Adsorbent For Removal Of Pb Research Articles

Synthesis and characterization of chitosan Schiff base grafted with formaldehyde and aminoethanol: As an effective adsorbent for removal of Pb(II), Hg(II), and Cu(II) ions from aqueous media

Grafted chitosan materials show the characteristics of high stability, easy separation and recovery, and good heavy metal adsorption capacity, and have received much attention in the adsorption process. Therefore, in this work, novel grafted chitosan-based adsorbent CS-EHBSB@F-AE was prepared by a one-pot reaction of chitosan (CS), 3-ethoxy-4-hydroxybenzaldehyde (EHB), formaldehyde (F) and aminoethanol (F). The microstructure and morphology of the as-prepared composite CS-EHBSB@F-AE were characterized by FT-IR, TGA, DSC, FE-SEM, and BET analyses. The adsorption performance of the as-prepared CS-EHBSB@F-AE composite on Pb(II), Hg(II), and Cu(II) ions from aqueous was investigated using batch experiment and the effects of the initial pH of the solution, contact time, and initial metal ions concentration and temperature on the adsorption efficiency were investigated and discussed. At the best conditions, CS-EHBSB@F-AE exhibited remarkable adsorption capacity of 246.7 mg/g, 203.9 mg/g, and 234.4 mg/g in absorbing Pb(II), Hg(II), and Cu(II), respectively. The adsorption equilibrium and the kinetic studies confirmed that the ions adsorption process fits well with the Langmuir isotherm and pseudo-second-order (PSO) models. Additionally, the adsorption efficiency of Pb(II), Hg(II), and Cu(II) metal ions by the composite CS-EHBSB@F-AE was reduced by increasing the temperature from 298 K to 318 K. In addition, after the sixth ads/des cycles, the as-prepared adsorbent still exhibited high removal efficiency with a decrease in adsorption efficiency of Pb(II) (5.53 %), Hg(II) (15.43 %) and Cu(II) (8.27 %). Finally, we proposed that the ions adsorption by CS-EHBSB@F-AE has happened using the coordination of active groups containing nitrogen and oxygen atoms on the surface of the adsorbent with the Pb(II), Hg(II), and Cu(II) metal ions.

Self-foaming calcium modified carbon foam derived from a liquefied product resin of tobacco stalks for the removal of Pb2+ in water

This study demonstrated a self-foaming plus in-situ modification strategy that led to an efficient and environmentally friendly carbon foam adsorbent for removal of Pb2+ from aqueous solution. Specifically, the resin derived from liquefied tobacco stalk (TSLPR resin) was used as the precursor of carbon foams. Various characterization techniques were employed to investigate the morphology, structure, surface area, pore size, and adsorption capacity of the materials. Upon carbonization of the resin foam at 800 ℃, considerable CaO and CaCO3 converted from Ca (NO3)2 were distributed on the surface of the cell wall, indicating the success of the in-situ modification. By using a carbon foam loaded with 7% calcium (Ca@CF-7) as an adsorbent for removal of Pb2+ at a pH of 4 and 25 ℃, the dynamic adsorption equilibrium was achieved within 480 minutes. The theoretical maximum adsorption capacity (qm) obtained by Sips model reached 348.8 mg·g−1, which is more than 4.5 times higher than the pristine carbon foam. The findings of this study indicated that the chemical co-precipitation of Pb3(CO3)2(OH)2 played a significant role for removal of Pb2+, which could be attributed to the surface alkaline environment provide by CaO and CaCO3. This study offers a novel approach for in-situ modification of carbon foam and also demonstrated the potential of the straw biomass with low lignin content in production of high-performance carbon adsorbents.

KINETICS AND MECHANISM MODELLING OF Pb(II) AND Ni(II) IONS SORPTION FROM AQUEOUS MEDIUM: EVALUATING THE PERFORMANCE OF Curcuma longa RHIZOME IN THE TREATMENT OF WASTE WATER.

