Immobilization Of Heavy Metal Ions Research Articles

Immobilization and leaching behavior of Cd2+ and Pb2+ heavy metal ions in Indonesian fly ash-based geopolymers

The immobilization of heavy metal ions in geopolymers is a promising solution to prevent environmental contamination. However, under acidic conditions, these ions can leach out. Our study focused on immobilizing Cd2+ and Pb2+ in fly ash-based geopolymers, assessing their effects on properties, and examining leaching kinetics at pH 5. We tested various ion concentrations (ranging from 1000 to 16000 ppm). Notably, the addition of 1000 ppm of Cd2+ and 4000 ppm of Pb2+ substantially improved compressive strength (24.28 and 35.56 MPa, respectively). Higher ion concentrations resulted in increased leaching. Post-leaching, we observed pore enlargement and surface cracks, indicating ion migration. The Shrinking Core Model best describes the leaching process, with diffusion being the primary mechanism, featuring reaction orders of 2.46 and 2.39 for Cd2+ and Pb2+, respectively. The model is suitable for predicting the release of immobilized heavy metal ions into the surrounding acidic environment.

Enrichment and immobilization of heavy metal ions from wastewater by nanocellulose/carbon dots-derived composite

Heavy metal ions (HMIs) have been widely applied in various industries because of their excellent physicochemical properties. However, their discharging without appropriate treatment brought about serious pollution problems. So it is desirable but challenging to rapidly and completely clean up these toxic pollutants from water, especially utilizing environmentally friendly and naturally rich biomass materials. In this work, we prepared nanocellulose/carbon dots/magnesium hydroxide (CCMg) ternary composite using cotton via a simple hydrothermal method. The removal mechanism towards Cd2+ and Cu2+ was investigated using a combination of experimental techniques and density functional theory calculations. CCMg shows a good ability to remove HMIs. It is realized that the interaction between each component of CCMg and cadmium nitrate is mainly of hydrogen/dative bonds. Cadmium nitrate is preferentially enriched by the Mg(OH)2 moiety, proved by calculated thermodynamics, interfacial interactions and charges. After transformation, the cadmium carbonate precipitate is fixed on the surface by nanocellulose (NC) via chemical coupling; and of interest is that copper ion precipitates in the form of basic sulfate. Due to its high adsorption effect and simple recovery operation, CCMg is having a wide range of application prospects as a water treatment agent.

A functionalized waste tire rubber powders for mitigating leaching of heavy metal ions and enhancing photocatalytic properties of rubberized cement mortar

In this study, waste tire rubber powder (R) was subjected to modification using tannic acid (TA) and ZnO to produce R-TA-ZnO composites, aiming to enhance the immobilization of heavy metal ions and improve the photocatalytic properties of rubberized cement-based materials. The characterization of R-TA-ZnO was conducted using a comprehensive range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible-diffuse reflectance spectroscopy (UV–Vis-DRS), and other relevant methods. The findings of the study revealed that R-TA-ZnO exhibited notable hydrophilicity, surface activity, and photocatalytic properties, resulting in effective containment of the leaching of heavy metal ions. FTIR and XRD analyses confirmed the retardation of R and R-TA-ZnO. Nevertheless, the strength of the rubberized cement mortar with 5% R-TA-ZnO exceeds that of the rubberized cement mortar with 5% R (28 days) due to the interfacial bonding. The SEM and X-ray Computed Tomography (XCT) results of the rubberized cement mortar indicated that R-TA-ZnO exhibited strong binding to the cement paste, reducing both the number and size of pores. However, a high concentration of R-TA-ZnO led to the formation of larger pores, which did not contribute to the reduction of porosity. Furthermore, the rubberized mortar incorporating R-TA-ZnO displayed remarkable photocatalytic capabilities. The results of the 5-cycle degradation experiments and microscopic characterization confirmed its exceptional structural stability and reusability.

