Adsorption Of Pb Research Articles

Adsorption of Pb(II) and Cd(II) on Modified Coal Gasification Slag: Competitive Adsorption, Leaching Toxicity, and Adsorption Mechanism

AbstractTo remove heavy metals from wastewater, coal gasification slag (CGS) was prepared as an adsorbent. Five modified materials were created, including HF‐CGSC, KOH‐HCl‐CGS, and three KOH‐CGS variants with different mass ratios. The adsorption tests showed KOH‐CGS (0.25) had the best efficiency for Pb(II) and Cd(II) via spontaneous chemisorption. Kinetic, thermodynamic, and 13C NMR analyses indicated that adsorption involved pore adsorption, functional group coordination, and π‐π interactions. Competitive adsorption results showed minimal interaction between Pb and Cd. Leaching tests confirmed the process's environmental safety. This study suggests new approaches for using coal gasification slag in wastewater treatment.

EFFECT OF CLAY MINERALS, CALCITE, AND ORGANIC MATTER ON ADSORPTION AND DESORPTION OF CADMIUM AND LEAD

A Factorial experiment of CRD was conducted, to study and evaluate the effectiveness of Calcite, Bentonite, and Kaolinite minerals, as well as organic matter, on adsorption and desorption of Pb and Cd. Bentonite and kaolinite clay minerals were treated by adding of 20 % calcite and 5 % organic matter of the weight of the mineral, so that the final weight became 100 g per treatment. Treatments were incubated for 180 days after that, and treated with five concentrations of Pb and Cd, (0, 10, 20, 30, 40, and 50 μg ml-1) as PbCl2 and CdSo4 respectively, The results showed the superiority of bentonite mineral over kaolinite in the maximum adsorption Xm and binding energy K by 137, 312.5, 20, and 193.5 % for Pb and Cd respectively. In the case of calcite mineral with both minerals, an increase in the binding energy and the greater adsorption were observed in the case of Cd and a decrease in the case of Pb with bentonite. In case of presence of organic matter with kaolinite, the maximum adsorption Xm for cadmium increased, as it was 204.08 μg g-1, while in the case of bentonite with organic matter it was 111.1 μg g-1. In the case of Pb, it reached 93.46 and 208.3 μg gm-1 for both minerals betonies and kaolinite, respectively. Regarding collective release, the results showed that the order of the treatment for the released Cd was as follows: M2 + O.M + C = M2 +O.M < M2 < M2 +C < M1 + C < M1 < M1 +O.M + C < M1 + O.M In the case of released Pb, the order of treatment was as follows: M1 < M1 + C = M1 + O.M < M1 + O.M + C < M2 + O.M + C < M2 + C < M2 + O.M < M2.

Correction: Yang et al. Preparation of Biomass Carbon Composites MgO@ZnO@BC and Its Adsorption and Removal of Cu(II) and Pb(II) in Wastewater. Molecules 2023, 28, 6982

Following publication, concerns were raised regarding the peer-review process related to the publication of this article [...]

Sugarcane Bagasse Based Adsorbents and their Adsorption Efficacy on Removal of Heavy Metals from Nakuru Industrial Wastewater: Optimization, Kinetic and Thermodynamic Aspects

