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Phytoremediation is currently a very popular remediation method for salvaging rare earth mining sites. However, there is still a challenge concerning how to use secondary resources such as plant biomass following the extraction of rare earth elements (REEs). Herein, Dicranopteris pedata (Houtt.) Nakaike, a REEs hyperaccumulator, served to fabricate REEs-rich carbonisation materials (REEs/C) at different temperatures. The results showed that the percentages of Pb(II) removed using REEs/C prepared at 400 °C (REEs/C-4) and 800 °C (REEs/C-8) were 85.1% and 84.0%, respectively. These amounts were better than that of REEs-C prepared at 600 °C (REEs/C-6 (67.0%)). Characterisation analysis confirmed that rich functional groups like aromatic, hydroxyl and C = C/C-C in REEs/C-4 provided more chelation sites to effectively complex with Pb(II), while the superior removal capacity of REEs/C-8 resulted from the enrichment of more REEs and abundant pore structure. Chemisorption, such as ion exchange and chelation, plays a significant role in adsorption. During the carbonisation process of REEs/C, the REEs enriched in Dicranopteris pedata contributed to the formation of rare earth oxides and oxygen vacancies in the material, and these properties enhanced the Pb removal ability of REEs/C. Moreover, the REEs contained in the material did not cause a leaching phenomenon during Pb removal, which is a safe and environmentally friendly material. Finally, the REEs/C was applied to wastewater, and it was found that this material could effectively adsorb Pb from wastewater. Overall, this study generates a new insight into: firstly, how to use phytoextracted biomass containing REEs as valuable REEs/C materials; and secondly, how to save the environment by using technology that promotes recycling of used materials. [ABSTRACT FROM AUTHOR]

The extensive release of water contaminated with lead (Pb(II)) and antimony (Sb(V)) constitutes a serious threat to the human living environment and public health, necessitating immediate attention. In this study, a novel MnFe@SBA composite was synthesized using the hydrothermal method through the in situ growth of MnFe2O4 on SBA-15. The MnFe@SBA exhibits an amorphous structure with a high specific surface area of 405.9 m2/g and pore sizes ranging from 2 to 10 nm. Adsorption experiments demonstrated that MnFe@SBA removed over 99% of Pb(II) and 80% of Sb(V) within 120 min at initial concentrations of 10 mg/L, whereas both MnFe2O4 and SBA-15 exhibited poor adsorption capacities. Additionally, the MnFe@SBA displayed excellent tolerance towards coexisting cations, including Na+, K+, Mg2+, Ca2+, Zn2+, Ni2+, and Cd2+, as well as anions such as Cl−, NO3−, CO32−, and PO43−. The adsorption behavior of Pb(II) onto MnFe@SBA was satisfactorily described by the pseudo-second-order kinetic model and the Freundlich isotherm, while the adsorption of Sb(V) was well-fitted by the pseudo-second-order kinetic model and the Langmuir isotherm. At 318 K, the maximum adsorption capacities of MnFe@SBA for Pb(II) and Sb(V) were determined to be 329.86 mg/g and 260.40 mg/g, respectively. Mechanistic studies indicated that the adsorption of Pb(II) and Sb(V) onto MnFe@SBA involved two primary steps: electrostatic attraction and complexation. In conclusion, the MnFe@SBA is anticipated to serve as an ideal candidate for efficient removal of Pb(II) and Sb(V) from contaminated water. [ABSTRACT FROM AUTHOR]

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Pb(II) is a heavy metal that is harmful to health and the environment. This metal is often found in industrial waste so it needs to be removed. One way to reduce these heavy metals is to use activated carbon. Various types of organic materials and agricultural waste can be made into activated carbon.. One of the agricultural wastes that has great potential as activated carbon is salak seeds. This research processed salak seeds into activated carbon and modified them into Magnetic Activated Carbon (MAC). The research aims to obtain: 1) the best operating conditions for activated carbon production and MAC; 2) characteristics of activated carbon and MAC; 3) % removal of Pb(II) from liquid waste with MAC; 4) isotherm adsorption equation Pb(II) by MAC; 5) the kinetics equation of Pb(II) adsorption by MAC. The research method is to make activated carbon by carbonization, chemical and physical activation. The chemical activator used is a mixture of phosphoric acid - hydrochloric acid with a composition (1: 1). The next step is to make a MAC from activated carbon. Activated carbon characteristics were tested using the BET, SEM, EDX, and ASTM standard proximate tests. The results showed that activated carbon met SNI standards with iodine number 1230.93-1256.31 mg/g, surface area 539.147 m²/g, pore volume 44.0262-112.5906 cc/g. MAC contains 1% water, 21.88% volatile matter, 38% ash, 39.12% fixed carbon, and 1243.62 mg/g iodine number. Further findings show that the adsorption isotherm equation is best using the Freundlich equation. The Freundlich equation constants n = 1.3530 and KF = 34.634 mg/g with R² = 0.913, while the Langmuir equations b = 0.7442 L/mg and qm = 78.125 mg/g with R² = 0.6692. The Pb(II) adsorption kinetics test by MAC showed pseudo-2nd order adsorption kinetics with the constant k² = 0.2737 g/mg.min and R² = 1. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine how well activated carbon made from kluwak shell (Pangium edule Reinw) works as an adsorbent to remove Pb(II) and Cu(II) heavy metal ions from wastewater used in laboratories. Kluwak shell was selected as an agricultural waste material due to its high carbon content, which makes it a promising material for activated carbon that can lower Pb(II) and Cu(II) heavy metal levels. Finding the ideal contact time, pH, and adsorption capacity as well as the kinetics and adsorption isotherm model are the main goals of this study. Using 25% KOH for carbonization and chemical activation, Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), and Surface Area Analyzer (SAA) for characterization are some of the research methods used. FTIR results showed the presence of O-H, C-H, C = C and C-O functional groups, while SEM showed more open pores after activation. SAA analysis indicated an activated carbon surface area of 3.11 m²/g, pore volume of 0.006 cm³/g, and pore diameter of 4.08 nm, categorized as mesoporous. The optimum condition for adsorption of Pb(II) ions is at pH 5 with contact time of 10 minutes and adsorption capacity of 21.83 mg/g. As for Cu(II) ions, the optimum condition is at pH 4 with a contact time of 20 minutes and adsorption capacity of 10.82 mg/g. The adsorption of metal ions is in accordance with the Langmuir isotherm model and pseudo second-order kinetics. The adsorption effectiveness of Pb(II) and Cu(II) ions from laboratory wastewater was 1.69 mg/g and 1.73 mg/g. It is concluded that activated kluwak shell can be used as Pb(II) and Cu(II) metal adsorbent. [ABSTRACT FROM AUTHOR]

The present study investigated the capability of cassava peel (Manihot Esculenta Crantz) in Pb(II) and Cr(VI) removal. The comparative study was conducted using batch method observing some parameters. The results indicated that the optimum adsorption of Pb(II) occurred at pH 5, initial concentration of 1000 mg/L, and contact time of 50 min. On the other hand, the optimal adsorption of Cr(VI) was achieved at pH 2, initial concentration of 1200 mg/L, and contact time of 70 min. The adsorption isotherms of both metals tended to follow the Langmuir model, while the adsorption kinetics suited to pseudo-second-order model. Thermodynamic parameters indicated that the adsorption process was spontaneous (ΔG° negative), endothermic (ΔH° positive), and exhibited surface dispersion on the biosorbent (ΔS° positive). Characterization using Fourier Transform Infrared (FTIR), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Thermogravimetry (TGA) provided evidence of both physical and chemical adsorption. The adsorption capacity of cassava peel was also tested on samples collected approximately 30 m from the bay shoreline, resulting in a removal percentage of 94.67% for Pb(II) and 82.28% for Cr(VI) under optimal pH and contact time conditions. [ABSTRACT FROM AUTHOR]

