Chrysophanol attenuates lead exposure-induced injury to hippocampal neurons in neonatal mice

Previous studies have shown that chrysophanol protects against learning and memory impairments in lead-exposed adult mice. In the present study, we investigated whether chrysophanol can alleviate learning and memory dysfunction and hippocampal neuronal injury in lead-exposed neonatal mice. At the end of lactation, chrysophanol（0.1, 1.0, 10.0 mg/kg） was administered to the neonatal mice by intraperitoneal injection for 15 days. Chrysophanol significantly alleviated injury to hippocampal neurons and improved learning and memory abilities in the lead-poisoned neonatal mice. Chrysophanol also significantly decreased lead content in blood, brain, heart, spleen, liver and kidney in the lead-exposed neonatal mice. The levels of malondialdehyde in the brain, liver and kidney were significantly reduced, and superoxide dismutase and glutathione peroxidase activities were significantly increased after chrysophanol treatment. Collectively, these findings indicate that chrysophanol can significantly reduce damage to hippocampal neurons in lead-exposed neonatal mice.

Application of Audio-Magnetotelluric Method for Exploration the Concealed Ore-Bodies in Yuele Lead-Zinc Ore Feild, Daguan County, NE Yunnan Province, China

The results of recent mineral exploration in the Yuele lead-zinc mining area of Daguan County, northeastern Yunnan province, showed that there are much early Paleozoic strata under thick late Paleozoic strata in northeastern Yunnan province, where developed some hidden salt structures (SSs), often with lead-zinc polymetallic mineralization varying degrees along the tension torsional fault (belts) or fracture (joint). The ore-bodies belong to the epigenetic hydrothermal filling vein-type deposit, and the prospecting potential is great. In this area, the superficial mineralization information displayed clear, but the deep mineralization is unknown, so the exploration work is restricted. The audio-megnetotelluric (AMT) surveying is an advantageous method to characterize the size, resistivity and skin depth of the polarizable mineral deposit concealed beneath thick overburden. This paper presents the surveying results using AMT method to evaluate the concealed lead-zinc mineralization in Yuele lead-zinc ore field, Daguancounty, NE Yunnan province, China. After comparing the interpretation result of AMT surveying data with the geological data and the drilling data, it is found that there is some distinct difference in resistivity and polarizable between ore-bodies hosted strata, upper strata and gypsum strata. The results show that AMT method is helpful to identify lead-zinc mineralization under this geological condition.

Lead-Bismuth and Lead as Coolants for Fast Reactors

Fast reactors used lead-bismuth eutectic (LBE) and lead as coolants possess very high level of inherent self-protection and passive safety against severe accident. So, population radiophobia can be overcome. That type of reactors can be simultaneously more safely and more cheaply. As all other coolants, LBE and lead coolant (LC) possess the certain virtues and shortcomings. The presented report includes the comparative analysis of characteristic properties of those coolants, their impact on reactor safety, reliability and operating characteristics. The conclusion is made about promising usage of FRs with these coolants in future NP after the experience in operating of the prototypes of such reactors has been obtained.

Grape Seed Extract (<i>Vitisvinifera</i>) Alleviate Neurotoxicity and Hepatotoxicity Induced by Lead Acetate in Male Albino Rats

