Initial Pb Concentration Research Articles

Effect of the interaction of fulvic acid with Pb(II) on the distribution of Pb(II) between solid and liquid phases of four minerals.

Lead (Pb) is one of the top metal pollutants worldwide, and its distribution between liquid and solid phases of soils is strongly controlled by its adsorption on minerals, organic matter, and their composites. This paper presented the effect of fulvic acid (FA) coexistence on the distribution of Pb(II) at the solid-liquid interface of four minerals, which provided reference for how to use humic substances to remove toxic Pb(II) in soils. The free Pb2+ of suspensions, measured by Pb ion selective electrode, was used to characterize the complexation of FA with Pb2+ at various pH. The adsorption isotherms of Pb(II) by montmorillonite, kaolinite, goethite, and gibbsite with and without FA were studied with batch experiments. Results indicated that the free Pb2+ decreased and complexed Pb(II) increased with the increase of FA concentration in Pb(II)-FA solutions, whether the initial concentration of Pb(II) was 0.1 or 1mM. Pb2+ hydrolysis was low and the free Pb2+ concentration in pure lead solution without FA was generally unchanged with increasing solution pH at pH < 6.0. But free Pb2+ decreased with the increase of pH in the presence of FA, suggesting that the complexation ability of FA with Pb2+ increased with the increase of solution pH. The adsorption of Pb(II) by the minerals without FA followed the order: montmorillonite > kaolinite ≈ goethite > gibbsite at pH5.0. The Pb(II) adsorption by montmorillonite and kaolinite significantly enhanced with 1g/L FA, while significantly inhibited with 3g/L FA at low initial Pb(II) concentration. However, the effect of FA on Pb(II) adsorption by montmorillonite was greater than that of kaolinite, which was mainly related to the crystal layer structure, adsorption area, and cation exchange capacity of the minerals. The Pb(II) adsorption by goethite and gibbsite was significantly enhanced by the addition of both 1g/L and 3g/L FA, and the enhancement was more evident in goethite system. The effect of FA on the distribution of Pb(II) between solid and liquid phases of the minerals was determined by the factors such as the initial concentration ratio of FA to Pb(II), the adsorption capacity of minerals for FA, and the number of soluble complexes of FA with Pb2+. Therefore, the distribution of FA between solid and liquid of four minerals affected the distribution of Pb(II) between solid and liquid phases of the minerals greatly. The results can provide an important reference for understanding the distribution of Pb(II) and the dynamics and mobility of active components in polluted soils.

Mechanism-Enhanced Active Attapulgite-Supported Nanoscale Zero-Valent Iron for Efficient Removal of Pb2+ from Aqueous Solution.

In this study, attapulgite-supported nano zero-valent iron (nZVI@ATP) was synthesized by a liquid-phase reduction method using active attapulgite (ATP) as raw material, and used for Pb2+ remediation in aqueous solution. To understand the mechanism of Pb2+ removal, various techniques were used to characterize nZVI@ATP. The results showed that spherical nZVI particles were uniformly dispersed on the surface of ATP, and the agglomeration of nZVI particles was significantly weakened. The adsorption performance of nZVI@ATP for Pb2+ was greatly improved compared with that of ATP ore, in which the Fe/ATP mass ratio of 1:2 was the best loading ratio. Under the conditions of a temperature of 25 °C and a pH of 5.00, the initial concentration of Pb2+ was 700 mg/L, and the Pb2+ removal rate of nZVI@ATP was 84.47%. The adsorption of nZVI@ATP to Pb2+ was mainly a spontaneous endothermic reaction of heterogeneous surfaces, and the adsorption rate of nZVI@ATP to Pb2+ was proportional to pH in the range of 2–5.5. The presence of Na+, Mg2+, and Ca2+ can inhibit the removal of Pb2+, and Ca2+ has the strongest inhibition effect on the removal of Pb2+. The removal mechanism of Pb2+ by nZVI@ATP obtained from SEM-EDS, BET, XRD, FTIR and XPS included reduction, precipitation, and the formation of complexes.