In this research Curcuma longa Rhizome, an agricultural product, available in large quantity in northern Nigeria, were used as low-cost adsorbent for removal of Pb(II) and Ni(II) ions from aqueous medium. Batch operation was used to study the equilibrium behaviour of Curcuma longa rhizome. The effect of solution pH, and contact time on the adsorbent for the removal of Pb(II) and Ni(II) ions were evaluated. To study the adsorption kinetics of Pb(II) and Ni(II) ions onto Curcuma longa Rhizome, pseudo-first-order, pseudo-second-order as well as three diffusion models: intraparticle diffusion model (Weber and Morris model), film diffusion model (McKay model) and liquid film Models were used. The sorption kinetics can be described well by the pseudo-second-order model due to the closeness between the qexp ( 49.26 mg/g) and qcal (52.63 mg/g) for Pb(II) and qexp (57.60) and qcal (55.56 mg/g) for Ni(II) ions. Moreover, the rate limiting step are liquid film and intraparticle diffusion controlled. In addition, the results suggest that Curcuma longa Rhizomes are very effective adsorbent for the removal of Pb(II) and Ni(II) ions from aqueous medium. This will serve as an indicator to consider in the design for waste water treatment plant for heavy metal detoxification using Curcuma longa Rhizome.

Bentonite-Chitosan composites or beads for lead (Pb) adsorption: Design, preparation, and characterisation

This study investigated the efficiency of mixing bentonite with chitosan via different preparation methods, subsequently the different forms were investigated for their ability to remove Pb(II) ions from solution. The different forms of bentonite-chitosan (Bt-Ch), composites and beads, were prepared via solution blending and precipitation methods, respectively and in the weight ratios of 90%/10%, 70%/30% and 50%/50%. The beads were further subdivided, identified as “beads-A" and “beads-B", and were formed by adding either bentonite suspension or bentonite powder, respectively, to solubilised chitosan solution. The composites and beads were characterised by X-ray fluorescence (XRF), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and pH at zero point charge. XRF analysis showed a cation exchange mechanism occurred when chitosan was initially mixed with the bentonite. TGA results confirmed that beads contained more chitosan compared to their corresponding weight ratio equivalent composites. XRD results showed that chitosan was intercalated within the interlayer space of the bentonite for Bt-Ch composites and Bt-Ch beads-A and that the interlayer spacings increased with increasing chitosan loading. Though similar amounts of chitosan were present in both Bt-Ch beads-A and beads-B, there were fewer reflection shifts for beads B suggesting less intercalation of chitosan when the bentonite was added as a powder. FTIR spectra from the Bt-Ch composites and beads confirmed the presence of both chitosan and bentonite, and the NH bands of chitosan shifted to lower frequencies demonstrating their involvement in the bonding mechanism of chitosan with bentonite. The experimental adsorption data correlated well with both non-linear Langmuir and Freundlich isotherm models, and in which both chemisorption and physisorption processes played crucial roles. The Langmuir-maximum adsorption capacities of Pb(II) ions for all the analysed Bt-Ch composites and beads was found to range from 42.48 ± 4.22 to 94.60 ± 5.63 mg/g. The amount of chitosan present in the adsorbent and its distribution within or outside the interlayer space of the bentonite was shown to have pronounced effects on the Pb(II) uptake by the different Bt-Ch composites/beads, and although the chitosan greatly enhanced the adsorption of Pb(II) a cation exchange mechanism with the clay was still a dominant process. The adsorption of Pb(II) was also significantly affected by the presence of other multi-competing ions. Moreover, the developed Bt-Ch composites/beads exhibited good potential for re-use after five cycles of regeneration, thus, indicating their potential as cost-effective adsorbents for removal of Pb(II) ions from both drinking and wastewater.

An MXene-Grafted Terpolymer Hydrogel for Adsorptive Immobilization of Toxic Pb(II) and Post-Adsorption Application of Metal Ion Hydrogel.

Toxic metal ions present in industrial waste, such as Pb(II), introduce deleterious effects on the environment. Though the adsorptive removal of Pb(II) is widely reported, there is a dearth of research on the suitable utilization and disposal of the Pb(II)-adsorbed adsorbent. In this work, an MXene-grafted terpolymer (MXTP) hydrogel has been designed for the adsorption of Pb(II) under ambient conditions of pH and temperature. The hydrogel MXTP was synthesized by facile one-pot polymerization in aqueous solvent, and the detailed structural characterization of terpolymer (TP), MXTP, and Pb(II)-loaded MXTP, i.e., Pb(II)-MXTP, was carried out by a combination of proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometric (XRD), thermogravimetric/differential thermogravimetric (TG/ DTG), and field emission scanning electron microscopic (FESEM) analyses. The specific capacitance and conductivities of Pb(II)-MXTP were studied with cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS), which unambiguously indicate successful post-adsorption application. The specific capacitance of MXTP decreased after Pb(II) adsorption, whereas the conductivity increased significantly after Pb(II) adsorption, showing that MXTP can be successfully deployed as a solid electrolyte/anode after Pb(II) adsorption. This study covers the synthesis of a novel MXene-grafted terpolymer hydrogel for adsorptive exclusion of Pb(II) and assessment of the as-adsorbed Pb(II)-loaded hydrogel as a solid electrolyte/anode material and is the first demonstration of such post-adsorptive application.