Grape seed extracts (GSE) are very potent antioxidant and exhibit numerous interesting pharmacologic activities, including an antioxidant property, and has been suggested to be of use in treatment of several diseases. The present study has been undertaken to investigate the protective and therapeutic effect of GSE against lead-induced neuro and hepatotoxicity in rat. Male albino rats were divided into six groups: the 1st group, rats were injected daily with saline vehicle and served as negative control, the 2nd group (positive control group), the rats were injected (i.p.) with subacute dose (100 mg/kg b·w/day) of lead acetate (LA). The 3rd group (protective group), the rats were injected (i.p.) with LA (100 mg/kg b·w/day) for 7 days after treatment with GSE (100 mg/kg b·w/day) for 3 weeks. The 4th, 5th and 6th groups (therapeutics groups), rats were injected (i.p.) with subacut dose (100 mg/kg b·w/day) of lead acetate for 7 days, then treated with GSE (100 mg/kg b·w/day) for one, two and three weeks, respectively. The level of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and 5-hydroxyindol acetic acid (5-HIAA) were evaluated in brain regions (cerebellum, brainstem, striatum, cerebral cortex, hypothalamus and hippocampus). The result indicated that the administration of subacute dose of LA (100 mg/kg/day, i.p.) induce a significant decrease in NE, DA, 5-HT and 5-HIAA content in all tested brain regions. Also the obtained data showed significant increase in liver enzymes: serum glutamate oxaloacetate transaminase (GOT), serum glutamate pyruvate transaminase (GPT) and Lactate dehydrogenase (LDH) level in group 2 (positive control). There is an improvement in neurotransmitters content. Also the obtained data showed significant in- crease in liver enzymes of protective (G3) and therapeutics groups (G4, G5 and G6) which received GSE compared with animal group that received lead acetate (G2). This is may be the presence of proanthocyanidins and procyanidins which have antioxidant and free radical scavenging activities. The result suggests that grape seed extract may prevent lead-induced neurotoxicity and hepatotoxicity.

Conformity Assessment of Lead Aprons Used in Conventional Radiology: A Multi-Centre Survey in Togo

Aim: Lead aprons are used to protect against scattered radiation from the patient during interventional procedures and certain special conventional radiological examinations. Given the importance of the role lead aprons are supposed to play in radiation protection, we propose to assess their conformity in medical imaging departments in public and religious hospitals in Togo. Materials and method: A multi-centre survey conducted from 26 November to 06 December 2021 in the radiology departments of public and religious health facilities in Togo. All aprons in use were included. The evaluation criteria were physical (visual), quantitative (radiographic) and qualitative (dosimetric). Results: We had registred 43 aprons among wich 27 (62.79%) leaded aprons were labelled non-compliant and 16 (37.21%) were labelled compliant. Of the aprons judged to be non-compliant, 70.37% were more than 10 years old and 96.30% showed defects on the radiographic images. The most common defects were vampire marks (18.64%), multiple folds (16.96%), cracks (16.96%), multiple cracks (15.25%), tears (8.47%), absence of lead (5.08%), holes (3.39%) and lead corrosion (1.69%). Defective aprons (62.96%) had at least two defects. The defects were of thoraco-abdomino-pelvic (74.07%), thoracic (14.82%) and abdomino-pelvic (11.11%) topography. For indirect exposure at 50 and 70 kilovolts, all the aprons had an attenuation factor greater than 90%. After dosimetric measurement, 13.95% of aprons had attenuation factors below 90% for indirect exposure at 100 kilovolts. Conclusion: The compliance of the leaded decks is trifactorial (physical, radiographic and dosimetric). However, there is no significant difference in X-ray attenuation capacity between defective and normal decks.

Olive leaf extract inhibits lead poisoning-induced brain injury

Olive leaves have an antioxidant capacity, and olive leaf extract can protect the blood, spleen and hippocampus in lead-poisoned mice. However, little is known about the effects of olive leaf extract on lead-induced brain injury. This study was designed to determine whether olive leaf extract can inhibit lead-induced brain injury, and whether this effect is associated with antioxidant capacity. First, we established a mouse model of lead poisoning by continuous intragastric administration of lead acetate for 30 days. Two hours after successful model establishment, lead-poisoned mice were given olive leaf extract at doses of 250, 500 or 1 000 mg/kg daily by intragastric administration for 50 days. Under the transmission electron microscope, olive leaf extract attenuated neuronal and capillary injury and reduced damage to organelles and the matrix around the capillaries in the frontal lobe of the cerebral cortex in the lead-poisoned mice. Olive leaf extract at a dose of 1 000 mg/kg had the greatest protective effect. Spectrophotometry showed that olive leaf extract significantly in- creased the activities of superoxide dismutase, catalase, alkaline phosphatase and acid phes- phatase, while it reduced malondialdehyde content, in a dose-dependent manner. Furthermore, immunohistochemical staining revealed that olive leaf extract dose-dependently decreased Bax protein expression in the cerebral cortex of lead-poisoned mice. Our findings indicate that olive leaf extract can inhibit lead-induced brain injury by increasing antioxidant capacity and reducing apop- tosis.

