Search results for "ammonium"
showing 10 items of 1070 documents
Iodine determination in food samples using inductively coupled plasma isotope dilution mass spectrometry.
1998
Two different sample treatment methods are used in connection with inductively coupled plasma isotope dilution mass spectrometry for accurate and precise determinations of iodine traces in food samples. 129I-enriched iodate is applied as a spike compound for the isotope dilution step. Extraction of iodine by tetramethylammonium hydroxide (TMAH) solution at high temperatures in a closed vessel is one of the sample treatment methods. The other one is a complete decomposition of the sample with a mixture of perchloric acid and nitric acid using microwave assistance. By analyzing different certified reference materials (three milk powders with different iodine levels, BCR CRM 63, 150, and 151; …
Post-elution processing of 44Ti/44Sc generator-derived 44Sc for clinical application
2009
The (44)Ti/(44)Sc (T(1/2)(44)Ti=60a) generator provides cyclotron-independent access to positron-emitting (44)Sc (T(1/2)=3.97d) for PET imaging. This work aims to post-elution processing of initial (44)Sc generator eluates in order to reduce its volume, HCl concentration and remove the oxalate anions. The on-line adsorption of (44)Sc on cationic resin AG 50W-X8 (200-400 mesh, H(+)-form) is achieved with >98% efficacy. Subsequently, the purified (44)Sc is desorbed by using 3ml of 0.25M ammonium acetate (pH=4.0). The post-processing takes 10min. The overall yield of the post-processing reached 90%, which is referred to the (44)Sc obtained from the (44)Ti/(44)Sc generator. In addition to the c…
Efficient vacuum deposited p-i-n and n-i-p perovskite solar cells employing doped charge transport layers
2016
Methylammonium lead halide perovskites have emerged as high performance photovoltaic materials. Most of these solar cells are prepared via solution-processing and record efficiencies (>20%) have been obtained employing perovskites with mixed halides and organic cations on (mesoscopic) metal oxides. Here, we demonstrate fully vacuum deposited planar perovskite solar cells by depositing methylammonium lead iodide in between intrinsic and doped organic charge transport molecules. Two configurations, one inverted with respect to the other, p-i-n and n-i-p, are prepared and optimized leading to planar solar cells without hysteresis and very high efficiencies, 16.5% and 20%, respectively. It is t…
Thermal regeneration of ammonium bi-carbonate solutions for closed-loop reverse electrodialysis
2016
Reverse electrodialysis is a novel technology that exploits a salinity gradient to generate electrical energy. The salinity gradient can be available from natural waters such as seawater and river water or they can be artificially generated and used within closed-loop applications. This last option has been recently investigated leading to the development of the RED heat engine concept. In this case, the deployed salinity gradient exiting the RED unit is regenerated in a thermally-driven unit using low-temperature heat, thus being able to convert heat to power within an integrated system. Among the different regeneration alternatives, the use of thermolytic salts has been presented as a pro…
Eh and pH gradients in Camembert cheese during ripening: Measurements using microelectrodes and correlations with texture
2007
International audience; This study investigated the use of microelectrodes to continuously and simultaneously monitor pH and redox potential (Eh) gradients in Camembert cheeses from the rind to the core, as a function of ripening time (15 and 35 days). Cheeses were shown to be heterogeneous throughout their mass. An Eh gradient existed from the rind to the core. The surface was oxidizing (+330 to +360 mV) and the core was reducing and became more so in the course of ripening (−300 to −360 mV). A relationship between firmness and Eh was shown. pH gradients were in line with those previously described in the literature and related to ammonium and lactate gradients. Gradients evolved from the …
Comparison between kinetics of autochthonous marine bacteria in activated sludge and granular sludge systems at different salinity and SRTs.
2019
Biological nutrient removal performances and kinetics of autochthonous marine biomass in forms of activated sludge and aerobic granular sludge were investigated under different salinity and sludge retention time (SRT). Both the biomasses, cultivated from a fish-canning wastewater, were subjected to stepwise increases in salinity (+2 gNaCl L−1), from 30 gNaCl L−1 up to 50 gNaCl L−1 with the aim to evaluate the maximum potential in withstanding salinity by the autochthonous marine biomass. Microbial marine species belonging to the genus of Cryomorphaceae and of Rhodobacteraceae were found dominant in both the systems at the maximum salinity tested (50 gNaCl L−1). The organic carbon was remove…
Comparison between moving bed-membrane bioreactor (MB-MBR) and membrane bioreactor (MBR) systems: Influence of wastewater salinity variation
2014
Two pilot plant systems were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were analyzed. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the por…
Short-term effect of ammonia concentration and salinity on activity of ammonia oxidizing bacteria.
2010
A continuously aerated SHARON (single reactor high activity ammonia removal over nitrite) system has been operated to achieve partial nitritation. Two sets of batch experiments were carried out to study the effect of ammonia concentration and salinity on the activity of ammonia-oxidizing bacteria (AOB). Activity of AOB raised as free ammonia concentration was increased reaching its maximum value at 4.5 mg NH 3 -N l −1 . The half saturation constant for free ammonia was determined (K NH 3 = 0.32 mg NH 3 -N l −1 ). Activity decreased at TAN (total ammonium–nitrogen) concentration over 2,000 mg NH 4 -N l −1 . No free ammonia inhibition was detected. The effect of salinity was studied by adding…
Cellulose Nanocrystals from Lignocellulosic Raw Materials
2017
Cellulose nanocrystals (CNCs) are unique, renewable top-down nano particles from which coatings with improved gas barrier properties and new functionalities can be prepared. In this paper, the potential for obtaining such high performing nanocrystals from low-cost lignocellulosic by-products or raw materials is proved by a comparison study on CNCs obtained both from cotton linters and kraft pulp, by means of the ammonium persulfate (APS) process. Morphological and chemical characterization of the nanocrystals obtained, as well as the main functional properties of the poly(ethylene terephthalate) coated films, showed quite similar characteristics and performances of CNCs obtained from pure c…
Influence of application method on the use of ammonium phosphate as preservative
2018
This work deals with the application of the Ammonium Hydrogen Phosphate as preservative and consolidant during the restoration and consolidation intervention on a twin columns group in the east side of the Santa Maria La Nova Cloister in Monreale, UNESCO Heritage from 2016. The Superintendency for Fine Arts in Palermo prescribes the use of ammonium phosphate as the only acceptable material for the consolidation of the Cloister, so this work deals with the influence of application method and solution concentration on the results achievable with this material. Particularly as the treatment have to be done on vertical surfaces the use of a supporting material is mandatory so the focus is on th…