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The electrospun fumarate ferroxane/polyacrylonitrile (Fum-F/PAN) nanocomposite nanofibers were prepared by immersing the pristine electrospun (PAN) nanofibers into the solution of Fum-F nanoparticles. The synthesized Fum-F nanoparticles were characterized using FESEM and FTIR. FESEM micrographs revealed the smooth surface of the pristine PAN nanofibers and the decoration of Fum-F nanoparticles on the surface of electrospun Fum-F/PAN nanocomposite nanofibers. The electrospun Fum-F/PAN nanocomposite nanofibers were evaluated in order to remove lead from aqueous solution. A central composite design (CCD) and response surface methodology (RSM) were applied to analyze and model the obtained adsorption data. The applied variables consisted of lead ion concentration, adsorbent dosage, pH solution and contact time which maximum lead removal percentage of 97.89% was achieved at initial concentration of 30.30 ppm, adsorbent dosage of 2.06 g/L, solution pH of 6.18 and contact time of 68.23 min. The lead adsorption data onto the electrospun Fum-F/PAN nanocomposite nanofibers were adjusted well with Langmuir isotherm model, indicating the interaction between lead molecules could be assumed negligible. The maximum adsorption capacity of lead ions was 357.14 mg/g which was much higher compared to the reported values of other functionalized PAN nanofibers adsorbents. Reusability study of adsorbent confirmed the durability of removal even after five cycles of adsorption-desorption. [ABSTRACT FROM AUTHOR]

In this study, a novel method to treat the persulfate-ZVI dewatered WAS by producing a magnetic biochar as an environmentally friendly biosorbent (nZVI-WSBC) to remove heavy metals (HMs) from wastewaters was proposed. The nZVI-WSBC exhibited good adsorption property of Pb 2+ and the adsorption isotherm data were fitted well to Langmuir isotherm. Corresponding reaction kinetics fitted well with the pseudo second-order adsorption model. Notably, nZVI-WSBC was successfully used for efficient removal of HMs from real. This study comprehensively demonstrates the mechanisms between Pb 2+ and nZVI-WSBC surfaces, providing a breakthrough in making a sustainable biosorbent from the dewatered iron-containing WAS. [ABSTRACT FROM AUTHOR]

Electrospun nanofibers have been successfully applied to remove toxic and carcinogenic contaminants such as heavy metals from polluted water. In this study, an efficient adsorbent based on poly(ethylene terephthalate) (PET) nanofibers was developed following a cheap, versatile and scalable process. PET nanofibers were first produced by electrospinning, and their surface was chemically functionalized using a simple aminolysis process. The capacity of the resulting material to adsorb Pb(II) from synthetic solutions was evaluated as a function of the contact time, pH and initial metal ion concentration. The adsorbent system presented a quick kinetic adsorption, reaching an extremely high maximum adsorption capacity of about 50 millimol (mmol) of Pb(II) per gram of adsorbent system after just 30 min. Moreover, the effect of competing metal ions, such as Ni(II), Cd(II) and Cu(II), was studied at different molar ratios. Finally, when tested in continuous flow mode, aminated PET (APET) nanofibers were able to remove 97% of Pb(II) ions in solution, demonstrating their potential for the remediation of heavy metal-contaminated water. [ABSTRACT FROM AUTHOR]

Various geographical duckweed isolates have been developed for phytoremediation of lead. The Pb removal efficiency of Lemna aequinoctialis, Landoltia punctata, and Spirodela polyrhiza was investigated in monoculture and polyculture at different levels of pH and initial Pb concentrations. L. aequinoctialis was not sensitive to the tested pH but significantly affected by initial Pb concentration, whereas synergistic effect of pH and initial Pb concentration on removal efficiency of L. punctata and S. polyrhiza was found. Although the majority of polycultures showed median removal efficiency as compared to respective monocultures, some of the polycultures achieved higher Pb removal efficiencies and can promote population to remove Pb. Besides, the three duckweed strains could be potential candidates for Pb remediation as compared to previous reports. Conclusively, this study provides useful references for future large-scale duckweed phytoremediation. [ABSTRACT FROM AUTHOR]

