Flow Injection Analysis Technique for Online Preconcentration of Lead Ions in Airborne Particulate Matter Using Imprinted Polymer as the Sorbent

This work reported a simple and sensitive flow injection analysis(FIA)technique coupled with a Flame Atomic Absorption Spectrophotometer(FAAS)for online preconcentration of lead(Ⅱ)ions in the airborne particulate matter samples(PM_(2.5))using ion-imprinted polymers as adsorbent packed in minicolumn.A bulk polymerization method was chosen to synthesize the polymer based on a ternary complex of lead ions with 4-2-pyridilazo resorcinol and 4-vinyl pyridine with methacrylic acid as a functional monomer.The optimum pH for sorption was 6,and other variables for the FIA system were optimized,including breakthrough volume,eluent concentration,and eluent volume.The optimum conditions were reached with a breakthrough volume of 4.45 mL,calculated as a dynamic retention capacity of 5.20 mg/g of Pb(II)40 mg/L,with a 1.5 mL/min flow rate.The eluent used for the FIA system was 0.5 mL HNO_(3)of 3 mol/L.Linearity,precision,and limits of detection of the FIA system were determined before being applied to preconcentration and analysis of lead ions in PM_(2.5)samples.The precision of the method was determined to be 3.09%by calculating the coefficients of the variant.Linearity of the method in the concentration range of 50-1000μg/L gave a coefficient correlation of 0.9925,showing a good response,and the limit of detection of the system was 5.11μg/L,better than that of the FAAS method.Performances of the FIA system were evaluated and showed good results with an enrichment factor of more than 20 times higher and a concentration efficiency of 11.65 min^(-1)with a consumptive index of 4.5 mL.Preconcentration and analysis of the PM_(2.5)samples in Bandung City showed the concentrations of Pb(II)were 26.67μg/L and 33.3μg/L with the accuracy of the method for each sample of104.75%and 107.86%.

Universal probe with oriented antibody to improve the immunochromatographic assay of lead ions in Procambarus clarkii

Objectives:Based on the information from the random inspection of foods by the China Food and Drug Administration in 2022,the contamin-ation levels of lead ions are high in many edible products.Traditional methods of detecting lead ions cannot meet the requirements of on-site analysis of food due to the need for large equipment.The immunochromatographic assay(iCA)is an effective,rapid,on-site analytical technique for determining lead ions in foods.However,the performance of ICA based on the traditional probe(AuNP-mAb)is limited by ignoring the influ-ence of theantibody orientation.Materials and Methods:In this study,we developed an efficient technology for constructing a universal probe(AuNP-PrA-mAb)based on the oriented immobilization of antibody.The performance of ICA was largely improved due to specific binding of the Fc region of the antibody with recombinant protein A(PrA)on the surface of a gold nanoparticle(AuNP).The ICA based on a universal probe was applied for the qualitative and quantitative detection of lead ions in Procambarus clarki within 30 min.Meanwhile,a simple and fast pretreatment method based on dilute acid extraction was developed forpretreating thePclarkii containing leadions.Results:The visual limit of detection and the scanning limit of quantization of the developed iCA strip for lead ions were O.5 ng/mL and 0.28 ng/mL,respectively.The sensitivity of ICA based on universal probe was 10-fold higher than that of the ICA using traditional probe.Furthermore,the detection results had no obvious difference between the ICA and ICP-MS with t-test statistical method.Conclusions:The developed ICA based on a universal probe presented broad application prospects in detecting contaminants in foods.