Facile Preparation of Magnetic CuFe2O4 on Sepiolite/GO Nanocomposites for Efficient Removal of Pb(II) and Cd(II) from Aqueous Solution.

CuFe2O4 nanoparticles were synthesized and immobilized on sepiolite fibers and graphene oxide sheets, producing a CuFe2O4/sepiolite/GO (CFSG) nanocomposite via a facile single-pot method. The synthesized nanocomposite was characterized using TEM, FTIR, SEM-EDX, XRD, and TGA techniques to determine its composition, structure, and thermal stability. The adsorptive removal of Pb(II) and Cd(II) heavy metal ions from aqueous solutions was studied using the synthesized CFSG nanocomposite. Adsorption parameters such as CFSG loading, pH, contact time, and temperature were investigated. The CFGS nanocomposite showed a higher Pb(II) removal (qm = 238.1 mg/g) compared to Cd(II) (qm = 14.97 mg/g) in a Pb(II) and Cd(II) binary system. The Pb(II) and Cd(II) adsorption fitted well with the Langmuir model, followed by the pseudo-second-order model, and was found spontaneous. Adsorption thermodynamic analysis showed that the Pb(II) adsorption process was exothermic while Cd(II) adsorption was endothermic. The CuFe2O4 nanoparticles on the CFSG surface could facilitate the adsorption of heavy metal ions through electrostatic interaction and complexation processes.

Performance of cross-linked chitosan-zeolite composite adsorbent for removal of Pb2+ ions from aqueous solutions: Experimental and Monte Carlo simulations studies

In this study, we investigated the performance of a cross-linked chitosan (Ch)-zeolite (Z) composite (Ch-Z) adsorbent for the removal of Pb2+ ions from water. The results revealed that the Ch-Z composite exhibited excellent adsorption performance for Pb2+ ions. The maximum adsorption capacity was found to be 275 mg g−1 at pH 4.5, Ch-Z composite dose of 5 g/L and an initial Pb2+ concentration of 1000 mg/L for 24 h. The adsorption equilibrium data and its kinetics followed a Langmuir and PSO models. Furthermore, thermodynamic parameters were determined, indicating that adsorption was spontaneous and endothermic. MC simulations were used to investigate the interaction between Pb2+ ions and the modeled composite. The considerable negative adsorption energy values confirm the strong affinity between the adsorbate molecules and the adsorbent surface. Overall, the Ch-Z composite adsorbent exhibited remarkable potential to remove Pb2+ ions from wastewater.

Adsorptive Removal of Pb (II) from Aqueous Solution using Pyoaurite Type Sorbent, Cerelite, Activated Carbon, Goethite and Rice Husk

Removal of divalent lead from aqueous solution, a comparative study of six sorbents was carried out by batch as well as column processes. The order of lead removal capacities for these chemical adsorbents was found to be IRA > PTS> PAC > PLC > FeO(OH) > RH. This is probably due to several factors such as molecular size, molecular polarity, pH lead reactivity and retentivity, sorbent properties and environmental conditions. The leaching order should be reverse of the sorption order. The sorption of lead ions goes on increasing as their concentration decreases from 10 to 0.1 mg/l. Thus, the removal was about 20 % less than what it was in the batch process Leaching increases as the flow rate increases. Solution pH significantly affected the extent of contaminant removal.

Synthesis, characterization, and application of hydroxyapatite grafted over pristine charcoal /activated charcoal for removal of pb2+ ions from aqueous solution

Hydroxyapatite (HAP) is one of the major components found in bones and teeth and has outstanding biocompatibility. Hydroxyapatite is a possible sorbent for heavy metals in contaminated water attributable to its high adsorption capabilities and solubility of water very low. However, pure hydroxyapatite is very difficult to use because it exists in the form of white power and also is too much costly. The above difficulties were overcome by the synthesis and characterization of hydroxyapatite grafted over Pristine charcoal/ activated charcoal for the expulsion of lead ions from aqueous solutions by the simple hydrothermal process at different temperatures like 120 °C and 150 °C. The result reveals that rod-like HAP nanocrystals with a range of 22––62 nm, are impregnated over charcoal. Characterization of synthesized hydroxyapatite samples by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and Energy-dispersive X-ray spectroscopy (EDX) methods. To investigate adsorbent for removal of Pb2+ from an aqueous solution of Pb (NO3)2, and to vary the adsorbent dosage to evaluate its influence on the adsorption efficiency. The observed that synthesis of HT-CH at 120 °C gives the best result, UV Analysis for the calculation of equilibrium sorption capacity of HT-CH120 and HT-ACH120 on the adsorption of Pb2+ ion is carried out by Lambert-Beer law. The equilibrium sorption capacity of HT-CH120 is 76.13 mg/gm while the equilibrium sorption capacity of HT-ACH120 is 15.8 mg/gm.