In this work, hydrozincite and Zn/Al-CO hydrotalcite supported on silica aerogel were prepared via a simple and economical process and used as adsorbents for Pb(II) removal. The supported hydrozincite and Zn/Al-CO hydrotalcite possess ultra-thin thickness, high surface area, and weak crystallinity. In the batch Pb(II) adsorption experiments, the adsorbents with higher Zn(II) contents showed higher Pb(II) adsorption capacities, and the adsorption data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating a mechanism of surface chemisorption. The adsorption capacities calculated based Langmuir isotherm model are 684.9 mg/g and 555.6 mg/g for the supported hydrozincite and Zn/Al-CO hydrotalcite, respectively, higher than the adsorption capacities of other hydrotalcite-based adsorbents and most of other inorganic adsorbents reported previously. The XRD diffraction peaks of hydrozincite and Zn/Al-CO hydrotalcite disappeared after the adsorption, and the Pb(II) species were uniformly dispersed in the adsorbents in form of Pb(CO)(OH) proven by TEM, EDS mapping and XRD analysis, demonstrating the nature of the adsorption is the precipitation conversion of hydrozincite or Zn/Al-CO hydrotalcite into Pb(CO)(OH). These results demonstrate the synergic Pb(II) removal effect of the CO and OH derived from hydrozincite and Zn/Al-CO hydrotalcite together with their ultra-thin thickness and high surface area contribute the excellent properties of the adsorbents. [ABSTRACT FROM AUTHOR]

As a recycled material, flue gas desulfurization gypsum has been used to prepare calcium sulfate hemihydrate whisker (CSHW) through hydrothermal synthesis for several decades. However, the subsequent utilization of this resultant material has not yet received considerable attention. In the present research, CSHW was successfully synthesized at a certain region, and was used for the adsorption of lead ions from aqueous solutions, thereby broadening the research field for the practical application of CSHW. Its adsorption capacity was significantly influenced by various parameters, particularly, the pH level and initial lead concentration. The pH value highly affected the hydrolysis degree of lead ions and dominated the adsorption of lead. The equilibrium isotherms under two different temperatures were simulated using Langmuir, Freundlich, and Temkin models. Both Langmuir and Temkin models showed a good fit to the data. Combined with the well-fitted pseudo-second-order model, the adsorption mechanism was thought to be a chemisorption process that was enforced by the ion exchange reaction. In addition, the specific crystal structure of CSHW revealed that ion exchange reaction occurred on the (010) and (100) facets due to their preferential growth and negatively charged property. The residual solid phase after adsorption was collected and detected using X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy. Results revealed that PbSO4 was formed on the surface of CSHW. The alkaline condition introduced the tribasic lead sulfate, and thus reduced the stability of the adsorption system. [ABSTRACT FROM AUTHOR]

Highly efficient magnetic sewage sludge biochar (MSSBC) discloses feasible fabrication process with lower production cost, superior adsorption capacity, usage of waste sewage sludge as resource, selected by external magnetic field and exceptional regeneration property. 2 g L −1 MSSBC exhibited a high adsorption capacity of 249.00 mg g −1 in 200 ppm Pb(II) and the lead-MSSBC equilibrium was achieved within one hour, owing to the existence of the copious active sites. The adsorption kinetics was well described by the pseudo-second-order model while the adsorption isotherm could be fitted by Langmuir model. Mechanism study demonstrated the adsorption involved electrostatic attraction, ion exchange, inner-sphere complexation and formation of co-precipitates at the surface of MSSBC. Additionally, adsorption performance maintained remarkable in a broad pH window. These outcomes demonstrated the promising waste resource utilization by a feasible approach that turns the solid waste of sewage sludge into biochar adsorbent with auspicious applications in elimination of Pb(II) from wastewater. [ABSTRACT FROM AUTHOR]

The development of hydroxyapatite nanorods (nHAp) and hydroxyapatite/chitosan nanocomposite (nHApCs) was sought as potential sorbents for the removal of lead ions from aqueous lead-containing solutions in a batch adsorption experiment. The high resolution transmission electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, Fourier transform infrared spectrophotometry and Zeta potential measurements were all combined to reveal the morphology, composition, crystal structure, functionality and stability of the prepared sorbents. The equilibrium concentration of Pb 2+ ions was identified by the atomic absorption spectrophotometry. The kinetics of the sorption process was investigated together with the influence of initial lead ions concentration, sorbent dosage and solution pH on the sorption capacity. The sorption process followed pseudo-second-order kinetics, where 20 min was quite enough to attain equilibrium. Two models of adsorption isotherms (Freundlich and Langmuir) were employed to correlate the data in order to understand the adsorption mechanism. Interestingly, in one of the experiments, for a 200 mL solution (pH = 5.6) containing 100 ppm lead ions, a sorbent dosage of 0.4 g nHAp could achieve a complete removal for lead ions. However, typically, the sorption capacities of nHAp and nHApCs to lead ions were 180 and 190 mg/g respectively, which appear excellent for lead removal. [ABSTRACT FROM AUTHOR]

