Lead Ions In Solution Research Articles

Preparation of a novel DNA-imprinted sensor based on chitosan and its highly sensitive detection of Pb2+

Lead ion is very harmful to the environment, so it is very important to study its detection methods. In this study, a novel electrochemical sensor was constructed by modifying deoxyribonucleic acid (DNA) on the electrode, which can be used for the detection of Pb2+ in the environment. Part of the mixed solution of chitosan (CS) and Pb2+ template ions was dropped onto the surface of a glassy carbon electrode. CS-Pb2+ film was cross-linked through sodium tripolyphosphate. And a novel DNA-imprinted sensor was prepared by electrodepositing CS-Pb2+ thin film with gold nanoparticles (AuNPs), removing Pb2+ templates, and immobilizing specific double-stranded DNA. The electroactive area, surface morphology, sensitivity, and electrochemical reaction mechanism of the DNA-imprinted sensor were analyzed. The elementary reaction steps were studied through electrochemical reaction kinetics analysis. The experimental results indicate that the DNA-imprinted electrochemical biosensor can quantitatively detect Pb2+ in the range of 10–100 μM (R2 = 0.9935), and its detection limit is 6.5074 μM (3σ/slope). The sensitivity of the electrochemical biosensor is 1.55233 × 10−6 A/μM, and its active areas is 6.233 cm2. The desorption mechanism and adsorption mechanism have been explored through dynamic parameter analysis. The novel DNA imprinted electrochemical biosensor developed in this paper provides a robust method for detecting lead ions in solution. Additionally, it establishes a solid groundwork for detecting other metal ions.

The Adsorption of Pb(II) from Aqueous Solution Using KOH-Modified Banana Peel Hydrothermal Carbon: Adsorption Properties and Mechanistic Studies.

Adopting banana peel as a raw material, the adsorption properties of banana peel hydrothermal carbon modified with a KOH solution for lead ions in aqueous solution were studied. The surface structure and functional groups of the modified hydrothermal carbon were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy, the Brunner-Emmet-Teller (BET) method, element analysis, and Raman spectroscopy. The results showed that an adsorption capacity of 42.92 mg/g and a removal rate of 86.84% were achieved when the banana peel hydrothermal carbon was modified with a KOH solution of 0.5 mol/L, with a pH of 6 and a solid-liquid ratio of 1 g/L. The equilibrium adsorption time for lead ions in solution being adsorbed using KOH-modified hydrothermal carbon was 240 min, the adsorption process satisfied the quasi-second-order kinetic model and the Redlich-Peterson isotherm equation, and the equilibrium removal efficiency was 88.62%. The adsorption of lead ions using KOH-modified hydrothermal carbon is mainly chemical-physical adsorption.

Gold-coated tilted fiber Bragg gratings for lead ion sensing.

Surface plasmon resonance sensor based on gold-coated tilted fiber Bragg gratings (SPR-TFBGs) are perfectly suited for fine refractometry. Thanks to the functionalization of the gold layer, they can be used for label-free biosensing. They have been largely used for the specific detection of proteins and cells. In this work, we experimentally demonstrate that they are enough sensitive to detect a very small entity like an environmental pollutant. In this context, we report here a bio-functionalization of the SPR-TFBG with thrombin aptamers for lead ion detection. We used aqueous solutions of lead ions with increasing concentrations from 0.001 ppb to 10 ppb. Based on the affinity bending of Pb2+ ions to the thrombin aptamer, we experimentally demonstrated low detection level of lead ion concentration (0.001 ppb) while the saturation limit is meanly fixed by the physical dimension of the sensor and the binding efficiency.

Spray-On Colorimetric Sensors for Distinguishing the Presence of Lead Ions.

Sprayable stimuli-responsive material coatings represent a new class of detection system which can be quickly implemented to transform a surface into a color-responsive sensor. In this work, we describe a dipicolylamine-terminated diacetylene-containing amphiphile formulation for spray coating on to a simple paper substrate to yield disposable test strips that can be used to detect the presence of lead ions in solution. We find the response to be very selective to only lead ions and that the sensitivity can be modulated by altering the UV curing time after spraying. Sensitive detection to at least 0.1 mM revealed a clear color change from a blue to red phase. This represents the first demonstration of a spray-on sensor system capable of detection of lead ions in solution.

