Initial Pb Concentration Research Articles

The Biosorption of Lead from Aqueous Solutions by a Wood-immobilized Fungal Biosorbent

Lead [Pb(II)] biosorption capacities of immobilized Talaromyces macrosporus on Moringa oleifera L. wood were compared against pure fungal and pure M. oleifera biomass. A Pb(II) contact test of 1000 ug/mL show similar Pb(II) removal of non-immobilized fungal biomass (F) and powdered wood colonized with fungi (WP+F), with WP+F producing more biomass. Powdered sorbents had higher Pb(II) uptake compared to whole sorbents analyzed through ICP-AES, possibly due to increased surface area for Pb(II) binding. FTIR analysis of the F, WP, and WP+F identified hydroxyl, amino, carbonyl, and sulfhydryl functional groups which constitute probable Pb(II)-affinitive binding sites. The biosorbents tested in a Continuous Flow Column (CF) adsorbed Pb(II) at 1000, 2000, and 4000 ug/mL in 30 minutes with the Pb(II) uptake of WP+F producing removal efficiencies at 91-95% regardless of initial Pb(II) concentration. WP+F also showed significantly higher q values than powdered wood (WP) at 42.67184.83 mg/g for the Pb(II) test concentrations. Recovery of Pb(II) from WP+F yielded 99.61% of adsorbed ions from 1000 ug/mL Pb(II), proving Pb(II) entrapment in the sorbent. This is the first study to describe biosorption capacities for T. macrosporus and M. oleifera softwood along with the wood’s viability as an immobilization scaffold. These results show the potential of using T. macrosporus immobilized on M. oleifera wood as a tool for removal of Pb(II) in wastewater with high Pb(II) concentrations.

Removal of Pb (II) from Synthetic Solution and Paint Industry Wastewater Using Activated Carbon Derived from African Arrowroot (Canna indica) Stem

This study aimed to investigate the potential of Canna indica stem‐based activated carbon (CISAC) for the removal of Pb (II) ions from synthetic solution and paint industry wastewater. The effects of pH, initial Pb (II) ion concentration, and adsorbent dose were studied using an aqueous solution prepared using pure lead nitrate (Pb(NO₃)₂) on a batch mode. Dried Canna indica stem (CIS) was carbonized in a rectangular furnace at 500°C for 2 h and treated with phosphoric acid (H3PO4) at a ratio of 1 : 1 (w/v). Results showed that the CISAC had 5.4% of moisture, 5.0% of ash, 26.7% of volatile matter, 62.9% of fixed carbon, and 797.5 mg/g of iodine number. The Fourier Transform Infrared (FTIR) results showed that the hydroxyl, carboxyl, and phenolic functional groups were dominant in the CISAC surface. Physicochemical characteristics revealed that raw wastewater had a concentration of 4.6 mg/L Pb (II), 3 mg/L Cu (II), 171 mg/L BOD5, 2402 mg/L COD, and 619 mg/L TSS. Better removal of Pb (II) ion from aqueous solution was achieved at a pH of 5.5, initial Pb (II) concentration of 102.4 mg/L, and an adsorbent dose of 1.4 g using response surface methodology. The highest removal efficiencies of Pb (II) which was achieved from aqueous solution and paint wastewater were 98% and 70%, respectively. The experimental data are fitted with Langmuir and Freundlich isothermic models. The results suggested CISAC as a promising adsorbent to remove Pb (II) ion from paint industry wastewater.

Potential Use of Alkaline-Activated Indonesian Pumice Powder as Lead Adsorbent in Solution System