Mechanical and Electrical Properties of Some Sn-Zn Based Lead-Free Quinary Alloys

Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ features. The eutectic Sn-9Zn alloy is among them. This paper investigated the mechanical and electrical properties of Sn-9Zn-x (Ag, Cu, Sb);{x = 0.2, 0.4, and 0.6} lead-free solder alloys. The mechanical properties such as elastic modulus, ultimate tensile strength (UTS), yield strength (YS), and ductility were examined at the strain rates in a range from 4.17 10−3 s−1 to 208.5 10−3 s−1 at room temperature. It is found that increasing the content of the alloying elements and strain rate increases the elastic modulus, ultimate tensile strength, and yield strength while the ductility decreases. The electrical conductivity of the alloys is found to be a little smaller than that of the Sn-9Zn eutectic alloy.

Interaction of RuO₂and Lead-Silicate Glass in Thick-Film Resistors

Results of investigation of X-ray diffraction, infrared and optical spectra of powders of the ruthenium dioxide, lead-silicate glass as well as their mixture before and after sintering are reported. Sintering conditions typical for thick film resistors were used. Intensity of main lines of RuO2 in X-ray diffraction patterns of sintered mixtures decreases and they slightly shift towards small angles. No new reflexes appear in these patterns. Absorbance of RuO2 in the range of 2.5-100 μm is proportional to and featureless. Infrared spectrum of lead-silicate glass has absorption bands of [SiO4]4- tetrahedra and Pb-O bonds only. Optical spectrum of RuO2 has wide absorption bands at 950 and 370 nm. Spectra of the mixture of RuO2 and glass powders before and after sintering are different indicating that there is interaction between them during the sintering process. Concentration of free charge carriers estimated from the optical spectra is about 1021 cm-3.

Gas Phase Activation of Methane Molecule with Lead Benzene Dication Complex Ion, [Pb(Benzene)₂]²⁺

Motivated by the search for ways of a more efficient usage of the ubiquitous, and unexploited resources of methane, recent progress in the gas-phase activation of methane by metal dication complex ion is discussed. The gas phase theoretical and experimental analysis on [Pb(Benzene)2]2+ was conducted. The [Pb(Benzene)2]2+ complex ions were prepared using a combination of the pick-up technique and high energy electron impact, and then held in a cold ion trap. Excitation with tuneable UV radiation resulted in the formation of [Pb(Benzene)2(H2O)]2+, [Pb(Benzene)2(H2O)2]2+, [Pb(Benzene)]+, Pb+ and Benzene+ ions when the experimental results were analysed. The two optimised geometries of [Pb(Benzene)2]2+ namely the C2V eclipse and C2 staggered were observed. Methane activation of [Pb(Benzene)2]2+ complex ion yielded [Pb(Benzene)2(Me)]2+. [Pb(Benzene)2(H2O)(Me)2]2+,? [Pb(Benzene)2(H2O)(Me)]2+, [PbBenzene(Me)3]2+ and [Pb(Benzene)(Me)]2+. The PEC calculated binding energy of methane to lead benzene dication complex ion was approximately 25.45% higher than the value recorded on DFT calculation. This difference was due to the charge differences on the lead metal centre. While the actual calculated charge on the Pb metal in the optimised geometry was 1.68 the charge of +2 on the Pb metal was considered in the PEC calculation.

Navigating the Lead Laws/Rules/Standards for Renovation and Repair Activities: A Guide for Contractors and Laborers

Children and adults are often exposed to lead in homes as a result of deteriorating lead-based paint surfaces and any disturbance to those surfaces. There are a number of laws, regulations, standards and guidance documents in place aimed at minimization of lead dust contamination following renovation and repair activities. These laws and regulations are oftentimes confusing and conflicting for the maintenance contractor who has limited time and resources for researching the right and appropriate course of action. This paper provides a comprehensive review and discussion of the lead laws, regulations, standards and guidelines for contractors.