Significantly enhanced sedimentation and adsorption of clay materials by plasma-initiated polymerization

Except for the high adsorption capacity, the color of the adsorbent suspension and the solid-liquid separation characteristics are also essential factors for adsorption material in wastewater management. Here, a novel carboxymethyl chitosan grafted magnetic montmorillonite (CMC@MMt) adsorbent-material with large metal ions uptake capacity, transparent solution, excellent turbidity, and low cytotoxicity in human hepatic cells (HepG2 cells) was successfully synthesized by plasma technology. The adsorption performance for different metal ions, the turbidity property, and the toxicity of CMC@MMt were evaluated by systematic studies. The results indicate that adding of CMC could enhance the adsorption capacity because of NH2, COOH, and OH functional groups. Especially the turbidity property of montmorillonite was also improved due to the enlarged grain size and the polarity reduction. This research will promote the application of clay mineral-based material in environmental pollution control, such as preconcentration and immobilization of heavy metal ions.

Assessment of agricultural waste biochars for remediation of degraded water-soil environment: Dissolved organic carbon release and immobilization of impurities in one- or two-adsorbate systems

This paper presents a method of agricultural waste management — the production of two biochars (BC) from potato and raspberry stems. It defines the potential of these materials for remediation of degraded water and soil environments. The performed study included analyses of BC physicochemistry, dissolved organic carbon (DOC) release and ability to immobilize copper (Cu), tetracycline (TC) and carboxin (CB) in one- and two-adsorbate systems. The BCs were obtained with pyrolysis at 600 °C for 30 min in a nitrogen atmosphere. Their DOC was predominantly constituted of substances with large molecular weights and high aromaticity, meaning that both BCs can be safely applied as soil additives. Potato-biochar (P-BC) had a more developed surface than raspberry-biochar (R-BC). The specific surface area (SBET) of P-BC was 122 m2/g, whilst of R-BC was 87 m2/g. As a result, the efficiency of impurity adsorption in the one-adsorbate systems was higher for P-BC (61.75% for Cu, 73.84% for TC, and 54.43% for CB). In the two-adsorbate systems, organic impurities improved the immobilization of heavy metal ions on BCs. The efficiency of Cu adsorption on P-BC when TC was present was 88.29%. Desorption of Cu from BC was highest using HCl, whilst that of TC and CB was highest using NaOH. Maximum desorption was observed in a two-adsorbate system with TC + CB (up to 63.6% for TC). These results confirmed that potato and raspberry stems can be used to produce highly effective BCs with large application potential, especially for remediation of degraded soils and polluted waters.

Cement-Based Solidification/Stabilization as a Pathway for Encapsulating Palm Oil Residual Biomass Post Heavy Metal Adsorption.

Heavy metal pollution is a serious issue currently affecting the environment and public health, which has been faced by applying several alternatives such as adsorption. In this work, the adsorption technique was employed to remove nickel and lead ions from an aqueous solution using palm oil residual biomass as a biosorbent. Desorption experiments were also conducted to evaluate the desorption capacity of this biomass over sorption–desorption cycles. The polluted biomass was used to prepare bricks (5 and 10% biomass content) to encapsulate heavy metal ions into the cement matrix. Both mechanical resistance and leaching testing were performed to determine the suitability of these bricks for construction applications. The experimental results revealed a good biosorbent dosage of 0.1 g/L. The highest desorption yields were calculated in 11 and 83.13% for nickel and lead, respectively. The compression resistance when 10% biomass was incorporated into the bricks was reported to be below the acceptable limit. Leaching testing suggested a successful immobilization of heavy metal ions onto the cement matrix. These results indicate that the application of this immobilization technique allows solving disposal problems of biomass loaded with heavy metal ions.

Preparation, crystallization kinetics and stabilization behavior of the heavy metal ions of all-solid waste-based glass-ceramics from steel slag and coal gangue

In this work, all solid waste-based glass-ceramics with 55% steel slag and 45% coal gangue were prepared by the conventional melt-quenching and two-step heat treatment methods. The effect of the heat treatment on the crystallization, microstructure, physical properties and stabilization behavior of the heavy metal ions for the glass-ceramics was researched by DSC, XRD, SEM and ICP-OES. Augite was the dominant crystal phase with a crystallinity about 94%. With a heat treatment of 750°C/6 h+900°C/2h, the flexural strength (328 MPa) and Vickers hardness (9.59 GPa) of the prepared glass-ceramic reached the optimal. The immobilization efficiencies of the glass-ceramics for the heavy metal ions almost reached above 90%. The above results suggest that the use of all-solid waste for the preparation of glass-ceramics may be a feasible way to achieve the immobilization of heavy metal ions.