Synthesis of lignin-poly(N-methylaniline)-reduced graphene oxide hydrogel for organic dye and lead ions removal

Lignin is one of the major contents of lignocellulose and can be used as feedstock for adsorbent materials for wastewater treatment.Here,a lignin-poly(N-methylaniline)-graphene oxide(lignin-PNMA-rGO)hydrogel has been prepared by a two-step method,microspheres of lignin-PNMA was synthesis by the polymerization of NMA monomer in the presence of lignin in aqueous solution,and then they were encapsulated by the as-prepared reduced graphene oxide(GO)hydrogel via a reduction induced self-assembly of the GO nanosheets.The scanning electron microscopy(SEM),Fourier transform infrared(FT-IR),X-ray diffraction(XRD),and UV-Vis studies have been carried out and revealed that the formation of the 3D porous nanocomposite hydrogel with multilevel structures and sufficient active sites.The lignin-PNMA-rGO adsorbent exhibited high adsorption capacity for both organic dye methylene blue(MB,201.7 mg/g)and Pb 2+ion(753.5 mg/g).The new lignin-based adsorbent is a low-cost,environmentally benign,which is an attractive adsor-bent for wastewater treatment.

Spallation Yield of Neutrons Produced in Thick Lead Target by 400 MeV/u Carbon Ions

Measurement of the neutron yield is performed at a primary energy of 400 MeV/u carbons for the Pb target.Water-bath activation-foil method is used in a moderation measurement with Au foils to detect the moderated neutrons. The neutron yield is determined to be 18.4±2.1 per carbon by integrating the neutron flux over the entire water volume. The corresponding simulation values are performed by Geant4 code with three models to compare with the experimental results. The comparison shows that the calculated result with the INCL model is in good agreement with the experimental data.

Preparation of Chelating Polymer Grafted Magnetic Adsorbent and Its Application for Removal of Pb(Ⅱ) Ions

A novel magnetic chelating adsorbent （CPMS） with iminodiacetate functionality was prepared by polymerization of glycidyl methacrylate-iminodiacetic acid （GMA-IDA） monomer with N, N-methylenebisacrylamide as crosslinker in the presence of monodisperse magnetic silica microspheres （MS）. CPMS was characterized by IR, SEM, VSM and TGA. The experimental results revealed that MS was embedded in the gel polymer, but the morphology of CPMS was irregular. The saturation magnetization for CPMS was found to be 28.4 emu/g, and the percentage of GMA-IDA polymer grafted on MS was about 46.5%. CPMS were shown to be efficient for the removal of Pb（II） ions at pH 3.0 - 6.0, and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 54.4 mg？g？1 at pH 5.0. Moreover, the adsorption rate of CPMS was fast and it took about 5 minutes to achieve adsorption equilibrium in aqueous solution of lower lead ions concentration.

Lead removal from aqueous solution by employing natural brucite

The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharprise of the adsorption amount of Pb^(2+) on brucite. The synergism of buffering and adsorptioncapacities of brucite is responsible for the removal of Pb^(2+) from the aqueous solution. Thecoexistence of Cu^(2+) with Pb^(2+) causes a decrease of their adsorption on brucite due to acompetition for surface sites and brucite exhibits a higher adsorption capacity for Pb^(2+) than forCu^(2+). The percentage adsorption of Pb^(2+) on brucite could reach 96.38 percent, 97.20 percentand 94.09 percent respectively with the initial pH of the suspension pH_i = 1.76 (initial Pb^(2+)concentration [Pb^(2+)]_i = 20 mumol/L), 1.82 ([Pb^(2+)]_i = 100 mumol/L) and 1.84 ([Pb^(2+)]_i =500 mumol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^(2+)removal from polluted acidic water.

Biosorption of lead by Phanerochaete chrysosporium in the form of pellets

The growth of Phanerochaete chrysosporium (ATCC 24725) in pellets was influenced by culture time, medium pH, C/N, surfactant concentration, spore number in inoculum, and shaking rate. The removal of Pb 2+ from aqueous solution by this kind of mycelial pellets was studied. The results indicated that many factors affected biosorption. These factors included pH, Pb 2+ concentration, co ion, adsorption time, and chemical pretreatments of biomass. Under optimum biosorption conditions(pH 4 5, 27℃, 16h), the highest lead uptake of 108 mg/g, was observed with mycelial pellets of 1 5-1 7 mm in diameter which were treated with 0 1 mol/L NaOH solution before adsorption. Pretreatment of biomass with NaOH further increased its biosorption capacity.

