Weight For Pb Research Articles

Elemental Analyses and Determination of Lead Content in Kohl (Stone) by Laser-Induced Breakdown Spectroscopy

Elemental analyses of kohl (stone) samples collected from three different parts of the world were performed using laser-induced breakdown spectroscopy (LIBS). The analyses indicated that lead (Pb), copper (Cu), silver (Ag), iron (Fe), calcium (Ca), aluminum (Al), silicon (Si), and sodium (Na) were present in all the kohl samples. In addition to these elements, the sample from Madina, Kingdom of Saudi Arabia (KSA), contained the elements tin (Sn), zirconium (Zr), and antimony (Sb). The sample from Mount Toor, Egypt, also contained Sn. Also, quantitative analysis for lead was carried out by the standard addition method using the LIBS technique. The result showed the presence of 14.12 ± 0.28% by weight of Pb in the sample from Madina, which compares well with the measurement done using atomic absorption spectroscopy (AAS) (13.31 ± 0.46%). The standard addition method used three calibration curves drawn for three emission lines of the LIBS spectra of Pb. The limits of detection (LoD) for these calibration curves varied from 0.27% to 1.16% by weight. The lead contents of the samples from Mount Toor and the local market of Bangladesh were also measured by the AAS technique, and the results were 14.61 ± 0.48% and 8.98 ± 0.35% by weight, respectively. The reason for determining only the lead content in kohl, which may be used as an eye cosmetic, is the adverse effect that lead has on health.

Effects of aqueous garlic (Allium sativum) extract on testicular morphology and function in lead nitrate (Pb(NO3)2)-treated albino rats

This study investigated the effects of aqueous garlic extract (Allium sativum) on testicular morphology and function in lead nitrate (Pb(NO3)2)-treated albino rats. Twenty four male albino rats, divided randomly into four groups of six rats per group, were used. Group A rats served as the control and received neither Pb(NO3)2 nor aqueous garlic extract (AGE) treatment. The treatments to the remaining three rat groups were as follows: group B, 300 mg/kg body weight of AGE; group C, 2 mg/kg body weight of Pb(NO3)2; and group D, 2 mg/kg body weight of Pb(NO3)2, and 300 mg/kg body weight of AGE 2 h later. Both the AGE and Pb(NO3)2 were orally given to these rats every 48 h for a period of 6 weeks. The testicular and epididymal (left and right sides) sperm reserves and the histomorphological features of the testes of the rats in the treatment groups were compared to the control rats. Results showed that testicular and epididymal sperm reserves were significantly (P < 0.05) reduced in rats that received only Pb(NO3)2 treatment. AGE ameliorated the changes in testicular morphology and function associated with Pb(NO3)2 treatment in group D rats. Garlic in this study enhanced spermatogenesis as evidenced from the significant (P < 0.05) increase in the epididymal (left and right sides) sperm reserves of the group B rats. This implies that garlic may serve as an agent that could be used in improving male fertility.

Levels of trace metals in soil and vegetation along major and minor roads in metropolitan city of Kaduna, Nigeria

Sample of soil and plant (Sida acuta burm F.) were collected from 30 sites of 24 roads. The samples were analyzed for Pb, Cd, Zn, Cu and Mn using flame atomic absorption spectrophotometry. The soil physico-chemical parameter, pH and particle size distribution was also determined. Levels of Pb, Cd, Zn, Cu and Mn in soil were 15.28 – 76.92, 1.96 – 9.80, 41.66 – 237.96, 1.60 – 4.88 and 76.00 – 132.00 mg/kg dry weight, respectively. Results of concentrations in plants ranged were from trace – 32.37, 4.88 – 14.93, 27.78 – 185.19, 1.67 – 3.89 and 20.00 – 110.00 mg/kg dry weight for Pb, Cd, Zn, Cu and Mn, respectively. The soil pH was from 6.22 – 8.44 while sand and loamy sandy textural classes constitute the soil samples. For both experimental soil and plant samples, the mean concentrations were found to follow the decreasing orders; Zn > Mn > Pb > Cu > Cd and Zn > Mn > Pb > Cd > Cu, respectively. Mild correlation between traffic density and metals in samples with the exception of plant Pb content, suggest that automobile emission couple with waste dispose along the roads remain a threat. The findings in general indicate the levels of metals in soil and plant samples were within the EU limits with the exception of Cd. In addition, the high level of Cd appears to reach pollution levels and metal dynamics up the food chain is highly possible. Key words: Trace metals, soil, plant, metropolitan.