Removal of lead and cadmium ions by single and binary systems using phytogenic magnetic nanoparticles functionalized by 3-marcaptopropanic acid

The present research study is focused on green fabrication of superparamagnetic Phytogenic Magnetic Nanoparticles(PMNPs), and then its surface functionalization with 3-Mercaptopropionic acid(3-MPA). The resulting material(i.e. 3-MPA@PMNPs) characterized by FTIR, powder XRD, SEM, TEM, EDX, VSM, BET and TGA techniques and then further employed for the investigation of the adsorptive removal of lead(Pb^2+) and cadmium(Cd^2+) ions from aqueous solutions in single and binary systems. The material showed fastest adsorptive rate(98.23%) for Pb^2+ and(96.5%) Cd2+within the contact time of 60 min at pH 6.5 in the single system. The experimental data were fitted well to Langmuir isotherm, indicated monolayer adsorption of both metal ions onto 3-MPA@PMNPs and an estimated comparable adsorptive capacity of 68.41 mg·g^-1(Pb2+) and 79.8 mg·g^-1(Cd2+) at p H 6.5. However, kinetic data agreed well with pseudo-second-order model, and indicated that the removal mainly supported chemisorption and/or ion-exchange mechanism. Thermodynamic parameters such asΔGo,ΔHo, and ΔSo, were-3259.20, 119.35 and 20.73 for Pb^2+, and-1491.10, 45.441 and 7.87 for Cd^2+ at temperature 298.15 K, confirmed that adsorption was endothermic, spontaneous and favorable. The material demonstrated higher selectivity of Pb2+ and its removal efficiency was(98.20 ± 0.3)% in binary system experiments. The material persisted performance up-to seven(07) consecutive treatment cycles without losing their stability and offered comparable fastest magnetic separation(35 s) from aqueous solutions. Therefore, it is recommended that the prepared material can be employed to remove toxic heavy metal ions from water/wastewaters and this "green" method can easily be implemented at large scale in low economy countries.

Measuring Conditions for the Determination of Lead in Iron-Matrix Samples Using Graphite Atomizers with/without a Platform in Graphite Furnace Atomic Absorption Spectrometry

In graphite furnace atomic absorption spectrometry (GF-AAS), the atomization process of lead occurring in graphite atomizers with/without a platform plate was investigated when palladium was added to an iron-matrix sample solution containing trace amounts of lead. Absorption profiles of a lead line were meas- ured at various compositions of iron and palladium. Variations in the gas temperature were also estimated with the progress of atomization, by using a two-line method under the assumption of a Boltzmann distribu- tion. Each addition of iron and palladium increased the lead absorbance in both the atomizers, indicating that iron or palladium became an effective matrix modifier for the determination of lead. Especially, palladium played a significant role for controlling chemical species of lead at the charring stage in the platform-type atomizer, to change several chemical species to a single species and eventually to yield a dominant peak of the lead absorbance at the atomizing stage. Furthermore, the addition of palladium delayed the peak after the gas atmosphere in the atomizer was heated to a higher temperature. These phenomena would be because the temperature of the platform at the charring stage was elevated more slowly compared to that of the furnace wall, and also because a thermally-stable compound, such as a palladium-lead solid solution, was produced by their metallurgical reaction during heating of the charring stage. A platform-type atomizer with palladium as the matrix modifier is recommended for the determination of lead in GF-AAS. The optimum condition for this was obtained in a coexistence of 1.0 × 10–2 g/dm3 palladium, when the charring at 973 K and then the atomizing at 3073 K were conducted.

CRT-D Upgrading in a Patient with Persistent Left Superior Vena Cava and Right Superior Vena Cava Atresia Using the Novel Active-Fixation Quadripolar Left Ventricular Lead

The persistence of left superior vena cava (PLSVC) is the most common congenital anomaly of the venous return system to the heart. Because of the increasing number of patients referred for cardiac resynchronization therapy (CRT) devices implantations, it is expected to encounter this venous anatomic variation. Left ventricular lead placement at an appropriate site is an integral and technically challenging part of successful CRT. In case of cardiac abnormalities could be difficult to achieve an optimal cardiac rhythm management devices implantation. Previous reports in patients with PLSVC highlighted the challenges to achieve an optimal cardiac rhythm device implantation. Recently, a new quadripolar active fixation left ventricular lead is available for CRT device implantation. Hereby we report a case of a device upgrading from dual-chamber pacemaker to CRT with defibrillator backup using the active fixation left ventricular quadripolar lead in a patient with PLSVC and right superior vena cava atresia.