Low-rank Pakistani coal was studied as an adsorbent for the removal of lead ions (Pb2+) from aqueous solutions. Adsorption efficiency was studied as a function of contact time, pH, amount of adsorbent, temperature, concentration of adsorbate and concentration of different acids using batch method and atomic absorption spectrometric technique. Maximum removal of lead ions was achieved at 5 pH, using 0.5 g of adsorbent for 10 mL of 4.826 × 10-5 mol L–1 lead concentration with equilibration time of 50 min. The adsorption of lead followed pseudo-second-order kinetics with rate constant “K2 ” of 1.261 g mg–1 min–1. The adsorption data obeyed the Freundlich, Langmuir and Dubinin–Radushkevich isotherms over the lead concentration range of 4.826 × 10-5 to 3.378 × 10-4 mol L–1. The characteristic Freundlich constants, that is, 1/n = 0.609 ± 0.016 and K = 2.164 ± 0.063 m mol g–1 have been computed for the adsorption system. Thermodynamic parameters for the adsorption process were determined and discussed. The adsorption of lead by the presence of high concentration of foreign ions has also been studied. The proposed method was successfully applied for the removal of lead from spiked tap water sample. [ABSTRACT FROM AUTHOR]

A bibliometric analysis was performed to reveal the trends in lead removal research in 1991-2015. The data used in this study were derived from the Science Citation Expanded Index of Web of Science. A total of 1,532 articles were found from the search results. An exponential growth of articles was observed for the period of 1991-2015 and Journal of Hazardous Materials was the most productive journal. USA was most active country in the lead removal research. The researchers were keen on investigating the new economical method for the removal of lead from wastewater and this work would be useful to the researchers to know the trends in lead removal research. [ABSTRACT FROM AUTHOR]

Removal of lead ions from aqueous solutions, in the presence and in absence of commercial TiO2, under UV-light was studied. The influence of catalyst mass, concentration of Pb(II) ions and of citric acid in the starting solution as well as the impact of illumination conditions on the removal rate were also investigated. The results were fitted on the pseudo-first order, pseudo-second order and Elovich kinetic models, Weber-Morris intraparticle and liquid film diffusion models, in order to establish the photoreduction mechanism. The Pb removal rate increased in time by a combined linear-exponential mechanism. The catalyst had a positive influence on the removal rate at the start of the photoreduction. At a low concentration of Pb(II) ions (20 mg/L), the amount of photoreduced Pb(II) ions was proportional to the concentration of the citric acid solution, but at high concentrations (240 mg/L), the correlation was inversely proportional. The rate limiting steps in the removal of lead were both the photoreduction on the TiO2 surface and the diffusion through the film surrounding the catalyst particle. The lead removal was significantly influenced by the mobility and by the concentration of the species in solution. [ABSTRACT FROM AUTHOR]

This study was aimed to compare the Pb(II) adsorption from aqueous solutions between raw phosphogypsum (UP) and lime-conditioned phosphogypsum (LCP) in batch systems. The Pb(II) adsorption by UP and LCP was investigated depending on the process variables, such as solution pH, contact time, and initial Pb(II) concentration. The adsorption capacity ( q ) of UP and LCP as mg/g was found to be 1.85 and 2.90, and the pseudo-second-order rate constant as g/mg min and the initial adsorption rate were found to be 0.27 and 7.57 for LCP and 0.74 and 7.52 for UP, respectively. Studies on the removal of Pb(II) from wastewater of storage battery industry by LCP and UP showed that these adsorbents can be used efficiently. [ABSTRACT FROM AUTHOR]

Fresh and dehydrated banana peels were used as biomass feedstock to produce highly effective sorbent biochars through a facile one-step hydrothermal carbonization approach with 20%vol phosphoric acid as the reaction medium. The elemental ratio of oxygen content of the two as-prepared biochars were about 20%, and the FT-IR analysis confirmed the existence of abundant surface functional groups such as hydroxyl and carboxyl which greatly enhanced the adsorption performance. The sorbents showed excellent lead clarification capability of 359 mg·g −1 and 193 mg·g −1 for dehydrated and fresh banana peels based biochars, respectively. The change of the C O/O C O and the appearance of Pb O/Pb O C on the surface after adsorption confirmed that the ion exchange might be the dominant mechanism. The dehydration and pulverization pre-treatment and the addition of phosphoric acid can benefit the formation of those functional groups and hydrothermal carbonization can be a promising method to transfer biomass like fruit peels into biochars with excellent adsorption performance. [ABSTRACT FROM AUTHOR]

Microwave pyrolysis of pecan nutshell ( Carya illinoinensis ) biomass was used to produce carbon-based solid products with potential application in contaminated water treatment. A range of analytical techniques were applied to characterize the intermediate products of microwave pyrolysis in order to monitor the physico-chemical effects of the interacting energy on the biomass. The performance of the carbon-based products was tested through evaluation of lead ion removal capacity from solution. Further analyses demonstrated that ion-exchange by calcium ions on the material surface was the main mechanism involved in lead removal. Calcium compound development was directly correlated to the interaction of the electromagnetic waves with the biomass. Through monitoring the physico-chemical effects of biomass–microwave interactions during microwave pyrolysis, we have shown for the first time that the intermediate products differ from those of conventional pyrolysis. We hypothesize that selective heating leads to the (hemi)cellulosic and lignin degradation processes occurring simultaneously, whereas they are largely sequential in conventional pyrolysis. This work provides optimization parameters essential for the large scale design of microwave processes for this application as well as an understanding of how the operating parameters impact on functionality of the resulting carbon-based materials. [ABSTRACT FROM AUTHOR]