Facile Processing of Polyelectrolyte Complexes for Immobilization of Heavy Metal Ions in Wastewater

Practical application of polyelectrolyte complexes (PECs) has been limited due to inadequate techniques to overcome processing challenges. This study aimed to explore seamless PEC processing techniques to fabricate adsorbents for wastewater treatment. The phase transition associated with poly(diallyldimethylammonium) and poly(styrenesulfonate) complexes in an aqueous solvent was studied as a function of polymer concentration, charge stoichiometry, and ionic strength. The complex-to-coacervate and coacervate-to-solution phase transitions were observed as the ionic strength increases for all the charge stoichiometries studied. We demonstrate that spherical PEC resins were prepared by injecting the liquid-like coacervates into pure water in a controlled manner. Also, the wastewater treatment experiment revealed that the PEC resins show outstanding performance for heavy metal adsorption with significant uptakes and easy separation. The maximum Pb(II) uptake was measured as 690 ± 0.2 mg/g by the Sips model, and the equilibrium adsorption rate was achieved within ∼2 h. This study thus lays down a protocol for the facile processing of PECs and the fabrication of PEC-based adsorbents for wastewater treatment and related applications.

Mechanism analysis of the immobilization of heavy metal ions with the water-soluble polymer: The influence of resin structure and the further adsorption of chelate

Polymer materials have become one of the potential materials for remediation of heavy metal (HM) contamination in water and soil. However, the specific advantages of polymers are rarely studied. Water-soluble thiourea formaldehyde resin (WTF) is one of the effective polymer amendments. Through leaching experiments, WTF can stabilize 93.0% of Cd2+ and 99.7% of Cu2+. The results of HM morphology analysis show that after adding WTF, most of the HMs have been transformed into a relatively stable state. For example, in the process of remediation of 6 mg/kg Cd contaminated soil, the proportion of acid-soluble Cd decreased from 56.5% to 12.8%, and the residual state increased from 13.5% to 45.4%. Compared with the resin-free structure, the three-dimensional structure of the resin plays an important role, but the efficiency of precipitation with HMs is doubled. According to the simulation of the adsorption process by Materials Studio, the characterization of the scanning electron microscope-energy dispersive instrument and the results of the adsorption experiment, in the solution, the precipitate formed by WTF and Cd2+ has multilayer adsorption of HMs, and can further adsorb HM by –OH. Soil enzyme activity experiments proved that the risk of secondary pollution by adding WTF is rare, and even WTF can achieve the effect of slow-release nitrogen fertilizer. In the WTF remediation process, the biological toxicity reduction of HMs is result from, on the one hand, the complexation of functional group of WTF; on the other hand, the resin structure of WTF; in addition, multi-layer adsorption and adsorption of end groups in the precipitation formed by WTF and HM. This work provides a theoretical basis for the potential capabilities of water-soluble resins and is beneficial to the design and development of subsequent amendments.

Development of technology of utilization of products of ferritization processing of galvanic waste in the composition of alkaline cements

A study of the products of ferritization processing of galvanic waste: sludge and spent process solutions is carried out. As a result of experiments on dynamic leaching of heavy metal ions, the immobilization properties of the sludge, obtained at different process parameters of ferritization are determined. It is shown that the level of immobilization of heavy metals in ferrite sludge after leaching is 99.96 wt % and in the sludge of traditional wastewater neutralization <97.83 wt %. The studies determine the possibility of reliable utilization of ferritized galvanic waste – introduction into the charge to produce alkaline cements. It is found that the main crystalline phases in the structure of alkaline cements with ferrite sludge are calcite, quartz and heavy metal ferrites. In addition, jelly-like formations are found, which are further capable of crystallization. Such formations reliably bind heavy metals in the chemical structure of cement. It is found that when using up to 10 wt % of ferrite sludge in the total weight of cement, the compressive strength of artificial stone reaches 40 MPa, which meets the requirements of the current standard. The chemical stability of the alkali cement matrix using ferrite sludge is confirmed by the study of leaching of heavy metals for one day in neutral, alkaline and acidic media. It is shown that the degree of immobilization of heavy metal ions in cement with a ferrite sludge content of 30 wt % is >99.98 %. In addition, the concentrations of heavy metal ions during leaching meet the national and international standards for their MPC in drinking water and soil. This approach will allow solving the problem of utilization of hazardous galvanic waste and production of general construction materials