Currently, researchers are seeking to reduce heavy metal contamination from the environment, using agricultural waste materials like rice husk, groundnuts shells among others. The study focused on the removal of Cu(II), Pb(II), Cd(II), Ni(II), and Cr(III) ions from aqueous solutions and Nakuru industrial wastewater using sugarcane bagasse (NSCB) and valorised bagasse ash (VSCB), as alternative low-cost agricultural waste bio-sorbents. To achieve this goal, sugarcane bagasse was collected from Nzoia sugar industry in western Kenya, while the valorised bagasse was obtained by heating sugarcane bagasse sample in a muffle furnace at 300°C for three hours. Furthermore, batch adsorption studies were performed, and the effects of several factors, i.e. adsorbent particle size, pH, contact time, initial heavy metal ions concentration and temperature were investigated to optimise the removal efficiency of Pb, Cu, Cd, Ni, and Cr. The optimal adsorption conditions were pH of 5.0, adsorbent dosage of 0.1 g and ≤ 150µm particle size, equilibrium time of 60 minutes and at 25 degrees Celcius. The removal kinetics of the metal ions onto both adsorbents fitted well with the pseudo-second-order model. The removal kinetics of the metal ions onto both adsorbents fitted well with the pseudo-second-order model. The adsorption of Pb2+ and Ni2+ onto NSCB fitted better with the Freundlich isotherm model, while Cd2+, Cu2+ and Cr3+ showed better fit for the Langmuir isotherm model. As for VSCB adsorbent, Cr3+ has a better fit with the Langmuir isotherm model whereas Pb2+, Ni2+, Cd2+, and Cu2+ fitted well on the Freundlich isotherm model. Freundlich constant’s (1/n) values and the separation factor (RL) from the Langmuir isotherm model indicate that the metal ions were favourably adsorbed onto the adsorbents. Langmuir isotherm model was used to estimate the maximum adsorption capacities (qmax) for Cu(II), Pb(II), Ni(II), Cd(II), and Cr(III). The negative free energy change (∆G) values revealed that adsorption process of the metal ions onto NSCB and VSCB was spontaneous. Fourier Transform Infrared Spectroscopy (FTIR) was used for characterization studies. Interactions with metal ions caused the frequencies of the active functional groups, –OH, C=O and C=C, on the bio-sorbent surfaces to shift to higher values. Therefore, sugarcane bagasse and valorised bagasse have demonstrated higher potential to remove relatively all selected heavy metals in the industrial wastewater at controlled pH.

PH-Responsive Alginate/Chitosan Gel Films: An Alternative for Removing Cadmium and Lead from Water.

Biosorption, a non-expensive and easy method for removing potentially toxic metal ions from water, has been the subject of extensive research. In this context, this study introduces a novel approach using sodium alginate and chitosan, versatile biopolymers that have shown excellent results as biosorbents. The challenge of maintaining high efficiencies and reuse is addressed by developing alginate/chitosan-based films. These films, prepared using solvent casting and crosslinking methods, form a hydrogel network. The alginate/chitosan-based films, obtained using the eco-friendly polyelectrolyte complex method, were characterized by FTIR, SEM, TGA, and DSC. The study of their swelling pH response, adsorption, and desorption behavior revealed promising results. The adsorption of Pb was significantly enhanced by the presence of both biopolymers (98%) in a shorter time (15 min) at pH = 6.5. The adsorption of both ions followed a pseudo-second-order kinetic and the Langmuir isotherm model. The desorption efficiencies for Cd and Pb were 98.8% and 77.6% after five adsorption/desorption cycles, respectively. In conclusion, the alginate/chitosan-based films present a highly effective and novel approach for removing Cd and Pb from water, with a promising potential for reuse, demonstrating their strong potential in potentially toxic metal removal.

Synthesis of magnetic zirconium oxide-iron oxide nanoparticles composite using chemical precipitation process for Pb (II) adsorption

The exploration and utilization of natural raw zircon minerals in Indonesia, particularly in Central Kalimantan, remain largely untapped in their potential as high-tech and commercially valuable substances with eco-friendly properties, particularly in water and industrial wastewater treatment. The primary objective of this research is to enhance the development and synthesis of natural raw zircon minerals by converting them into zirconium oxide and integrating them with magnetic nanoparticles. The magnetic nanoparticle composite material for zirconium oxide (MNP@ZrO2) was synthesized using the chemical co-precipitation method. Zirconium and its oxides have gained significant application in water and wastewater treatment in recent years. Through chemical co-precipitation processes (MNP@ZrO2), the natural raw zircon minerals were transformed into zirconium oxides and combined with magnetic nanoparticles due to their exceptional potential as effective adsorbents for anions and cations in water and industrial treatment processes. In the utilization of Scanning Electron Microscopy (SEM), magnetic nanoparticles with a diameter of less than 50 nm emerged on the surface of the zirconium crystals within the magnetic nanoparticle composites. X-ray diffraction (X-RD) analysis indicated that the treatment of zirconium minerals resulted in 11.19% decrease in the Crystallinity Index and a significant reduction of 98% in silica content. By maintaining a pH level of approximately 7 ± 0.2 over 360 min with a stirring rate of 150 rpm, and at ambient temperature, the optimal conditions for Pb (II) adsorption were achieved with the adsorption capacity of 68.98 mg/g using MNP@ZrO2 as adsorbent. The successful synthesis of magnetic zirconium oxide-iron oxide nanoparticles at various pH levels using the chemical co-precipitation process has facilitated a comprehensive assessment of their performance in Pb (II) adsorption.