Emulsion liquid membrane was used with the aim of lead removal from storage battery industry wastewaters. The effects of several parameters such as emulsification rate, reactor mixing rate, the change of membrane and internal phase component ratios on the removal efficiency were examined. Sorbitan Monooleate (Span 80) as surfactant, Di-(2-ethylhexyl) phosphoric acid (D2EHPA) as carrierextractant and mineral oil and kerosene as diluents were used to compose emulsion liquid membrane system. Also vegetable oils which were not hazardous and toxic as much as the organic diluents mentioned above were used to see the effect of them on lead removal. Extraction rate was found optimum at 300 rpm, while the emulsification rate was 7940 rpm for 30 minutes treatment. The best removal efficiency for only 15 minutes treatment was found as 92% at an emulsification rate of 12000 rpm. Sunflower oil was found suitable for lead removal from wastewater with a treatment efficiency of 86%. Treatment was accomplished with this system in five minutes and the treatment performance was not altered at the end of 20 minutes. [ABSTRACT FROM AUTHOR]

The present study focuses on the response surface methodology (RSM) for the optimization of lead removal from an aqueous solution by a novel superparamagnetic nanocomposite. A rotatable central composite design and the response surface methodology were used to conduct and to analyze the experiments, respectively. The adsorption process was investigated as a function of the four factors consisting of pH (4.0-6.0), temperature (20°C-60°C), initial lead concentration (10-90 mg/L) and adsorbent dosage (0.2-1.0 g/L). The maximum lead adsorption capacity was obtained to be 124.955 mg/g under the optimal conditions of 5.49, 60°C, 89.08 mg/L, and 0.48 g/L for the solution pH, temperature, initial lead ion concentration, and the adsorbent dosage, respectively. The desirability function was used to find an optimum point where the desired conditions could be obtained. The superparamagnetic nanocomposite could be used as an adsorbent for the removal of toxic heavy metals from water and wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • PDA-mediated MoS 2 nanocomposite with enhanced stability and Pb(II) removal performance was prepared. • It showed fast adsorption kinetics, excellent adsorption capacity and selectivity to Pb(II). • Pb(II) adsorption attributing to the synergistic effect of the host and MoS 2 nanoparticle. • A considerable working capacity was observed in fixed-bed column tests. • It can be used repeatedly without significant capacity loss. The engineering of macroscopic architectures by loading MoS 2 nanosheets onto larger framework materials is an efficient strategy to overcome the limitations preventing the application of nanosized MoS 2 -based adsorbents for Pb(II) removal. However, the large-scale utilization of these nanocomposites still faces several challenges as a result of their poor stability, slow adsorption kinetics, and low MoS 2 utilization. Herein, a practical and efficient nanocomposite (MoS 2 /PDA/MPS) was prepared by coating MoS 2 nanoflowers onto micron-sized polystyrene beads (MPS) via the construction of a strong adhesive polydopamine (PDA) interlayer. The PDA interface can adhere to the MPS surface and immobilize the MoS 2 nanopartices, thus facilitating the application of MoS 2 /PDA/MPS in flow-through systems. Further, the flower-like structure of the MoS 2 on the outer surface of the host exposes active sites and facilitates mass transfer compared to those of traditional nanocomposites. Meanwhile, the R-SO 3 - groups of MPS can enhance permeation and preconcentrate the Pb(II) ions via the Donnan membrane effect, resulting in improved adsorption kinetics and capacity. Batch adsorption experiments revealed that MoS 2 /PDA/MPS shows fast adsorption kinetics (<45 min), exceptional adsorption capacity (371.7 mg/g, calculated from the Langmuir model at 298 K), and high adsorption selectivity for Pb(II) uptake. The excellent stabilities and reusability of the nanocomposite were tested over 10 adsorption–desorption cycles. In addition, a considerable working capacity (approximately 2000 BV) in synthetic wastewater was observed in fixed-bed column tests, and the used adsorbent could be readily regenerated with a binary NaCl–EDTANa 2 solution for reuse without significant capacity loss. Thus, MoS 2 /PDA/MPS has great applications for the remediation of lead-containing wastewater, and our findings provide new insights into the preparation of efficient MoS 2 -based adsorbents having practical applications. [ABSTRACT FROM AUTHOR]