Green activating silica-alumina insoluble phase of fly ash to synthesize zeolite P with high adsorption capacity for Pb(II) in solution

Using fly ash as a raw material to synthesize zeolite is an effective way to obtain cheap adsorbent. However, the high energy consumption of activating the insoluble silica-alumina phase of fly ash limits its practical application. In this study, a low-energy, wet-grinding hydrothermal method was used to activate the insoluble phase of fly ash to synthesize zeolite P, and the adsorption capacity of zeolite for lead ion in solution was studied. Wet-grinding can reduce fly ash particle size to nanometer scale and break long-chain Q4(Al) into short-chain low-polymer. Without aging, the activated material could directly synthesize zeolite P with a relative crystallinity of 89.37 %. Compared with the common alkali-fusion method, the wet-grinding method reduced energy consumption by 45.93 % and increased synthetic zeolite relative crystallinity by 7.51 %. The synthesized zeolite P could effectively remove Pb2+ ions from solution through ion exchange and hydroxyl reaction, and the adsorption capacity reached 497.01 mg/g.

Carbon Microspheres Composite PbO2 Anode to Enhance Electrode Activity for Degradation of Isopropylantipyrine: Kinetics and Mechanism

An innovative CMS-PbO2 electrode was fabricated by combining hydrothermally synthesized carbon microspheres (CMS) on a PbO2 electrode by electrodeposition. Using the CMS-PbO2 electrode, the main factors affecting Isopropylantipyrine (PRP) degradation were studied. Under optimum process conditions, the concentration of PRP was 50 mg l−1, the applied current density was 30 mA cm−2, the electrolyte (Na2SO4) concentration was 0.1 mol l−1, and pH was 7. The PRP degradation rate reached 100%, and chemical oxygen demand (COD) removal rate reached 43.42% after 120 min of electrochemical oxidation. Using field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy, the electrochemical performance of the two electrodes was discussed. The composite of carbon microspheres successfully improved the electrochemical activity of the electrode and its conductivity. Furthermore, the ability of the two electrodes to generate hydroxyl radicals was compared and the possible degradation pathway of PRP was considered. In addition, electrode stability and safety were evaluated by accelerated lifetime experiments and detection of lead ions in solution after electrochemical oxidation. The CMS-electrode was more stable and safer than the PbO2 electrode. The CMS-PbO2 electrode provides a new strategy for the treatment of pharmaceutical wastewater.

Fabrication of sodium alginate-melamine@ZIF-67 composite hydrogel and its adsorption application for Pb(II) in wastewater.

A low-cost and environmental-friendly sodium alginate-melamine@zeolitic imidazolate framework-67 (SA-ME@ZIF-67) adsorbent was fabricated by chemical grafting and in situ growth for the removal of lead ions in wastewater. Firstly, melamine (ME) was grafted onto sodium alginate (SA) by amide reaction, and then SA-ME was dropped into a solution of calcium chloride to form hydrogel bead, and ZIF-67 was grown on the SA-ME hydrogel bead by the in situ growth method. The SA-ME@ZIF-67 adsorbent was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The SA-ME@ZIF-67 adsorbent was used to effectively adsorb Pb(II) from aqueous solutions. The initial concentrations of lead ions, adsorbent dose, initial pH of lead ion solution, temperature, and adsorption time for the material were optimized. The adsorption isotherms and kinetics fitted to Langmuir isotherm model (R2 = 0.9281, 0.9420, and 0.9623 at the temperatures of 288.15K, 298.15K, and 308.15K, respectively) and pseudo-second-order kinetic model (R2 = 0.9901) respectively. According to the Langmuir model at 308.15K, the maximum adsorption capacity of the adsorbent for Pb(II) was 634.99mg/g. The recycling application of the adsorbent was possible as it was easily collected and reused after five adsorption-regeneration cycles. In addition, the Pb(II) in real wastewater samples has been efficiently removed using the fabricated hydrogel. The results showed that the SA-ME@ZIF-67 adsorbent had high adsorption capacity, removal efficiency, and easy recyclability for Pb(II).