Biosorption of Pb(II) Ions through Nanostructured Teff Straw based Magnetized Activated Biocarbon: Aspects on Modeling, Optimization, and Kinetics

<p>In this study, activated carbon (AC) was prepared from teff grass straw via chemical activation and microwave-assisted pyrolysis. The AC was modified by magnetization followed by it was characterized by particle size, FTIR, XRD, thermogravimetric study, pore size, and magnetic properties. Further, it was evaluated for its adsorptive removal performance of lead (II) ions from aqueous solution. A statistical model was developed by response surface method (RSM) and the crucial parameters, concentration of initial Pb(II), biosorbent loading, solution pH, and contact time were optimized for maximizing the adsorption of Pb(II) ions. The optimal values were 95.36 mg/L, 0.656 g/100 mL, 5.5, and 88.7 min, respectively for aforementioned parameters. Under the optimal condition, the Langmuir isotherm exhibited the most accurate correspondence with the obtained experimental data. The findings from the kinetic analysis were found to be statistically fit to the pseudo-2nd order model.</p>

Adsorption isotherms and removal of lead (II) and cadmium (II) from aqueous media using nanobiochar and rice husk

Removal of Cd(II) and Pb(II) from aqueous solutions is a challenging task and the search for novel adsorbents is underway. This study examined the efficiency of nanobiochar (NB) and rice husk (RH) in the adsorption and removal of Cd(II) and Pb(II) from water. The effect of various physicochemical parameters such as initial pH, initial Cd and Pb concentration, adsorbent dosage, and contact time were tested. SEM/EDX images confirmed the adsorption of Pb and Cd with surface physical and chemical changes. The maximum Pb removal was noted at pH 6 using NB (96%) and at pH 8 for RH (90%), and the maximum Cd removal by NB was recorded at 8 pH (91%) and by RH at pH 6 (87%). The decline in adsorption intensity at lower pH suggested protonation of the adsorbent surface causing cation-cation repulsion. Most of the adsorption occurred within the initial 60 min. A continuous gradual increase in the adsorption with time suggested multilayer formation. Of the three isotherms, the Freundlich model fits the present data best, implying an infinite surface coverage and indicating the potential for multilayer adsorption of Pb and Cd on the surfaces of RH and NB adsorbents. In conclusion, this study highlights the promising potential of NB as a cost-effective adsorbent for the removal of Cd and Pb ions from aqueous solutions.

Fabrication of thiosemicarbazide-modified biochar/carrageenan composite beads based on Eichhornia crassipes for effective removal of Pb (II) from aqueous medium

Several biomasses have been applied as environmentally friendly substitutes to produce biochar, which can be utilized to remediate effluents that contain inorganic chemicals. This study applied water hyacinth (Eichhornia crassipes) as a foundation source for the assembly of thiosemicarbazide-modified biochar (BC), which then was modified with potassium carrageenan (KC). Thiosemicarbazide-modified biochar (BC), potassium carrageenan (KC), and thiosemicarbazide-modified biochar/carrageenan composite beads (BKC) were described by several physicochemical methods. The adsorption of Pb (II) onto the three solid adsorbents was investigated under various experimental conditions. The BKC composite beads revealed a surface area of 687.43 m2/g and a mesoporous structure. The best adsorption conditions were found to be 25 min as an equilibrium time, 1.2 g/L of adsorbent dose, and a solution pH of 5 at a temperature of 15 °C. The pseudo-second-order, Elovich kinetic models, Langmuir, and Temkin isotherms were well familiar to the experimental data, inferring that the progression was physical monolayer adsorption onto the homogenous surface. The highest capacity of Pb (II) adsorption onto BKC was 460.45 mg/g at 15 °C. Thermodynamic measurements proved that adsorption was a spontaneous process and endothermic in the case of BC and BKC while exothermic for KC. Furthermore, BKC showed high reusability conditions.