Synthesis and Characterization of Hausmannite‐Activated Carbon Nanocomposites for Removal of Lead from Aqueous Solutions

AbstractNano‐hausmannite (Mn3O4; NH) was prepared together with its composites with activated carbon (AC), namely, HAC‐1 and HAC‐2. These materials were characterized by different techniques, and the adsorption properties of the studied sorbents NH, AC, HAC‐1, and HAC‐2 for Pb(II) were evaluated considering the effects of shaking time, pH, sorbent weight, initial Pb(II) concentrations, and temperature using batch experiments. The kinetics of sorption was described by the pseudo‐first‐order model. The adsorption isotherm was well fitted to the Sips model. The adsorption process was endothermic. Desorption experiments indicated that Pb(II) was released from the loaded adsorbents: NH, AC, HAC‐1, and HAC‐2 using 1.0 M HCl (97 % efficiency). Infrared spectral analysis suggested adsorption of Pb(II) through chemical bonding between the negatively charged functional groups of Mn–O, Mn–O–Mn, OH, and COO− with Pb(II).

The Impact of the Storage Conditions and Type of Clearomizers on the Increase of Heavy Metal Levels in Electronic Cigarette Liquids Retailed in Romania

The growing popularity of electronic cigarettes has raised several public health concerns, including the risks associated with heavy metals exposure via e-liquids and vapors. The purpose of this study was to determine, using atomic absorption spectrometry, the concentrations of Pb, Ni, Zn, and Co in some commercially available e-liquid samples from Romania immediately after purchase and after storage in clearomizers. Lead and zinc were found in all investigated samples before storage. The initial concentrations of Pb ranged from 0.13 to 0.26 mg L−1, while Zn concentrations were between 0.04 and 0.07 mg L−1. Traces of nickel appeared in all investigated e-liquids before storage but in very small amounts (0.01–0.02 mg L−1). Co was below the detection limits. We investigated the influence of the storage period (1, 3, and 5 days), storage temperature (22 °C and 40 °C), and type of clearomizer. In most cases, the temperature rise and storage period increase were associated with higher concentrations of heavy metals. This confirms that storage conditions can affect metal transfer and suggests that the temperature of storage is another parameter that can influence this phenomenon.

Innovative Recovery of Winemaking Waste for Effective Lead Removal from Wastewater

Every year, important quantities of winemaking waste create problems for wine producers. These problems arise from the difficulty of disposing of grape marc, which can pollute the environment and affect nearby agricultural crops. The present research proposes a new direction for the valorization of this agri-food waste in residual water depollution. Four biomaterials obtained from winemaking waste were tested for Pb removal: raw Merlot grape marc (MR), raw Sauvignon Blanc grape marc (SbR), Merlot grape marc biorefined (ME) and Sauvignon Blanc grape marc biorefined (SbE). The effects of biosorbent mass and initial Pb concentration, adsorption kinetic, equilibrium isotherms and the matrix influence from a mine effluent were assessed. Very good perspectives for the practical application in lead uptake from wastewaters arise, with better results for biorefined grape marc compared to raw material. The lead removal percentage from an initial solution containing 20 mg Pb/L, at optimum pH (5.5 ± 0.5) was 71%—MR, 78%—SbR, 80%—ME, and 97%—SbE. A Langmuir model revealed a very good removal capacity for ME (40 mg/g) and SbE (64 mg/g). Thus, the grape marc, a polluting waste, can turn into a low-cost and easy-to-prepare sorbent for the bioremediation of contaminated water.

Novel Mesoporous Organosilicas with Task Ionic Liquids: Properties and High Adsorption Performance for Pb(II).

Removal of toxic contaminants such as Pb(II) from waste solutions is environmentally requested. Therefore, in this paper, for potential novel sorbents, mesoporous ionic liquid-functionalized silicas were synthesized and tested for the removal of Pb(II) from aqueous solutions. The successful synthesis of the adsorbents was proved by nuclear magnetic resonance (29Si and 13C NMR), Fourier transform infrared spectroscopy (FTIR), and elemental analysis. The structural and textural properties were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), and low-temperature N2 sorption, and the result showed that the applied procedure made it possible to obtain highly ordered particles with a two-dimensional mesostructure. The effects of several parameters including initial pH, contact time, adsorption temperature, and Pb(II) concentration were studied in detail and were discussed to evaluate the adsorption properties of the fabricated materials towards Pb(II). The obtained results confirmed a very high potential of the sorbents; however, the adsorption properties depend on the structure and amounts of the functional group onto fabricated materials. The sample ILS-Ox3-40 showed fast kinetics (equilibrium reached within 10 min) and capacity of 172 mg/g, and that makes it a promising sorbent for the cleanup of water contaminated by lead. It was also indicated that, regardless on structure of the tested materials, the Pb(II) removal was spontaneous and exothermic. The fabricated mesoporous silicas exhibited that they were easy to regenerate and had excellent reusability.