Removal Mechanism of Aqueous Lead by a Novel Eco-material: Carbonate Hydroxyapatite

Kinetics and mechanisms on the removal of aqueous lead ion by carbonate hydroxyapatite （CHap） are investigated in the present work. Experimental results show that, in the whole pH range, the lead removal percentage increases with decreasing pH values and reaches a maximum at pH=2-3. Under some conditions, the lead residual concentration is below national integrated wastewater discharge standard, even drinking water standard. The removal behavior is a complicated non-homogeneous solid/liquid reaction, which can be described by two stages from kinetic point of view. At the earlier stage, reaction rate is so fast that its kinetic course is intricate, which requires further study. At the latter stage, the rate of reaction becomes slow and the process of reaction accords with one order reaction kinetic equation. Experimental results show that the relationship between reaction rate constant k1 and temperature T accords to Arrhenius Equation, and the activation energy of sorption （Ea） is 11.93 kJ/mol and frequency factor （A） is 2.51 s^-1. X-ray diffraction （XRD）, scanning electron microscopy with an energy dispersive X-ray fluoresence spectrometer （SEM-EDS） and toxicity characteristic leaching procedure （TCLP） test were conducted in this work. It is indicated that the main mechanism is dissolution-precipitation, accompanying with superficial sorption.

Activated Carbon Based on Acacia Wood (<i>Auriculeaformis</i>, Côte d’Ivoire) and Application to the Environment through the Elimination of Pb²⁺Ions in Industrial Effluents

The objective of this study is to develop carbon, that of Acacia auriculeaformis through its activation in order to eliminate lead in an aqueous medium. A series of activated carbon has been prepared by chemical activation with phosphoric acid, sodium hydroxide and sodium chloride. The determination of the physico-chemical properties of the prepared carbon guided the choice of phosphoric acid activated carbon as the best adsorbent for the elimination of lead(II) in an aqueous solution. Pb2+ adsorption tests in batch mode have shown that the adsorption capacity is influenced by various parameters such as mass, pH, concentration of Pb2+ ions and contact time linked to the medium and the adsorbent. Adsorption isotherms, kinetic models and thermodynamics have been used to describe the adsorption process. The equilibrium data for activated charcoal correspond well to the model of Freundlich, Langmuir, Temkin and Kiselev. The kinetic adsorption data proved to be better described by the pseudo-second order model with external and intraparticle diffusion which are two decisive steps in the adsorption process of Pb2+ ions. Thermodynamics and adsorption isotherms predict a spontaneous exothermic surface reaction, of the chemisorption type, with ion retention in orderly monolayers on the heterogeneous surface of the adsorbent. Tests carried out with this adsorbent material have contributed to the elimination of the Pb2+ ions contained in an industrial effluent with a reduction rate reaching 42.52% against 85.90% in a synthetic solution.

An ionic liquid supported CeO_2 nanoparticles-carbon nanotubes composite-enhanced electrochemical DNA-based sensor for the detection of Pb^(2+)

An electrochemical sensor incorporating a signal enhancement for the determination of lead （II） ions （Pb2＋） was designed on the basis of the thrombin-binding aptamer （TBA） as a molecular recog- nition element and ionic liquid supported cerium oxide （CeO2） nanoparticles-carbon nanotubes compo- site modification. The composite comprises nanoparticles CeO2, multi-waU carbon nanotubes （MWNTs） and hydrophobic room temperature ionic liquid （RTIL） 1-ethyl-3-methylimidazolium tetrafluoroborate （EMIMBF4）. The electrochemical sensors were fabricated by immersing the CeOa-MWNTs-EMIMBF4 modified glassy carbon electrode （GCE） into the solution of TBA probe. In the presence of Pb2＋, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb2＋ and TBA. The TBA-bound Pb2＋ can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb2＋. The reduction peak current is linearly related to the concentration of Pb2＋ from 1.0 ＊ 10-8 M to 1.0 ＊ 105 M with a detection limit of 5 ＊ 109 M. This work demonstrates that the CeOz-MWNTs-EMIMBF4 nanocomposite modified GCE provides a promising platform for immobi- lizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.