Effective removal of Pb(II) ions using Fe3O4/MgO adsorbent: A comprehensive study  

The effective removal of heavy metal ions, particularly Pb(II), from contaminated water sources remains a pressing environmental concern. This study explores the potential of Fe3O4/MgO nanocomposites as an efficient adsorbent for selective Pb(II) removal. The Fe3O4/MgO nanocomposite was synthesized using a controlled sol-gel method and characterized using various techniques. X-ray diffraction (XRD) analysis confirmed the presence of cubic MgO and cubic Fe3O4. Pb(II) adsorption induced a crystallographic transformation, forming hexagonal Mg(OH)2 crystals, indicating interaction with the adsorbent. Scanning Electron Microscope (SEM) analysis revealed pyramid-like and irregular crystal morphologies. Pyramid-like structures provided a larger surface area and active sites for effective Pb(II) interaction, while irregular crystal particles, representing magnetic Fe3O4, contributed to stability and dispersibility. Vibrating sample magnetometer (VSM) results confirmed superparamagnetic behaviour with a saturation magnetization of 32.02 emu g-1, indicating potential for magnetic separation and recovery in various wastewater treatment applications. Adsorption experiments utilized optimized conditions: an initial concentration of 600 mg L-1, adsorbent dosage of 0.25 g L-1, pH of 7, and 120 minutes of reaction time. The Fe3O4/MgO nanocomposite exhibited exceptional performance with a remarkable 99.98% removal efficiency and a high adsorption capacity of 2399.44 mg g-1. These impressive results underscore the outstanding adsorption potential of the nanocomposite. Adsorption kinetics followed the pseudo-second-order model (R2 = 0.99), confirming suitability for Pb(II) removal. The Freundlich model indicated a heterogeneous surface with different adsorption sites. Overall, the Fe3O4/MgO nanocomposite exhibits potential as a cost-effective, environmentally friendly adsorbent for removing Pb(II) ions, providing a promising solution for water purification and environmental remediation.

Interaction of biochar with extracellular polymers of resistant bacteria restrains Pb(II) adsorption onto their composite: Macro and micro scale investigations

Pb(II) sequestration in extracellular polymers-biochar composites (EPS-BC) was explored using macroscopic models and microscopic technology. The results showed that the actual adsorption capacity of EPS-BC was 52.2% lower than the calculated capacity based on adsorption onto pure components due to the interaction of polysaccharide and amide group in extracellular polymers with biochar, which masked the reactive sites related to Pb(II) in EPS-BC. The bond of Pb–O (40.8%) and Pb–OOC (31.5%) mainly contributed to Pb(II) speciation on the EPS-BC surfaces. Furthermore, each Pb atom coordinated with 6O atoms in the first shell and with 0.5C atoms in the second shell, indicating that the carboxyl group in composite was complexed with Pb(II) as a monodentate inner-sphere structure. The findings provide an in-depth understanding of the adsorption mechanism of heavy metals by extracellular polymers coupled with biochar at molecular scale, guiding bioremediation with respect to heavy metal contamination.

Insights into Pb (II) adsorption mechanisms using jackfruit peel biochar activated by a hydrothermal method toward heavy metal removal from wastewater

Understanding adsorption mechanisms plays an instrumental role in designing and operating adsorption-based wastewater treatment systems. This research systematically demonstrated the comprehensive adsorption mechanism of Pb(II) ions onto biochar synthesized from jackfruit peel in an aqueous solution using theoretical adsorption models and cutting-edge analytical techniques, such as FT-IR, TG-DSC, and SEM-EDX. The results showed that the adsorption process followed the Redlich-Peterson isothermal model and the intraparticle diffusion kinetic model under optimized conditions. The key mechanisms contributing to effective Pb(II) adsorption include complexation, ion - exchange, and intradiffusion. Furthermore, using the hydrothermal method to active biochar improves the surface area of JPT, leading to the maximum Pb(II) adsorption capacity of jackfruit peel-derived biochar to be 83.86 mg/g, higher than biochars from other parts of jackfruit waste (seeds and stems) and some materials from different agricultural residues in previous studies. These findings contribute to narrowing the gap in understanding heavy metal adsorption using biomass residues, theoretical models, and their mechanisms. Additionally, these indicate that agricultural by-products such as jackfruit peel are environmentally friendly and economical materials for implementing strategies aimed at mitigating heavy metal pollution in wastewater.