Efficient adsorption of Pb(II) by sodium dodecyl benzene sulfonate intercalated calcium aluminum hydrotalcites: kinetic, isotherm, and mechanisms.

Two novel adsorbents of CaAl-LDHs and sodium dodecyl benzene sulfonate (SDBS) intercalated CaAl-LDHs (SDBS-CaAl-LDHs) were successfully prepared by co-precipitation. The main composition and physical properties of two samples were characterized by XRD, XPS, FT-IR, TG, and SEM. Batch adsorption experiments were conducted to study the effect of pH, adsorption time, and initial concentration of Pb2+. The results showed that the prime adsorption conditions obtained were pH of 5.2 after 60min with the initial concentration of 300mgg-1 for CaAl-LDHs and 350mgg-1 for SDBS-CaAl-LDHs. At 303K, the adsorption capacities and removal rates of CaAl-LDHs and SDBS-CaAl-LDHs were found to be 456.05mgg-1, 91.21% and 682.26mgg-1, 97.47%, respectively. For CaAl-LDHs, the kinetic data for Pb2+ was best fitted with pseudo-2nd-order model, and the adsorption isotherms followed Langmuir and Freundlich isotherm model. The adsorption data of SDBS-CaAl-LDHs can be best described by the pseudo-second-order kinetic and Langmuir model. The Pb2+ adsorption mechanism on SDBS-CaAl-LDHs was explored by XRD, XPS, and SEM, and the important roles of the electrostatic attraction, precipitation, complexation, and ion exchange were demonstrated. The Langmuir adsorption capacities for SDBS-CaAl-LDHs were 797.63, 828.76, and 854.29mgg-1 at 293k, 303k, and 313k, respectively. Thus, SDBS-CaAl-LDHs may be a highly economical adsorbent for the treatment of contaminated water.

Removal characteristics of Pb(II) and Cd(II) from aqueous single metal solutions by vermicompost combined with nano-CaO

ABSTRACT Vermicompost (CV) and nanomaterials have been identified as potential amendments to adsorb environmentally toxic heavy metals. This study analyzes multi-aspect properties of CV and its nanocomposite (CV-nCa) with nano calcium oxide (nCaO), which include pH, electrical conductivity (EC), cation exchange capacity (CEC), ash content and surface characteristics, aiming to compare their potential for removing aqueous Pb(II) and Cd(II). The results demonstrated that CV-nCa had a higher pH, EC, CEC, ash content, pore parameters and specific surface area than CV. Adsorption isotherm studies showed that CV-nCa had a higher adsorption capacities for Pb(II) and Cd(II), with the maximum adsorption capacities being 255.1 mg/g and 137.7 mg/g. The adsorption rates (ARs) by CV-nCa were both above 99.72% within the initial concentration of Pb(II) being 200–800 mg/L and Cd(II) being 100–200 mg/L. In addition, CV-nCa can effectively remove Pb(II) and Cd(II) within a wider pH range (3–6) and a lower mass concentration (MC) of 4 g/L. Kinetic studies showed that the Pb(II) and Cd(II) adsorption by CV-nCa were both best fitted with the pseudo-second-order model. FTIR analysis demonstrated that the interaction of CV and CV-nCa with Pb(II) and Cd(II) mainly depended on thearomatic/aliphatic acids, some primary/secondary alcohols and some silicate and carbonates. XRD analysis showed that the addition of nCaO into CV mainly increased CaCO3 content and affected the adsorption characteristics. Thus, combining nCaO with vermicompost may broaden heavy metal remediation and vermicompost utilization in the environment.

Novel and Green Fe3O4@Sio2-L-Cys Magnetic Absorbent for Efficient Removal of Pb (II) from Aqueous Solution

