Residual Concentrations Of Pb Research Articles

Investigation of biodegradable polyaspartate as an effective chelant for washing of lead from soil: response surface methodology approach

ABSTRACT In this work, a biodegradable chelant (polyaspartate) was synthesised by using L-aspartic via polysuccinimide and used for removal of lead from polluted soil. The interactive effects of operating parameters, polyaspartate dose, metal concentration, polyaspartate/soil ratio, pH and extraction time, were examined via 35 factorial face-centred central composite design matrix and response surface methodology. The examined responses for the two models developed were (i) concentration of extracted Pb in polyaspartate solution and (ii) residual concentration of Pb in the treated soil. The optimal removal efficiency was 90%, which yields 18 mg/L of extracted Pb and 50 mg/kg of residual Pb in the treated soil, at conditions of pH 3, extraction time of 6 h under highest level of initial Pb concentration (500 mg/kg), polymer/soil ratio of 25 and polyaspartate dose of 36 mmol/L. However, at the lowest level of polymer/soil ratio of 5, the maximum removal efficiency dwindled to 59% with higher residual Pb and extracted Pb concentrations of 205 mg/kg and 59 mg/L, respectively. The results showed that higher soil washing efficiency was linked to lower initial pH, increase in initial lead ions concentration and polyaspartate/soil ratio. The study signifies eco-friendly polyaspartate as an efficient chelant for remediation of Pb polluted soil via washing technique.

Facile in situ synthesis of cellulose microcrystalline-manganese dioxide nanocomposite for effective removal of Pb(II) and Cd(II) from water.

A novel cellulose microcrystalline-manganese dioxide nanocomposite (CMC-NMO) was synthesized by the redox reaction between potassium permanganate and ethanol based on cellulose microcrystalline. The cellulose microcrystalline (CMC) as support providing growth sites for the manganese dioxide nanowhiskers produced by the redox reaction and its application for Pb(II) and Cd(II) removal from aqueous was investigated. The characterization of as-synthesized material was revealed by various spectroscopic and microscopic techniques. Infrared-transform infrared (FITR) indicates that the incorporation of manganese oxide to CMC does not change the initial structure of it. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) data show that the manganese dioxide nanowhiskers with a few nanometers are uniformly dispersed on the surface of cellulose. Kinetics experiments reveal that Pb(II) and Cd(II) adsorption on CMC-NMO is a fast process and pseudo-second-order model fits the adsorption better. The maximum adsorption capacities of Pb(II) and Cd(II) obtained from the Langmuir model are 290.8mg/g and 67.4mg/g, respectively. The mechanism is mainly attributed to surface complexation and electrostatic attraction by energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analysis. In addition, depth removal experiments show that the residual concentrations of Pb(II) and Cd(II) in natural water after adsorption are lower than 0.01mg/L. The regeneration and cyclic utilizing studies indicate that CMC-NMO has good adsorption stability. Therefore, the results indicate that this material can be employed as a potential adsorbent for current serious Pb(II) and Cd(II) pollution caused by industrial emissions. Graphical abstract.

Heavy metal redistribution mechanism assisted magnetic separation for highly-efficient removal of lead and cadmium from human blood

Magnetic nano capture agent (MNCA)-based magnetic separation is considered as a promising approach to rapidly isolate heavy metals from blood. Limited removal efficiency and potential biosafety risks are the major challenges for the clinical use of MNCA-based magnetic separation. Here, we report a highly-efficient MNCA-based magnetic separation of heavy metals from blood in continuous multi-stage adsorption mode. The interactions between MNCA and blood components (e.g. blood cells and plasma proteins) and the MNCA-induced cellular immune responses are studied in detail. The distribution and redistribution of heavy metals in blood are quantitatively analyzed. It demonstrates that concentration dependent redistribution can increase the contact between heavy metals and MNCA, leading to improvement on heavy metal removal efficiency. The removal performance is tested in batch mode and in continuous mode. Results show that 97.97% of Pb and 96.53% of Cd are removed from blood in 120 min using continuous multi-stage adsorption mode, and the residual concentrations of Pb and Cd in blood decrease from 400 μg L−1 to 8.11 μg L−1 and 13.84 μg L−1, respectively. This study paves an effective way for heavy metal intoxication therapy by MNCA-based magnetic separation.