Study on the difference in adsorption performance of graphene oxide and carboxylated graphene oxide for Cu(II), Pb(II) respectively and mechanism analysis

Graphene oxide has been widely studied as a new type of adsorbent due to its strong affinity for heavy metal ions. However, limited by the number of oxygen-containing functional groups on its surface, there are still some defects in the field of heavy metal ion adsorption. In this paper, graphene oxide (GO) was prepared by modified Hummers method, and carboxylated graphene oxide (GO-COOH) was further synthesized by the derivatization reaction of bromoacetic acid with hydroxyl group under strong alkali conditions. The physical and chemical properties of the material were characterized by XRD, SEM, TEM, XPS and FT-IR. Taking copper and lead ion solutions as pollution models, the adsorption behaviors of the two heavy metal ions solutions on GO were investigated through batch adsorption experiments, adsorption kinetic model, adsorption isotherm model and Van't Hoff equation. The experimental results showed that the maximum adsorption capacity of GO for Cu(II) after carboxyl group treatment increased from 55.47 mg/g to 62.02 mg/g, and the maximum adsorption capacity of GO-COOH for Pb(II) increased from 85.17 mg/g to 96.21 mg/g. In this paper, the reasons for the difference in the adsorption capacity of GO for Cu(II) and Pb(II) and the significant enhancement of the adsorption performance of GO-COOH were discussed, and the possible adsorption mechanism was proposed. The research in this paper provides a new way to realize the efficient utilization of graphene oxide materials in the purification process of water environment and the development of modern materials science.

Enhancement of SERS performance using hydrophobic or superhydrophobic cotton fabrics

Because the hydrophobic surface can reduce the diffusion of probe molecules and enrich the detection materials effectively, two types of hydrophobic Surface-enhanced Raman spectroscopy (SERS) substrates were prepared in this work. Cotton fabrics were used as raw material, employing printing and spraying methods to fabricate substrates with various levels of hydrophobicity. A silver layer was deposited on the surface of the hydrophobic substrates by vacuum evaporation to prepare hydrophobic and super-hydrophobic SERS substrates, and p-aminothiophenol (PATP) was used as probe molecule to explore SERS performance of different samples. The analyzed results show that the enhancement factor of the optimized hydrophobic SERS substrate is 1.57 × 106, and the detection sensitivity can reach up to 10−10 M and the relative standard deviation (RSD) value is 11.19%. The enhancement factor of the optimized super-hydrophobic SERS substrate is 1.93 × 106, its detection limit is low to 10−11 M, RSD value is 8.11%, and it still has the effect of enhancing Raman signal after 6 months of storage. The detection limit of the optimized super-hydrophobic substrate for lead ion solution is as low as 200 nM. Compared with hydrophilic substrates, the SERS performances of the substrates with hydrophobic surface are improved significantly.

A green strategy to synthesize two-dimensional lead halide perovskite via direct recovery of spent lead-acid battery

Hybrid organic-inorganic perovskite is a class of emerging materials with promising application prospects in optoelectronics. However, the consumption of lead resources and poor stability in moisture environment have limited their practical applications. Herein, a family of air-stable two-dimensional (2D) hybrid organic-inorganic perovskite crystal (C4H9NH3)2PbX4 (X=Cl, Br, I or mixed halides of them) is efficiently synthesized by direct recovery of spent lead-acid battery (LAB) paste. More than 95 wt% of the total lead element in spent lead paste could be recovered and converted into low-impurity lead ion solution via a facile recovery process at room temperature. Then 2D hybrid perovskite crystal is synthesized from the recovered lead ion solution with a one-pot solvent evaporation method. Excellent air stability is observed for the prepared perovskite crystals after exposure in high-humidity air at a high temperature of 75 °C, attributing to its layered structure which is capped with long-chain hydrophobic alkyl groups. The emission wavelengths of the synthesized perovskite crystals are tunable from 380 to 560 nm (corresponding to visible purple to yellow light) by compositional modulations, demonstrating their potential applications as optoelectronic materials. This research has proposed a promising strategy to synthesize high-value 2D hybrid perovskite optoelectronic materials directly recovered from spent LAB.