ENVIRONMENTAL ASPECTS OF WASTE-DERIVED BOTTOM BLEND CLAY LINERS INCORPORATING ZEOLITE AND BENTONITE

This research investigated the effects of incorporating bentonite and zeolite into bottom blended clay liners (BBCLs) on their engineering properties and adsorption capacity. BBCLs composed of clay, water treatment residue, and calcium carbide in a 40:40:20 ratio by volume were investigated with the addition of 1, 2, and 3 wt.% bentonite or zeolite. The experimental results indicated that bentonite and zeolite had positive effects on the slake durability index and the equilibrium time for the adsorption of lead (Pb) and chromium (Cr) from the leachate, whereas the unconfined compressive strength (UCS) and coefficient of permeability were negatively affected compared to those of the samples without bentonite and zeolite. At 56 days, the UCS of BBCLs with bentonite and zeolite decreased from 3.4 to 2.2MPa, while the coefficient of permeability of all the samples met the regulatory limit of sanitary landfills, which was given at 1×10-7cm/s. The slake durability index of all samples was lower 50% but it remained higher compared to BBCLs without bentonite and zeolite (approximately doubled). Both additives enhanced the equilibrium time and percentage of Pb and Cr adsorption by about 20% and 200%, respectively. SEM-EDS results show the adsorption of Pb and Cr onto the raw materials, calcium silicate hydrate (CSH), zeolite, and bentonite. Therefore, the addition of zeolite can increase the ability to adsorb heavy metals form leachate, which is suitable for use in secured landfills.

Defect-Engineered MOF-801/Sodium Alginate Aerogel Beads for Boosting Adsorption of Pb(II).

Metal-organic frameworks (MOFs) are attractive adsorbents for heavy metal capture due to their superior stability, easy modification, and adjustable pore size. However, their inherent microporous structure poses challenges in achieving a higher adsorption capacity. Defect engineering is considered a simple method to create hierarchical MOFs with larger pores. Here, we employed l-aspartic acid as a mixed linker to bind Zr4+ clusters in competition with fumaric acid of MOF-801 to create defects, and the pore size was increased from 4.66 to 15.65 nm. Mercaptosuccinic acid was subsequently used as a postexchange ligand to graft the resultant MOF-801 by acid-ammonia condensation to further expand the pore size to 22.73 nm. Notably, the -NH2, -COOH, and -SH groups contributed by these two ligands increased the adsorption sites for Pb(II). The obtained defective MOF-801 with larger pores was thereafter loaded onto sodium alginate to form aerogel beads as adsorbents, and an adsorption capacity of 375.48 mg/g for Pb(II) was achieved, which is ∼51 times that of pristine MOF-801. The aerogel beads also exhibited outstanding reusability with a removal efficiency of ∼90.23% after 5 cycles of use. The adsorption mechanism of Pb(II) included ion-exchange interaction, as well as chelation interactions of Pb-O, Pb-NH2, and Pb-S. The versatile combination of defect engineering and composite beads provides novel inspirations for MOF modification for boosting heavy metal adsorption.

Functionalization of activated carbon with melamine binder for adsorption of metallic species from aqueous environments

ABSTRACT In the face of the increasing exposure to heavy metals in the environmental scenario, there arose the need for further research by the scientific community. In this perspective, the present work reports the application of a material made from Typha sp. leaf, activated and functionalised with molecules of 1,3,5-Triazine-2,4,6-triamine (melamine), for the selective adsorption of metal ions Cu(II), Cd(II), and Pb(II) in aqueous solutions. Confirmation of material functionalization occurred through infrared vibrational spectroscopy, revealing bands at 3467, 3424, and 1338 cm−1 associated with the stretching vibration of -NH2. These results provide evidence of the possible anchoring of the ligand on the material surface. Elemental nitrogen analysis corroborated the results of infrared spectroscopy and showed 2.21% nitrogen in the functionalised material, while 1.30% in activated carbon. X-ray photoelectron spectroscopy showed the modification of the material surface composition after the functionalization reaction. The specific surface area was calculated as 193.876 m2/g. Adsorption studies revealed a rapid kinetics, best described by the pseudo-second-order model. The optimised pH for adsorption was 6.0 (pHPZC = 7.5), aligning with conditions found in natural waters. The maximum adsorption capacity was 0.4388, 0.4025, and 0.2792 mmol g−1 for Cu(II), Pb(II), and Cd(II), respectively, following the Langmuir model. Furthermore, to facilitate practical application, parameters such as mass and flow rate were optimised. The results suggest that the developed material exhibits promising adsorptive properties, emerging as a potential solution for remediating areas contaminated by metallic species.