Understanding the immobilization mechanisms of hazardous heavy metal ions in the cage of sodalite at molecular level: A DFT study

Abstract The geopolymer containing the special porous structure unit sod (t-toc) cage, which can be made from fly ash, is a possible economic solution to reduce toxicity of hazardous heavy metals by its excellent immobilization potential. Herein, the zeolite sodalite which is composed of sod (t-toc) cage was selected to model the geopolymer to uncover the immobilization mechanisms for the hazardous heavy metal ions Cr3+, Pb2+, Zn2+, Cu2+, Hg+, Cd2+ and Ni2+ in this work. Based on experimental crystalline structures, exchange energy was introduced for the first time to quantitatively evaluate the immobilization long-term stability theoretically. The immobilization of hazardous heavy metal ions were discovered to be determined by the solvation from the crystalline H2O and bonding from the sod (t-toc) cage. Based on the analysis of exchange energies, it was found that the immobilization for these heavy metals was correlated with the solvation radius: the larger the solvation radius was, the more favorable the immobilization was. Further detailed solvation effect analysis indicates that the immobilization of heavy metal ions is very sensitive to solvation effect based on the crystalline H2O molecules. Due to the synergistic effect between the solvation effect and the adsorption of the sod (t-toc) cage, the immobilization of Zn2+ is always favorable inside sodalite whereas Cr3+, Cd2+, Cu2+, Ni2+ and Pb2+ could be unfavorable in the case of insufficient solvation. This study provides a fast, convenient and objective way to evaluate the immobilization of heavy metals.

Efficient elimination of organic and inorganic pollutants by biochar and biochar-based materials

Biochar have received multidisciplinary attention because of their extraordinary physicochemical properties. In this review, the application of biochar and biochar-based materials for the efficient elimination of organic and inorganic pollutants are summarized. The sorption of organic chemicals and heavy metal ions/radionuclides, degradation/transformation of organic pollutants, and sorption–reduction–solidification of high-valent metal ions are described in detail. The interaction mechanism at molecular level from advanced spectroscopic techniques and theoretical calculations is discussed. Finally, the challenges in the application of biochar and biochar-supported materials in the immobilization of heavy metal ions and photocatalytic degradation of persistent organic pollutants in soils or wastewater are pointed out. This review is helpful for the graduate students to understand the recent works about biochar and biochar-supported materials in environmental pollutants management.

Biomass-derived porous carbon highly efficient for removal of Pb(II) and Cd(II)

The utilization of abundant and renewable biomass to fabricate advanced functional materials is considered a promising route for environmental applications. Herein, Lignin-based porous carbon with layered graphene-like structure (LPC) is successfully synthesized and applied to efficiently remove Pb(II) and Cd(II). The as-synthesized LPC materials are systematically characterized and these results show that LPC has a porous graphene-like structure, facilitating the diffusion and immobilization of heavy metal ions. The influence of different reaction parameters (solution pH, initial concentration of metal ions, contact time and adsorbent amount) on the adsorption performance is investigated in details. The results demonstrate that LPC can achieve superior adsorption capacities of 250.5 mg g−1 for Pb(II) and 126.4 mg g−1 for Cd(II), which are far superior to the previously reported adsorbents. Pseudo-second order kinetics model and Freundlich isotherm model describe the adsorption process well. Furthermore, the exhausted LPC can be regenerated easily and exhibits the removal efficiency of 96% and 92% for Pb(II) and Cd(II) after five continuous runs, respectively. This study shows a sustainable strategy for the design of porous carbon material from naïve biomass and highlights the great potential in wastewater treatment.

Enhanced Cr(vi) immobilization on goethite derived from an extremely acidic environment

Iron (hydr)oxides play an indispensable role in the immobilization of heavy metal ions in environmental geochemical processes.