Optical Properties Of Mn²⁺Doped Lead Phosphate (Lp) Glasses

Doping of MnO (less than One mole %) in LP glass system promotes the transparency and the general quality of the LP glass.- Mn2+ occupying an Oh site in the LP glass network - The influence of the LP glass network on Mn2+ energy levels and its electronic structure seems to be different when the concentration of MnO is extremely small (0.2 mole%) - The observation of single band of Mn2+ in this case probably correlates well with the observation of forbidden hyperfine EPR transitions in the same glass.

Electrowinning of Copper Using Rotating Cylinder Electrode Utilizing Lead Anode

The effect of lead anode, rotating cylinder electrode (RCE), amount of 1,2-dihydroxypropane (12-DHP), temperature and rotation on the electrowinning of copper from low concentration acidified copper sulphate solution has been investigated. Copper powder was electrodeposited onto RCE that made of pure copper. From cyclic voltammetry experiments, an empirical parameter called the departure percent, S, was obtained which may represent the stability of the organic additive in the given medium and under the experimental conditions. The inhibition percentage, P, was 0.00 - 89.91% depending on the experimental variables. P was affected by temperature and mole fraction of 12-DHP, while rotation did not show any influence on it. Values of activation energy of electrodeposition process, Ea, were found to be less than 28 kJ mol-1 indicating diffusion controlled process. The overall mass transfer correlations under the present conditions have been computed using the dimensional analysis method. The data were valid for 90 < Sh < 1098, 737 < Sc < 59284 and 271 < Re < 7046 and the results agreed with the previous studies of mass transfer to rotating cylinders in turbulent flow regimes. The effect of time, content of 12-DHP, temperature and the speed of rotation on the morphological changes of the electrodeposited copper powder as well as deposits composition and crystallite size have been studied. Various crystallite sizes ranged 7.1 nm - 250.6 nm were obtained and characterized by EDS and XRD. Different topographs proved that the rate of copper electrodeposition increased by increasing deposition time, temperature and the speed of rotation. Also, they proved that the deposition rate decreased by adding 12-DHP to the solution. Therefore, the results obtained by SEM supported those achieved by measuring the limiting current density and follow the normal manner when organic solvents were added to the electrodeposition bath.

Preconcentration of Lead in Sugar Samples by Solid Phase Extraction and Its Determination by Flame Atomic Absorption Spectrometry

A simple and sensitive solid phase extraction utilizing C18 filled cartridges incorporated with dithizone for preconcentration of lead and its subsequent determination by flame atomic absorption spectrometry (FAAS) was developed. Several parameters such as type, concentration and volume of eluent, pH of the sample solution, flow rate of extraction and volume of the sample were evaluated. The effect of a variety of ions on preconcentration and recovery was also investigated. At pH = 7.4 and 1.0 mol?L–1 HCl eluting them, lead ions were recovered quantitatively. The limit of detection (LOD) defined as 3Sbl was determined to be 8.1 μg L–1 for 500 mL of sample solution and eluted with 5 mL of 1.0 mol?L–1 HCl under optimum conditions. The accuracy and precision (RSD %) of the method were >90% and <10%, respectively. In the end, the proposed method was applied to a number of real sugar samples and the amount of lead was determined by spiking a known concentration of lead into the solution.

Evaluation of Lead Exposure by Hand Wipes: A Review of the Effectiveness of Personal Hygiene on Industrial Sites

To evaluate the effectiveness of personal hygiene (handwashing) amongst workers at industrial sites to remove lead from their hands, a retrospective analysis of hand wipe samples was conducted using data collected by two contractors from two bridge painting projects for total lead using method ASTM E-1979-17/EPA SW846 7000B. Exposures resulted from the removal of lead-based paint from the structure and trace elements of lead found in the abrasive blast media. In total, six work tasks were evaluated and sixty unique hand wipe samples were evaluated. Thirty samples were collected during the worker’s lunch break, after they had reportedly washed their hands with a further 30 collected at the end of the workday following the same protocol. To be included in this evaluation, the contractors were required to follow NIOSH Method 9105 (Lead in Dust Wipes-Dermal Surfaces) with subsequent analysis of samples for total lead by an American Industrial Hygiene Association (AIHA) accredited laboratory. All 60 samples contained detectable lead. The lead exposures ranged from 19.5 μg to 3420 μg. The geometric mean for the samples collected was 337 μg. These results indicate that current personal hygiene practices at the evaluated sites are not effective at removing lead from worker’s hands during and after the workday. They also suggest that the residual lead measured on the workers’ hands, at the end of the shift, is likely contributing to the elevated blood lead levels in this population.