Application of Modified Nickel Slag Adsorbent on the Removal of Pb^(2＋) and Cu^(2＋) from Aqueous Solution

Al（OH）_3 modified nickel slag adsorbent was prepared by sintering technology. The structure of the sample was characterized by BET, XRD, IR, SEM and EDAX. The sample＇s adsorption performance of Pb^（2＋） and Cu^（2＋） from aqueous solution was studied. Results indicated that the adsorbent is a loose and porous mesoporous material. Its surface had mass aluminosilicate, high-activity γ-Al_2O_3 and its p H ranges from 4 to 12 that all have negative charges. The BET surface of the adsorbent is 23.90 m^2/g. Furthermore, its surface contains rich oxygenic functional groups, which could not only provide abundant adsorption sites for Pb^（2＋） and Cu^（2＋）, but also improve the adsorption performance of Pb^（2＋） and Cu^（2＋） from waste water through the complexation of heavy metal ions. The best p H values selected in the adsorption of Pb^（2＋） and Cu^（2＋） are 6 and 5, respectively. With the increase of the initial concentration of simulated solution, the adsorption capacities of Pb^（2＋） and Cu^（2＋） gradually increased but the removal rates showed a downward trend. The competitive adsorption results of Pb^（2＋） and Cu^（2＋） showed that Pb^（2＋） has better preferential adsorption than Cu^（2＋）.

Adsorption of Pb^2+and Cu^2+with Unburned Desulphurization Slag Modified Nickel Slag

Desulphurization slag modified nickel slag adsorbent was prepared by unburned forming technology. The structure of the sample was characterized by BET,XRD,IR,SEM and EDAX. The adsorption performance of Pb^2＋ and Cu^2＋ onto the resultant adsorbent from aqueous solution was studied. Results indicated that the adsorbent possesses a network pore structure formed by the AFt and C–S–H through cross lapping; the adsorbent contains a large number of Si–OH and Al–OH functional groups. The presence of functional groups not only provides abundant adsorption sites for Pb^2＋ and Cu^2＋,but also improves the adsorption performance of Pb^2＋ and Cu^2＋ from waste water through the complexation of heavy metal ions. The result of specific surface area analysis showed that the adsorbent sample possesses mesoporous structure and the BET specific surface area is 27.15 m^2/g. The solution p H values for the adsorption of Pb^2＋ and Cu^2＋ were optimized to be 6 and 5.5,respectively. The adsorption capacities of Pb^2＋ and Cu^2＋ gradually increase,whereas the removal rates of the two metal ions decrease with increasing the initial concentration of simulated solution. The resultant adsorbent gives a higher adsorption capacity for Cu^2＋ than for Pb^2＋ in the single ion solution. However,it shows preferential adsorption of Pb^2＋ rather than that of Cu^2＋. Meanwhile,results of recyclability indicate the remarkable regeneration capacity,re-adsorption ability and reusability performance of the adsorbent sample.

Synthesis and adsorption performance of lead ion-imprinted micro-beads with combination of two functional monomers

A novel ion-imprinted polymer, lead ion-imprinted micro-beads with combination of two functional monomers, was synthesized using the W/O/W polymerization method. Two functional monomers, 1,12-dodecanediol-O,O’-diphenyl-phosphonic acid （DDDPA） and 4-vinylpyridine, were used to form a suitable construction with micro-pores fitting the template and recognition sites. The eflects of adsorbent dosage, solution pH and the competitive ions on the adsorption and separation eflciency of lead ions were investigated. The lead ion-imprinted micro-beads were eflcient for lead ions removal from aqueous solution in a broad pH range （4–9）, when the adsorbent dosage was above 0.1 g/L. The adsorption process obeyed the pseudo second-order kinetics model and it only took half an hour to reach the equilibrium. The adsorption isotherm of lead ion was described by the Langmuir model （R2 0.99） with a maximum adsorption capacity of 116.9 mg/g. In the presence of competitive ions Co2＋ and Cd2＋, the lead ion-imprinted micro-beads showed a high selectivity for lead ions. The selectivity coeficient of Pb2＋/Cd2＋ and Pb2＋/Co2＋are 99.3 and 114.7, respectively.