Thermodynamic analysis of possibility of using calcium compounds for removal of heavy metal ions from aqueous solutions

The aim of this investigation is the thermodynamic simulation of processes, occurring at interaction of calcium compounds (silicates etc.) with water solutions containing heavy metals, as well as the analysis of the obtained results by explanation of the effects observed in the binding and immobilization of heavy metal ions from water solutions. The results of the thermodynamic modelling allowed the authors to make a number of conclusions that are converged with the literature experimental data. In particular, the main components of the cement clinker during the contact with water allow reaching the high pH value of the water medium. This is sufficient to convert most heavy metal ions into insoluble compounds. The processes, occurring during the interaction of calcium compounds with water and dissolved heavy metals, in the case of equilibrium achieving, should lead to a significant decrease in the concentration of heavy metals in water. These processes should be accompanied by the increase in the concentration of calcium ions in the solution. The presence of carbon dioxide in excess in the system leads to the fact that the solution pH will correspond to a neutral or weakly acidic medium. However, even in this case, there will be a decrease in the concentration of heavy metal ions by several orders of magnitude.

The Effect of Pb<sup>2+</sup> and Cd<sup>2+</sup> Addition to Mechanical Properties of Fly Ash Geopolymer Paste

Immobilization of heavy metal ions using geopolymer paste is a promising way to solve the problem with heavy metal waste from industries. This research focused on the immobilization of Pb2+ and Cd2+ which are common heavy metal waste with distinctive cation size. The cations were immobilized by geopolymerization process to form geopolymer paste. The paste was prepared by using fly ash from a power plant in Cilacap, Indonesia, with SiO2/Al2O3 ratio = 3 and S/L = 1.6. According to XRF analysis, the ash is type C fly ash and additional Al(OH)3 was needed to achieve the SiO2/Al2O3 ratio. A solution of Cd2+ or Pb2+ from their respective nitrate salts was added to the geopolymer mixture to make an immobilized Cd2+ or Pb2+ in a fly ash geopolymer matrix. Compressive strength tests showed that the maximum strength was achieved when 3855 ppm of Cd2+ or 765 ppm of Pb2+ was added to the geopolymer mixture. The change of strength is explained to be caused by the filling of geopolymer cavities that were formed during the geopolymerization process. Due to the smaller size of Cd2+ than Pb2+, the strongest geopolymer paste was achieved at higher Cd2+ concentration than Pb2+. X-ray diffraction analyses results show that the addition of Cd2+ or Pb2+ shift the position on hump to larger 2θ.

The use of dialdehyde starch derivatives in the phytoremediation of soils contaminated with heavy metals

ABSTRACTProducts of the reaction between dialdehyde starch and Y-NH2 compounds (e.g. semicarbazide or hydrazine) are effective ligands for metal ions. The usefulness of these derivatives was tested in the experiment, both in terms of the immobilization of heavy metal ions in soil and the potential application in phytoextraction processes. The experimental model comprised maize and the ions of such metals as: Zn(II), Pb(II), Cu(II), Cd(II), and Ni(II). The amount of maize yield, as well as heavy metal content and uptake by the aboveground parts and roots of maize, were studied during a three-year pot experiment. The results of the study indicate the significant impact of heavy metals on reduced yield and increased heavy metal content in maize. Soil-applied dialdehyde starch derivatives resulted in lower yields, particularly disemicarbazone (DASS), but in heavy metal-contaminated soils they largely limited the negative impact of these metals both on yielding and heavy metal content in plants, particularly dihydrazone (DASH). It was demonstrated that the application of dihydrazone (DASH) to a soil polluted with heavy metals boosted the uptake of Zn, Pb, Cu, and Cd from the soil, hence there is a possibility to use this compound in the phytoextraction of these metals from the soil. Decreased Ni uptake was also determined, hence the possibility of using this compound in the immobilization of this metal. The study showed that dialdehyde starch disemicarbazone was ineffective in the discussed processes.