<p>Pumice is a volcanic material that found abundant in Indonesia. Owing to its physicochemical characteristics it can be utilized as a low-cost natural adsorbent for cationic contaminants. This study aimed to assess the performances of adsorbents prepared from NaOH-activated powder of Lombok and Kediri pumices for lead removal in solution systems based on their maximum adsorption capacity and removal efficiency parameters. The adsorption tests were done in batch experimentation using pumice powder of 74 μm particle size activated with 0.5, 1, and 2 <em>M</em> NaOH and lead solutions with initial concentrations of 0-260 mg.L<sup>-1</sup>. The most favorable NaOH activation concentration for both pumices was 0.5 <em>M </em>which resulted from Lombok pumice prepared-adsorbent with Pb maximum adsorption capacity based on linearized conventional and rearranged Langmuir isothermal adsorption models of 236.4 and 186.3 mg.g<sup>-1</sup>, while those of Kediri pumice were of 218.4 and 210.8 mg.g<sup>-1</sup>, respectively. The removal efficiency of both adsorbents were >80% at the initial Pb concentration of <100 mg.L<sup>-1 </sup>and around 50-80% at 100-260 mg.L<sup>-1</sup>. Both pumices are therefore considered potential to be utilized as an adsorbent for cationic contaminants in solution systems with reliable performances.</p>

Highly efficient removal of Pb(II) from aqueous systems using a new nanocomposite: Adsorption, isotherm, kinetic and mechanism studies

In this research, amino-guanidinopentanoic acid (AGPA) functionalized benzene dicarboxylic coated magnetic nanoparticles (Fe3O4@BDC) was synthesized (Fe3O4@BDC@AGPA) by in situ co-precipitation process for removal of toxic Pb(II) ions from aqueous environment. The Fe3O4@BDC@AGPA nanocomposite was characterized by various instrumental technique viz., Fourier-transform infrared spectroscopy, X-ray diffraction, zeta potential, thermogravimetric analysis, energy-dispersive, and transmission electron microscopy, The effect of various parameters such as contact time, adsorbent dose, pH solution, initial Pb(II) concentration and temperature on the adsorption capacity of Pb(II) by the Fe3O4@BDC@AGPA nanocomposite was achieved. The results reveal that the adsorption process conforms to Langmuir adsorption isotherm models and the pseudo-second-order kinetic. The maximum Pb(II) adsorption capacity of Fe3O4@BDC@AGPA was 157 mg/g at condition factors min (Co– 300 mg/L; pH– 5.6; adsorbent dosage- 20 mg; temperature– 25 °C). After Pb(II) ions removal, Fe3O4@BDC@AGPA were separated using external magnetic field from aqueous medium and efficiently regenerated using 0.01 M HCl eluting. The percentage of leaching of iron in both adsorbents Fe3O4 and Fe3O4@BDC@AGPA in 0.01 M HCl for 24 h were 6.32% and 0.01%, respectively which indicating the good stability under acidic condition. The Fe3O4@BDC@AGPA possessed excellent regenerative performance after five cycles.

Synthesis and characterization of halloysite/graphene quantum dots magnetic nanocomposite as a new adsorbent for Pb(II) removal from water

Graphene quantum dots (GQDs) were covalently immobilized onto the NiFe2O4-halloysite nanotubes (NiFe2O4-HNTs) surface to fabricate a nanocomposite material utilized as an active adsorbent to eliminate Pb(II) ions from water. NiFe2O4 nanoparticles were synthesized and simultaneously deposited on HNTs. Then, the material surface was coated by APTES (aminopropyltriethoxysilane) to cause GQDs be connected to the external layer via an amide bond. The prepared nanomaterial structure was identified by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer-Emmet-Teller (BET) isotherm, energy dispersive X-ray spectroscopy (EDS) analysis and VSM (vibrating sample magnetometry). Box-Behnken design incorporated with response surface method (RSM) was utilized to find out the impact of pH, time, initial concentration of Pb(II) and adsorbent dose on lead removal. Study discovered that adsorption operation is the quasi-second-order kinetic model and adapted more precisely with Langmuir adsorption model. The Langmuir highest uptake capacity of 42.02 mg/g at 298 K was acquired. The Elovich model recommended that the process is a kind of chemisorption. The calculated thermodynamic variables verified that the uptake process is endothermic and spontaneous. Additionally, the adsorbent can be simply separated with the aid of a magnet.

Phosphate rock solubilization and the potential for lead immobilization by a phosphate-solubilizing bacterium (Pseudomonas sp.)