Fungal biomass is as a cost-effective and sustainable biosorbent utilized in both active and inactive forms. This study investigated the efficacy of inactivated and dried biomass of Fusarium sp. in adsorbing Ni2+ and Pb2+ from aqueous solutions. The strain underwent sequential cultivation and was recovered by filtration. Then, the biomass was dried in an oven at 80 ± 2 °C and sieved using a 0.1-cm mesh. The biosorbent was thoroughly characterized, including BET surface area analysis, morphology examination (SEM), chemical composition (XRF and FT-IR), thermal behavior (TGA), and surface charge determination (pH-PZC and zeta potential). The biosorption mechanism was elucidated by fitting equilibrium models of kinetics, isotherm, and thermodynamic to the data. The biosorbent exhibited a neutral charge, a rough surface, a relatively modest surface area, appropriate functional groups for adsorption, and thermal stability above 200 °C. Optimal biosorption was achieved at 25 ± 2 °C, using 0.05 g of adsorbent per 50 mL of metallic ion solution at initial concentrations ranging from 0.5 to 2.0 mg L−1 and at pH 4.5 for Pb2+ and Ni2+. Biosorption equilibrium was achieved after 240 min for Ni2+ and 1440 min for Pb2+. The process was spontaneous, mainly through chemisorption, in monolayer for Ni2+ and multilayer for Pb2+, with efficiencies of over 85% for both metallic ion removal. These findings underscore the potential of inactive and dry Fusarium sp. biomass (IDFB) as a promising material for the biosorption of Ni2+ and Pb2+. [ABSTRACT FROM AUTHOR]

This study synthesized biochar through a one-pot pyrolysis process using IALG as the raw material. The physicochemical properties of the resulting biochar (IALG-BC) were characterized and compared with those of biochar derived from acid-treated lignin with the ash component removed (A-IALG-BC). This study further investigated the adsorption performances and mechanisms of these two lignin-based biochars for Pb(II). The results revealed that the high ash content in IALG, primarily composed of Na, acts as an effective catalyst during pyrolysis, reducing the activation energy and promoting the development of the pore structure in the resulting biochar (IALG-BC). Moreover, after pyrolysis, Na-related minerals transformed into particulate matter sized between 80 and 150 nm, which served as active adsorption sites for the efficient immobilization of Pb(II). Adsorption results demonstrated that IALG-BC exhibited a significantly superior adsorption performance for Pb(II) compared to that of A-IALG-BC. The theoretical maximum adsorption capacity of IALG-BC for Pb(II), derived from the Langmuir model, was determined to be 809.09 mg/g, approximately 40 times that of A-IALG-BC. Additionally, the adsorption equilibrium for Pb(II) with IALG-BC was reached within approximately 0.5 h, whereas A-IALG-BC required more than 2 h. These findings demonstrate that the presence of inorganic mineral components in IALG plays a crucial role in its resource utilization. [ABSTRACT FROM AUTHOR]

Copper and lead ions are the most important toxic metals that cause significant environmental and health problems. In this study, we focused on the development of a very cost-effective and environmentally friendly (renewable) remediation technique using vine sprout, an industrial beer waste and readily available agricultural biowaste. In this study, it was aimed to remove the copper and lead that enter the body for various reasons orally, from the simulated stomach medium (SSM) by adsorption in order to reduce their toxic effects on human health. Activated carbon (ACVS) obtained from vine shoots was used as adsorbent. By preparing an artificial stomach medium, the most suitable adsorption parameters (pH, time, mixing speed, amount of adsorbent, and the effect of other components) were examined in the batch system. Equilibrium adsorption data was interpreted using the Langmuir model. The initial Cu(II) and Pb(II) ion concentrations were 10 mg/L and the adsorbent amount was 0.3 g, and the maximum adsorption efficiency of Cu(II) and Pb(II) ions was 100% in the pH 3.5–6.5 range. The performance variables of the adsorbent used were compared with the performance variables of the commercial activated carbon (CAC) used in the emergency response. It was determined that the adsorbent used was more effective in removing copper and lead. [ABSTRACT FROM AUTHOR]

A novel chelating adsorbent based on (3-iminodiacetic acid) propyltriethoxysilane graphene oxide (IAT-GO) has been developed, showing exceptional promise for capturing lead. IAT-GO is made by combining a high-surface-area graphene oxide with a specially designed chelating ligand, which can selectively and efficiently remove lead. The synthesis of IAT-GO involves a two-step progression. In the first step, covalent bonds form between graphene oxide and (3-aminopropyl)-triethoxysilane (AT) through hydrolysis, condensation, and epoxide ring opening reactions. In the second step, nucleophilic substitution reactions occur between the primary amines and chloroacetic acid (CAA). A comprehensive suite of characterization techniques, including XPS, UV–Vis, XRD, Raman, FTIR, TEM, and SEM, provides detailed insights into the IAT-GO adsorbent's chemical composition and physical form, elucidating its intricate structure and morphology. Optimizing the experimental conditions for using the adsorbent material to remove Pb(II) ions from contaminated water revealed a maximum adsorption capacity of 124.0 mg/g at pH 5 and 30 min. The IAT-GO displays high selectivity for Pb(II) in a mixture of six metal ions containing 100 ppm of each one. Moreover, the IAT-GO shows 100% removal of Pb(II) for concentrations lower than 50 ppm. The excellent fit of the experimental data with the Langmuir adsorption isotherm and pseudo-second-order kinetic models (R2 > 99%) indicates that Pb(II) ion uptake onto the IAT-GO surface occurs via the monolayer formation of mercury ions. IAT-GO demonstrates exceptional potential as an innovative adsorbent for lead-contaminated water. Nitric acid (0.4 M) effectively regenerates the material, while its reusability remains impressive even after five cycles (> 97% removal efficiency). Therefore, this study highlights the development of a groundbreaking material, IAT-GO, with exceptional potential for remediating lead-contaminated water. Its high efficiency, selectivity, reusability, and cost-effectiveness make it a promising candidate for real-world applications. [ABSTRACT FROM AUTHOR]

This study describes a novel adsorbent with a multidentate ligand that was facilely fabricated by covalently bonding 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole on graphene oxide (AHMT-PRGO). The AHMT-PRGO nano-adsorbent was used for the effective removal of Hg(II), Pb(II), and Cr(VI) from wastewater. The AHMT-PRGO nano-adsorbent was synthesized by a nucleophilic substitution reaction between GO acyl chloride and AHMT chelating ligand in the presence of tetrabutyl-ammonium bromide as a catalyst. The successful modifications were confirmed via several spectroscopic and electron microscopy instrumentations including UV–Vis, FTIR, Raman, XRD, XPS, SEM, and TEM. The maximum adsorption capacities of Hg(II), Cr(VI), and Pb(II) on the AHMT-PRGO nano-adsorbent were 370.0, 136.2, and 109.6 mg/g, respectively, exceeding those of most previously reported adsorbents. Additionally, the equilibrium contact times for Hg(II), Pb(II), and Cr(VI) were 60, 30, and 400 min, respectively. In a mixture of nine heavy metal ions containing 250 ppm of each ion, the AHMT-PRGO nano-adsorbent exhibited high selectivity for Hg(II) ions. Furthermore, the AHMT-PRGO nano-adsorbent showed high stability over five adsorption–desorption cycles. Additionally, the AHMT-PRGO nano-adsorbent was successfully applied to remove heavy metal ions from real water samples. The novelty of AHMT-PRGO lies in the combination of a multidentate ligand for strong and selective binding with the high surface area and stability offered by covalently bonded graphene oxide. This combination offers potential advantages over traditional adsorbents in terms of adsorption capacity, selectivity, and reusability. [ABSTRACT FROM AUTHOR]

