reagents prepared and installed by the operator and eliminated the need for cleaning. Setup time and manual interventions were reduced. We confirmed that ARC-P HS+ could complete the demanding synthesis of [F-18]FAC, a novel probe for oncology, as well as [F-18]FMAU. Performance of both syntheses was comparable to previous reports. Conclusions: ARC-P HS+ is capable of producing the [F-18]FAC family of probes as well as probes with similar stringent synthesis requirements. Commercialization of this system with disposable cassette-based kits could facilitate production of these tracers, as well as providing a path to make other probes currently used in the clinic ([F-18]FDG, [F-18]FLT, [F-18]F-DOPA, etc.) more readily available. With minimal modifications in only software and reagents, this unit can be used to produce essentially all classes of F-18 labeled probes involving a wide range of reaction conditions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5746. doi:1538-7445.AM2012-5746

Synthesis and photocatalytic activity of TiO2 nanoparticles prepared by chemical vapor condensation method with different precursor concentration and residence time

Nanosized TiO2 photocatalysts were synthesized using a chemical vapor condensation method under a range of synthesis conditions (precursor vapor concentration and residence time in a tubular electric furnace). X-ray diffraction showed that the prepared TiO2 powders consisted mainly of anatase (>94%) with a small amount of rutile. The mean particle diameter from the Brunauer–Emmett–Teller surface area and transmission electron microscopy measurements ranged from 9.4 to 16.6nm. The specific surface area (92.5–163.5m2g−1) of the prepared TiO2 powders was found to be dependent on the synthesis conditions. The content of hydroxyl groups on the surface of the prepared TiO2 sample was higher than those on commercial TiO2, resulting in increased photocatalytic oxidation. The photocatalytic activity of the TiO2 samples prepared in a methylene blue solution was strongly dependent on the crystallinity and specific surface area, which were affected by the TTIP vapor concentration and residence time.

Plasma-chemical synthesis of silicon carbonitride films from trimethyl(diethylamino)silane

Silicon carbonitride films of different compositions have been synthesized by plasma-enhanced chemical vapor deposition with the use of trimethyl(diethylamino)silane as the initial compound. The conditions used for the deposition of the films have been chosen from the thermodynamic modeling. The properties of the films prepared have been investigated using ellipsometry, scanning electron microscopy, X-ray photoelectron spectroscopy, IR spectroscopy, and synchrotron X-ray powder diffraction. It has been established that the synthesis temperature substantially affects the kinetics of growth and physicochemical properties of silicon carbonitride layers in the range of synthesis conditions under investigation. The films prepared consist of nanoparticles whose size increases with increasing synthesis temperature. The refractive index of the films increases from 1.6 to 2.8 with an increase in the temperature.

High Molecular Weight Poly(methacrylic acid) with Narrow Polydispersity by RAFT Polymerization

Poly(methacrylic acid) is an adaptable macromolecule that offers many benefits in the development of new materials for a host of applications. Herein we report the reversible addition−fragmentation chain transfer (RAFT) polymerization of methacrylic acid (MAA) under a range of synthesis conditions by adjusting the ratio of reactants and the type of solvent employed. The RAFT system was composed of 4,4-azobis(cyanopentanoic acid) and 4-cyanopentanoic acid dithiobenzoate as the radical initiator (I) and chain transfer agent (CTA), respectively. This system was previously applied to synthesize MAA oligomers, but high molecular weight MAA homopolymers, to our knowledge, have yet to be reported. Three distinct [MAA]0:[I]0:[CTA]0 ratios (150:0.25:1, 250:0.25:1, and 150:0.1:1), in addition to two solvents (methanol and water/1,4-dioxane), initial monomer concentration and pH were evaluated and contrasted. It was determined that the polymerization evolved in a controlled fashion particularly in methanol. In addit...