Lead (Pb) pollution is getting more and more serious in phosphate mining wastelands recently. However, seldom studies focused on the bioremediation of Pb pollution in phosphate mining wastelands by phosphate-solubilizing bacterium (PSB). In this study, a PSB named LA with high Pb tolerance was isolated from a phosphate mining wasteland. Based on its cell morphology, physiology, and phylogenetic analysis, it was identified as Pseudomonas sp. Its capabilities to solubilize mid-low-grade phosphate rock (PR) and immobilize Pb were assessed in this study. It was found that LA could effectively solubilize PR on PKO culture medium and release soluble phosphate in the culture medium. PR solubilization and Pb immobilization were investigated at different initial Pb concentrations and pH levels. The results showed that soluble phosphate was highly effective in immobilizing Pb and that when the initial concentration of Pb2+ was 100 mg/L, the immobilization rate of Pb was enhanced. Further, the mechanisms underlying solubilization of PR and biomineralization of Pb ions in LA were evaluated by Fourier transform infrared spectroscopy and X-ray diffraction. The results showed that some functional groups on the PR surface and LA were altered, and LA could form hydroxyapatite and pyrophosphate with Pb ions.

Removal of Pb(II) from Aqueous Solutions by Periclase/Calcite Nanocomposites

Periclase/calcite nanocomposites (PCN) were synthesized via calcination and carbonation treatment of dolomite. The surface and structural properties of PCN were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption isotherm, thermogravimetry (TG), and transmission electron microscopy (TEM). The potential of PCN to remove Pb(II) from aqueous solutions was examined by batch experiments. The effects of solid-liquid ratio (0.1–1 g L−1), initial solution pH (2–7), reaction time (0–60 min), temperature (303–323 K), and initial Pb(II) concentration (100–500 mg·L−1) on lead removal were investigated. The results showed that the removal rate of Pb(II) firstly increased and then kept stable with the increasing initial pH from 2 to 7, and the optimal solid-liquid ratio was determined as 0.2 g L−1. The adsorption kinetics of Pb(II) on PCN was well fitted to pseudo-second-order model. The adsorption equilibrium isotherm of Pb(II) over PCN could be well fitted by Langmuir model, and the maximum removal capacity was 1150.06 mg g−1 at 323 K. The thermodynamic parameters indicated that the adsorption of Pb(II) was an endothermic and spontaneous process. According to the mechanism study, the gradual release of OH− and CO32− from the dissociation of periclase and calcite can react with Pb(II) to form hydrocerussite (Pb3(CO3)2(OH)2) on PCN surface.

In Situ Copolymerized Polyacrylamide Cellulose Supported Fe3O4 Magnetic Nanocomposites for Adsorptive Removal of Pb(II): Artificial Neural Network Modeling and Experimental Studies.

The inimical effects associated with heavy metals are serious concerns, particularly with respect to global health-related issues, because of their non-ecological characteristics and high toxicity. Current research in this area is focused on the synthesis of poly(acrylamide) grafted Cell@Fe3O4 nanocomposites via oxidative free radical copolymerization of the acrylamide monomer and its application for the removal of Pb(II). The hybrid material was analyzed using different analytical techniques, including thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. The efficacious impact of variable parameters, including contact time, pH, material dose, initial Pb(II) concentration, and the temperature, was investigated and optimized using both batch and artificial neural networks (ANN). Surface digestion of metal ions is exceedingly pH-dependent, and higher adsorption efficiencies and adsorption capacities of Pb(II) were acquired at a pH value of 5. The acquired equilibrium data were analyzed using different isotherm models, including Langmuir, Freundlich, Temkin, and Redlich–Peterson models. In this investigation, the best performance was obtained using the Langmuir model. The maximum adsorption capacity of the material investigated via monolayer formation was determined to be 314.47 mg g−1 at 323 K, 239.74 mg g−1 at 313 K, and 100.79 mg g−1 at 303 K.