Anodic Stripping Voltammetric Determination of Lead(II) Using Glassy Carbon Electrode Modified with Novel Calix[4]arene

A new glassy carbon electrode modified with novel caHx[4]arene derivative was prepared and then applied to the selective recognition of lead ion in aqueous media by cyclic and square wave voltammtry. A new anodic stripping peak at - 0.92 V (vs. Ag/Ag+) in square wave voltammogram can be obtained by scanning the potential from - 1.5 to - 0.6 V, of which the peak current is proportional to the concentration of Pb2+. The modified electrode in 0.1 moVL HNO3 solution showed a linear voltammetric response in the range of 2.0 x 10(-8)-1.0 x 10(-6) mol/L and a detection limit of 6.1 x 10(-9) mol/L. In the modified glassy carbon electrode no significant interference occurred from alkali, alkaline and transition metal ions except Hg2+, Ag+ and Cu2+ ions, which can be eliminated by the addition of KSCN. The proposed method was successfully applied to determine lead in aqueous samples.

One pot synthesis of monodispersed L-glutathione stabilized gold nanoparticles for the detection of Pb^2＋ ions

Direct mixture of Au^3＋ with glutathione （GSH）, which act as both reduction agents and stabilizers, in aqueous solution gave rise to production of gold nanoparticles （Au NPs） with uniform sizes of around 21 nm. The GSH stabilizer Au NPs in solution show immediate aggregation after addition of 1 mol/L NaCI aqueous solution containing Pb^2＋ ions. The Pb^2＋-induced aggregation in Au NP solution is monitored by both colorimetric response and UV-vis spectroscopy. A rather broad linear range （from 0.1 to 30 pmol/L） and low detection limit （0.1 pmol/L） are explored for Au NP sensors used for detection of Pb^2＋ ions. Furthermore, the response of GSH-stabilized Au NPs toward Pb^2＋ ions is specific compared with other possible interferants （Hg^2＋, Mg^2＋, Zn^2＋, Ni^2＋, Cu^2＋, Co^2＋, Ca^2＋, Mn^2＋, Cd^2＋, and Ba^2＋）.

Electrochemical sensor for Cd2+ and Pb2+ detection based on nano-porous pseudo carbon paste electrode

An electrochemical sensor based on self-made nano-porous pseudo carbon paste electrode(nano-PPCPE)has been successfully developed,and used to detect Cd^2+ and Pb^2+.The experimental results showed that the electrochemical performance of nanoPPCPE is evidently better than both glassy carbon electrode(GCE)and pure carbon paste electrode(CPE).Then the prepared nano-PPCPE was applied to detect Cd^2+ and Pb^2+in standard solution,the results showed that the electrodes can quantitatively detect trace Cd^2+ and Pb^2+,which has great significance in electrochemical analysis and detection.The linear ranges between the target ions concentration and the D PASV current were from 0.1-3.0 μmol/L,0.05-4.0 μmol/L for Cd^2+ and Pb^2+,respectively.And the detection limits were 0.0780 μmol/L and 0.0292 μmol/L,respectively.Moreover,the preparation of the nano-PPCPE is cheap,simple and has important practical value.