Effect of nanohydroxyapatite on surface mineralization in acid-etched dentinal tubules and adsorption of lead ions

To study the effect of nanohydroxyapatite (nHA) for promoting surface mineralization of demineralized dentin discs and adsorption of lead ions in simulated sewage water. Sixty dentin disks were prepared from freshly extracted teeth with intact crown (including 30 premolars and 30 molars) and treated with 10% citric acid for 2 min to simulate dentinal tubules with dentin hypersensitivity. The etched dentin discs were brushed with distilled water, 0.2 g HA or 0.2 g nHA for 2 min twice a day for 7 consecutive days, after which scanning electron microscopy (SEM) was performed and calcium and phosphorus contents in the dentin discs were detected using EDS. Lead ion adsorption capacities of HA and nHA were tested by mixing 1 mL serial concentrations of HA and nHA suspensions with 50 mL lead ion solutions (1.0 mg/L). After 24 h, the residual lead ion concentration in the supernatant was measured using ICP to calculate lead ion adsorption rate and adsorption capacity of the materials. SEM showed a smooth surface and empty dentin tubules in the acid- etched dentin dics. The dentin dics treated with HA were covered with masses of particles that loosely attached to the surface, and the diameter of the dentin tubules was reduced. In nHA group, the dentin discs showed a fine and homogeneous surface clogging with a tight attachment, and the dentin tubule diameter was obviously reduced. Daily brushing with HA and nHA, especially the latter, significantly increased calcium and phosphorus contents on the surface of the dentin dics (P < 0.000). In lead ion adsorption experiment, the lead ion adsorption rate of HA decreased as its concentration increased with the highest adsorption rate of 83.01%; the adsorption rate of nHA increased with its concentration until the adsorption equilibrium was reached, and its highest adsorption rate was 98.79%. A good liner relationship was found between the adsorption ability and concentration of HA. Compared with HA, nHA has a better capacity for surface mineralization of acid-etched dentin discs and also a better ability of lead ion adsorption.

Removal and characterisation of Pb(II) ions by xylenol orange-loaded chitosan: equilibrium studies

ABSTRACT In this study chitosan (CS) was modified by coating with xylenol orange (XO). The batch adsorption of Pb(II) ions on modified chitosan (CS/XO) was investigated. The modification of chitosan was confirmed by FT-IR spectroscopy, scanning electron microscopy (SEM) and x-ray diffraction (XRD). The adsorption behaviour of the modified chitosan against Pb(II) ions were evaluated. Among these, pH effect, adsorbent dosage and initial concentration of Pb(II) ions. The results showed that the modified chitosan possesses good capacity for lead ions. The modified surface exhibited an affinity to chelating lead ions in solution, forming complex. The experimental results were examined by the Langmuir and Freundlich isotherm models. The maximum adsorption capacities of Pb(II) ions based on the Langmuir isotherm model were 0.457 mg/g.

Activation Mechanism of Lead(II) to Ilmenite Flotation Using Salicylhydroxamic Acid as Collector

In this study, salicylhydroxamic acid (SHA), which exhibits superior flotation performance to conventional collector benzohydroxamic acid (BHA), was first introduced in ilmenite flotation. The addition of lead(II) can significantly increase the recovery of ilmenite using SHA as collector. Thus, the adsorption mechanism of SHA on lead(II)-activated ilmenite surface was systematically studied using micro-flotation tests, adsorption analysis, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Micro-flotation results revealed that SHA had stronger collecting ability than BHA, and ilmenite floatability could be activated by lead ions with either SHA or BHA as collector. Ilmenite showed good floatability at pH 6–8 (over 90% recovery) in the presence of Pb2+ and SHA. In such conditions, the main lead species of Pb(OH)+ and Pb2+ acted as active sites and caused positive surface potential shifts, thereby increasing the adsorbed amounts of negatively charged SHA on the surface of the mineral. FTIR and XPS analyses suggested that the lead species was chemically adsorbed on the surface of ilmenite to form active sites chelated by SHA. Moreover, the free lead ions in solution might form the Pb–SHA complexes to adsorb on the mineral surface, thereby increasing the floatability of ilmenite.