Adsorption of Pb2+ and Cu2+ ions on the CS2-modified alkaline lignin

A kind of alkaline lignin (AL)-based modified material (FLAL) was fabricated, in which CS2 was selected as the modifier. FLAL can be used to treat Pb2+ and Cu2+ ions loaded water. When the initial concentrations of Pb2+ and Cu2+ ions were 30 mg/L, the removal efficiencies were 97% for Pb2+ at 100 min while 98% for Cu2+ at 5 min, respectively. The maximum adsorption capacities (qm) of Pb2+ and Cu2+ ions were 0.322 and 1.010 mmol/g, indicating that the adsorption capacity of FLAL for Cu2+ ions was better than for Pb2+ ions. The groups of hydroxyl, methoxyl and dithiocarbamate carried by FLAL contributed to binding with Pb2+/Cu2+ ions. Dithiocarbamate (CSS) was proved to be the primary active site, in which the binding energy (Ead) of SCuS and SPbS were −1.1739 and −0.8709 Ha. These results suggest the interaction between FLAL and Cu2+ ions was stronger and FLAL-Cu2+ complexes were more stable, revealing the reason why the uptake of Cu2+ ions by FLAL was quicker in speed and larger in amount. The reusing ability of FLAL was evaluated through a four-adsorption–desorption cycle. The values of qm for Pb2+ and Cu2+ ions were 0.258 and 0.878 mmol/g corresponding to the fourth regeneration, decreased by 19.87% and 13.06% compared to fresh FLAL. The adsorption performance of both fresh and regenerated FLAL is better than many other biomass-based adsorbents. FLAL can be regarded as a promising material with high application potential, which warrants future studies on optimizing FLAL for real-world applications.

SYNTHESIS OF STARCH MODIFIED MONTMORILLONITE AS AN EFFECTIVE ADSORBENT FOR Pb (II) REMOVAL FROM WATER

The adsorbent is prepared by the montmorillonite co-modification with starch for the removal of Pb (II) ions from aqueous solution. The Fourier-transformed infrared (FTIR), X-ray diffraction (XRD) spectroscopies were used to determine the structure and characteristics of the adsorbent. The main factors affecting the removal of Pb (II) ions were investigated, including the effect of pH, contact time, adsorbent dosage and the initial concentration of Pb (II). Batch process can be used for adsorption and equilibrium studies. The experimental data were fitted using Freundlich and Langmuir adsorption models. The Langmuir isotherm best fitted the experimental data with R2> 0.99 and maximum Pb (II) adsorption capacity of 21.5 mg/g indicated monolayer adsorption. Kinetic studies using pseudo-first-order and pseudo-second-order rate models showed that the process complied well with the pseudo second-order rate model.

New effective 3-aminopropyltrimethoxysilane functionalized magnetic sporopollenin-based silica coated graphene oxide adsorbent for removal of Pb(II) from aqueous environment

A new effective adsorbent, 3-aminopropyltrimethoxysilane functionalized magnetic sporopollenin (MSp@SiO2NH2) based silica-coated graphene oxide (GO), (GO@SiO2-MSp@SiO2NH2) was successfully synthesized and applied for the first time in the removal of hazardous Pb(II) ions from aqueous solution. The properties of the composite were characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX) and vibrating-sample magnetometery (VSM). Evaluation of GO@SiO2-MSp@SiO2NH2 adsorption performance at optimum conditions revealed that the adsorbent has a maximum adsorption capacity of 323.5 mg/g for Pb(II) using 50–200 mg/L initial Pb(II) ions concentrations. Initial and final concentrations of Pb(II) ions in aqueous solution were analyzed using graphite furnace atomic absorption spectroscopy (GF-ASS). The adsorption behavior of Pb(II) ions onto GO@SiO2-MSp@SiO2NH2 was studied using Langmuir, Freundlich and Temkin isotherms models. The values of coefficient of determination showed that the adsorption best fitted the Langmuir model (R2 = 0.9994). Kinetic studies suggested that the adsorption of Pb(II) ion followed a pseudo-second-order rate model (R2 = 1.00) and thermodynamic studies revealed that the adsorption process is endothermic and spontaneous. The effect of co-existing ions on Pb(II) ion adsorption were also studied and found to have considerable effects only at higher matrix concentration. The adsorbent can be reused up to ten times and retain its good adsorption capacity. In addition, GO@SiO2-MSp@SiO2NH2 showed great potential for Pb(II)removal from industrial wastewater samples.