Heavy metal pollution and organic wastewater treatment have attracted extensive attention of researchers. Adsorption method is widely used in wastewater treatment because of its low price and high efficiency. As a natural, cheap biomass material, bamboo powder is of great significance to develop it into an economical and efficient biochar for wastewater treatment. A new type of ball-milled biochar (BMBC) adsorbent was prepared by pyrolysis of bamboo powder under an inert atmosphere, activated with sodium hydroxide solution and ball milling. The specific surface area of BMBC increased from 29.21 to 60.49 m2/g, and the carboxyl and hydroxyl groups on the pyrolyzed carbon surface also obviously increased after ball milling. The results of bath adsorption experiments showed that BMBC exhibited excellent adsorption capacity towards both Pb(II) (170.52 mg/g) and methylene blue (MB, 419.11 mg/g) at 308 K. Based on a systematic study on the effect of various working conditions (including concentration, temperature, pH value, and ionic strength), it was demonstrated that pseudo-second-order kinetic equation might match the adsorption process (R2 > 0.9934) and Langmuir model (R2 > 0.9924); adsorptions were thermodynamically endothermic and occurred spontaneously. The ball milled alkalization-modified bamboo biochar can potentially be applied to remove heavy metal and cationic pollutants from wastewater. [ABSTRACT FROM AUTHOR]

To develop cost-effective heavy metal adsorbents, we employed water-soluble lignin from black liquor to modify activated attapulgite, resulting in the creation of a novel adsorbent called Lignin-modified attapulgite (LATP). In this study, scanning electron microscopy and Fourier transform infrared spectrometer techniques were utilized to characterize the structural details of LATP. The results revealed that lignin occupies the micropores of attapulgite, while additional functional groups are present on the attapulgite surface. We conducted adsorption tests using LATP to remove five types of heavy metal ions (Cd2+, Pb2+, Zn2+, Mn2+, Cu2+), and it was found that LATP exhibited greater removal mass and binding strength for Pb(II) compared to the other ions. For further investigation, batch experiments were performed to evaluate the adsorptive kinetics, isotherms, and thermodynamics of Pb2+ removal from aqueous solutions using LATP. The results indicated that the adsorption capacity of Pb(II) on LATP decreased with decreasing pH, while the presence of Na+ had no effect on adsorption. The adsorption process reached equilibrium rapidly, and the Langmuir adsorption capacities increased with temperature, measuring 286.40 mg/g, 315.51 mg/g, and 349.70 mg/g at 298 K, 308 K, and 318 K, respectively. Thermodynamic analysis revealed positive values for ΔH0 and ΔS0, indicating an endothermic and spontaneous adsorption process. Furthermore, ΔG0 exhibited negative values, confirming the spontaneous nature of the adsorption. Consequently, LATP demonstrates great potential as an effective adsorbent for the removal of Pb(II). Therefore, LATP shows great potential as an effective adsorbent for the removal of Pb(II) from natural water environments, contributing to the sustainable development of man and nature. [ABSTRACT FROM AUTHOR]

Activated carbon nonwoven nanofibres (ACNN) mat derived from polyacrylonitrile was manufactured through the electrospinning method followed by thermal treatment steps. The ACNN ability to adsorb Pb(II) from a liquid solution was evaluated. The fabricated ACNN was characterized using scanning electron microscope, Fourier-transform infrared spectroscopy, and Brunauer-Emmett-Teller method. The resulting ACNN exhibited nanofibres with a diameter of 530 nm and a surface area of 550 m2/g. Various adsorption experiments were performed in batch scale to study the impact of factors like contact time, initial Pb(II) ions concentration, and pH. At pH 5, ACNN achieved a removal efficiency of 98% of Pb(II). The equilibrium data for Pb(II) ions was analysed using the Freundlich and Langmuir isotherm models. Both kinetic models (pseudo-first-order and pseudo-second-order) and isotherm models were tested. Results revealed that the Langmuir model accurately described the adsorption isotherm of Pb(II) with a maximum capacity of 15.72 mg/g. Data analysis suggested that the pseudo-second-order model better represented the kinetic adsorption behaviour of Pb(II). [ABSTRACT FROM AUTHOR]

Using peanut shells, a sustainable agricultural waste product, as its raw material, the acid group-modified biochar (AMBC) was prepared through phosphoric acid activation, partial carbonization, and concentrated sulfuric acid sulfonation for efficient removal of lead ion from aqueous solutions. Characterization techniques such as N2 isothermal adsorption–desorption, SEM, XRD, FT-IR, TG-DTA, and acid–base titration were utilized to fully understand the properties of the AMBC. It was found that there were high densities of acidic oxygen-containing functional groups (-SO3H, -COOH, Ph-OH) on the surface of the AMBC. The optimal adsorption performance of the AMBC for Pb(II) in water occurred when the initial concentration of Pb(II) was 100 mg/L, the pH was 5, the dosage of the adsorbent was 0.5 g/L, and the contact time was 120 min. Under the optimal conditions, the removal ratio of Pb(II) was 76.0%, with an adsorption capacity of 148.6 mg/g. This performance far surpassed that of its activated carbon precursor, which achieved a removal ratio of 39.7% and an adsorption capacity of 83.1 mg/g. The superior adsorption performance of AMBC can be caused by the high content of acidic oxygen-containing functional groups on its surface. These functional groups facilitate the strong binding between AMBC and Pb(II), enabling effective removal from water solutions. [ABSTRACT FROM AUTHOR]

In the present research, the presence of water hyacinth (Eichhornia crassipes) on the surface of the San Jose Dam located in the city of San Luis Potosi, S.L.P, Mexico, was monitored and mapped. The monitoring was conducted for 2 years (2018–2020) with remote sensing data from OLI Landsat 8 sensors, based on the normalized difference vegetation index (NDVI). The results demonstrated the capability and accuracy of this method, where it was observed that the aboveground cover area, proliferation, and distribution of water hyacinth are influenced by climatic and anthropogenic factors during the four seasons of the year. As part of a sustainable environmental control of this invasive species, the use of water hyacinth (WH) root (RO), stem (ST), and leaf (LE) components as adsorbent material for Pb(II) present in aqueous solution was proposed. The maximum adsorption capacity was observed at pH 5 and 25 °C and was 107.3, 136.8, and 120.8 mg g−1 for RO, ST, and LE, respectively. The physicochemical characterization of WH consisted of scanning electron microscopy (SEM), N2 physisorption, infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), charge distribution, and zero charge point (pHPZC). Due to the chemical nature of WH, several Pb(II) adsorption mechanisms were proposed such as electrostatic attractions, ion exchange, microprecipitation, and π-cation. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of PbCl2 in NaCl–KCl molten salt on graphite and molybdenum electrodes was investigated using cyclic voltammetry, square wave voltammetry, chronopotentiometry, and open circuit chronopotentiometry at 750°C. A pair of redox peaks for Pb(II)/Pb was observed from the cyclic voltammetry (CV) results, with cathodic peak potentials of –0.16 and –0.2 V at the molybdenum and graphite electrodes, respectively. It was also confirmed that the reduction of Pb(II)/Pb was a one-step reduction process with a two-electron transfer and a quasi-reversible process. Square wave voltammetry (SWV) was also used to confirm the accuracy of the CV results further. The diffusion coefficients of Pb(II) ions on molybdenum and graphite electrodes were calculated using the Berzins-Delahay equation, which were 3.85 × 10–5 and 7.42 × 10–5 cm2 s–1, respectively. Similarly, the diffusion coefficients were also calculated using the Sand equation, which were 2.89 × 10–5 and 4.55 × 10–5 cm2 s–1, respectively. In addition, the deposition and dissolution behavior of Pb(II) on molybdenum and graphite electrodes were further investigated with chronopotentiometry (CP) and open circuit chronopotentiometry (OCP), respectively, and the results obtained were in agreement with the CV and SWV results. This study lays a foundation for the recycling of secondary Pb resources and the preparation of Ti–Pb alloys by electrodeposition method in molten salt. [ABSTRACT FROM AUTHOR]