In this study, Fe3O4@Sio2-NH2 was synthesized by the modification of Fe3O4 particles with tetraethyl orthosilicate(TEOS) and 3-aminopropyl-Triethoxysilane (APTES), and then the cysteine was grafted with glutaraldehyde as cross-linking agent.The material was characterized by XRD,FIIR and TEM. The effects of temperature, time, initial concentration of Pb(II) and pH value on the adsorption rate of Pb(II) were investigated, and the adsorption mechanism and the regeneration performance of the adsorbent were discussed.The results indicated that when the amount of adsorbent was 0.4g/L, the temperature was 303K, the adsorption time was 2.5h and the pH was 5.02, the adsorption rate of Pb(II) in water can reach up to 98.25%.The adsorption kinetics of Pb(II) on the material accorded with Lagergren quasi-second-order kinetic equation, which belonged to the chemisorption process.Adsorption isothermal curve studies showed that the adsorption of Pb(II) on the material complied with the Langmuir isothermal adsorption model and was a monolayer adsorption.The maximum adsorption capacity of Pb(II) is 120.77mg/g. Adsorption thermodynamics studies showed that the whole system was endothermic reaction,and warming was conducive to the adsorption,which happens spontaneously.After 4 times of the adsorption recycling,the adsorption rate can still reach 92.7%.

Electro-enhanced adsorption of lead ions from slightly-polluted water by capacitive deionization

• CDI technology effectively removed Pb 2+ from slightly-polluted water. • The doping of NCDs improved the structural and electrochemical properties. • A monolithic mesh electrode was prepared by electrospinning method. • The Langmuir isotherm and the pseudo-first-order model fitted the electrosorption. • The hydrated radius and valence affected the order of ion adsorption. Capacitive deionization (CDI) technology is an effective method for the removal of Pb 2+ from slightly-polluted water. In this study, reduced graphene oxide/nitrogen-doped carbon quantum dots (rGO/NCDs) composites with different NCDs mass ratios were successfully synthesized by hydrothermal method and the preparation process of CDI electrode was optimized by electrospinning method to obtain monolithic mesh-like structure. The results showed that the doping of NCDs improved the structural and electrochemical properties of the composites. rGO/25%NCDs composite possessed well-developed three-dimensional porous structure, high specific surface area (347.65 m 2 /g) and excellent specific capacitance (284.0 F/g). The prepared CDI electrodes had a fish scale-like graded interfacial structure, and this unique structure made the electrodes exhibit superhydrophilic property. The results of CDI tests showed that the electrosorption capacity of rGO/25%NCDs electrode could reach 19.26 mg/g which was higher than that of the pure rGO electrode and many reported electrodes, when the initial concentration of Pb 2+ was 5 mg/L and the voltage was −1.0 V. The adsorption process was consistent with the Langmuir adsorption isotherm and the pseudo-first-order kinetic model. In addition, the study on the competitive adsorption in a co-existed system revealed that the electrosorption capacity was strongly dependent on the ionic valence rather than hydrated radius.

Novel carbazole-based porous organic frameworks (CzBPOF) for efficient removal of toxic Pb(II) from water: Synthesis, characterization, and adsorption studies

Herein, a novel carbazole-based porous organic framework CzBPOF was synthesized successfully via aldol triple condensation reaction and was used to remove toxic Pb(II) from aqueous media. The synthesized CzBPOF was characterized by FTIR, TGA, BET, SEM, EDX, EMA 13 C CP/MAS NMR and XPS analysis The Brunauer–Emmett–Teller (BET) specific surface area of CzBPOF was found to be 615 m 2 g −1 . The influence of different parameters on adsorption of Pb(II) on CzBPOF was investigated and the outcomes revealed that the optimal contact time, pH, initial Pb(II) concentration, and temperature were found to be 80 min, 5, 200 mg/L, and 30 °C, respectively. The adsorption process followed Langmuir isotherm and PSO kinetic models, indicating that the adsorption process belongs to monolayer adsorption and chemisorption. The CzBPOF adsorbent had a maximum monolayer capacity of 318.4 mg/g at 30 °C. The thermodynamic results confirmed that Pb(II) adsorption using CzBPOF was endothermic, spontaneous, and the adsorption process follows a physicochemical mechanism. The FTIR, XPS, and EDX analysis confirm the adsorption of Pb(II) ions using CzBPOF adsorbent. The CzBPOF adsorbent shows excellent reusability with a removal efficiency of 84.26% after three cycles. In summary, the as-prepared CzBPOF adsorbent is effective and provides a promising prospect for the elimination of Pb(II) from an aqueous media. • A novel carbazole-based porous organic framework CzBPOF was synthesized. • The BET surface area of CzBPOF adsorbent was found to be 615 m 2 /g. • CzBPOF showed excellent adsorption capacity for Pb(II) with 318.4 mg/g. • Adsorption of Pb(II) ions using CzBPOF was spontaneous and endothermic in nature.