The discharge of lead containing effluents into the environment and water bodies is harmful for the human, animals, aquatic flora and fauna. Herein, a novel surface engineered magnetic nanoparticle for removing Pb2+ ions was studied. After surface modification of the magnetite by 3-amino-propyltriethoxysilane (APTES) magnetic nanoparticles with covalently linked porphyrins were synthesized. Two atropisomers of meso-tetrakis(2-carboxy-4-nonylphenyl) porphyrin (TCNP) were tested to analyze the atropisomeric effect on lead uptake. For characterize the synthesized nanosorbents methods like: Transform Infrared Spectroscopy, X-ray diffraction, Transmission Electron Microscopy and Thermo-Gravimetric Analysis were used. The effects of pH, contact time, sorbent dosage and some co-existing cations were investigated. Regeneration of lead adsorbed material could be possible and the modified magnetic nanoparticles exhibited good reusability. The use of such a system can provide fast and efficient removal of the lead ion by using an external magnetic field. The competitive adsorption tests showed good adsorption selectivity for lead ion.

Background/Purpose: Transarterial lead implantation in the left ventricle or aorta is a rare complication. Percutaneous lead removal is associated with significant thromboembolic and bleeding risk. We present two cases of lead removal from the left ventricle via the left subclavian artery with concurrent carotid embolic protection followed by stent graft placement in the subclavian artery. Methods/Results: Patient 1 underwent prior pacemaker implant with atrial and ventricular active fixation leads positioned in the right coronary cusp and the left ventricle, respectively. Patient 2 had prior ICD implant with a single active fixation lead positioned in the left ventricular apex. Lead removal was performed in a hybrid operating room. Distal embolic filter wires were deployed in the carotid arteries following anticoagulation. Intravascular ultrasound of the left subclavian artery was performed and as the leads were withdrawn, a covered stent was deployed at the removal site. Final angiography demonstrated no evidence of embolic phenomena. Both patients underwent transvenous lead implantation followed by an uneventful postoperative clinical course. Conclusions: Transarterial percutaneous lead removal may be safely performed using embolic filter protection of the cerebral circulation and stent graft placement of the arterial entry site.

Removal of heavy metals from water and wastewater has received a great deal of attention. Adsorption is one of the most technologies being used for treatment of polluted water. This study records lab scale experiments to test efficiency of activated carbon as an adsorbent and comparing it with low-cost naturally occurring materials (sand & egg shells) in removing lead ions from wastewater. The adsorption of lead ions from solutions containing different initial lead concentrations (100, 150 and 200 ppm pb as lead nitrate) using different particle size (140, 300 and 500 ìm) and different doses of activated carbon, sand and egg shells at different pH (4, 7 and 10) was examined. Also the metal concentration retained in the adsorbent phase (mg/g) was calculated. This method of heavy metals removal proved highly effective as removal efficiency increased with increasing adsorbent dose while it decreased with increasing metals concentration. The results revealed that of the studied adsorbents, the activated carbon showed the highest adsorption capacity and the maximum adsorption can be obtained by using particle size of 140 ìm in neutral media (pH 7). This technique might be successfully used for the removal of lead ions from liquid industrial wastes and wastewater.

Majority of lead content found in the environment is the result of human activities. Heavy metals can be hazardous because they tend to bioaccumulate. Complexation-microfiltration process for the removal of Pb(II) ions was studied. The aim of microfiltration of the model wastewater containing heavy metal ions was finding an optimum ratio between the concentrations of the complexing agent and metal, and determining the most favorable pH value. The microfiltration experiments were carried out in a stirred dead-end cell. Diethylaminoethyl cellulose (DEAE 23) was selected as the complexing agent. Versapor membranes were used to separate formed polymer-metal complex. The concentration of heavy metal ions after microfiltration in aqueous solution was determined using the atomic absorption spectroscopy (AAS). Effects on the amount of complexing agent, concentration of metal ion, pH value and operating pressure on the flux, J, and rejection coefficient, R, were investigated. Experimental results indicate that the pH of the solution has considerable influence on the rejection coefficient. An increase in pH and the amount of complexing agents enabled us to obtain very high retention coefficient (99%).

The adsorption of lead(II) on to activated carbon developed from an indigenous Ethiopian medicinal plant leaves namely Birbira (Militia ferruginea) was investigated to assess the possible use of this adsorbent. The influences of contact time, adsorbent dose, Pb(II) concentration, pH and temperature on adsorption were investigated. The maximum adsorption took place at 3 h. at a dose of 4.0 g of adsorbent, and 97.3 % of Pb2+ adsorption at pH of 4.0. The amount of lead ion adsorbed per gram of the adsorbent increased with decreasing concentration of Pb2+. The percentage of adsorption had increased with the increasing temperature. The positive value of ∆H indicated that the adsorption of lead ions on the adsorbent was an endothermic process. The values of free energy (∆G) were negative as expected for a spontaneous process. The decrease in ∆G value with increasing temperature revealed that adsorption of the ion on the adsorbent became favorable at a higher temperature. The calculated value of ∆H was 25.05 kJ mol–1, ∆S was 135.48 JK–1 mol–1 and ∆G was also calculated for each temperature. The two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Freundlich adsorption isotherm best fits and adsorption capacity was calculated to be 3.3 mg of Pb(II) per g of adsorbent. The adsorption followed the first order kinetics and was found to be pH dependent being maximum at pH 4.0. The pH effect and desorption studies showed that ion exchange mechanism might be involved in the adsorption process. Reuse of the desorbed bio-adsorbent is possible. The effect of foreign ions on the removal of Pb(II) has been investigated. The removal of Pb(II) from industrial wastewater sample was also tested and showed that more than 97 % removal was possible. The results showed that activated carbon prepared from Birbira (Militia ferruginea) leaves could be used for the removal of Pb(II) from wastewater.

