Search results for "Slurry"
showing 10 items of 44 documents
On-line microwave oven digestion flame atomic absorption analysis of solid samples
1990
Abstract A manifold has been developed for on-line microwave oven digestion and flame atomic absorption spectrometric (FAAS) determination of metallic elements in solid samples. The use of a closed flow system permits sample treatment before analysis by FAAS, the direct injection of slurries avoids a filtration step and the interconnection of two conventional rotary injection valves allows the rapid introduction of samples and standards. The determination of lead in sewage sludge was employed as a test system for the proposed on-line sample digestion manifold. The procedure has a limit of detection of 0.2 μg Pb g−1.
On-line speciation of mercury in fish by cold vapour atomic fluorescence through ultrasound-assisted extraction
2004
A fully mechanized procedure has been developed for the speciation of mercury in fish samples by using cold vapour atomic fluorescence spectrometry (CV-AFS). Sample slurries in an acid mixture in the presence of a surfactant and with traces of K2Cr2O7, were injected into a flow system, sonicated and merged with 1 ml of an oxidant mixture of KBr/KBrO3 heated at 50 °C in a water bath and total Hg determined by CV-AFS. Sonicated sample slurries were also measured, in the absence of KBr/KBrO3, in order to obtain a second series of data which could be employed to establish the concentrations of free Hg(II). Different compositions of the acidic extractant solutions were evaluated by mixing HCl, H…
Determination of As, Sb, Se, Te and Bi in milk by slurry sampling hydride generation atomic fluorescence spectrometry
2003
A simple and fast analytical procedure has been developed for the determination of As, Sb, Se, Te and Bi in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS). Samples were treated with aqua regia for 10min in an ultrasound water bath and pre-reduced with KBr for total Se and Te determination or with KI and ascorbic acid for total As and Sb, the determination of Bi being possible in all with or without pre-reduction. Slurries of samples, in the presence of antifoam A, were treated with NaBH(4) in HCl medium to obtain the corresponding hydrides, and AFS measurements were processed in front of external calibrations prepared and measured in the same way as samples. Re…
Direct FIA—AS determination of potassium and magnesium in cement samples by use of the slurries approach
1992
A direct procedure has been developed for the flame atomic determination of potassium and magnesium in cement samples. A 50-mg sample is dispersed in 25 ml of 0.13M nitric acid; 100 mul of this slurry is injected in a double channel FIA manifold simultaneously with 100 mul of a 10% (w/v) lanthanum solution. This procedure allows the rapid extraction of potassium and magnesium by leaching of the sample; nitric acid is not necessary if only potassium must be determined and the sample can be diluted with only distilled water. Aqueous standards are used. The manifold employed includes a well-stirred mixing chamber, which provides an adequate on-line dilution of the sample, in order to obtain em…
Chlorophenanthrenes, alkylchlorophenanthrenes and alkylchloronaphthalenes in kraft pulp mill products and discharges
1994
Abstract Chlorinated phenanthrenes (PCPHs; P=1–5), alkylphenanthrenes (C4-PCPHs; P=1–3), dimethylnaphthalenes (C2-PCNs; P=1–4) and trimethylnaphthalenes (C3-PCNs; P=1–2) were analyzed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) in pulp, effluent and biosludge of two kraft pulp mills (mills 1 and 2). These compounds were indicated to be formed in the manufacture of both bleached hardwood and softwood kraft pulp. Different compound groups dominated in mill 1 samples compared to mill 2 samples. Differences between birch and pine pulp from mill 1 were observed for all substance groups but in mill 2 pulp only for PCPHs. The highest concentrations of PCPHs …
Organometallic vanadium‐based heterogeneous catalysts for ethylene polymerization. Study of the deactivation process
1998
Slurry polymerizations of ethylene over vanadium catalysts (based on VCl4 and VOCl3) and their MgCl2(THF)2-supported equivalents were studied. Unsupported vanadium catalysts were found to be unstable while the vanadium active sites deposited on the MgCl2(THF)2 complex are stable. A sharply outlined correlation was found between the concentration of vanadium(III) and catalyst productivity. The high activity and stability of the vanadium catalyst when supported on the magnesium complex is attributed to the increase of resistance to reduction of active vanadium(III) to inactive vanadium(II) by an organoaluminium co-catalyst.
Rapid on-line sample dissolution assisted by focused microwave radiation for silicate analysis employing flame atomic absorption spectrometry: iron d…
2004
An on-line automated flow injection system with microwave-assisted sample digestion was used to perform silicate rock dissolution in acid medium for iron determination. For this purpose, a continuous flow system was built up by using an automatic flow injection analysis (FIA) system coupled to a flame atomic absorption spectrometer (FAAS), including a focused microwave oven unit. Inside the microwave cavity was inserted a polytetrafluoroethylene (PTFE) reactor coil (300cm length and 0.8mm i.d.) where the dissolution takes place. Chemical and flow variables as well as iron determination parameters were studied. In the flow system, a slurry of the rock sample (50mg in 200ml of acid mixture HF…
Slurries Introduction in Flow Injection Atomic Absorption Spectroscopic Analysis of Sewage Sludges
1990
Abstract The direct introduction of slurries in flow Injection-flame atomic absorption spectroscopy has been studied using a single-channel manifold. The influence of flow Injection parameters on the sensitivity and accuracy of this procedure has been established. A method has been developed for the determination of copper, manganese, and lead In sewage sludge where batch digestion of the samples In a microwave oven is carried out before dilution. Both sensitivity and limit of detection of the flow Injection analysis procedure are adequate for the analysis of actual samples (the limit of detection was 0.06, 0.05, and 0.3 ppm for copper, manganese, and lead, respectively). The accuracy of th…
Hydrocarbons removal from real marine sediments: Analysis of degradation pathways and microbial community development during bioslurry treatment
2022
In this study, real marine sediments polluted by petroleum compounds were treated by means of a bioslurry pilot scale reactor. The treatment performance was evaluated by measuring the removal of total petroleum hydrocarbon (TPH), coupled to further analyses required to understand the mechanisms involved in the biodegradation process. The maximum TPH-removal efficiency reached 86 % at the end of experiments. Moreover, high throughput 16S RNA gene sequencing was used to describe the microbiome composition in sediment prior to, and after, bioslurry treatment, in order to identify the taxa mostly entailed in the TPH removal process. The raw sediment was mostly colonized by members of Sulfurimon…
Physical and mechanical properties of sustainable hydraulic mortar based on marble slurry with waste glass
2021
This paper aims to propose and characterize a sustainable hydraulic mortar entirely obtained by the reuse of waste materials, with marble slurry coming from quarries in the north-western Sicily and glass powder coming from a waste collection plant in Marsala (Province of Trapani). The first was used as raw material to produce the mortar binder by a kilning and slaking process, while the second was used as a pozzolanic additive. The chemical and morphological characterization of the marble slurry was done by XRD, FTIR, STA and SEM analyses. Glass powder was analyzed through particle size distribution measurements, XRD and standard pozzolanic tests. Hydraulic mortars constituted by slaked lim…