Experimental Studies of Heat Transfer Characteristics and Properties of the Cross-Flow Pipe Flow Melt Lead

The process of heat transfer in a HLMC cross-flow around heat-transfer tubes is not yet thoroughly studied. Therefore, it is of great interest to carry out experimental studies for determining the heat transfer characteristics in a lead coolant cross-flow around tubes. It is also interesting to explore the velocity and temperature fields in a HLMC flow. To achieve this goal, experts of the NNSTU performed the work aimed at the experimental determination of the temperature and velocity fields in high-temperature lead coolant cross-flows around a tube bundle. The experimental studies were carried out in a specially designed high-temperature liquid-metal facility. The experimental facility is a combination of two high-temperature liquid-metal setups, i.e., FT-2 with a lead coolant and FT-1 with a lead-bismuth coolant, united by an experimental site. The experimental site is a model of the steam generator of the BREST-300 reactor facility. The heat-transfer surface is an in-line tube bank of a diameter of 17 × 3.5 mm, which is made of 10H9NSMFB ferritic-martensitic steel. The temperature of the heat-transfer surface is measured with thermocouples of a diameter of 1 mm being installed in the walls of heat-transfer tubes. The velocity and temperature fields in a high-temperature HLMC flow are measured with special sensors installed in the flow cross section between the rows of heat-transfer tubes. The characteristics of heat transfer and velocity fields in a lead coolant flow were studied in different directions of the coolant flow: The vertical (“top-down” and “bottom-up”) and the horizontal ones. The studies were conducted under the following operating conditions: The temperature of lead was t = 450°C - 5000°C, the thermodynamic activity of oxygen was a = 10-5 - 100, and the lead flow through the experimental site was Q = 3 - 6 m3/h, which corresponds to coolant velocities of V = 0.4 - 0.8 m/s. Comprehensive experimental studies of the characteristics of heat transfer in a lead coolant cross-flow around tubes have been carried out for the first time and the dependences for a controlled and regulated content of the thermodynamically active oxygen impurity and sediments of impurities have been obtained. The effect of the oxygen impurity content in the coolant and characteristics of protective oxide coatings on the temperature and velocity fields in a lead coolant flow is revealed. This is because the presence of oxygen in the coolant and oxide coatings on the surface, which restrict the liquid-metal flow, leads to a change in the characteristics of the wall-adjacent region. The obtained experimental data on the distribution of the velocity and temperature fields in a HLMC flow permit studying the heat-transfer processes and, on this basis, creating program codes for engineering calculations of HLMC flows around heat-transfer surfaces.

An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.

Equilibrium Sorption of Lead and Nickel from Solutions by Flame of the Forest (<i>Delonix regia</i>) Pods: Kinetics and Isothermic Study

Batch adsorption techniques were used to study the biosorption of Lead and Nickel from aqueous solutions by Flame of the forest pods. The effects of optimum pH, contact time, metal ion concentration, biosorbent dose, biosorbent particle size and the presence of sodium, calcium and magnesium interfering ions on the sorption were investigated. Experimental results showed that Delonix regia biomass was effective in removing these metals from aqueous solutions as the equilibrium biosorption of both metals was attained within 60 minutes of interaction with 98% of the metals removed within this period. Sorption of these metals was dependent on pH as maximum removal was attained at pH 4 and pH 5 for Lead and Nickel ions respectively. Adsorption experiments showed that the process followed the pseudo second order kinetic model with high r2 (0.9999) and the equilibrium data fitted well with Langmuir and Freundlich isotherm models. The presence of competing ions impacted negatively on the sorption process irrespective of the type used. 27% and 36% of lead (II) were recovered from the spent biosorbents with 1 MHCl and disodium salt of EDTA solutions respectively.