Seashells: Detoxifying Agents for Metal-Contaminated Waters

Effective treatments of industrial waste streams and toxic spills containing heavy metals depend on the rapid removal of high concentrations of metal ions. Here we describe such a method using minimally-processed waste mollusk and crustacean exoskeletons. The process of metal extraction and immobilization was studied using atomic absorption, SEM/EDAX, and x-ray diffraction to investigate both solution and mineral phases. Compared to calcium carbonates of geologic origin, biomineralized shell materials exhibit extremely rapid sequestration of metal ions: a 10,000 mg L−1 Pb solution for example, can be reduced to less than about 0.5 mg L−1 in five minutes using comminuted shell of clam (M. mercenaria), while at higher initial concentrations, both clam and oyster (C. virginica) shell can extract almost twice their weight of Pb. The uptake mechanism involves the exchange of Ca for Pb in the inorganic fraction of the shell structure. Results highlight the importance of both surface area and the presence of the organic matrix of biominerals in determining the rate and quantity of metal ions abstracted, and the uniquely coherent residues produced in the process.

Degradation of Ferroelectric Pb(Zr,Ti)O3 Under Reducing Conditions

AbstractThe degradation mechanism of Pb(Zr,Ti)O3 (PZT) under reducing conditions was revealed. In contrast to the significant decrease in the sample weight of SrBi2Ta2O9 due to decomposition, the weight of Pb(Zr,Ti)O3 samples change little during H2-annealing at typical process temperatures. Although no apparent changes were detected by thermogravimetric and x-ray diffraction measurements after annealing, the PZT material did actually change. The main mechanism of the degradation is introduction of oxygen defects into the materials. The oxygen defects produce a donor level within the band gap, and light absorption by this donor level accounts for the change in sample appearance from white to black. Different endurance behaviors of materials against reducing conditions were also found: PbZrO3 decomposes through oxygen dissociation more easily than PbTiO3. Oxygen atoms in PbZrO3 are more weakly bonded to Zr than to Ti in PbTiO3 because of a significant anti-bonding component in the hybridized orbitals.

The shell as a site of lead deposition inHelix aspersa

Snails from a contaminated urban car park were fed an experimental diet for 64 days. One group received a high Pb diet for the duration, and another group were removed from the high Pb diet after two days. Shells were analyzed at various intervals to measure Pb uptake and loss. Regression analysis of twenty-eight shells for each treatment suggests that the weight of Pb in the shell increased linearly with time, but loss from the shell was correlated with soft tissue Pb levels. The shells of fourteen snails from an uncontaminated site accumulated Pb less quickly on the high Pb diet, and had lower Mg and Ca concentrations. All snails lost Mg from the shell following the initial dose, possibly as part of a detoxification mechanism for heavy metals. The shell may lose Pb over a number of days, serving as a short-term sink for Pb which it releases when soft tissue concentrations fall.

The vapour pressure of solutions saturated with silver nitrate and with lead nitrate

AbstractThe vapour pressure of the four‐phase equilibrium solid AgNO3‐solid Pb(NO3)2‐saturated solution‐water vapour was measured from 10° C to the end point of this four‐phase line. This end‐point is the eutectic of the binary system AgNO3‐Pb (NO3)2. This eutectic was subjected to exact investigation; the eutectic temperature was found to lie at 203.1° C, while the eutectic melt consists of 92.8 percent by weight of AgNO3 and 7.2 percent by weight of Pb (NO3)2.The measured vapour pressure line appears to possess 2 stable maxima, namely at 155.8°C and at 163.1° C; the corresponding values of the vapour pressure are 824 and 822 mm Hg, respectively.This system exhibits the phenomenon of 2 boiling points at atmospheric pressure, namely at 140.9° C and at 176.1° C.Neither the presence of 2 stable maxima, nor the occurrence of 2 boiling points (at 1 at) had till now ever been observed in solutions saturated with two salts.

The vapour pressure of solutions saturated with lead nitrate and ammonium nitrate

AbstractThe vapour pressure of the four‐phase equilibrium: solid Pb (NO3)2‐solid NH4,NO3‐saturated aqueous solution‐water vapour, was measured from 10° C to the end‐point of the four‐phase curve. That end‐point is the eutectic point of the binary system Pb (NO3)2‐NH4NO3. This eutectic point was accurately determined and found to lie at a temperature of 133.8° C and a composition of 32.1 percent by weight of Pb(NO3)2 and 67.9 percent by weight of NH4NO3.The vapour pressure curve measured has a maximum at a temperature of 102.1° C and a pressure of 114.4 mm Hg.Miss Korvezee and DingemansMiss A. E. Korvezee and P. Dingemans, Rec. trav. chim. 62, 625 (1943). previously discovered that for binary systems the relative vapour pressure of aqueous solutions saturated with one salt is in many cases a linear or almost linear function of the temperature. This rule is found to hold also for the ternary system now investigated, consisting of an aqueous solution saturated with respect to two salts, as well as for all other ternary salt systems previously measured in this laboratory.