This research studies on the visible photocatalytic improvement and separable ability of TiO2 by Fe doping and Fe3O4 magnetizing from iron rusty waste. The doping and magnetizing were performed by hydrothermal and precipitation methods, respectively. The Fe doped TiO2 (TiO2–Fe) prepared was magnetized with Fe3O4 having fraction of 33.3 wt%. The research results assign that from the characterization of the prepared photocatalysts by means of X-ray diffraction (XRD), diffuse reflectance UV–visible (DRUV–Visible), and Fourier Transform infrared (FTIR), the Fe doped and Fe3O4 precipitated into TiO2 to form TiO2–Fe/Fe3O4 photocatalyst has been successfully synthesized. Furthermore, the doping and magnetizing have considerably enhanced the activity of TiO2–Fe/Fe3O4 photocatalyst under visible light and given good magnetic separable properties. The highest photo-oxidation of Pb(II) 10 mg/L in 100 mL of the solution can be obtained by applying 50 mg weight of TiO2–Fe/Fe3O4 photocatalyst, solution pH of 6 and 60 min of the reaction time, reaching 83% efficiency. The photo-oxidation of Pb(II) is supposed to transform the toxic Pb (II) into a handleable PbO2 with less hazardous properties. Hence, circular environmental management would be expected for this study from utilizing the priceless waste to enhance material properties in the reducing the toxic contaminant. [ABSTRACT FROM AUTHOR]

The adsorption property of the costless green cellulose acetate (CA) was boosted by the dual modifications: inner modification by incorporating carboxylated graphene oxide (COOH-GO) into the CA spheres and outer modification by the surface modification of the COOH-GO@CA spheres by iminodiacetic acid (IDA) for removing Pb(II). The adsorption experiments of the Pb(II) proceeded in a batch mode to evaluate the adsorption property of the COOH-GO@CA@IDA spheres. The maximal Pb(II) adsorption capacity attained 613.30 mg/g within 90 min at pH = 5. The removal of Pb(II) reached its equilibrium within 20 min, and the removal % was almost 100% after 30 min at the low Pb(II) concentration. The Pb(II) adsorption mechanism was proposed according to the kinetics and isotherms studies; in addition, the zeta potential (ZP) measurements and X-ray Photoelectron Spectroscopy (XPS) analysis defined the adsorption pathways. By comparing the XPS spectra of the authentic and used COOH-GO@CA@IDA, it was deduced that the contributed chemical adsorption pathways are Lewis acid–base, precipitation, and complexation. The zeta potential (ZP) measurements demonstrated the electrostatic interaction participation in adsorbing the cationic Pb(II) species onto the negatively charged spheres (ZP = 14.2 mV at pH = 5). The unique channel-like pores of the COOH-GO@CA@IDA spheres suggested the pore-filling mechanism of Pb(II). The promising adsorption results and the superb recyclability character of COOH-GO@CA@IDA enable it to extend of the bench scale to the industrial scale. [ABSTRACT FROM AUTHOR]

In this study, eco-friendly casein-copper hybrid nanoflowers (CAS-Cu HNFs) were synthesised and their applicability for the removal of Pb(II) and Cd(II) ions was investigated. Hybrid nanoflowers were synthesised by adding CuSO4 solution on casein in PBS medium. According to the evaluation of SEM images, regular nanoflower structures were obtained after the addition of 40 µL of 100 mM CuSO4 and 12 h incubation. Characterisation studies were performed by XRD, SEM-EDX, FTIR and TGA. The effects of contact time, pH, temperature and heavy metal ion concentration on the adsorption performance were investigated. Optimum adsorption was achieved at 60 min contact time and 35 and 30 °C for Pb(II) and Cd(II) ions, respectively. The performance of CAS-Cu HNFs was evaluated by linear and non-linear forms of adsorption isotherms and adsorption kinetics, respectively. The linear Langmuir isotherm model showed compatibility and the maximum adsorption capacity was found to be 769.23 and 156.25 mg/g for Pb(II) and Cd(II) ions, respectively. CAS-Cu HNFs has great potential as an eco-friendly, nanoscale, flower-like, organic–inorganic hybrid nano-flower adsorbent for the effective removal of Pb(II) and Cd(II) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

To improve the removal capacity of rice straw biochar for heavy metals in acidic mine wastewater, magnesium-modified rice straw biochar (MBC) was prepared by impregnation-pyrolysis method. The effects of impregnation ratio, solution pH,adsorption time,and initial concentration on the removal of Cd(II) and Pb(II) from acid mine wastewater by MBC were investigated through batch adsorption experiments, and the features of MBC before and after adsorption were analyzed by characterisation techniques to explore the potential adsorption mechanisms. The results showed that the MBC prepared by impregnation-pyrolysis possessed a well-developed pore structure. The adsorption experiments showed that the removal efficiency for 10 mg/L of Pb(II) and Cd(II) by MBC reached the optimum values of 93. 58% and 97. 95% at impregnation ratio 2 : 1 and solution pH 5. 0 respectively. The removal process of Cd( II) and Pb(II) by MBC was consistent with the pseudo second order kinetic model and Langmuir adsorption isotherm model. According to the Langmuir model,the maximum adsorption capacities of MBC for Cd(II) and Pb(II) were 90. 45 mg/g and 138. 50 mg/g, respectively. FTIR and XRD analyses showed that the removal mechanism of Cd (II) and Pb (II) by MBC contained complexation, co-precipitation, ion exchange, and electrostatic interaction. After five regenerations, the removal efficiency of Cd(II) and Pb(II) by MBC was maintained at 85. 62% and 80. 16%, respectively. The above results indicated that MBC had great potential for treating acid mine wastewater containing Cd(II) and Pb(II). [ABSTRACT FROM AUTHOR]

The biosorption of Pb(II) from an aqueous environment was studied using a mixed biofilm of microalgal biomass (Chlorella vulgaris) and natural pectin. A gas sorption analyzer, Fourier transform infrared spectrometer, field emission scanning electron microscope, point of zero charge determination, and texture analyzer were used for the adsorbent's characterization. Various sorption parameters such as contact time, initial pH, initial metal concentration and temperature were studied. The results were also used to conduct isotherm and kinetic studies. Subsequently, the second-order polynomial model following the response surface methodology was obtained with an R2 of 0.9941 indicating acceptable accuracy. Under the following condition: an initial pH of 4.27, an initial metal concentration of 300 mg/L, and a temperature of 55.2 °C, a maximum Pb(II) uptake of 121.89 mg/g was observed. The results show that the developed composite biofilm can effectively remove Pb(II) ions from contaminated water. [ABSTRACT FROM AUTHOR]