Synthesis of b-type Strontium Hydrogen Phosphate Nanosheets and Its Immobilization of Pb^(2+) in Acidic Aqueous Solution

Highly crystalline β-type strontium hydrogen phosphate （β-SrHPO4） nanosheets were prepared by a hydro- thermal method and used for the immobilization of lead ions （Pb2＋） from acidic aqueous solution. The effects of various parameters on the immobilization process, including solution pH value, contact time, initial ion concentrations, and coexistent competing cations, were studied to optimize the conditions for maximum immobilization. The β-SrHPO4 nanosheets exhibited a capacity of （1,120 ± 22） mg/g toward Pb2＋ in acidic solution （pH value is 3.0）, and the equilibrium was achieved within 8 rain. The competing cations such as Cu2＋, Zn2＋, Cd2＋, and Co2＋ affected slightly on the selective immobilization of Pb2＋. The results revealed that the removal mechanism of Pb2＋ by the β-SrHPO4 nanosheets was the dissolution/precipitation process in the acidic solution.

Flavonoid moiety-incorporated carbon dots for ultrasensitive and highly selective fluorescence detection and removal of Pb^2＋

A new type of self-targeting carbon dot （CD-Fla） for the detection of the toxic heavy metal ion Pb^2＋ was synthesized via a one-pot hydrothermal route using flavonoid extracts of Ginkgo biloba leaves as the starting material. As-prepared CD-Fla exhibited excellent biocompatibility and strong blue emission with a quantum yield of 16.1% and significant fluorescence quenching selectivity for Pb^2＋ without using any additional targeting molecules. CD-Fla could detect Pb^2＋ quantitatively within the range 0.1-20.0 nM, with an ultrahigh sensitivity of 55 pM. The selectivity of CD-FIa for Pb^2＋ was nearly one order of magnitude higher than that for other relevant metal ions. This was much better than ever reported CD-based metal ion sensors. The high sensitivity and selectivity were due to the incorporation of certain flavonoid-like moieties into CD-Fla. CD-Fla was also demonstrated to be a good probe for fluorescence tracing of intracellular Pb^2＋. The capability of CD-Fla was further improved when it was doped on agarose hydrogel. CD-Fla-doped agarose hydrogel （CD-AHG） allowed for visual fluorescence detection and removal of Pb^2＋ from water. This was confirmed by testing CD-AHG in actual water samples taken from the Jialing River （Chongqing, China）. The Pb^2＋ adsorbed CD-AHG was regenerable in HC1 solution. This study will open a new avenue for synthesizing intelligent materials capable of simultaneously targeting, detecting, and treating heavy metal ions.

Pb(II)adsorption by biochar from co-pyrolysis of corn stalks and alkali-fused fly ash

Numerous studies have reported the potential of silica as a biochar(BC)modifier.However,despite its high silica content,fly ash is rarely used for BC modification.Herein,modified BCs were produced by co-pyrolysis of corn stalks with alkali-fused fly ash(AFFA)at 200 and 600℃(denoted as AFFA/BC).The Pb(Ⅱ)adsorption mechanism and adsorption performance were investigated.The AFFA/BC had larger specific surface areas than the pure BC samples(2.54-137 vs.0.50 m2 g^(−1))owing to their stable carbon structure.The Pb(Ⅱ)adsorption capacity of AFFA/BC in water was approximately 6%higher than that of BC owing to the increased cation(Na+)exchange and new bonding sites,such as C-O and Si-O.AFFA/BC exhibited good Pb(Ⅱ)adsorption performance in high-concentration simulated wastewater(pH 4-6),with a maximum adsorption capacity of 110.29 mg g^(−1).The Pb(Ⅱ)adsorption mechanism was in accordance with the pseudo-second-order kinetic and Langmuir isotherm models.At 25℃and pH 5,the theoretical Pb(Ⅱ)adsorption capacities of AFFA200/BC and AFFA600/BC were 201.66 and 186.81 mg g^(−1),respectively,compared to 145.98 mg g^(−1)of BC.Physical adsorption,precipitation,cation exchange,and complexation were identified as the main Pb(Ⅱ)adsorption mechanisms through X-ray photoelectron spectrometry.