Efficient Adsorption of Lead Ions onto Alginate–Grape Marc Hybrid Beads: Optimization and Bioadsorption Kinetics

The present work analyses the adsorption capacity of lead ions onto two bioadsorbents consisting of biodegraded grape marc (BGM) and free or encapsulated in calcium alginate, forming hybrid beads (alginate–grape marc hybrid beads (AGMHB)). It has been verified that the removal effectiveness of BGM was always lower than that of AGMHB. Moreover, the pH of lead ion solution had a significant influence on the removal efficacy of both bioadsorbents tested. A Box-Behnken factorial design optimized the most influential variables (amount of bioadsorbent, concentration of lead ions and pH solution) involved in the adsorption of lead ions onto AGMHB. Theoretical equations were validated by means of additional experiments, resulting in a good agreement between both experimental results and estimated values. In addition, different kinetic models were evaluated in order to obtain kinetic parameters associated to the bioadsorption process. The intraparticle diffusion model was also employed to interpret the diffusion of lead ions among the particles of the bioadsorbent.

Flotability of laurionite and its response to sulfidization flotation

Laurionite is the main highly hazardous lead bearing waste in iron ore sintering dust due to its poor stability and high content, while its flotability and flotation separation have not been adequately investigated. In this study, the flotation behavior of laurionite and its interaction with Na2S were investigated in detail to find an economic and promising way for the separation of lead from sintering dust. The flotability and sulfidization flotation of laurionite were examined by micro-flotation experiments, zeta potential measurement, Fourier transform infrared spectroscopy (FT-IR) analysis and X-ray photoelectron spectroscopy (XPS) studies and solution chemistry calculation. The micro-flotation experiments results indicated that Na2S would improve the flotability of laurionite within a moderate dosage, otherwise decrease its float. The negativity of zeta potential observably increased when adding an appreciate amount of Na2S prior to NaBX, indicating a better adsorption of BX− on mineral surface, which would increase the flotation recovery. To figure out the mechanism behind that, the laurionite surface was analyzed by XPS, which found the formation of PbS films after adding Na2S. The FT-IR analysis showed the BX− absorbance on laurionite significantly decreased after treating with high concentration of Na2S. Moreover, the solution chemistry calculations demonstrated that the proper dosage of Na2S could enhance the flotation of laurionite by reduce free lead ion in solution and covered some part of lead mineral surface, which sharply reduced the demand of collectors in flotation. However, the excess S2− would inhibited the adsorption of BX− on laurionite surface since the formation Pb(BX)2 was weaker than PbS. These results did not only expose that the addition of appropriate amount of Na2S could enhance laurionite’s sulfidization flotation, but also provide an effective way to separate laurionite from iron ore sintering dust.

The, Mineralization of natural hydroxyapatite for high efficiency of Pb2+ ion removal in aqueous solution

Mineralized hydroxyapatite (m-HA) was prepared by soaking natural hydroxyapatite (n-HA) extracted from pig bone in the simulated body fluid (SBF) for 3 days. XRD and FE-SEM characterizations confirmed the formation of new HA crystal layer in the structure of m-HA. Experiments of lead ion adsorption were performed for both n-HA and m-HA by immersing 50 mg of each different powder samples in 100 mL of lead ion solution at a concentration of 100 ppm. Results analyzed by ICP-MS showed that m-HA has an excellent ability to remove lead ions compared to n-HA. After 4 hours of adsorption experiments, m-HA material eliminated almost 100% of lead ions while n-HA only removes 65.4%. The mechanism of lead ion removal for m-HA was determined, including the ion-exchange and physical adsorption.

