black precipitate
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2021 ◽  
Vol 6 (2) ◽  
pp. 99-102
Author(s):  
Rahmadani ◽  
Tuti Alawiyah ◽  
Rina Herowati

Background: Impurities produced from the basic ingredients of making cosmetics, one of which is lead (Pb). Lead is a substance that is harmful and toxic to the human body. Lead can affect the hematopoetic system, nervous system, reproductive system, endocrine system and is carcinogenic. Objective: To determine the presence of lead (Pb) heavy metal contamination in mascara products circulating in the Banjarmasin traditional market. Methods: This study used a descriptive observational method. Testing qualitatively using KI, NaOH, and HCl reagents. Results: The test results obtained from the sample after being reacted with the three reagents showed a positive presence of lead (Pb) heavy metal. With KI solution shows a yellow-black precipitate, with NaOH solution shows a white precipitate and with HCl solution shows a white precipitate. Conclusion: Qualitative tests on mascara cosmetic products taken at different points of sale in the Banjarmasin traditional market using color reagents in KI solution, NaOH solution, and HCl solution, it can be concluded that the qualitative test results show a positive presence of heavy metal lead (Pb). on mascara products.



Author(s):  
Michael Watson ◽  
Benjamin White ◽  
Joseph Lanigan ◽  
Tom Slatter ◽  
Roger Lewis

Every autumn rail networks across the world suffer delays, accidents and schedule changes due to low friction problems caused by leaves landing on the rails. These leaves form a layer that can reduce the friction between the wheel and the rail to a similar level as that between ice and an ice-skate ( μ = 0.01 – 0.05 ). Previous works have generated several hypotheses for the chemical reactions and low friction mechanism associated with these layers. In this work, the reaction between an aqueous extract of sycamore leaves and metallic iron is investigated. This reaction has been shown to produce a black precipitate, which matches field observations of leaf layers, while friction tests with these extracts produce characteristic ultra low friction. The reaction is investigated through FTIR, XPS, CHNS and ICP-MS analysis as well as wet chemical testing. The impact of the reaction on friction is investigated through three rounds of tribological testing. The results indicate that the black precipitate produced is iron tannate, formed by complexation of tannins with dissolved iron ions. Friction testing showed that eliminating tannins from the leaf extract resulted in a significant increase in the friction coefficient compared with the control.



2020 ◽  
Vol 1000 ◽  
pp. 203-209
Author(s):  
Ahmad Fadli ◽  
Amun Amri ◽  
Esty Octiana Sari ◽  
Sukoco Sukoco ◽  
Deden Saprudin

Magnetite nanoparticles have been successfully prepared by hydrothermal method from FeCl3 as starting material. The properties and morphology of the products with different synthesis time and FeCl3 concentration were investigated. Firstly, the FeCl3 with concentration of 0.05 – 0.15 M and 0.10 M sodium citrate as well as 0.15 M were mixed with distilled water containing 0.1 g polyethylene glycol. Subsequenly, the solution was transferred into a Teflon-lined autoclave and it heated into an oven at 210°C for 12 hours. The black precipitate that formed was separated by a bar magnet, then washed with water and ethanol, and dried at 60°C overnight. The magnetite formation begun at 3.5 hours synthesis time with crystal diameter in range of 9.4-30 nm. The crystallinity and crystal size of magnetite increased with reaction time and concentration of FeCl3. The magnetite nanoparticles had a mesoporous structure and bigger pores at higher concentration. The saturation magnetization (Ms) of magnetite was in the range of 59 – 81 Emu/g with coercivity value was near to zero showing that magnetite nanoparticle had superparamagnetic properties.



2019 ◽  
Vol 43 (9-10) ◽  
pp. 367-379 ◽  
Author(s):  
M John Plater ◽  
Andrea Raab

Mauveine chromophores and a family of phenosafranins have been extracted from the Colour Experience Museum black precipitate with boiling ethanol and separated by chromatography. Phenosafranin (287.1295), monomethylphenylsafranin (301.1452) and a dimethylphenosafranin (315.1609) were observed. Tentative evidence for small quantities of N- tert-butylmauveine A and N- tert-butylmauveine B has been found by comparison of the data to standard retention times and accurate mass data. A synthetic method which reproduces the composition of mauveine extracted from the black precipitate, which is rich in mauveine A, is described.