Chitosan cross-linked and grafted with epichlorohydrin and 2,4-dichlorobenzaldehyde as an efficient adsorbent for removal of Pb(II) ions from aqueous solution

Epichlorohydrin-modified chitosan-Schiff base composite (CS/24Cl/ECH) prepared via the one-pot reaction as characterized by Fourier transform Infra-Red spectroscopy (FT-IR), X-ray powder diffraction (XRD), Differential scanning calorimetry (DSC) and Scanning electron microscope (SEM). Its removal ability of Pb(II) ions from aqueous solution was investigated. The adsorption of Pb(II) ions carried out at different initial pH, dose of CS/24-Cl/ECH, contact time and co-existing ions. The maximum adsorption capacity of Pb(II) ions was 170 mg/g. Finally, based on the absorption results, the adsorption of Pb(II) ions was fitted by single-layer Langmuir isotherm model and the pseudo-second-order (PSO) kinetics model. The absorption mechanism of Pb(II) ions was controlled by chemical coordination Pb(II) ions with the active sites on the surface of CS/24Cl/ECH composite. Also, CS/24Cl/ECH showed excellent recyclable efficiency up to 5 cycle and potential sorbent for other heavy metal ions.

Column study using modified banana pseudo stem as adsorbent for removal of Pb (II)

Eco-friendly adsorbents such as banana pseudo stem play a fundamental role in the removal of heavy metal elements from the wastewater. Key water resources and chemical industries have been encountering difficulties in removing heavy metal elements using existing conventional methods. The lead-removal process is currently a challenging task for environmental scientists and engineers in terms of cost, effluent disposal, and safety concerns. Hence, this work demonstrates the adsorption of Pb (II) onto modified banana pseudo stem (MBPS) powder as a potential adsorbent to treat different effluents. A characterization of modified banana pseudo-stem powder was performed using scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy which confirms the material. Experiments carried out using a column process for the removal of lead (II) from an aqueous solution at a fixed concentration of 50 ppm, pH 6 and contact time 120 min. The BET surface area of MBPS was found to be 7.27 m2/g. The results showed that the column studies explain better performance for the removal of Pb (II) and the maximum removal was found to be 49% at lower flow rate (5 mL/min) of fixed initial concentration of 50 ppm.

Adsorption of Pb (II) Using Sheep Fur: Isotherm, Kinetics and Thermodynamic Studies

Sheep fur (SF), a keratinous biomaterial, was used as a low cost adsorbent for removal of Pb (II) from aqueous solution. The sorbent was characterized, where moisture content, pH, bulk density and loss on ignition were determined. The experimental data were analyzed by Langmuir, Freundlich, Temkin and Dubinin Radushkevich model with the Langmuir model showing the best fit. Maximum adsorption capacity of Pb (II) by the SF was 45.46 mg/g. Separation factor RL was 0.037 indicating a favourable adsorption process. The results also indicated that kinetic data were best described by the pseudo second-order model with a correlation coefficient (R2) of 0.997. Negative standard Gibb’s free energy (ΔG) obtained indicated that the Pb (II) adsorption process was spontaneous and thermodynamically feasible. Fourier Transform Infra-red Spectroscopy (FTIR) analysis confirmed the presence of carboxyl, hydroxyl, amino and sulphur-containing functional groups on the SF.