Industrial processes are the main source of Pb(II) contamination of natural water bodies. Pb(II) is a non-biodegradable heavy metal and carcinogen. The recent study explored the ability of citric acid-modified-kepok banana peel (CA-BP) to remove Pb(II) from an aqueous solution using the batch method. The adsorption capacity of kepok banana peel (BP) was also investigated for comparison. The optimum conditions for Pb(II) removal using kepok banana peel were achieved at pH 5, initial concentration of 600 mg l-1, contact time of 75 min, and agitation speed of 100 rpm, with an adsorption capacity of 36.478 mg g-1. Meanwhile, the adsorption capacity of citric acid modified-kepok banana peel was 64.088 mg g-1, which was reached at pH 5, initial concentration of 850 mg l-1, contact time of 75 min, and agitation speed of 150 rpm. The adsorption of Pb(II) onto both sorbents followed the Langmuir isotherm model and pseudo-second-order model, indicating monolayer adsorption with chemical interaction as a rate-limiting step. A Fourier Transform Infra-Red (FTIR) analysis was conducted to identify the functional groups present in the biosorbent and demonstrate a change in the wave number. The surface morphology of the biosorbent was examined using Scanning Electron Microscopy (SEM) before and after the absorption of Pb2+ metal ions. The objective of Energy Dispersive X-ray (EDX) is to quantify the elemental composition of the biosorbent derived from the surface of the kepok banana peel. An X-ray fluorescence (XRF) analysis was conducted to determine the chemical composition of the surface of the kepok banana peel biosorbent. Thermogravimetric Analysis (TGA) was conducted to observe the decrease in mass of the biosorbent as the temperature increased. [ABSTRACT FROM AUTHOR]

Some heavy metals such as Pb, Cd, Hg and As are extremely hazardous to the human beings because of their non-biodegradable nature even at very low levels of exposure. Besides the standard methods such as Inductively Coupled Plasma (ICP)-Mass Spectrometry and ICP-Optical Emission Spectrometry, the other methods with fast, accurate and cheap requirements also need to be developed to detect these toxic heavy metals ions in aquatic sources. Recently the application of porous materials in the anodic stripping voltammetry has gained a great attention owing to high selectivity, sensitive and low cost. In the present study, a glassy carbon electrode (GCE) modified by ZnO- electrochemically reduced graphene oxide (ZnO/ErGO) was used for the electrochemical detection of Pd(II) and Cd(II). It is found that the surface area of ZnO/ErGO-GCE is 0.130 cm2 much larger than that of the bare GCE (0.083 cm2).The charge transfer resistance decreases significantly from 3212 Ω for the bare GCE to 924 Ω for ZnO/ErGO-GCE. These results manifest a fast electron transfer ratio of kinetics for the ZnO/ErGO-modified electrode. ZnO/ErGO-GCE exhibits excellent electrochemical performance towards the detection of Pb(II) and Cd(II) compared with ErGO-GCE and bare GCE. The peak current has a linear relationship with the Cd(II) and Pb(II) concentration in the 2.5–200 µM range. The limit of detection for Cd(II) and Pb(II) is 1.69 and 0.45 ppb, respectively. In addition, the electrochemical sensor exhibits excellent selectivity, stability, and repeatability in experimental studies, and it opens up great potential for detecting a trace amount of metals. [ABSTRACT FROM AUTHOR]

Toxic heavy metals are ubiquitous in the aquatic environment and show a significant danger to human health. Carbon nanotubes have been extensively used in treating the contamination of groundwater due to their porous multi-layer nature. Batch tests revealed that oxidized multiwalled carbon nanotubes (O-MWCNTS) offer better removal of Pb(II). The removal rate of Pb(II) was 90.15% at pH 6 within 24 h, which was ~58% more than that of Cd(II). The removal rate decreased to 55.59% for Pb(II) and to 16.68% for Cd(II) when the initial concentration of Pb(II)/Cd(II) ranged from 5 to 15 mg·g−1. The removal rate in the competitive tests was about 60.46% for Pb(II) and 9.70% for Cd(II). The Langmuir model offered better description of the adsorptive data for both ions. And the Qm of Pb(II) was 5.73 mg·g−1, which was 2.39 mg·g−1 more than that of Cd(II) in a single-icon system, while Qm was 7.11 mg·g−1 with Pb(II) and 0.78 mg·g−1 with Cd(II) in competitive water. And thermodynamic tests further indicated that the activating energy of Pb(II) and Cd(II) was 83.68 and 172.88 kJ·mol−1, respectively. Lead and cadmium adsorbed on the surface of O-MWCNTS are antagonistic in the competitive system. Based on XPS analyses, it was concluded that the absorbed lead/cadmium species on O-MWCNTS were (-COO)2Pb, (-COO)Pb(-O)/(-COO)2Cd, and (-COO)Cd(-O). Additionally, they offered theoretical evidence supporting the practicality of using nanocomposite membranes as a means to remove cadmium and lead. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Applied Chemical Industry is the property of Shaanxi Research Design Insitute of Petroleum & Chemical Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A kind of adsorbent (Hydrogel-I) derived from sodium alginate and modified alkaline lignin (MAL) has been proved to possess a good adsorption performance for Pb(II)-loaded wastewater based on batch experiments. However, practical removal of Pb(II)-loaded-wastewater is a continuous and dynamic process. Herein, Hydrogel-I was further evaluated by packing it into a fixed-bed column. The breakthrough curves were established under different inflow rates (0.159–0.318 L/min), inflow directions (down-inflow mode and top-inflow mode), initial concentrations (5–20 mg/L) of Pb(II), and bed depths (20–60 cm). The results indicated that the slower inflow rate (0.159 L/min), down-inflow mode, lower initial concentration (5 mg/L), and higher bed depth (60 cm) prolonged breakthrough times (tb) and saturation times (ts). Compared to the top-inflow mode, the down-inflow mode guaranteed enough contact between Hydrogel-I and Pb(II). The values of adsorption capacity at tb, ts, and the removal efficiency under the down-inflow mode were higher than that under top-inflow mode by 2.33, 0.78, and 0.07 times, respectively. Hydrogel-I beads exhibited better adsorption performance than other adsorbents by comparing the rate constant (kAB) and the adsorption capacity (N0). The kAB and N0 of Hydrogel-I beads were calculated to be 0.0034 L/(mg·min−1) and 678 mg/L. Hydrogel-I beads showed good regeneration ability in a three-adsorption-desorption cycle. Meanwhile, FT-IR analysis showed that the groups of –NH/–NH2, C=S, and C–S were proved to be the adsorption sites. This study could prove valuable insight into the practical application of Hydrogel-I for dynamic removal of Pb(II) in an inflow-through column. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a strategy for the establishment of an aerobic granular sludge (AGS) system for simultaneous nitrogen and Pb(II) removal from inorganic wastewater. AGS was stored in lead nitrate solution to select functional bacteria resistant to lead poison, and then an AGS system for ammonia nitrogen (180-270 mg/L) and Pb(II) (15-30 mg/L) removal was established based on carbon dosing and a two-stage oxic/anoxic operational mode. After storage for 40 days, the stability of AGS decreased because specific oxygen uptake rate, nitrification rate and abundance of Nitrosomonas decreased to different degrees compared with those before storage. During the first 70 days of the recovery process, AGS in R1 (the blank reactor) and R2 (the control reactor) both experienced a first breakage and then regranulation process. The main properties of AGS in reactors R1 and R2 tended to be stable after days 106 and 117, respectively, but the structure of steady-state AGS in R2 was more compact. The total inorganic nitrogen (TIN) in effluent from R1 and R2 basically remained below 25 mg/L after days 98 and 90, respectively. The Pb(II) concentration in effluent from R2 was always below 0.3 mg/L. On day 140, the relative abundance of Nitrosomonas in R2 (6.17%) was significantly lower than that in R1 (12.15%), whereas the relative abundance of denitrifying bacteria was significantly higher than that in R1 (62.44% and 46.79%). The system removed 1 kg of influent TIN only consuming approximately 1.85 kg of carbon source, demonstrating clear advantages in energy savings. [ABSTRACT FROM AUTHOR]