Modeling mass transfer for adsorptive removal of Pb(II) onto phosphate modified ordered mesoporous carbon (OMC)

Phosphate modified ordered mesoporous carbon (MOMC-NP) has been synthesized and proven to be an effective adsorbent for Pb(II) removal from aqueous solutions. However, the key application components of the mass transfer operations and diffusion coefficient have not been determined. In this study, a modified Finite Bath Diffusion Control Model was mathematically developed containing a constant related to the radius of the adsorbent particle and the fractional attainment of adsorption. The adsorption experiments were conducted under various initial Pb(II) concentrations ranging from 60 mg L−1 to 100 mg L−1. The results suggested that the modified Finite Bath Diffusion Control Model was more applicable to the experimental data than the original Finite Bath Diffusion Control Model. The average value of the diffusion coefficient (λD¯) obtained from the modified finite bath diffusion control model was 1.63 × 10−2 cm2 s−1 indicating the effective diffusivity in the adsorption of Pb(II) on MOMC-NP. Overall, the modified Finite Bath Diffusion Control Model exhibited the precise description and simulation of the mass transfer kinetics for Pb(II) adsorption onto MOMC-NP. Therefore, the modified Finite Bath Diffusion Control Model could be effectively used to investigate the mass transfer kinetics of the adsorption process.

Parametric modelling of Pb(II) adsorption onto chitosan-coated Fe3O4 particles through RSM and DE hybrid evolutionary optimization framework

In this study, response surface methodology (RSM) was discussed as an efficient method for the optimization of Pb(II) adsorption onto Fe3O4 nanoparticles and chitosan-coated Fe3O4 particles. To retain the non-linearity of isotherm/kinetic models and inherent characteristics of mechanism involved in adsorption process, the model parameters in these models are estimated using differential evolution (DE) based hybrid optimization. The lack of fit for first-order response-surface model and two-way interactions model were insignificant, but a higher lack-of-fit was observed in the second-order model and reduced second-order model. The results of these computations (F-value: 29.3 on 6 and 37 DF; p-value: 1.226e−12; R2: 0.8261, and LOF: 0.99) showed that the RSO model fit well with Pb (II) removal by Ch-Fe. Based on the RSM model, the optimal conditions were found to be 10.95, 5.5 mg/L, 66.59 min, and 0.1 g/L for pH, Ch-Fe dosage, initial Pb (II) concentration and residence time, respectively, resulting in maximum (93.6%) removal efficiency. Based on the findings, the model predictions from the DE based optimized parameters provided optimal parameter sets which better represent the adsorption rate models and infer the inherent mechanisms of the adsorption process.

Removal of Pb(II) by Pellicle-Like Biofilm-Producing Methylobacterium hispanicum EM2 Strain from Aqueous Media

As concerns are increasing about drinking water contamination with heavy metals, we investigated the possible use of a pellicle (floating biofilm)-like biofilm-producing microorganism as a biosorbent for the treatment of Pb(II) in aqueous solutions. The bacterial pellicle-producing Methylobacterium hispanicum EM2 strain (EM2) was newly isolated from mine tailing soil, and we investigated its use as a biosorbent for treating a Pb(II)-contaminated aqueous solution. The EM2 strain was strongly resistant to Pb(II) up to a concentration of 800 mg/L, and achieved remarkable adsorption performance (adsorption rate and maximum adsorption capacity of 96% ± 3.2% and 79.84 mg/g, respectively) under optimal conditions (pH, biomass content, contact time, and initial Pb(II) concentration of 7.1 g/L, 60 min, and 10 mg/L, respectively). The adsorption of Pb(II) was characterized by scanning electron microscopy-energy dispersive x-ray spectroscopy and Fourier-transform infrared analysis. The equilibrium data matched the Freundlich isotherm model well, indicating the occurrence of multilayer adsorption of Pb(II) onto the heterogeneous surface of the EM2 strain, which was also consistent with the pseudo-second-order kinetic model (R2 = 0.98). The high Pb(II) removal efficiency was also confirmed by conducting an adsorption experiment using Pb(II)-contaminated industrial wastewater.