Cotton fabric functionalized with nanostructured MoS2: Efficient adsorbent for removal of Pb, Hg, Cd and Cr from water

In the present work, nanostructured Molybdenum disulphide (MoS2), supported on a cotton fabric, was prepared in situ via a hydrothermal approach using ammonium heptamolybdate and thiourea as precursors, combining the mechanical strength and flexibility of cotton textile with the outstanding adsorption performance of layered MoS2. Evidence for the in situ generation of crystalline MoS2 at the cotton fibres surface was obtained by XRD, Raman and XPS spectroscopies and the morphology of the appended MoS2 layer was analysed by FESEM microscopy, revealing a flower-like structure uniformly grown onto the cotton fibres. Batch adsorption experiments have demonstrated the effective adsorption of Hg(II), Pb(II), Cd(II) and Cr(VI) from aqueous solutions within a short time (less than 15 min) and with adsorption capacities between 300 and 1200 mg/g, depending on the metal ion. A distribution coefficient (Kd) exceeding 104 was achieved for Hg, Pb and Cd, confirming the exceptional adsorption efficiency of the hybrid structure, made of cotton and MoS2 (Cot-MoS2), for these classes of highly toxic heavy metal ions. A Langmuir model was fitted to kinetics experimental results through a non-linear least square fitting with good correlation values. Isotherm studies showed that the adsorption process, while well described by a Langmuir model, was better described by a Sips equation mixing Langmuir and Freundlich adsorption models, the exponent α, being not very different from 1, confirms that the dispersion of energy adsorption is not very large.As a proof-of-concept for the potential applicability of the hybrid structure Cot-MoS2 for the in-flow water decontamination from toxic heavy metal ions, a column filled with Cot-MoS2 was tested under continuous filtration conditions, achieving a removal efficiency of more than 99%.

Kinetic and thermodynamic investigation on adsorption of lead onto apatite extracted from mixed fish bone

Fish bone derived apatite has been used as adsorbent to remove lead from aqueous solution. The mixed fish bone was treated at three different temperatures starting from 300 °C with an increment of 100 °C. Variation in calcination temperature effects the particle size and the adsorption efficiency of the apatite. The calcined fish bone samples were investigated using XRD, FT-IR, SEM, EDS and XPS. A batch experiment was carried out to examine the effect of pH, initial concentration, and contact time on lead adsorption. The observation shows that the efficiency of adsorption was affected with the contact time, pH, and initial concentration. The highest lead removal efficiency was above 99 %, which was obtained at pH 8 with initial concentration of lead was 25 mg/L and contact time of 60 min. Furthermore, adsorption equilibrium and kinetics of lead were then examined. Kinetics data were analysed by pseudo first and second order models. The adsorption data were then associated with the Langmuir and Freundlich isotherm models. The results obtained indicate that the fish bone derived apatite can be used as an effective adsorbent for removal of Pb(II) from aqueous solution.

Synthesis of magnetic graphene quantum dots–chitosan nanocomposite: an efficient adsorbent for removal of Pb2+ from aqueous solution

Synthesis of magnetic graphene quantum dots–chitosan nanocomposite: an efficient adsorbent for removal of Pb2+ from aqueous solution

Removal of lead (Pb+2) from contaminated water using a novel MoO3-biochar composite: Performance and mechanism

Removal of toxic chemicals from the environment using novel adsorbents is of great concern. In this study, a novel composite of molybdenum trioxide (MoO3)-engineered biochar (MoO3-BC) was derived from corn straw and synthesized for the removal of Pb(II) from water. The pyrolysis temperature of 600 °C was suitable for the thermal self-assembly of MoO3-BC. Although MoO3-BC had lower SBET (59.3 m2/g) than the pristine BC (157.8 m2/g), it had a stronger adsorption affinity to Pb(II). The Pb(II) removal capacity of MoO3-BC was 229.87 mg/g at pH 4.0, and the adsorptive removal of Pb(II) was fit using a pseudo-second-order model and the Langmuir model. High temperature favored the removal of Pb(II) by MoO3-BC; However, the removal of Pb(II) was inhibited with increasing the ion strength. The MoO3-BC revealed an acceptable stability and reusability, since the removal efficiency of Pb(II) remained above 80.7%, even after 8 cycles. The MoO3-BC effectively reduced ≥99.9% of Pb(II) in the polluted irrigation water. The Pb(II) removal mechanisms involved surface electrostatic attraction, ion exchange and surface complexation. These findings conclude that the MoO3-BC is a novel composite that can be used for the removal of Pb from contaminated water. More studies are needed to investigate the potentiality of MoO3-biochar composite for the removal of other metals from water in a mono and competitive sorption system.