This study aimed to extract pectin from local Majiayou pomelo (Citrus grandis (L.) Osbeck) peel in Jiangxi province with distilled water, hydrochloric acid and citric acid, respectively, and analyze the physicochemical components of pectin and its adsorption properties on Pb(II), and explicit the effect of adsorption parameters (initial pH value, initial ion concentration, adsorption time) on Pb (II) and its adsorption mechanism by adsorption isotherms and adsorption kinetics. The results showed that the yield of pectin by citric acid extraction (CEP) was highest (28.62%), followed by hydrochloric acid extraction (HEP) and distilled water extraction (WEP). In addition, the esterification degree (58.20%) and molecular weight (598.40 ku) of CEP were significantly lower than those of WEP and HEP (P<0.05), indicating that CEP had more carboxyl and higher solubility. The three pectins showed optimal adsorption of Pb (II) at initial pH 5.0, and reached equilibrium after 120 min adsorption. In addition, the adsorption capacity of CEP on Pb (II) was significantly higher than that by WEP and HEP. The adsorption isotherms of the three pectins were in accordance with Langmuir monolayer adsorption model, and the adsorption kinetics of the three pectins was consistent with pseudo first-order kinetics model. The adsorptions of three pectins on Pb (II) were the result of physical and chemical adsorption. Conclusion: The physicochemical properties of pectin and its adsorption capacity on Pb (II) were closely related to the extraction method, and CEP has a high adsorption capacity on Pb (II), which could be used as a low-cost, efficient, natural and environmental friendly adsorbent for removal of Pb (II). [ABSTRACT FROM AUTHOR]

Pyromellitic dianhydride-modified polyvinylamine gel (PAPVAM) as absorbent for Pb(II) ion was prepared. Pyromellitic dianhydride acted as cross-linking agent for polyvinylamine and chelating agent for Pb(II) ion. The structure of PAPVAM was confirmed by Fourier transform infrared spectroscopy and solid-state 13C nuclear magnetic resonance. Plenty of pores existed in freeze-drying PAPVAM. The energy-dispersive X-ray mapping and X-ray photoelectron spectroscopy of PAPVAM with Pb(II) showed that Pb(II) was complexed with amino groups and carboxylic groups in PAPVAM. The adsorption of Pb(II) by PAPVAM was consistent with the pseudo-second-order kinetic model. The differential scanning calorimetry showed that the adsorption of Pb(II) by PAPVAM was an exothermal process. The adsorption process was also fitted with the Freundlich isotherm equation. Pb(II) penetrated into PAPVAM. Programmed-temperature was designed to improve the adsorption capacity of Pb(II). More precisely, Pb(II) was absorbed by PAPVAM at 50 °C for 2 h and then at 30 °C for 2 h. The adsorption of Pb(II) at 50 °C contributed to its penetration into PAPVAM gel, and its adsorption at 30 °C contributed to the improvement of the adsorption capacity in thermodynamics. Finally, the adsorption capacity of Pb(II) by PAPVAM was 140.42 mg g−1 under programmed-temperature above mentioned. [ABSTRACT FROM AUTHOR]

The new polymer–mineral composite materials have been obtained by in situ immobilization of poly-[5-(p-nitrophenylazo)-8-methacryloxyquinoline] on the saponite of Tashkivsky deposit (Sap-AzoQN) and clinoptilolite of the Tushinsky deposit (Clin-AzoQN) surface. The fact of polymer immobilization on the surface of minerals by the selected method was confirmed by thermogravimetric analysis combined with mass spectrometry and IR spectroscopy. Scanning electron microscopy showed that the immobilized polymer is located on the surface of both minerals in the form of needles, located in different directions to the surface, and acicular formations. The properties of the composite materials have been determined by means of a sorption test when removing ions Pb2+, Fe3+, and Cu2+ from the model solutions in static conditions. A twofold increase in the sorption capacity of the Sap-AzoQN composite for Cu(II) and Pb(II) ions and a 5.6-fold increase in the Clin-AzoQN composite for Fe(III) ions were recorded compared to the original minerals. As a result, composite materials revealed high-efficiency sorption of heavy metals. [ABSTRACT FROM AUTHOR]