Ultrahigh removal performance of lead from wastewater by tricalcium aluminate via precipitation combining flocculation with amorphous aluminum

Abstract Lead (Pb) removal is an urgent issue of industrial wastewater treatment due to its fatal harm on human health. In this study, for the first time, the efficient removal of Pb by cement-based material tricalcium aluminate (C3A) have been reported. The ultrahigh removal capacity of 1747.1 mg·g−1 for Pb by C3A was achieved at the dosage of 0.5 g·L−1 within 1 h. The removal behaviors investigated by batch experiments illustrated that the C3A dosage and initial Pb concentration significantly influenced the removal behavior. And the removal process was identified to be a pH-independence process accompanying with a chemical reaction. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the chemical precipitation thermodynamic model PHREEQC were employed to elucidate the removal mechanism. Amorphous aluminum released by C3A hydration played a major role in Pb removal via flocculation at low Pb concentration ( 600 mg·L−1). C3A could remove Pb to an acceptable level (WHO standard) from authentic wastewaters at low Pb concentration (∼20 mg·L−1), or remove ∼70% Pb from authentic wastewaters at high concentration (ca. 700 mg·L−1). This work presents C3A as an excellent material for lead removal and broadens the potential application of cement-based materials in environmental remediation.

Kajian Metode foto-Fenton untuk Penurunan Konsentrasi Ion Logam Berat Pb(II) dan Cu(II) dalam Larutan Secara Simultan dan Sinergi

To prevent an environmental pollution by hazardous heavy metals, in the present study, a simulatenous decrease of the concentration of Pb((II) and Cu(II) in the solution by photo-Fenton method has been systematically studied. Photo-Fenton process proceeded in a close reactor by batch technique. The process was conducted by exposure solutions containing Pb(II) and Cu(II) ions, and Fenton’s reagent (Fe2+ and H2O2) under UV-A lamp. In this study, the initial concentations of Pb(II) and Cu(II), and the exposure time were optimized. The synergyc effect that may be appeared on the decrease of Pb(II) and Cu(II) ion concentrations simultaneously through photo-Fenton process was also addressed. The concentrations of Pb(II) and Cu(II) in the solution were determined by AAS. The research results exhibited that photo-Fenton process could decrease Pb(II) and Cu(II) concentrations, and the maximum decreases, 46.12 % dan 16.86% for Pb(II) and for Cu(II) respecticely, were found by applying both initial concentration of Pb(II) and Cu(II) as much 35 mg/L, and 60 min of the time. The concentration decreases of Pb (II) and Cu(II) were results of oxidation by OH and by electron to form PbO2 and Cu particles respectively as probed by EDX data. Furthermore, photo-Fenton process toward a solution containing Pb(II) and Cu(II) ions allowed oxidation of Pb(II) and reduction of Cu(II) simultaneously and showed a synergic effect. Such effect was demonstrated by the fact that the presence of Cu(II) ion in the photo-Fenton process of Pb(II) solution could improve the Pb(II) oxidation and the highest improvement of Pb(II) oxidation (81.06%) was shown by 35 mg/L of the Cu(II) concentration. Similarly, the presence of Pb(II) in the photo-Fenton process of Cu(II) solution could enhance the reduction of Cu(II), and the highest effect on the Cu(II) reduction enhancement was exhibited by 35 mg/L of the Pb(II) concentration.

Reuse potential of residues of artichoke (Cynara scolymus L.) from industrial canning processing as sorbent of heavy metals in multimetallic effluents

The suitability of reusing artichoke agrowaste biomass from industrial canning processing as a low-cost and ecofriendly sorbent for the bioremoval of Pb(II), Cd(II) and Cu(II) in multi-metallic aqueous solutions is reported. Understanding the dynamic of heavy metals in the sorption process is critical to assess the removal of these contaminants in aquatic systems. The Taguchi approach was used to design a series of experiments to find the optimum conditions for maximum total sorption capacity, analysing the signal-to-noise (S/N) ratio to assess the experimental responses. Ranks of five controllable factors (the initial concentrations of Pb(II), Cd(II) and Cu(II), sorbent dosage and pH), at three levels each one, in a L27 array were conducted in batch sorption tests. The highest sorption capacity (241 μmol·g−1) was shown with initial concentrations of 315 μmol L−1 Cu(II), 445 μmol L−1 Cd(II) and 241 μmol L−1 Pb(II), pH 5 and 0.5 g L−1 of sorbent dosage. The metal ion predominantly adsorbed was Pb(II). Adsorption kinetics followed a pseudo-second order model. The study of the shares of each metal ion on the total sorption capacity revealed that Cd(II) is actually prone to be adsorbed but the presence of Pb(II) and Cu(II) hinders its adsorption. The valorization of artichoke agrowaste biomass as metal sorbent is considered a way to assist in the promotion of a circular economy.

