Papers by Keyword: Pb²⁺

Abstract: Lead (Pb²⁺) contamination poses a serious health risk. In this study, silver nanoparticles (AgNPs) were synthesized using bignay leaf extract (BLE) for the colorimetric detection of Pb²⁺ in water. UV-vis spectroscopy confirmed the formation of AgNPs with a surface plasmon resonance peak at 415-417 nm. EDX analysis revealed that the AgNPs had an elemental composition of 66.53% Ag, 13.47% O, and 11.54% C. DLS analysis showed an average hydrodynamic size of 140.2 nm. The reaction between AgNPs and Pb²⁺ resulted in the decolorization of the solution, which was attributed to the formation of Pb-GA complexes. The limit of detection (LOD) and limit of quantification (LOQ) were 50 ppb and 500 ppb, respectively.

Abstract: The aim of this study is to investigate the effect of natural zeolites characteristics on the adsorption capacity of Pb²⁺ from an aqueous environment. The used natural zeolites were originated from 3 regions in Indonesia. i.e. Bayah, Banten (coded as ZB) and two samples from South Lampung (coded as ZL-1 and ZL-2) and Nanggung, Bogor (ZN). The characteristics of each natural zeolite were evaluated through a series of detailed analysis including XRD, FTIR, XRF, SEM and N₂ physisorption. It was revealed that ZB, ZL-1 and ZL-2 were dominated by clinoptilolite (HEU) frameworks while the major phase of ZN was mordenite (MOR) type. From XRF data, the three natural zeolites (ZB, ZL-1 and ZN) possessed a comparable Si/Al ratio (ca. 5.5 to 6) whereas ZL-2 had slightly lower Si/Al ratio (ca. 4). We found that, at comparable Si/Al ratio, clinoptilolite frameworks has a higher adsorption capacity of Pb²⁺ compared to that of mordenite due to the compatibility of Pb²⁺ inside the pores of clinoptilolite. Lower Si/Al ratio of natural zeolite tended to show higher adsorption capacity of Pb²⁺ since the net charge of zeolite frameworks became more negative. These two factors, the framework type and the Si/Al ratio, are significant for the adsorption capacity. Another factor, i.e. surface area, had no certain effect on the adsorption capacity in this case.

Abstract: In the Pb²⁺ stress experiments, the concentrations of Pb²⁺ were 1, 5, 10, 50, and 80 mg/L respectively, BG11 culture medium was served as the control. The results showed that Pb²⁺ affected markedly on the growth and physiological characteristics of chlorella pyrenoidosa under certain concentration. As the exposure time, chlorella pyrenoidosa biomass is restrained gradually. Pb²⁺ also have significant inhibition to effect chlorophyll content and have an effect relationship with the malondialdehyde content of chlorella pyrenoidosa . Lead concentrations and the soluble protein content are time effect relationship . And the longer the inhibitory effect becomes more obvious. Superoxide dismutase (sod) activity increased first then decreased with the increase of the concentration of Pb²⁺.

Abstract: An novel Lead (II)-dithizone-xylenol orange tenary complex spectrophotometry was developed for the determination of Pb²⁺ in wastewater. For this purpose, the parameters of spectrophotometry such as the detection wavelength, pH value, the dosage of dithizone-xylenol orange and reaction time were studied and optimized through orthogonal tests. The method was linear in the ranges from 2.1×10^-3 to 6.0 μg·mL^-1 for Pb²⁺ with R² ≥ 0.999. The procedure allowed efficient recovery of the investigated Pb²⁺ ranging between 95 % and 103 % with a relative standard deviation (RSD) ≤ 2.1 for actual wastewater samples spiked with 1.00, 2.00 and 3.00 μg·mL^-1 of standard Pb²⁺, respectively. These results show the method can be applied to the direct determination of Pb²⁺ in wastewater, avoiding the use of toxic extrant (chloroform) and masking reagent (sodium cyanide) in the traditional methods and time-consuming procedures, moreover, the investigated method is simple, accurate, reliable, and inexpensive, which implies the potential of this technique for Pb²⁺ monitoring in wastewater samples.

Abstract: In this paper, graft copolymer of starch-acrylamid-propylene hydroxamic acid was synthesized by inverse emulsion polymerization. Effects of the dosage of the graft copolymer, pH value and reaction time on the capability of trapping heavy metal ion Pb²⁺ were investigated. The results showed that the optimum conditions for treating lead-containing wastewater were: pH=7-9, reaction time≧30min , the dosage of polymeric ferric sulfate and graft copolymer in wastewater were 10mg·L^-1 and 250-300mg·L^-1, respectively. The Pb²⁺ removal rate is not less than 99.8% and meanwhile the copolymer possess good removal performance of turbidity.