One-step green synthesis of melamine-modified cellulose nanofiber composite aerogels for efficient removal of Pb(II) and Cu(II): Experiments and DFT calculations

A composite aerogel (CGMA) with high porosity (98.32 %) and multiple active sites was prepared for the adsorption of Pb(II) and Cu(II) by sol-gel combined with freeze-drying process using melamine and (3-Glycidyloxypropyl)trimethoxysilane as cellulose nanofiber modifying materials. Characterized by SEM-EDS, XPS, FTIR, BET, MIP and TG, CGMA has a hierarchical pore structure and abundant adsorption sites. At pH = 6, the adsorption reached equilibrium within 120 min, following the Pseudo second-order kinetic model and the Langmuir model, with maximum capacities of 268.1 mg/g for Pb(II) and 152.6 mg/g for Cu(II). The process was primarily governed by homogeneous chemisorption. The coexisting ion, organic matter, and water quality experiments confirmed the excellent anti-interference properties of CGMA. Competitive adsorption experiments showed that CGMA has excellent selective adsorption performance for Pb(II). After 5 cycles, Pb(II) and Cu(II) adsorption performance decreased to 79.21 % and 83.40 %, respectively. FTIR, XPS, DFT and RDG analysis showed that amino groups and oxygen-containing groups were the main sites of adsorption. CGMA forms coordination bonds and complexes with Pb(II) and Cu(II) via amine and oxygen groups and adsorbs via electron transfer, hydrogen bonding, and van der Waals forces, with Pb(II) being more selective. CGMA has good prospects for application in heavy metal ion treatment.

Amidoximated Bacterial Cellulose Film for Pb2+ Adsorption in Aqueous Environment

Abstract This study investigated the application of amidoximated bacterial cellulose (AMO-BC) film for lead (Pb) adsorption from aqueous solutions. In our previous study, bacterial cellulose has been successfully modified through amidoximation to enhance its metal adsorption capacity. In order to modify the bacterial cellulose (BC) film, acrylonitrile was grafted onto it initiated by an electron beam to create BC-grafted-polyacrylonitrile (BC-g-PAN). After that, amidoximated bacterial cellulose (AMO-BC) was generated when BC-g-PAN reacted with hydroxylamine hydrochloride to add amidoxime functional groups to the cellulose backbone. Then, AMO-BC before and after lead adsorption was characterized using Fourier-transform infrared spectroscopy (FTIR). The adsorption capacity of AMO-BC for lead ions was evaluated through batch adsorption experiments with the initial lead concentration of 200 mgL−1 and an adsorbent dose of 20 mg, on pH 6 for two hours of the adsorption process. The results showed that AMO-BC exhibited higher lead adsorption capacity than pristine bacterial cellulose i.e., 44.56 and 50.96 mg/gram for BC and AMO-BC films, respectively.

Heavy metal adsorption on yellow loam clay modified by biomass- and biochar-decomposed liquids from Ficus microcarpa

In studing the heavy metal adsorption effect of decomposed liquid (Dl) on yellow loam clay (C), biomass-Dl (BmDl) and biochar-Dl (BcDl) from Ficus microcarpa leaves were used to modify C. The different Dl-modified Cs (Dl-Cs) were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. A batch method was used to study the adsorption kinetics and thermodynamics of Pb(II) and Cd(II), as well as the effects of decomposition time, modification ratio, pH, temperature, and ionic strength on the adsorption process. Results of microscopic morphology indicated that Dl was modified on the C surface, and it changed the surface properties. The adsorption isotherms of Pb(II) and Cd(II) by different Dl-Cs conformed to the Langmuir and Freundlich model, with the maximum adsorption capacity (qm) maintained at 65.64–163.89mmol/kg (BmDl-Cs) and 77.68–235.63mmol/kg (BcDl-Cs). Under the same conditions, the peak value of qm was reached at decomposition time of 14 days and 50% of Dl modification. pH = 6, ionic strength of 0.1mol/L, and 30 ℃ were the optimum conditions for the adsorption of Pb(II) and Cd(II) by different Dl-Cs. Pb(II) and Cd(II) adsorption was a spontaneous, endothermic, and entropy-increasing process, and pseudo-first-order kinetic equation was suitable to characterize adsorption.