In situ polymerization of magnetic graphene oxide-diaminopyridine composite for the effective adsorption of Pb(II) and application in battery industry wastewater treatment.

The efficient removal of heavy metals from aqueous environment is imperative and challenging. A novel ternary composite constructed of diaminopyridine polymers, graphene oxide, and ferrite magnetic nanoparticles was designed by a facile in situ polymerization strategy for the removal of Pb(II) from aqueous solution. Detailed characterization of morphological, chemical, and magnetic properties was employed systematically to confirm the formation of the composite material. Batch adsorption experiment studies suggested that the composite was an excellent adsorbent for Pb(II) which was easily collected after use via exposure to an external magnetic field for 30 s. The effects of different parameters such as solution pH, adsorbent dosage, contact time, initial Pb(II) concentration, temperature, and co-existing ions were examined. The maximum adsorption capacity at pH = 5 was estimated to be 387.2 mg g-1 at 298 K by the Langmuir isotherm model, accompanied by favorable adsorption recyclability according to the investigation of regeneration experiments. Thermodynamic studies revealed that the Pb(II) adsorption via our ternary composite was endothermic and spontaneous. The corresponding removal performance for effluent containing Pb(II) from the battery industry was successfully examined. The present results indicated that our designed adsorbent is beneficial to the practical Pb(II) removal in wastewater purification.

High-efficiency removal capacities and quantitative sorption mechanisms of Pb by oxidized rape straw biochars

Chemical oxidation is an effective method to improve the ability of biochars for metals removal, but there are too few studies on screening of high-efficiency oxidants and quantitative analysis of sorption mechanisms. In this study, rape straw biochars (BC) were oxidized with HNO3, H2O2, and KMnO4, and noted as BC-HNO3, BC-H2O2, and BC-Mn, respectively. The Pb removal capacities and quantitative sorption mechanisms of biochars were explored through batch sorption experiments. Compared with that of BC (175 mmol kg−1), the maximum Pb sorption capacities of BC-HNO3 and BC-H2O2 increased to 526 and 917 mmol kg−1, in which contribution of surface complexation accounted for 55.1% and 39.0%, respectively. Due to the large surface area and abundant newly formed MnO2, BC-Mn showed the maximum Pb sorption capacity of 1343 mmol kg−1, and its high removal efficiency appeared even at low pH value (pH = 2) and high initial Pb concentration (1.0 mol L−1). The contribution of cation exchange accounted for 97.4% of the Pb sorption by BC-Mn. These results suggested BC-Mn had great potential for Pb removal from aqueous solution, and the quantitative analyses of sorption mechanisms revealed the contribution of each mechanism and provided a basis for evaluating application prospects of biochars.

Facile synthesis of graphene oxide/palygorskite composites for Pb(II) rapid removal from aqueous solutions.

As a kind of earth-abundant and cheap natural clay mineral, palygorskite (Pal) was facilely modified by grafting with graphene oxide (GO) to fabricate GO/Pal composites for rapid removal of Pb(II) from aqueous solutions. The results of characterization confirmed that the GO/Pal composites were successfully grafted between GO sheets and Pal nanorods. The effects of pH, adsorbent dosage, adsorption time, initial Pb(II) concentration and temperature on the adsorption of Pb(II) onto the GO/Pal composites as adsorbents were systematically investigated. The maximum adsorption capacity over 106.6 mg/g was obtained within a short adsorption time of less than 1 h even at 298.15 K. The adsorption of Pb(II) was a fast process that more accurately followed the pseudo-second-order kinetic equation. This process also could be described better with the Langmuir equation model than the Freundlich model. The negative values of ΔG° and the positive values of ΔH° and ΔS° indicated that it was a spontaneous, endothermic and entropy-increasing adsorption process. Compared with pristine Pal and GO powders, such the GO/Pal composites as a cost-efficient and eco-friendly adsorbents could significantly improve the adsorption properties of Pb(II) and would have potential application in the industrial wastewater treatment for rapid removal of Pb(II).