This paper presents the utilization of sodium alginate (SA) as a raw material to construct a double network structure through the incorporation of chitosan (CS) and the electrostatic polymerization of SA. Subsequently, by employing polyvinyl alcohol (PVA) as a functional material, a modified SA/CS/PVA composite hydrogel (SCPH) was prepared via the Ca(II) ion exchange method. The hydrogel exhibited a flocculent form, thereby greatly enhancing the removal of Pb(II). The adsorption process of Pb(II) by the SCPH reached equilibrium within 30 min, achieving a remarkable removal rate of 97.45% and a maximum adsorption capacity of 147.93 mg/g (298 K). A series of characterization analyses have been employed to investigate the structure and adsorption mechanism of hydrogels, and the adsorption mechanism involves ion exchange, electrostatic attraction, as well as the complexation of hydroxyl and carboxyl groups. Batch adsorption experiments were conducted at different temperatures and pH levels, and the kinetics and isotherms were investigated. The Langmuir isotherm and pseudo-second-order kinetic model were found to best fit the experimental data, suggesting the feasibility of using the SCPH as an efficient adsorbent for Pb(II) removal. Moreover, the dual network structure constructed by SA and CS significantly enhances the adsorption performance of SCPH. At the same time, PVA strengthens the mechanical strength of SCPH, which is favorable for recycling. As a low-cost and efficient adsorbent, SCPH can be widely used in water treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND: The non‐distilled property and prolonged production period of yellow rice wine have significantly increased the metal residue problem, posing a threat to human health. In this study, a magnetic carbon‐based adsorbent, named magnetic nitrogen‐doped carbon (M‐NC), was developed for the selective removal of lead(II) (Pb(II)) from yellow rice wine. RESULTS: The results showed that the uniformly structured M‐NC could be easily separated from the solution, exhibiting a high Pb(II) adsorption capacity of 121.86 mg g−1. The proposed adsorption treatment showed significant Pb(II) removal efficiencies (91.42–98.90%) for yellow rice wines in 15 min without affecting their taste, odor, and physicochemical characteristics of the wines. The adsorption mechanism studied by X‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared (FTIR) analyses indicated that the selective removal of Pb(II) could be attributed to the electrostatic interaction and covalent interaction between the empty orbital of Pb(II) and the π electrons of the N species on M‐NC. Additionally, the M‐NC showed no significant cytotoxicity on the Caco‐2 cell lines. CONCLUSION: Selective removal of Pb(II) from yellow rice wine was achieved using magnetic carbon‐based adsorbent. This facile and recyclable adsorption operation could potentially address the challenge of toxic metal pollution in liquid foods. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study is aiming to prepare the porous PBAT/modified zeolite composite by the simple, rapid, and efficient method of preparing them by the solution coating process with modified zeolite as adsorbent, as well as with PBAT as carrying agents and with ethanol as porogenic agent. Some influencing factors for adsorbing PBAT/modified zeolite composite membrane in Lead‐Ion‐Heavy Metal wastewater were researched in this paper, including the effects of zeolite content, modifier type, initial pH, pore‐making agent, adsorption time, adsorption temperature, initial concentration, and feeding quantity. In addition, the adsorption processes of the porous PBAT/modified zeolite composite membrane are studied by means of the adsorption kinetics and adsorption isotherm models. The finding shows the kinetic data were consistent with the pseudo‐second‐order model, and the data fitting of isothermal adsorption experiment is closer to the Langmuir adsorption model, which is a single‐molecule adsorption process and belongs to chemisorption, with a saturation adsorption amount of about 106.3 mg/g. Therefore, zeolite has great prospects for the removal of Pb(II) in wastewater, and provides a theoretical basis for the efficient treatment of heavy metal‐containing wastewater. Highlights: A composite film that can effectively remove Pb(II) from water was prepared.The composite exhibits rational pore structure and high specific surface area.This composite has advantages of biodegradability and reproducibility. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangxi Normal University - Natural Science Edition is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lead and cadmium are toxic to human, animal, and plant health; they enhance oxidative stress indirectly while simultaneously acting through other toxicodynamic mechanisms. In this study, pristine vermiculite (VER) was functionalized with butylamine (BUT) and a novel organoclay (BUT-VER) adsorbent material was produced for simultaneous removal of Pb(II) and Cd(II) in aquatic medium. The adsorbents were characterized by spectroscopic, microscopic, spectrometric, and potentiometric techniques. The adsorption affecting parameters, including pH, time, initial concentration, temperature, and co-existing cations were investigated and optimized. The kinetic data results were in better agreement with pseudo-second-order (PSO) model (R2 > 0.992). Multiple isotherm models were used to study the adsorption system and results showed that adsorption was monolayer. The BUT-VER showed an improvement in adsorption capacity in a single system (Pb(II): from 134.2 to 160.6 mg g−1) and (Cd(II): from 51.1 to 58.9 mg g−1) while in binary system (Pb(II): from 107.3 to 114.5 mg g−1) and (Cd(II): from 33.7 to 39.7 mg g−1), respectively. Furthermore, BUT-VER was tested in real river water and removed efficiency of >99% was achieved in just 1 h. The dominant mechanisms were electrostatic attraction and complexation. BUT-VER was regenerated for five consecutive cycles and showed >90% removal efficiency. These findings suggest that the proposed inexpensive adsorbent has the potential for practical applications of toxic metals removal from water. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the growing population, industrialization, and agriculture, water contamination not only affects people but entire ecosystems. Metal–organic frameworks (MOFs), because of their large surface area and porosity, show great potential as adsorbents for removing pollutants, such as heavy metals, from contaminated water. The current research aims at examining copper (II) benzene-1,3,5-tricarboxylate (Cu-BTC) MOFs and understanding the mechanism for their adsorption of Pb(II) from aqueous solution. The Cu-BTC samples were characterized using FTIR and XRD, and their surface area and porosity were determined based on N2 adsorption isotherms. The concentration of Pb(II) in the solutions was measured using atomic absorption spectroscopy (AAS). Both kinetic and equilibrium adsorption data were collected and then analyzed using numerical models. The analyses led to the findings that the limiting steps in the adsorption of Pb(II) on Cu-BTC are (a) pore diffusion of Pb(II) and (b) the availability of the active sites on Cu-BTC MOFs. It was further revealed that the former step is more dominant in the adsorption of Pb(II) when the lead concentration is low. The latter step, which is directly proportional to the surface areas of the MOFs, affects the adsorption to a greater extent when the lead concentration is high. The results also show that adsorption of Pb(II) ions on Cu-BTC is mainly a multi-layer heterogeneous process. [ABSTRACT FROM AUTHOR]

Blast furnace slag (BFS) was exploited as an adsorbent for the removal of Cr(III), Pb(II), and Cr-Pb. In discontinuous mode, the influence of the contact time, stirring speed, pH, mass of the adsorbent, initial concentration, and temperature were examined. The physico-chemical tests indicated that the BFS is formed from a mixture composed mainly of silicates, aluminates, lime, and magnesium oxide. Its specific surface is 325.6 m² g-1 and the pHzpc value corresponds to 3.8. Experimental results have indicated that the equilibrium is obtained after 60, 50, and 80 min for Cr(III), Pb(II), and the Cr-Pb mixture, respectively. Under our experimental conditions (pH 4.8, Vag: 150 rpm, T: 20 °C, Øs: 200 μm, and Ms: 1 g), the adsorption capacities of Cr(III), Pb(II), Cr-Pb, Cr(III) in the mix, and Pb(II) in the mix were 43.16, 50.12, 39.91, 17.05, and 22.66 mg g-1, respectively. Moreover, BFS has more affinity for lead in the binary mixture. The adsorption isotherms revealed that the Langmuir model was the best fit for the metal ion adsorption processes examined (R2 = 0.99). The kinetics indicated that the adsorption of the metal ions studied follows the pseudo-second-order model and that their transfers from the solution to the adsorbent are controlled by external and intraparticle diffusion. The thermodynamic study has shown that all the processes applied are spontaneous, exothermic, and less entropic. The desorption of the binary mixture revealed that saturated BFS can be efficiently exploited over four cycles, and it is more efficient in the presence of HCL at 0.1 N. [ABSTRACT FROM AUTHOR]

In this work, zeolite based on coal fly ash was firstly synthesized via wet milling for the adsorption of lead (Pb(II)). The effects of contact time, solid-to-liquid ratio and initial pH of solution on Pb(II) removal were investigated in detail. The experimental data showed that synthesized zeolite has high adsorption capacity of 99.082 mg of Pb(II) per gram of adsorbent. Coal fly ash zeolite synthesized by wet milling has good Pb(II) adsorption performance when the initial pH of the solution is above 5. The adsorption kinetic results demonstrated that removal of Pb(II) via the synthesized zeolite followed pseudo-second-order kinetic model. X-ray photoelectron spectroscopy results directly demonstrated the adsorption between Pb(II) and synthesized zeolite, and a possible reaction pathway was proposed. Specifically, the removing mechanism of Pb(II) from aqueous solution via the synthesized zeolite involves two stages: one is that Pb(II) in aqueous solution is absorbed on the interior of the synthesized zeolite, and the other is chemical precipitation. [ABSTRACT FROM AUTHOR]

The removal of lead from water and wastewater is a serious term for protecting the public and the environmental. Herein, an agriculture waste of sorghum bagasse modified with NaOH was used to adsorb Pb(II) from an aqueous solution. The modified sorghum bagasse (MSB) was characterised by field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET) method and Fourier transform infrared spectroscopy (FTIR). MSB with NaOH shows smoother, increasing porosity and pore size (mesopore). In a batch system, the parameter adsorption was investigated. The adsorption of Pb(II) by the adsorbents was optimum at pH 5.0, contact time: 15 min, adsorbent dosage: 6 g L−1 and initial concentration: 80 mg L−1. The pseudo second-order model was suitable to describe the kinetic of the process with the diffusion model of the Elovich model. Meanwhile, the adsorption isotherm model was suitable with the Langmuir model and gives a maximum adsorption capacity (qmax) 12.29 mg g−1. The Gibbs free energy was negative, and the enthalpy was negative, indicating the adsorption was a spontaneous and exothermic process. These results indicated that the MSB had potentially become an efficient, sustainable and low-cost adsorbent for Pb(II) uptake from an aqueous solution. [ABSTRACT FROM AUTHOR]