Abstract: Modified polyurethane fiber was prepared by wet spinning method, Different amount of chitosan powder that dissolving in polyurethane solution to get spinning solution were examined. This materials presents excellent adsorption capacity on Pb²⁺. the absorption type on Pb²⁺ of this modified fibers was monomolecular. The modified fibers get the maximum adsorption 25.53mg/g when the quality ratio of chitosan and polyurethane was 1:1 under the condition of 30°C and pH 6.

Abstract: The corn stalk/montmorillonite(CS/MMT) nanocomposite was prepared by a solution intercalation technique. The effects of the initial pH value of Pb2+ solution, contact time and the dosage of adsorbent on the adsorption capacitiy of CS/MMT nanocomposite for Pb2+ were investigated. The adsorption kinetics and isotherms of nanocomposite were also studied. The results indicated that with the initial pH value increasing, the adsorption capacity of the CS/MMT nanocomposite increased. Compared with the adsorption capacity of CS (6.32 mg/g), the nanocomposite exhibited the higher adsorption capacity (31.95 mg/g). The adsorption behaviors of CS/MMT nanocomposite showed that the adsorption kinetics was in accorded with pseudo-second-order equation and the adsorption isotherms followed the Langmuir and Freundlich equation.

Abstract: Using Streptomyces erythreus isolated from pharmaceutical residues as a biosorbent, the characteristics and mechanism of its absorbing Pb2+ was studied. The results showed that absorptive ability of bacterial mycelia modified by sodium hydroxide was improved greatly. The reaction mechanism of modified bacterial mycelia uptake Pb2+ was analyzed by back scattered electron microscope(BSEM) and infrared spectroscopy (IR). The results of experiments indicated that some chemical groups such as -COO-、C-H and O-H among cell walls of bacterial mycelia might play the key functions adsorbing Pb2+. It was presumed that the process of modified bacterial mycelia lead uptake might be a chemical and physical process collaboratively which occurred on the cell surface of bacterial mycelia chiefly based on exchangeable reaction.

Abstract: In the condition of 1.24 mmol/L EDTANa₂, 16.7 mmol/L NaCl and 0.17 mmol/L Tris, the substrate chain of double-stranded DNA (dsDNA) could be cracked by Pb²⁺ to release single-stranded DNA (ssDNA) that adsorb onto AuPd nanoparticle (AuPdNP) and form stable AuPdNP-ssDNA, but the dsDNA can not protect AuPdNP that were aggregated to big AuPdNP aggregations (AuPdNPA) under the action of NaCl. The AuPdNP-ssDNA and AuPdNPA could be separated by centrifugation. With the concentration of Pb²⁺ increased, the released ssDNA increased, the AuPdNP-ssDNA in centrifugation solution increased and the catalytic effect enhanced on the fluorescence quenching reaction of Rhodamine 6G (Rh6G) and NaH₂PO₂, which led the fluorescence intensity at 552nm to decrease. The decreased fluorescence intensity (ΔF_552nm) was linear to the concentration of Pb²⁺ in the range of 0.33-8.00 nmol/L, a detection limit of 0.21 nmol/L. The proposed method was applied to detect Pb2+ in water samples, with satisfactory results.

Abstract: A new functionalized composites (PPy/c-MWNT) by carboxylic multiwalled carbon nanotube (c-MWNT) with polypyrrole (PPy) was studied. PPy/c-MWNT modified glassy carbon electrode (PPy/c-MWNT/GCE) for determination of Cd2+ and Pb2+ was described by cyclic voltammetry, electrochemical impedance spectroscopy, and anodic stripping voltammetry (ASV). PPy/c-MWNT/GCE greatly improved the sensitivity of determining Cd2+ and Pb2+. The striping peak currents changed linearly with the concentration of Cd2+ from 1.0×10-4 to 2.0×10-7 mol/L for an accumulation time of 400 s, and Pb2+ from 1.0×10-4 to 1.0×10-7 mol/L. The high sensitivity, selectivity, and stability of the PPy/c-MWNT/GCE demonstrated its practical application for a simple, rapid and economical determination of trace level of Cd2+ and Pb2+ in water samples