Application of cluster analysis and optimization to determine the synthesis conditions of macroreticular poly(styrene-co-divinylbenzene) microparticles with enhanced structural and adsorption properties

Abstract A suitable porous structure and high mechanical strength are extremely valuable properties in adsorbent polymeric microparticles. To achieve this objective, macroreticular poly(styrene- co -divinylbenzene) microparticles with high amounts of cross-linker and diverse proportions of porogen agent were synthesized according to the methodology of the factorial design of experiments. The structural characteristics of the microparticles and their adsorption properties of a model macromolecule (bovine serum albumin (BSA)) were studied. From the results obtained, as well as those observed in previous works [C. Garcia-Diego, J. Cuellar, Synthesis of macroporous poly(styrene-co-divinylbenzene) microparticles using n -heptane as the porogen: quantitative effects of the DVB concentration and the monomeric fraction on their structural characteristics, Ind. Eng. Chem. Res. 44 (22) (2005) 8237–8247; C. Garcia-Diego, J. Cuellar, Determination of the quantitative relationships between the synthesis conditions of macroporous poly(styrene-co-divinylbenzene) microparticles and the characteristics of their behaviour as adsorbents using bovine serum albumin as a model macromolecule, Ind. Eng. Chem. Res. 45 (10) (2006) 3624–3632], it was decided to apply a cluster analysis to all the adsorbents with a view to determining the range of synthesis conditions that would allow the synthesis of microparticles with high mechanical strength and a porous structure appropriate for absorbing the BSA macromolecule. This range was found to be 0.50–0.60 for the monomeric fraction and 25.0–55.0% for the divinylbenzene concentration in the monomeric mixture. Additionally, through use of the desirability function, the results revealed that the adsorbent with the optimum adsorption characteristics, as regards both adsorption equilibrium and adsorption kinetics, should be synthesized with a DVB concentration of 42.5% and a monomeric fraction of 0.50.

A New Method for Direct Preparation of Tin Dioxide Nanocomposite Materials

In the current work, a novel combustion method is demonstrated for the direct synthesis of nanocomposite materials. Specifically doped tin dioxide (SnO2) powders were selected for the demonstration studies due to the key role SnO2 plays in semiconductor gas sensors and the strong sensitivity of doped SnO2 to nanocomposite properties. The synthesis approach combines solid and gas-phase precursors to stage the decomposition and particle nucleation processes. A range of synthesis conditions and four material systems were examined in the study: gold–tin dioxide, palladium–tin dioxide, copper–tin dioxide, and aluminum–tin dioxide. Several additive precursors were considered including four metal acetates and two pure metals. The nanocomposite materials produced were examined for morphology, phase, composition, and lattice spacing using transmission and scanning electron microscopy, x-ray diffractometry, and energy-dispersive spectroscopy. The results using the combustion synthesis approach indicate good control of the nanocomposite properties, such as the average SnO2 crystallite size, which ranged from 5.8 to 17 nm.

Guest/host relationships in zeolite synthesis: ring-substituted piperidines and the remarkable adamantane mimicry by 1-azonio spiro [5.5] undecanes

This paper explores the contribution to high silica zeolite syntheses based upon derivatives of a six-ring heterocycle, piperidine. The zeolite product selectivity can be rationalized in terms of the type and location of ring substitution in the derivatives studied as structure-directing agents (SDAs) in zeolite crystal growth. A number of new zeolite products were found as the substitution leads to spatially larger molecules. The pure phase MEL was produced by one very specific SDA. As well as the synthesis studies presented, a select group of derivatives built around the azaspiro [5.5] undecane architecture were also studied as to their hydrophobic transfer from water to chloroform during solvent partitioning studies. One surprising discovery was that a single spiro derivative produced five different zeolite products over a range of synthesis conditions, and these five zeolites were initially encountered in studies with a single adamantyl derivative. Attempts were made via molecular modeling to determine why these two disparate SDAs yield almost the same zeolite product selectivities.

A New Equilibrium Model for the Bazarov Urea Synthesis Process

A new equilibrium model for the high temperature and pressure Bazarov urea synthesis process is presented. By including the formation of ammonium hydroxide as an important equilibrium in the process the model can quantitatively predict the yield of urea under the following range of synthesis conditions: NH3/C02 ratios (L) greater than 2, when no excess water is added, in the temperature range 170-210�C. The model also predicts the observed maximum in urea yield with temperature for a given L> 2. New experimental data for L> 9 are presented that confirm the model's prediction that the yield of urea asymptotically approaches 100% at high L ratios. These data also reveal a pressure dependence for the urea yields which becomes more pronounced with increasing temperature and L ratio. In this region the agreement between theory and experiment is generally within 3% in the pressure range 30-50 MPa. Enthalpies of reaction for the formation of urea from ammonium carbamate and for the formation of ammonium hydroxide under urea synthesis conditions have been derived, and are 26 and -40 kJ mol-1 respectively, the former being in good agreement with a value estimated from literature data.