A novel tri-functional probe HEX-OND was developed for detecting Pb(II), cysteine (Cys), and K(I) by fluorescence quenching, recovery, and amplification strategies respectively, based on Pb(II)-induced chair-type G-quadruplex (CGQ) and K(I)-induced parallel G-quadruplex (PGQ). The thermodynamic mechanism was illustrated as that HEX-OND transformed into CGQ by associating equimolar Pb(II) (K1 = 1.10 ± 0.25 × 106 L/mol), forcing (G)2 spontaneously approaching and static-quenching HEX (5′-hexachlorofluorescein phosphoramidite) in the photo-induced electron transfer (PET) way by the van der Waals force and hydrogen bond (K2 = 5.14 ± 1.65 × 107 L/mol); the additional Cys recovered fluorescence in the molecular ratio of 2:1 via Pb(II)-precipitation induced CGQ destruction (K3 = 3.03 ± 0.77 × 109 L/mol); the equimolar K(I) induced HEX-OND transforming into PGQ (K4 = 3.53 ± 0.30 × 104 L/mol) and specifically associating with the equimolar N-methyl mesoporphyrin IX (NMM) by hydrophobic force (K5 = 3.48 ± 1.08 × 105 L/mol), leading to the fluorescence enhancement. Moreover, the practicability results showed that the detection limits reached a nanomolar level for Pb(II) and Cys and micromolar for K(I), with mere disturbances for 6, 10, and 5 kinds of other substances, respectively; no significant deviations of the real sample detection results were found between the well-understood methods with ours in detecting Pb(II) and Cys, and K(I) could be recognized and quantified even in the presence of Na(I) with 5000 and 600 fold respectively. The results demonstrated the triple-function, sensitivity, selectivity, and tremendous application feasibility of the current probe in sensing Pb(II), Cys, and K(I). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shaanxi University of Science & Technology is the property of Journal of Shaanxi University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a novel amino-functionalized Fe3O4-MnO2-SiO2-NH2 adsorbent material was prepared by successive modifying Fe3O4 with KMnO4 and SiO2 to remove heavy metal ions in mixed solution of Pb(II), Cu(II), and Ni(II). The adsorption experiments showed that initial pH value had a significant effect on the adsorption capacity of the materials for heavy metals in solution. Moreover, the materials exhibited strong selective adsorption for Pb(II). Transmission electron microscopy (TEM) results showed that the innermost dark center was the Fe3O4 core with a thickness of about 200 nm, and the outermost light circle was a coated SiO2 shell with a thickness of about 30 nm, while MnO2 can be seen between the dark center and the light circle. Various factors affecting the uptake behavior such as contact time, temperature, pH, and initial concentration of Pb(II) were investigated. The kinetics were evaluated utilizing the Lagergren pseudo-first-order and pseudo-second-order models. The best interpretation for the equilibrium data was given by Freundlich isotherm. The recycling experiment showed that Fe3O4-MnO2-SiO2-NH2 kept its adsorption and desorption efficiencies constant over 5 cycles. Importantly, the Fe3O4-MnO2-SiO2-NH2 was able to selectively remove over 73% of Pb(II) not only in mixed solution of Pb(II), Cu(II), and Ni(II) but also remove 94.7% in only Pb(II) solution at pH 6 within 1 h. [ABSTRACT FROM AUTHOR]

With the development of industry, the concentration of lead (Pb) in water bodies is gradually increasing, the forms of Pb pollution in water are becoming increasingly diversified, and the environmental and human health hazards caused by Pb pollution are receiving increasing attention. A HCO–(Fe3O4)x composite adsorbent prepared by the coprecipitation method of Fe3O4 mixed in cerium-rich grinding and polishing sludge was used to remove Pb from water. The effects of Ce/Fe molar ratio, pH, dosing amount, and time on the adsorption of HCO–(Fe3O4)x for Pb removal were investigated and the adsorption isotherm model, adsorption kinetics, and adsorption mechanism were studied. The results showed that the maximum adsorption capacity of HCO–(Fe3O4)x on Pb(II) was 35.93 mg·g−1 at a Ce/Fe molar ratio of 1.5:1, pH 4–5, and temperature of 25 °C, and the removal rate could reach 96.05%; the process of Pb(II) adsorption by HCO–(Fe3O4)x was in accordance with the Langmuir isothermal adsorption model and the pseudo-second-order reaction kinetic model; chemisorption was dominant. Characterization results, such as EDS, XRD, and XPS, showed that the composite preparation of HCO with Fe3O4 increased the specific surface area of HCO–(Fe3O4)x and generated amorphous iron oxides, such as FeCe2O4, FeOOH, Fe3O4, and Fe2O3, which provided conditions for the formation of Fe-O-Pb and Ce-O-Pb complexes during the adsorption process, thus facilitating the adsorption removal of Pb(II). [ABSTRACT FROM AUTHOR]

Synthesis, characterization, Pb(II) adsorption, recovery, preconcentration and reusability of different nanoadsorbents were investigated in detail. With green synthesis, silver, iron oxide and iron copper nanoparticles (AgNPs, Fe3O4NPs and Fe/CuNPs) were synthesized and modified with chitosan and alginate natural polymers to form nanocomposite beads (Fe3O4‐CS, Fe3O4−AT, Fe/Cu−CS and Fe/Cu−AT). When the adsorption efficiencies of the seven synthesized nanoadsorbents from the aqueous medium were compared, it was seen that the magnetic bimetallic Fe/Cu−CS beads provided the highest adsorption with 100 % efficiency for Pb(II). The adsorption mechanism, effects of temperature, initial lead ion concentration and pH of the solution on the Pb(II) adsorption capacity of Fe/Cu−CS beads were investigated. The recovery studies have shown that Fe/Cu−CS beads have good adsorption/desorption performance around 90 % of desorption was achieved with 5 mM HNO3. These results show that Fe/Cu−CS beads have potential to be a promising material for adsorption, preconcentration and desorption of Pb(II) from aqueous solution. [ABSTRACT FROM AUTHOR]

A novel magnetic solid-phase extraction adsorbent using deep eutectic solvent-coated magnetic graphene oxide (EgLiCl-mGO) was proposed for simultaneous preconcentration of Pb(II) and Cd(II). The nanocomposite was characterized by Fourier Transform Infrared Spectroscopy, X-ray diffractometry, and alternative gradient force magnetometer. Parameters that could affect the preconcentration recoveries of the target ions were investigated via the one-factor-at-a-time method. The optimum conditions are pH of 4 ± 0.5, EgLiCl-mGO amount of 1.0 × 10−2 g, adsorption time of 5 min, eluent of HNO3 (1 mL, 2 mol L−1), and desorption time of one minute. The swelling property of the adsorbent versus pH was studied. The linearity of the dynamic range for Pb(II) (5.0 × 10−6–4.0 × 10−4 g L−1) and Cd(II) (5.0 × 10−6–15 × 10−5 g L−1) was recorded. The limits of detection were Pb(II): 1.2 × 10−6 g L−1 and Cd(II): 47 × 10−8 g L−1. The preconcentration factor of 50 was calculated for both ions and the relative standard deviations were 1.27% for Pb(II) and 0.94% for Cd(II). Reusability, effect of interference ions, selectivity, isotherm adsorption, kinetic adsorption, and thermodynamic adsorption were established. The adsorbent was successful at preconcentrating the ions in legumes. [ABSTRACT FROM AUTHOR]