Novel miniaturized sensors for potentiometric batch and flow-injection analysis (FIA) of perchlorate in fireworks and propellants

Three planar miniaturized perchlorate membrane sensors (3×5mm2) are prepared using a flexible Kaptan substrate coated with nitron-perchlorate (NT-ClO4) [sensor 1], methylene blue-perchlorate (MB-ClO4) [sensor II] and indium-porphyrin (In-Por) [sensor III] as electroactive materials in PVC membranes plasticized with 2-NPPE. Sensors I, II and III display near-Nernstian response for 1.0×10−5–1.0×10−2, 3.1×10−5–1.0×10−2 and 3.1×10−6–1.0×10−2molL−1ClO4− with lower detection limits of 6.1×10−6, 6.9×10−6 and 1.2×10−6molL−1, and anionic calibration slopes of 50.9±0.4, 48.4±0.4 and 57.7±0.3mV decade−1, respectively. Methods for determining perchlorate using these sensors offer many attractive advantages including simplicity, flexibility, cost effectiveness, wide linear dynamic response range (0.1–1000ppm), low detection limit (<1.2×10−6molL−1≡0.1ppm), small sample test volume (100μL), safety, short response time (<20s), long life span (~8 weeks), and extended wide working pH range (4.5–8.0). The sensors show high selectivity in the presence of some inorganic ions (e.g., PO43−, SO42−, S2O32−, NO2−, NO3−, N3−, CN−, Cl−, Br−, I−) and automation feasibility. Indium-porphyrin based membrane sensor (sensor III) is used as a detector in a wall-jet flow injection set-up to enable accurate flow injection analysis (FIA) of perchlorate in some fireworks without interferences from the associated reducing agents (sulfur and charcoal), binders (dextrin, lactose), coloring agents (calcium, strontium, copper, iron, sodium), color brighten (linseed oil) and regulators (aluminum flakes) which are commonly used in the formulations. The sensor is also used for perchlorate assessment in some propellant powders. The results fairly agree with data obtained by ion-chromatography

Fluctuations of Pythium fluminum var. fluminum in pond water

Population densities of Pythium fluminum Park var. fluminum (P. fluminum) in pond water are given for a year sampling period. Colony number per liter ranged from 0 to 260. A fluctuation in population density is clearly detectable being highest in winter and decreasing gradually until reached zero in summer. When the pond water temperature exceeded 25℃ the fungus was not detected. P. fluminum is different from any other species of Pythium in its capability for decomposing insoluble cellulose and reducing the filter paper weight by 20% in one month. A quantitative estimation of this fungus can be carried out by filtering pond water through filter paper circles using suction force. The filter papers were then seeded on CPV selective medium. After keeping for two weeks at 15℃, the pale salmon pink colonies could easily be counted

Understanding ethanol hydrogen abstraction mechanism on CuNi catalyst

In this work we report the synthesis of copper oxide nanoparticles using solution combustion synthesis. These nanopowders are used as catalyst in ethanol decomposition reaction for hydrogen production. In situ study of ethanol decomposition has been conducted in FTIR using DRIFTS reactor at temperature of 50°C and 400°C over the reduced catalyst obtained after passing H2 at 300°C for one hour. XRD, SEM and TEM analysis were conducted to identify the phase and morphology of catalyst before and after reaction.Qatar Foundation;Qatar National Research Fund;Qatar UniversityScopu

Understanding ethanol hydrogen abstraction mechanism on CuNi catalyst

In this work we report the synthesis of copper oxide nanoparticles using solution combustion synthesis. These nanopowders are used as catalyst in ethanol decomposition reaction for hydrogen production. In situ study of ethanol decomposition has been conducted in FTIR using DRIFTS reactor at temperature of 50°C and 400°C over the reduced catalyst obtained after passing H2 at 300°C for one hour. XRD, SEM and TEM analysis were conducted to identify the phase and morphology of catalyst before and after reaction.Qatar Foundation;Qatar National Research Fund;Qatar UniversityScopu

Study of reaction mechanism in solution combustion synthesis of transition metals

In this paper, we investigate the reaction mechanism followed during the solution combustion synthesis of transition metals (Cu, Ni and Co) and their alloys. Metal nitrates were mixed with a choice of fuel (glycine, and urea) and mixed in deionized water to get a homogeneous mixture of solution with uniform properties. The solution thus obtained is heated to initiate the highly exothermic combustion reaction resulting in the synthesis of metals/metal-oxides. TGA-DTA analysis of the reactants (metal-nitrates, fuel, and cellulose) along with the XRD of the final products obtained helped in deducing the reaction mechanism.Scopu