Theoretical and experimental study of ion-exchange process on zeolites from 5-1 structural group

In this work the DFT calculations were carried out by means of Gaussian09 program for chosen model cluster—mor Composite Building Unit of zeolites structures. Vibrational frequencies computations and infrared spectra were obtained subsequently for above model. The results of calculations have been compared with IR (MIR and FIR range) spectroscopic studies of zeolites belonging to 5-1 structural group (mordenite and ferrierite) after heavy metal cations (Ag+, Zn2+, Cd2+, Pb2+, and Cr3+) immobilization. Changes in intensities and positions of the bands corresponding to the characteristic ring and Me–O vibrations have been observed. These rings occur in pseudomolecular complexes (built of [SiO4] and [AlO4] tetrahedra) which constitute the secondary building units and form zeolite framework. Based on the results of DFT method calculations, normal vibrations of the 5-1 unit terminated by different cations (Na+, K+) have been visualized. Obtained results have been applied for interpretation of experimental spectra of selected zeolites. The most significant changes have been determined in the region of pseudolattice vibrations (800–500 cm−1), as well as Me–O vibrations (below 400 cm−1). It was proven those cations’ sorption causes changes in the experimental spectra of zeolites. Sorption has been conducted on monoionic forms of mordenite and ferrierite. Based on the results of the sorption/desorption experiments, the proportion of ion-exchange to chemisorption in the process and the effective cation exchange capacity of the individual samples have been estimated. Results of AAS studies have been compared with those obtained by vibrational (IR and Raman) spectroscopy. Changes in intensities and positions of the bands corresponding to the characteristic ring vibrations, due to the immobilization of heavy metal ions, have been observed.

Immobilization of cadmium onto activated carbon by microwave irradiation assisted with humic acid

Adsorption is an effective method for the removal of heavy metal ions from wastewater. However, technologies are needed to regenerate the saturated adsorbents for reuse and to immobilize the adsorbed heavy metal ions for the final disposal of the disused adsorbents. The presence of humic acid in water may influence adsorption and the subsequent immobilization of heavy metal ions. In this study, microwave irradiation was adopted to regenerate granular activated carbon (GAC) saturated with Cd2+ and to also immobilize Cd2+ onto GAC. The effects of humic acid on adsorption of Cd2+ onto GAC and the immobilization of Cd2+ by microwave irradiation were investigated. The results showed that specific concentrations of humic acid promoted the adsorption of Cd2+ onto GAC as well as the immobilization of Cd2+ by microwave irradiation, which may be attributed to the complexation of humic acid with Cd2+, as indicated by the three-dimensional fluorescence spectra. Several important parameters including microwave power, irradiation time and water content of GAC were found to have significant effects on the immobilization of Cd2+ onto GAC by microwave irradiation. Evaluation based on the toxicity characteristic leaching procedure (TCLP) showed that for the dried GAC, approximately 89% immobilization of Cd2+ was achieved with 750W of microwave irradiation for 10min. This technology may also be effective for the immobilization of other metal ions, including Cu2+, Zn2+ and Pb2+.

Application of IR spectra in the studies of zeolites from D4R and D6R structural groups

This work presents results of FT-IR spectroscopic studies (MIR and FIR range) of zeolites (belonging to D4R and D6R structural groups) after heavy metal cations (Ag+, Cu2+, Cd2+, Pb2+, Zn2+, Ni2+ and Cr3+) immobilization. Sorption has been conducted on monoionic forms of synthetic zeolite A (LTA) and Y (FAU) as well as on natural chabazite (CHA).It was proven that those cations’ sorption causes changes in the spectra of the zeolites. Changes in intensities and positions of the bands corresponding to the characteristic ring and MeO vibrations have been observed. These rings occur in pseudomolecular complexes (built of alumino- and silicooxygen tetrahedra) which constitute the secondary building units (SBU) and form spatial framework of the zeolite. Based on the results of DFT method (B98 HF 6–31G(d)) calculations, normal vibrations of the SBU terminated by different cations (Na+, K+) have been visualized. Obtained results have been applied for interpretation of experimental spectra of selected zeolites. The most significant changes have been determined in the region of pseudolattice vibrations (800–550cm−1). On the other hand, an introduction of heavy metal cations into the structure of zeolites has caused the considerable modification of bands due to MeO vibrations in FIR spectra (below 400cm−1).In both cases systematic changes connected with the type of cation (its chemical character) have been revealed. Based on changes in the spectra due to immobilization of heavy metal ions, a scale of sorption can be established.