Immobilization of Pb, Cd, and Cr in contaminated soil around mining areas using Mg/Al LDH-zeolite and evaluation of maize growth

Abstract This study conducted simultaneous adsorption of Pb, Cd, and Cr ions using Mg/Al LDH-zeolite on contaminated soils from lead-zinc and tin mining areas. The optimal conditions were a 3% adsorbent-to-soil ratio, a 30-day incubation period, and 70% soil moisture. Characterization of the materials revealed that Mg/Al LDH-zeolite has superior physicochemical properties to natural zeolite, with a higher surface area and better adsorption capacity. Results indicated significant reductions in exchangeable heavy metal content: in lead-zinc mining area soil, exchangeable Pb decreased from 139.79 mg kg−1 to 10.95 mg kg−1, Cd−1 from 1.518 mg kg−1 to 0.533 mg kg−1, and Cr from 2.636 mg kg−1 to 0.461 mg/kg using Mg/Al LDH-zeolite. In tin mining area soil, exchangeable Pb decreased from 583.97 mg kg−1 to 48.22 mg kg−1, Cd−1 from 0.498 mg kg−1 to 0.122 mg kg−1, and Cr from 106.095 mg kg−1 to 38.038 mg/kg. Maize cultivation on post-adsorption soil showed improved growth performance, with plants exhibiting increased height and ear and reduced heavy metal accumulation in roots, shoots, and grains. Pb, Cd, and Cr concentrations in maize roots decreased significantly, with Pb reducing to 0.113 mg kg−1 in the lead-zinc area and 0.203 mg kg−1 in the tin area, Cd reducing to 0.061 mg kg−1 and 0.037 mg kg−1, respectively, and Cr reducing to 0.036 mg kg−1 and 0.243 mg kg−1 respectively. Mg/Al LDH-zeolite consistently demonstrated higher efficiency in reducing the bioavailability and translocation of heavy metals in maize tissues, confirming its potential as an effective adsorbent for soil remediation. Key mechanisms, including adsorption, surface complexation, ion exchange, precipitation, and structural incorporation, reduce metal mobility and bioavailability.

Comparison of Pb adsorption and transformation behavior induced by chicken manure and its DOM in contaminated soil

Organic fertilizer derived from animal manure can significantly improve soil fertility. However, limited research has investigated the capacity of exogenous organic fertilizer dissolved organic matter (DOM) to migration and transform heavy metals. In this study, the effect of chicken manure organic fertilizers with different maturity and their DOM on changes of Pb bioactivity was evaluated and the role of soil environmental factors driving the changes was determined through soil incubation, adsorption and leaching experiments. The FTIR results indicated that DOM derived from farmhouse chicken manure organic fertilizer (FCMD) contained more protein-like compounds and low maturity, while DOM from commercial chicken manure organic fertilizer (CCMD) contained more humic/fulvic acid and high maturity. FCMD and CCMD reduced the content of RES-Pb by 16.3–27.52 % and 6.66–13.98 %, respectively. And the effects of organic fertilizers and their DOM on Pb migration and activation follow the order of FCMD> CCMD> CK> commercial chicken manure organic fertilizer (CCM)> farmhouse chicken manure organic fertilizer (FCM). FTIR analysis showed that FCMD was primarily composed of aromatic unsaturated functional groups, and its adsorption capacity for Pb2+ was significantly lower than that of FCM. In addition, the application of FCMD significantly altered the physicochemical properties of soil and promoted the migration and leaching of Pb. FCMD not only causes the soil Pb2+ to be released into the effluent but also activates Pb from the stable form into the active form. In summary, animal manure with lower maturity has a risk to activate heavy metals and should be applied with cautions.