Coconut shell (CS) was used as a neglected agricultural waste to produce the activated carbon through chemical activation process with phosphoric acid (activated coconut shell (ACS)). This process is easy and environmental friendly. The activated carbon (ACS) as biosorbent was evaluated for sorption of lead from wastewater using a series of batch adsorption experiments and compared with pyrolysis CS. The characterization results showed that this biosorbent (ACS) has high surface area and functional groups. The efficiency of adsorption process was studied at various parameters: pH, contact time, initial concentration, and competing ions for the removal of Pb(II) ions from aqueous solution. Adsorption equilibrium data were analyzed by the two parameters models (Langmuir, Freundlich, Temkin, and R–D) and the three parameters models (Generalized, Toth, Radke–Prausnitz, and Fritz–Sclunder models). The adsorption equilibrium data was well described by Langmuir and the monolayer adsorption capacities were found to be 49.92 and 26.14 mg/g onto ACS and CS, respectively, which are agreement with those obtained from the three-parameter isotherm models. The experimental kinetic data were best fitted with Bangham’s, Weber–Morris and pseudo-second-order models. The diffusion mechanism was controlled by both boundary layer and pore diffusion for the two adsorbents CS and ACS. It is noteworthy that the effect of Cd(II) and Fe(III) on the adsorption of Pb(II) is very weak, even with high concentration of Cd(II) or Fe(III), which means that the investigated adsorbents have higher affinity for sorption of Pb(II) than that of the other competing ions. The results showed that ACS can be used as a low-cost adsorbent for the removal of Pb(II) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

The role of Fe-modified sporopollenin (Fe-Sp) biomass in Pb2+removal from aqueous solutions was investigated by batch biosorption technique. The prepared biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy. The influence of pH, contact time, biosorbent dose, and initial concentration on biosorption process were optimized by using a four factor Box–Behnken design combined with response surface methodology. The results indicated a positive adsorption behavior of Fe-Sp and a strong pH dependency of the process. The optimum predicted parameters were determined as follows: biosorbent dosage 0.5 g, pH of 6.75, contact time 104 min, and initial Pb2+concentration of 25.42 ppm. The Freundlich isotherm model provided a better fit (R2 = 0.994) for the experimental data, indicating biosorption on a heterogeneous surface. Maximum biosorption capacity (qmax) was 22.72 mg g−1as indicated by the Langmuir isotherm. Kinetically, the adsorption process followed a pseudo-second-order model, indicating that chemisorption was the rate-limiting step. [ABSTRACT FROM PUBLISHER]

In this study, the zero-valent iron nanoparticles (Fe 0 NPs) were immobilized on the sintered activated carbon (SAC). The prepared Fe 0 NPs-SAC was characterized with using scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analyzer and atomic absorption spectrophotometry (AAS). The SEM morphology illustrated that Fe 0 NPs were well embedded in the SAC. The XRD peaks revealed that the addition of Fe 0 NPs did not change the crystal degree. The BET data showed that its surface area was 436.96 m 2 /g, average pore diameter was 2.377 nm and total pore volume was 0.060 cm 3 /g, while the corresponding values of SAC were 513.29 m 2 /g, 2.225 nm and 0.065 cm 3 /g. The AAS results indicated the iron loading amount was related with Fe 0 NPs/SAC ratio and reaction time in the preparing process. Subsequently, Fe 0 NPs-SAC was used as adsorbent to treat simulated lead bearing wastewater. The effects of pH, adsorbent dosage and iron loading amount were investigated. Moreover, water erosion resistance of the Fe 0 NPs-SAC was determined through released iron content in the static and shaking water. The results showed the prepared Fe 0 NPs-SAC was not only effective but also safe adsorbent for purification of drinking water. [ABSTRACT FROM AUTHOR]