Efficient removal of Pb(II) using modified chitosan Schiff base@Fe/NiFe

A novel modified chitosan Schiff base@Fe2O3-NiFe2O4 (CsSB@Fe/NiFe) was prepared and characterized using FT-IR, XRD, SEM, EDX, TGA, DSC and VSM. FT-IR and XRD results confirm that the nanoparticles of Fe/NiFe distributed throughout the surface of CS-OH and successfully prepared CsSB@Fe/NiFe. SEM image shows that the Fe/NiFe nanoparticles were assembled in the surface and inside of CS-OH. Coercivity (Hc) of CsSB@Fe/NiFe is ≈ 110 Oe, indicated that it was kind of soft-magnetic materials with saturation magnetization (Ms) of 6.45 emu/g. In addition, CsSB@Fe/NiFe was further explored as an new sorbent for the removal of Pb(II) ion from aqueous solution and the influence of various important parameters such as solution pH, contact time, dosage of adsorbent and initial Pb(II) concentration were studied and optimized. Optimum conditions for Pb(II) removal were found to be pH 5, adsorbent dosage 0.05 g, initial Pb(II) concentration of 75 ppm and contact time of 120 min. The maximum Pb(II) removal percentage was found to be 97%. Also, CsSB@Fe/NiFe shows about 88% Pb(II) removal after five adsorption-desorption cycles. The results suggested that the sorption of Pb(II) onto CsSB@Fe/NiFe was feasible and spontaneous.

Efficient sequestration of lead from aqueous systems by peanut shells and compost: evidence from fixed bed column and batch scale studies

Lead (Pb) is a pervasive contaminant and poses a serious threat to living beings. The present study aims at batch and fixed bed column scale potential of commercial compost (CCB) and peanut shells biosorbents (PSB) for the sequestration of Pb from contaminated aqueous systems. The PSB and CCB were characterized with FTIR, SEM and Brunauer Emmett-Teller (BET) to get insight of the adsorption behavior of both materials. Fixed bed column scale experiments were performed at steady state flow (2.5 and 5.0 mL/min), initial Pb concentrations (25 and 50 mg/L) and dosage of each adsorbent (3.0 and 6.0 g/column). Columns packed (15.9 cm2) with PSB and CCB have revealed excellent adsorption of Pb with PSB as compared with CCB. The total volume of injected contaminated water was 1,500 mL and 3,000 mL at 2.5 and 5.0 mL/min, respectively while total bed volume number was 157. A series of batch experiments with CCB and PSB was conducted at adsorbent dosage (1.25–5.0 g/L), initial Pb level (25–100 mg/L), interaction time (0–180 min) and solution pH (4–10) at room temperature. Batch scale results revealed that PSB removed 92% Pb from water at 25 mg Pb/L concentration as compared with CCB (79%). The presence of competing ions in groundwater showed less Pb removal as compared with synthetic water. The experimental data were simulated with equilibrium isothermal models: Langmuir, Freundlich, and kinetic models: pseudo first order, pseudo second order and intra-particle diffusion. The Freundlich and pseudo second order models better described the equilibrium and kinetic experimental data, respectively with maximum sorption of 42.5 mg/g by PSB which is also evident from FTIR functional groups and SEM results. While equilibrium sorption of Pb onto CCB was equally explained by Freundlich and Langmuir models. These findings indicate that PSB could be an active and ecofriendly biosorbent for the sequestration of metals from contaminated aqueous systems.

Potassium-assisted synthesis of SUZ-4 zeolite as an efficient adsorbent for Pb2+ removal from wastewater

With the assistance of K+, the amount of organic template (TEAOH) in the synthesis was enormously reduced to only 3% of that in the traditional synthesis for the SUZ-4 zeolite. Characterizations such as XRD, SEM, XRF, N2 adsorption/desorption, and 27Al MAS NMR were carried out to determine the physicochemicalproperties of SUZ-4 zeolites (T1 and T13) synthesized with different TEAOH amount. The specific role of the additional K+ in the synthesis was determined by the combination of experimental data and density functional theory (DFT) calculations. It showed that K+ co-caged with TEA+ preferentially locate in the cages containing 8-MR, and the role of the co-caging K+ ions is to arrange the formed composition building units (CBU) into the SUZ-4 framework. The SUZ-4 zeolite exhibited a fast adsorptive equilibrium of 5 min and high selectivity for Pb2+ in wastewater. The effects of temperature, contact time, adsorbent dosage, pH and initial concentration of Pb2+ solution on adsorption capacity were studied to optimize process conditions. The adsorption kinetics and isotherms suggested that the adsorption rate is determined by the chemical adsorption on the adsorbent surface, and the adsorption ability is related to the physisorption sites in the pores. The adsorption process was composed of two steps and was the comprehensive contribution of ion exchange and chemical adsorption of PbO formation. There was no downtrend in the adsorption of SUZ-4 for Pb2+ after ten adsorption-desorption cycles, demonstrating the excellent application prospects of SUZ-4 in removing Pb2+ in wastewater.