Synthesis ◽  
2018 ◽  
Vol 50 (07) ◽  
pp. 1499-1510 ◽  
Author(s):  
Wei Chen ◽  
Xiao-Yan Lu ◽  
Bei-Hua Xu ◽  
Wei-guo Yu ◽  
Zi-niu Zhou ◽  
...  

Eight precatalysts containing carboxylic-functionalized thiourea ligands are prepared and their activities and recyclability are evaluated in aerobic aqueous Suzuki–Miyaura reactions. A bulky monothiourea–Pd complex, functionalized with four carboxylic groups, shows the best activity and recyclability in the coupling of aryl bromides with arylboronic acids. The catalyst can be reused at least five times without any significant reduction in its catalytic activity. TEM analysis and the confirmed catalytic activity of the observed black precipitate reveal that Pd nanoparticles are formed during the reactions and are stabilized by the carboxylic-functionalized thiourea ligands.



2001 ◽  
Vol 67 (10) ◽  
pp. 4583-4587 ◽  
Author(s):  
Gilles De Luca ◽  
Pascale de Philip ◽  
Zorah Dermoun ◽  
Marc Rousset ◽  
André Verméglio

ABSTRACT Resting cells of the sulfate-reducing bacteriumDesulfovibrio fructosovorans grown in the absence of sulfate had a very high Tc(VII)-reducing activity, which led to the formation of an insoluble black precipitate. The involvement of a periplasmic hydrogenase in Tc(VII) reduction was indicated (i) by the requirement for hydrogen as an electron donor, (ii) by the tolerance of this activity to oxygen, and (iii) by the inhibition of this activity by Cu(II). Moreover, a mutant carrying a deletion in the nickel-iron hydrogenase operon showed a dramatic decrease in the rate of Tc(VII) reduction. The restoration of Tc(VII) reduction by complementation of this mutation with nickel-iron hydrogenase genes demonstrated the specific involvement of the periplasmic nickel-iron hydrogenase in the mechanism in vivo. The Tc(VII)-reducing activity was also observed with cell extracts in the presence of hydrogen. Under these conditions, Tc(VII) was reduced enzymatically to soluble Tc(V) or precipitated to an insoluble black precipitate, depending on the chemical nature of the buffer used. The purified nickel-iron hydrogenase performed Tc(VII) reduction and precipitation at high rates. These series of genetic and biochemical approaches demonstrated that the periplasmic nickel-iron hydrogenase of sulfate-reducing bacteria functions as a Tc(VII) reductase. The role of cytochromec 3 in the mechanism is also discussed.



1997 ◽  
Vol 35 (5) ◽  
pp. 293-299 ◽  
Author(s):  
Wendy R. Tyrrell ◽  
David R. Mulligan ◽  
Lindsay I. Sly ◽  
L. Clive Bell

The large number of wetlands treating mining wastewaters around the world have mostly been constructed in temperate environments. Wetlands have yet to be proven in low rainfall, high evaporation environments and such conditions are common in many parts of Australia. BHP Australia Coal is researching whether wetlands have potential in central Queensland to treat coal mining wastewaters. In this region, mean annual rainfall is < 650 mm and evaporation > 2 000 mm. A pilot-scale wetland system has been constructed at an open-cut coal mine. The system comprises six treatment cells, each 125 m long and 10 m wide. The system is described in the paper and some initial results presented. Results over the first fourteen months of operation have shown that although pH has not increased enough to enable reuse or release of the water, sulfate reduction has been observed in parts of the system, as shown by the characteristic black precipitate and smell of hydrogen sulfide emanating from the wetlands. These encouraging signs have led to experiments aimed at identifying the factors limiting sulfate reduction. The first experiment, described herein, included four treatments where straw was overlain by soil and the water level varied, being either at the top of the straw, at the top of the soil, or about 5 cm above the soil. The effect of inoculating with sulfate-reducing bacteria was investigated. Two controls were included, one covered and one open, to enable the effect of evaporation to be determined. The final treatment consisted of combined straw/cattle manure overlain with soil. Results showed that sulfate reduction did occur, as demonstrated by pH increases and lowering of sulfate levels. Mean pH of the water was significantly higher after 19 days; in the controls, pH was < 3.3, whereas in the treatments, pH ranged from 5.4 to 6.7. The best improvement in sulfate levels occurred in the straw/cattle manure treatment.