Lead Ion Sorption by Perlite and Reuse of the Exhausted Material in the Construction Field

This paper deals with the possibility of using perlite as a lead ion sorbent from industrial wastewater. Dynamic (laboratory column) operations were carried-out using beads, which were percolated by metals in a 2–10 mg·L−1 concentration range. To this purpose, lead ion solutions were eluted in columns loaded with different amounts of sorbent (2–4 g) within a 1–2 mm bead size range, at 0.15–0.4 L·h−1 flow-rates. Tests were performed to complete sorbent exhaustion (column breakthrough). The highest retention was obtained at 0.3 L·h−1, with 4 g of perlite and 10 mg·L−1 of influent, lead ion concentration. Film diffusion control was the kinetic step of the process in the Nerst stationary film at the solid/liquid interface. At the end of the sorption, perlite beads were used as lightweight aggregates in the construction field (i.e., for the preparation of cement mortars). Specifically, conglomerates showing different weights and consequently different thermal insulating and mechanical properties were obtained, with potential applications in plaster or panels.

Impedimetric phosphorene field-effect transistors for rapid detection of lead ions

Stimuli-responsive field-effect transistors (FETs) based on 2D nanomaterials have been considered as attractive candidates for sensing applications due to their rapid response, high sensitivity, and real-time monitoring capabilities. Here we report on an impedance spectroscopy technique for FET sensor applications with ultra-high sensitivity and good reproducibility. An alumina-gated FET, using an ultra-thin black phosphorus flake as the channel material, shows significantly improved stability and ultra-high sensitivity to lead ions in water. In addition, the phase angle in the low frequency region was found to change significantly in the presence of lead ion solutions, whereas it was almost unchanged in the high frequency region. The dominant sensing performance was found at low frequency phase spectrum around 50 Hz and a systematic change in the phase angle in different lead ion concentrations was found. Applying the impedance spectroscopy technique to insulator-gated FET sensors could open a new avenue for real-world sensor applications.

Behavior of Lead Ions in Cassiterite Flotation Using Octanohydroxamic Acid

The effects of lead ions on the flotation performance of the cassiterite system have been investigated using microflotation tests. Adsorption experiments, X-ray photoelectron spectroscopy (XPS), contact angle measurement, and zeta (ζ)-potential measurements were conducted. Octanohydroxamic acid and lead ion solution speciation simulations were used. These were used to correlate surface properties of lead-activated with cassiterite flotation performance. Flotation results indicate that the addition of lead ions activates the cassiterite flotation. The addition of lead ions enhanced the adsorption of octanohydroxamic acid on cassiterite, and the wetting characteristic of cassiterite decreased in the presence of octanohydroxamic acid and the addition of lead ions. ζ-Potential measurements and solution chemistry analyses confirmed that flotation recovery of the cassiterite increases due to Pb(OH)+ and Pb3(OH)42+ sites on the cassiterite surface. XPS results indicated the adsorption of octanohydroxamic acid on...

Selective adsorption of Pb (II) over the zinc-based MOFs in aqueous solution-kinetics, isotherms, and the ion exchange mechanism.

Two series of metal-organic frameworks (MOFs) with similar formula units but different central metal ions (M) or organic linkers (L), M-BDC (BDC=terephthalate, M=Zn, Zr, Cr, or Fe), or Zn-L (L=imidazolate-2-methyl, BDC, BDC-NH2), were prepared and employed as the receptors for adsorption lead ions. It was found that the Zn-BDC exhibited a much higher adsorption capacity than the other M-BDC series with various metal ions which have very closely low capacities at same conditions. Furthermore, the Zn-L (L=imidazolate-2-methyl, BDC, BDC-NH2) still have highly efficient adsorption capacity of lead ions, although the adsorption capacity varies with different ligand, as well as the adsorption rate and the equilibrium pH of the solution. This significant high adsorption over Zn-L, different from other M-BDC series with various metal ions (Zr, Cr, or Fe), can be explained by ion exchange between the central metal ions of Zn-L and lead ion in solution. Based on the analysis of FT-IR, X-ray diffraction pattern, the nitrogen adsorption isotherms, the zeta potentials, and the results, a plausible adsorption mechanism is proposed. When equivalent Zn-L were added to equal volume of aqueous solution with different concentration of lead ion, the content of zinc ion in the solution increases with the increase of the initial concentration of lead ions. The new findings could provide a potential way to fabricate new metal organic frameworks with high and selective capacities of the heavy metal ions.