Preparation of Functional Attapulgite Composite and Its Adsorption Behaviors for Congo Red

Heavy metal ion wastewater poses a serious threat to human health and the environment. The adsorption method is an important method to remove heavy metal ions from heavy metal wastewater. Magnetic attapulgite (ATP) composite nanomaterials with excellent adsorption properties were prepared by grafting the Fe3O4 nanoparticles and using 3-aminopropyl triethoxy silane (APTES) modification. The prepared ATP-Fe3O4-APTES materials were used as adsorbents and applied to the treatment of heavy metal ion wastewater. The structure and surface properties of the materials were characterized by FT-IR, XRD, SEM, TEM, and BET characterization, Zeta potential, and VSM. The effects of pH, adsorption time, adsorption temperature, and initial concentration of Pb2+ on the adsorption properties of the ATP-Fe3O4-PEI materials were investigated. The results show that the maximum adsorption capacity of the materials for Pb2+ was 129.32 mg·g-1 under optimum conditions. The adsorption process conformed to the pseudo second order kinetic model and Langmuir adsorption isotherm, which indicates that the adsorption of Pb2+ is a monolayer chemical adsorption and a spontaneous endothermic process. The driving force of adsorption mainly comes from the coordination between the amino group (-NH2) on the ATP-Fe3O4-APTES surface and Pb2+. These results indicate that the functionalized magnetic attapulgite adsorbent has good adsorption properties for heavy metal ions and is expected to be used in the treatment of heavy metal ion wastewater.

Mild Hydrothermal Synthesis of 11Å-TA from Alumina Extracted Coal Fly Ash and Its Application in Water Adsorption of Heavy Metal Ions (Cu(II) and Pb(II))

Non-biodegradable copper (Cu) and lead (Pb) contaminants in water are highly toxic and have series adverse effects. Therefore, it is very important to extract heavy metals from wastewater before it is discharged into the environment. Adsorption is a cost-effective alternative method for wastewater treatment. Choosing a low-cost adsorbent can help reduce the cost of adsorption. In this study, conversion of reside after extracting aluminum (REA) produced by sub-molten salt method transform high-alumina coal fly ash (CFA) into 11Å-tobermorite to adsorb Cu(II) and Pb(II) from aqueous solutions at room temperature. The synthesis of the adsorbent was confirmed using scanning electron microscope (SEM), X-ray diffractometer (XRD) and Brunauer–Emmett–Teller (BET) method surface analysis. To study the adsorption characteristics, factors such as initial Cu(II) and Pb(II) concentration, pH, contact time, adsorption characteristics and temperature were investigated in batch mode. The maximum adsorption capacity of Cu(II) and Pb(II) was 177.1 mg·g−1 and 176.2 mg·g−1, respectively. The Langmuir adsorption model was employed to better describe the isothermal adsorption behavior and confirm the monolayer adsorption phenomenon. The pseudo-second-order kinetic model was used to highlight Cu(II) and Pb(II) adsorption kinetics. Thermodynamic analysis indicated the removal Cu(II) and Pb(II) by TA-adsorbent was a nonspontaneous and exothermic reaction. The obtained results are of great significance to the conversion of industrial waste to low-cost adsorbent for Cu(II) and Pb(II) removal from water.