This research study deals with lead(II)/Pb 2 + removal from aqueous solutions by calcium alginate (CA) and chitosan coated calcium alginate (CCCA) as adsorbents, in batch experiments. A simple synthesis method was used to prepare both adsorbent materials. CA and CCCA were characterized using infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TG). The main parameters determining the quantity of lead(II) ions adsorbed are: the initial pH solution, the lead(II)ions initial concentration and the temperature. The experiments revealed that the adsorption capacity, thus, the removal efficiency are higher for CCCA compared to CA. The adsorption of lead(II) ions onto both CA and CCCA materials is an endothermic spontaneous process, as resulted from the thermodynamic experiments. Consequently, a moderate increase of temperature improves the adsorption capacity. The thermodynamic equilibrium sorption experimental data are well fitted by Freundlich adsorption isotherm for both tested adsorbents, better than Langmuir's. Accordingly, lead(II) ions adsorption onto CA and CCCA develops obeying a multilayer mechanism. The kinetic experimental data were fitted by both pseudo-first, and pseudo-second order models. The former approaches better the experimental results for both adsorbents. The mechanism involved in lead removal is a combination between ion-exchange and coordination/chelation based on experimental results. [ABSTRACT FROM AUTHOR]

Nano-magnetite was successfully immobilized onto the isolated lead resistant bacteria species using co-precipitation technique to synthesize novel nano-magnetic bacterial bio-composite material. This isolated bacteria was identified as Enterobacter sp. B2 under accession number KT213696. Scanning Electron Microscope micrographs implied that the magnetite nano-particles were dispersed onto the surface of bacteria. The magnetic properties of magnetic bio-composite material were determined using Vibrating Sample Magnetometer (VSM). VSM evident that the bio-composite is characterized by its supermagnetic properties with 50.8 emu/g saturation magnetization that facilitate the material handling and separation. The feasibility of the novel synthesized magnetic bio-composite material for lead decontamination was explored against the variation of the processing parameters during the bioremediation process. The results elucidated that the equilibrium of lead bioremediation process achieved 90.5% within 60 minutes with bio-composite dosage of 0.1 g. The increments of both initial lead concentration and solution temperature have negative impact on the bio-remediation process. [ABSTRACT FROM AUTHOR]

A novel ion-imprinted microspheres of copolymerized diallylaminomethyl-calix [4] resorcinarene and divinylbenzene were prepared through precipitation polymerization. These microspheres were used for the adsorption experiments of Pb (II) ions mixture solution containing Pb (II), Ni (II) and Cu (II). The selective complexion towards Pb (II) ions was examined. The adsorption was conducted in batches by investigating the effects of pH and initial concentration of a heavy metal solution. The adsorption of Pb (II) metal ions on the adsorbents had the optimum pH rating in region of 6. For single ion system, the imprinted polymer showed that the adsorption capacity of Pb (II) metal ions was 64 mg/g, while for Cu (II and Ni (II) were 24 mg/g and 8 mg/g, respectively. Competitive extraction experiments in the presence of Cu (II) and Ni (II) ions were also carried out and high selectivity of the imprinted polymer adsorbents towards Pb (II) over Cu (II) and Ni (II) was found. In ternary mixture of heavy metal ions, the imprinted polymer showed effective adsorption to Pb (II) obeying Langmuir isotherm. The outstanding adsorption abilities for Pb (II) metal ion have exhibited good prospects for disposal application of polluted water and environmental protection. [ABSTRACT FROM AUTHOR]

A novel magnetic carboxylated cellulose nanocrystal composite (CCN-Fe 3 O 4 ) was prepared as an adsorbent for the adsorption of Pb(II) from aqueous solution. The new adsorbent was characterized by transmission electron microscopy, vibrating sample magnetometry, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Batch experiments were carried out to investigate the effects of contact time, adsorbent dose, pH, and temperature on adsorption capacity. Pb(II) adsorption onto CCN-Fe 3 O 4 reached equilibrium in 240 min, and the maximum adsorption capacity of Pb(II) was 63.78 mg g −1 at 298.2 K. The equilibrium data fitted the Langmuir isotherm model better than the Freundlich isotherm model, and they were well explained in terms of pseudo-second-order kinetics. Thermodynamics studies indicated that the adsorption of Pb(II) onto CCN-Fe 3 O 4 was spontaneous and endothermic in nature. The adsorbent could also be regenerated with acid treatment and successfully reapplied. [ABSTRACT FROM AUTHOR]

The alkalization-intercalated MXene (Alk-MXene: Ti 3 C 2 (OH) 2 ) has recently confirmed as a new and effective material for removing Pb heavy metal. Herein, taking into account of the complexity and diversity of MXenes, the Pb adsorption behavior of different MXenes with the highest valuable applied structure of M 2 X (OH) 2 (M = Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and X = C or N) has been systemically investigated by first principles calculations utilizing the generalized gradient approximation with the density functional theory, which paves a desirable trajectory for the applications of MXenes. Basically, the formation energies of M 2 N(O 2 H 2−2x Pb x ) are lower than those of M 2 C(O 2 H 2−2x Pb x ), suggesting the substitution of N is more effective for the Pb adsorption in contrast to C due to the different valence electron numbers between C and N atoms. In addition, the results show that the Ti 2 C(OH) 2 is the most favorite one for the lowest mass fraction to lead removal. Notably, both Sc 2 C(OH) 2 and Zr 2 C(OH) 2 structures don’t have the ability of Pb removal. The kinetics of the lead removal was elucidated on the variation of potential wells by virtue of the density of states and electron localization function. [ABSTRACT FROM AUTHOR]