1994 ◽  
Vol 59 (11) ◽  
pp. 2375-2382 ◽  
Author(s):  
Simon Krásenský ◽  
Marie Studničková

The electroreduction of neutral aqueous solutions of 0.1 - 0.5 M Et4NBF4 on a mercury cathode at room temperature at -2.8 - -2.4 V produces a black precipitate of Et4N . Hgx with simultaneous evolution of hydrogen (the pH value increases to 12). No anodic oxidation of the amalgam has been observed in the interval of 0 - 2.8 V. The composition of the precipitate, collected by filtration under nitrogen, has been determined from the decrease of Et4N+ in the solution after electrolysis and from analysis of mercury in the binary compound Et4N . Hgx. The value x = 2.9 ± 0.8 has been found.



Author(s):  
Donna M. Brandelik ◽  
Richard L. Sutherland ◽  
Hao Jiang ◽  
Pamela Lloyd ◽  
W. Wade Adams

Investigation of laser irradiated purple C60/toluene solutions revealed a photochemical change of the solution at high incident laser fluences. The initial purple solution turned pink and a black precipitate formed which was insoluble in toluene. Interaction at the cell surface was indicated as cell damage occurred before the solution changes were seen. Subsequent chemical analysis by Mass Spectroscopy showed that the pink solution contained C60 and adducts. The black precipitate was found to contain no C60, but instead contained only adducts and lower fuller-enes NMR on the pink solution revealed a SiCHx peak as evidence of glass etching.Scanning electron microscopy revealed needle crystals from a pure C60 sample, in figure 1. Figure 2 shows the crystals from the pink solution. The black precipitate appears to have a porous,very grainy texture and lacks the crystalline structure of the other samples (figure 3). All three samples were deposited on carbon coated grids. The pyrex glass cell was damaged by the laser and showed an etching pattern (figure 4).



1992 ◽  
Vol 29 (4) ◽  
pp. 308-315 ◽  
Author(s):  
S. Ekman ◽  
Y. Ridderstråle

The histochemical localization of carbonic anhydrase in the normal and osteochondrotic epiphyseal growth cartilage from 15 growing pigs (6 to 18 weeks old) was studied. All animals were clinically normal. The entire thickness of the articular-epiphyseal cartilage complex from the femoral condyles was fixed in 2% glutaraldehyde and embedded in a water-soluble glycolmethacrylate. Sections (1–2 μm) were incubated on the surface of a medium containing cobalt, phosphate, and bicarbonate. A black precipitate formed at sites of enzymatic activity. This method shows the activity of all different isoenzymes of carbonic anhydrase. The specificity was checked by adding the carbonic anhydrase inhibitor acetazolamide to the incubation medium. Osteochondrosis in the epiphyseal growth cartilage was characterized by chondronecrotic areas in resting, proliferative, hypertrophic, and calcifying regions. When the hypertrophic and calcifying regions were involved, insufficient cartilage calcification and focally impaired ossification were seen. The chondronecrotic areas were surrounded by groups of morphologically viable cells, or so-called “clusters.” Carbonic anhydrase was present in chondrocytes of hypertrophic and calcifying regions of the normal growth cartilage and in osteoclasts and erythrocytes. No evidence of carbonic anhydrase activity was found in the articular cartilage or in the resting region of normal growth cartilage in any of the pigs. No enzyme activity was found in the osteochondrotic cartilage, either in clusters or dead cells. The lack of carbonic anhydrase in the osteochondrotic cartilage demonstrated in this study may result in an inability to produce the alkaline matrix necessary for calcification and could be one reason for the insufficient calcification typical of this cartilage.



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