Simple and low-cost production of magnetite/graphene nanocomposites for heavy metal ions adsorption

It is challenging to produce economical magnetic graphene-based adsorbents on an industrial scale for heavy metal ions removal. Here, magnetite/graphene nanocomposite embedded in activated carbon matrix (magnetite/G-AC) was synthesized via in situ catalytic graphitization of iron-impregnated biochar to obtain graphene encapsulated iron nanoparticles (GEINs) embedded in biochar (BC) matrix, and followed by steam activation of GEINs-BC. Steam activation aimed to upgrade biochar to activated carbon with oxygen functional groups, crack encapsulated graphene shell to graphene nanosheets, and obtain magnetic Fe3O4 by oxidation of iron, thereby improving the adsorption capacity of magnetite/G-AC-800 (153.2 mg/g) four times higher than that of GEINs-BC. The parameters on the adsorption capacity were investigated using Pb(II) ions as a typical pollutant as a function of solution pH (3–7), contact time (5–300 min), initial Pb(II) concentration (50–400 mg/L), and adsorbent dosage (0.05–0.25 g). The fitted pseudo-second-order kinetic model and Langmuir model indicated that the main adsorption mechanism was chemical adsorption over monolayer. This research developed a low-cost magnetic adsorbent with the advantage of simple large-scale production and excellent adsorption capacity per unit cost for remediating wastewater.

Regenerable zeolitic imidazolate frameworks@agarose (ZIF-8@AG) composite for highly efficient adsorption of Pb(II) from water

The composite zeolitic imidazolate frameworks@agarose (ZIF-8@AG) was prepared by ZIF-8 and agarose (AG) in this study. The composite ZIF-8@AG with a good quality, was assessed for Pb(II) adsorption and regeneration from water. The effects of the contact time, initial concentration of Pb(II), adsorbent dosage, pH, coexisting ions (Ca2+ and Mg2+), temperature and other factors on the adsorption performance of Pb(II) on ZIF-8@AG were investigated. The pseudo-second-order kinetic model can well describe the adsorption process of Pb(II) on ZIF-8@AG. Thermodynamic parameters (ΔG, ΔH and ΔS) confirmed exothermic and spontaneous process. In the regeneration experiment, ZIF-8@AG maintained a high adsorption capacity for Pb(II) after 6 times of adsorption-desorption cycles. The experimental results showed that the ZIF-8@AG not only has a high adsorption efficiency for Pb(II), but also has a good stability for recycling.

Biosorption of Cu(II), Pb(II) from electroplating industry effluents by treated shrimp shell

The current investigation focuses on a systematic study of application of treated shrimp shell waste (TSSW) as a potential biosorbent in removal of Cu(II) and Pb(II) from hazardous industrial effluents. The surface characterization and morphological studies indicated that biosorption is owing to ion complexation and exchange, and chemical adsorption mechanism. The effects of pH (1–10), time dependency (1–60 min), initial concentration of Cu(II) and Pb(II) (20–100 mg L−1), TSSW loading (0.1–0.5 g) and temperature (303–333 K) on biosorption efficiency using TSSW were examined through experiments. The experimental discoveries indicated that maximum biosorption efficacies were 96.42% at pH 5, 40 min for Cu (II) and 89.77% at pH 6, 30 min for Pb(II), 20 mg L−1 concentration, 0.1 g loading and 303 K temperature. Langmuir, Freundlich, Temkin, and Dubinin - Radushkevich isotherm models were used to examine experimental findings and the Langmuir model was well fitted one. The maximum Cu(II), Pb(II) removal capacities by TSSW were 22.67, 15.32 mg g−1 according to Langmuir model. Pseudo second order model was excellent suited to kinetics which shows that chemisorption was involved for the transfer of Cu(II), Pb(II) to TSSW surface with three different intra particle diffusional stages. Hence, this study revealed that TSSW has a great potential to be an environment friendly and economic biosorbent for removal of Cu(II) and Pb(II) containing industrial effluent.

Raphia-Microorganism Composite Biosorbent for Lead Ion Removal from Aqueous Solutions.

This study investigated the possibility of obtaining a raphia-microorganism composite for removing lead ions from aqueous solutions using immobilized yeast cells Saccharomyces cerevisiae on Raphia farinifera fibers. The obtained biocomposite was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Studies were conducted to determine the influence of contact time, initial concentration of Pb(II), and pH allowed for the selection of nonlinear equilibrium and kinetic models. The results showed that the biocomposite had a better Pb(II) removal capacity in comparison to the raphia fibers alone, and its maximum Pb(II) adsorption capacity was 94.8 mg/g. The model that best describes Pb(II) sorption was the Temkin isotherm model, while kinetic studies confirmed the chemical nature of the sorption process following the Elovich model. The obtained research results provide new information on the full use of the adsorption function of biomass and the ubiquitous microbial resources and their use in the remediation of aqueous environments contaminated with heavy metals.