Hydrochar produced via hydrothermal carbonization of grape pomace was considered as novel sorbent of Pb 2+ from aqueous solution. In order to enhance the adsorption capacity, hydrochar was chemically modified using 2 M KOH solution. Both materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction technique. Batch experiments were performed to examine the effect of sorbent dosage, pH and contact time. Obtained results showed that the KOH treatment increased the sorption capacity of hydrochar from 27.8 mg g −1 up to 137 mg g −1 at pH 5. Adsorption of lead on either of the materials was achieved through ion-exchange mechanism, chemisorption and Pb 2+ -π interaction. The Sips isotherm model gave the best fit with the experimental data obtained for Pb 2+ sorption using activated hydrochar. The adsorption kinetic followed a pseudo second-order model. Thermodynamic parameters implied that the Pb 2+ binding for hydrochar surface was spontaneous and exothermic process. Findings from this work suggest that the hydrothermal carbonization is a promising route for production of efficient Pb 2+ sorbents for wastewater treatment. [ABSTRACT FROM AUTHOR]

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Phytoremediation, is a promising biochemical process which has gained wide acceptance in remediating the contaminants from the soil. Phytoremediation process comprises of biochemical mechanisms such as adsorption, transport, accumulation and translocation. State-of-the-art modelling methods used for studying this process in soil are limited to the traditional ones. These methods rely on the assumptions of the model structure and induce ambiguity in its predictive ability. In this context, the Artificial Intelligence approach of Genetic programming (GP) can be applied. However, its performance depends heavily on the architect (objective functions, parameter settings and complexity measures) chosen. Therefore, this present work proposes a comprehensive study comprising of the experimental and numerical one. Firstly, the lead removal efficiency (%) from the phytoremediation process based on the number of planted spinach, sampling time, root and shoot accumulation of the soil is measured. The numerical modelling procedure comprising of the two architects of GP investigates the role of the two objective functions (SRM and AIC) having two complexity measures: number of nodes and order of polynomial in modelling this process. The performance comparison analysis of the proposed models is conducted based on the three error metrics (RMSE, MAPE and R) and cross-validation. The findings reported that the models formed from GP architect using SRM objective function and order of polynomial as complexity measure performs better with lower size and higher generalization ability than those of AIC based GP models. 2-D and 3-D surface analysis on the selected GP architect suggests that the shoot accumulation influences (non-linearly) the lead removal efficiency the most followed by the number of planted spinach, the root accumulation and the sampling time. The present work will be useful for the experts to accurately determine lead removal efficiency based on the explicit GP model, thus saving the waste of input resources. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have gained increasing amounts of interest due to their involvement in variety of applications. In this study, we synthesized six DESs systems based on choline chloride and six different hydrogen bond donors (HBD). Next, the synthesized DESs were used as functionalization agents with carbon nanotubes (CNTs) for use as adsorbents of lead ions, specifically Pb(II), from water. Screening studies for 24 different DES-CNT based adsorbents were conducted. The selected adsorbents samples were characterized using Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, XRD, FESEM, EDX, BET surface area, Zeta potential, and thermogravimetric analysis (TGA). Removal percentages and uptake capacities of Pb(II) on the novel selected adsorbents were optimized by RSM-CCD experimental design. The optimum conditions were found to be pH 5 with adsorbent dosage of 5 mg and contact time of 15 min. The maximum adsorption capacity of the selected adsorbent was found to be 288.4 mg/g. Langmuir and Freundlich adsorption isotherm models were also investigated and three kinetic models of adsorption were studied. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop an ecological method for the removal of Pb2+ ions from industrial wastewater. The electrocoagulation (EC) process of Pb2+ has been studied, using an electrolytic flow cell (flow rate of 20, 40, 60 mL/min) equipped with sacrificial Al electrodes, operated under galvanostatic mode (current density of 5, 10 and 15 mA/cm2). In all experimental conditions the concentration of Pb2+ was lowered below the maximum allowable concentration (0.5 ppm). The experimental results showed that the performances of the process are more strongly dependent on the applied current density than on the applied flow rate. The electrolytic flow cell has proved to be quite effective, allowing the complete removal of lead with a specific energy consumption of 3.08 kWh/kg Pb removed. [ABSTRACT FROM AUTHOR]