Synthesized analcime zeolite: an effective adsorbent for removal of Pb(II) ions from aqueous solution

In this study, analcime zeolite was synthesized via a simple and low-cost hydrothermal approach, and its absorption performance for the removal of Pb(II) ions from an aqueous solution was investigated. The effects of various parameters such as pH, adsorbent dosage, initial lead concentration, time, and temperature on adsorption were studied. The optimum values of pH, adsorbent dosage, and contact time were obtained, 6, 4 mg, and 30 min, respectively. The removal efficiency reached 95% under optimum conditions. It was demonstrated that the adsorption of Pb(II) ions could be properly described by the pseudo-second-order equation, suggesting that the adsorption process is presumably chemisorption. Besides, the equilibrium data fitted well with the Langmuir model, and the maximum adsorption capacity (q m) was obtained 54.64 mg g−1. Moreover, the results of the temperature effect studies confirmed that the removal of Pb(II) ions was endothermic.

Adsorptive removal of Pb(II) using nanostructured γ-alumina in a packed bed adsorber: Simulation using gPROMS.

In this work, convective-dispersive and pore volume and surface diffusion models have been used to analyze Pb(II) adsorption from an aqueous solution over a nanostructured γ-alumina adsorbent in a packed bed adsorber. The models encompassing partial differential equation and a linear algebraic equation coupled with isotherm have been simulated in gPROMS using the backward finite difference approach. The predicted breakthrough curves of Pb(II) adsorption concerning flow rate, initial metal concentration, and bed height were matched with the experimental data. The accuracy of model predictions was analyzed through statistical measures such as coefficient of determination (R2), root mean square error, and chi-squared value. The simulation results also predicted the axial dispersion, distribution coefficient, mass transfer coefficient, pore volume, and surface diffusion coefficient, which are, otherwise, difficult to measure experimentally and, in turn, have been used to assess the mass transfer characteristics of continuous Pb(II) adsorption. Additionally, the values of breakthrough time, exhaustion time, adsorption column capacity, and mass transfer zone were determined as a function of flow rate, bed height, and initial metal concentration. Surface and pore volume diffusions (10-11-10-10 m2/s) apparently controlled the continuous adsorption process, with surface diffusion being dominant. The transport parameters evaluated in the current study could be beneficial for the large-scale Pb(II)/nanostructured γ-alumina adsorption system. As evident from the successful simulation, the developed gPROMS program can also be applied to other adsorbate/adsorbent systems with a slight modification concerning the operating parameters.

Humic acid and nano-zeolite NaX as low cost and eco-friendly adsorbents for removal of Pb (II) and Cd (II) from water: characterization, kinetics, isotherms and thermodynamic studies

Humic acid as a green-sorbent was synthesized from marine sediments. While kaolin was modified to nano-zeolite NaX. Different tools such as FT-IR, SEM, EDX and XRD were applied to confirm the characteristics of the generated green-sorbents. Different factors such as pH, contact time, sorbent dosage, initial metal ion concentration, temperature and interfering ions were carefully examined and used to optimize the batch adsorption process for Cd2+ and Pb2+. A small dose of nano-zeolite of 100 mg was required to attain the maximum adsorption of Pb2+ at pH about 7, shacking time at 60 min and Pb2+ concentration at 30 ppm. Also, the maximum sorption capacity of Cd2+ ions on nano-zeolite was achieved in a neutral medium and very short contact time implying the economic feasibility of the adsorption process. In the case of humic acid, the maximum removal capacity for Pb2+ and Cd2+ was operated at acidic medium and shacking time was 40 min. Metal ions remediation results were evaluated by some adsorption isotherm models at different temperatures. The kinetic and thermodynamic variables were also computed. The data fitted very well with the linear Langmuir and the pseudo-second-order model implying a favourable adsorption process. The sorption of Cd2+ and Pb2+ was regulated by both external mass transfer and intraparticle diffusion steps over the whole range of concentrations, as shown by the results. The metal ions removal percentage from four real water samples by green sorbents were applied and provides good evidence of two sorbents as promising eco-sorbent for removal of heavy metal ions.

Preparation of Honeycomb-Structured Activated Carbon-Zeolite Composites from Modified Fly Ash and the Adsorptive Removal of Pb(II).

In this paper, fly ash (FA) was successfully prepared into a honeycomb carbon–zeolite composite (CZC) with good adsorption and used for the removal of Pb(II) by a two-step method. Compared with general FA, the honeycomb structure of the CZC resulted in a ∼6× increase in the specific surface area, and the average pore size increased from 3.4 to 12.7 μm. The maximum adsorption capacity of CZCs for Pb(II) reached 185.68 mg/g in 40 min. The experimental data for the adsorption of Pb(II) by CZC showed that the results were in good agreement with the Langmuir adsorption model. The adsorbent prepared in this study has good application prospects in wastewater treatment and provides a new method for the resource recovery of FA.