PURIFICATION OF WATER FROM PHENOL AND IONS OF HEAVY METALS BY THE ASSOCIATION OF BACTERIA OF THE GENUS PSEUDOMONAS

Aim. Purification of water from phenol and heavy metal ions using bacteria of the genus Pseudomonas. Methods. The effectiveness of microbial purification is estimated by the degree of extraction from the water of cyclic aromatic compounds - phenol and heavy metals [Pb (II), Cd (II), Zn (II)]. The phenol concentration was determined by the extraction-photometric method using 4-aminoantipyrine; heavy metals – by atomic absorption method on flame atomic absorption spectrophotometer Saturn in the flame of the air-propane-butane mixture. Results. The strains of P. fluorescens ONU328, P. maltophilia ONU329, P. cepacia ONU327 were used for the first time to purify water from cyclic aromatic compounds (phenol) and heavy metal ions. It was found that in the presence of individual strains of microorganisms in the amount of 7.5×105 CFU/ ml for 18–22 days (depending on the chosen strain) complete dephenolization of aqueous solutions occurs. When using the association of strains P. fluorescens ONU328, P. maltophilia ONU329, P. cepacia ONU327 (1: 1: 1 in volume ratio), the deep water purification from phenol with the initial concentration in water of 300 mg/dm3 is reduced to 10 days. The degree of extraction of Pb (II), Cd (II), Zn (II) from concentrated solutions by individual strains of microorganisms in the composition of biofloques reaches 95,00–99,95% with residual content of heavy metal ions in solution (0,03–1,0) mg/dm3. Using the association of strains of P. fluorescens ONU328, P. maltophilia ONU329, P. cepacia ONU327 provides the greatest efficiency of water purification from cations of heavy metals. In the treatment of metal-containing solutions immobilized in a biofloaclular bacterial cell, the residual concentration of Pb (II), Cd (II), Zn (II) is 0,03 ± 0,001, 0,02 ± 0,001 and 0,03 ± 0,004 mg/dm3 accordingly, that does not exceed the maximum permissible concentration in purified waters for discharge into the sewage system. Conclusion. The used strains of bacteria of the genus Pseudomonas are characterized by polyfunctional potential of biotechnological purpose – destructive to phenol and sorption-accumulating relative to ions of heavy metals, which reveals the prospects of their use in complex biotechnology of environmental purification from the pollutants of different nature.

Lead sorption performance on active silica derived from fly ash.

The object of this study was to estimate the sorption property of active silica derived from fly ash after separation of silica and aluminum. The specific surface area of active silica enlarged to 115 m(2)/g was compared with the original fly ash (4 m(2)/g). Field emission scanning electron microscopy displayed the active silica, which looked like a honeycomb or curly layer with many lamellae that formed many mesopores. The uptake kinetics indicated that the residual concentration of Pb(2+) in the aqueous solution decreased rapidly from the initial 1.25 mg/L to less than 10 μg/L within 45 min. The removal efficiency of Pb(2+) on active silica was pH dependent. The increase in pH value promoted Pb(2+) removal because the negative surface provided more electrostatic attraction sites. A stepwise non-linear isotherm was obtained because the lamellae of active silica provided a heterogeneous surface with various kinds of active sites. The maximum sorption amount of Pb on active silica was more than 90 mg/g, which was better than some pristine-activated carbon.

Non-stoichiometric binding of lead(II) ions by sodium alginate

The capability of sodium alginate to bind up to 500 Pb 2+ ions per uronide unit is shown. The residual concentration of Pb 2+ ions in solution is as small as 4·10 −4−3·10 −3 mol·1 −1 (concentration of sodium alginate—2·10 −4−1·10 −3 g-equiv·1 −1; initial concentration of a lead salt —0.001−0.5 mol·1 −1; ionic strength—0.15; ambient temperature). This does not depend on the concentrations of reagents. Interactions are reversible. They can at least in part result from the sorption of the excess of Pb 2+ ions by the initially formed lead alginate gel.