Heavy Metal Oxide Research Articles

Structural, elastic and gamma-ray attenuation properties of potassium borate glasses doped with BaO, Bi2O3, or Pb3O4: A comparative assessment

This study investigates the effect of substituting boron oxide (B2O3) with heavy metal oxides (HEMOs) on the structural, mechanical, and gamma-ray shielding properties of potassium borate (KB) glass systems. The glass compositions analyzed include 80B2O3–20K2O and 65B2O3–20K2O-15HEMO (where, HEMO = BaO, Bi2O3, or Pb3O4). All samples were prepared using the melt-quenching method, and their amorphous nature was confirmed through X-ray diffraction (XRD). Fourier-transform infrared spectroscopy (FTIR) had revealed BO3, BO4, and BiO6 groups beside the B–O–B linkages. The density increased with the addition of HEMOs, following the order: Pb3O4 (KB4) > Bi2O3 (KB3) > BaO (KB2) > and pure KB (KB1). This trend was also observed in the molar volume (Vₘ) and oxygen molar volume (Vₒ), while the oxygen packing density (Pρ) decreased. Mechanical properties assessed using the Makishima-Mackenzie model indicated that KB3 exhibited the highest elastic modulus (Yₘ) and Poisson's ratio (μ). The microhardness (Hₘ) followed the sequence KB2 > KB3 > KB4 > KB1, attributed to the higher bonding energy in KB2. Gamma-ray shielding parameters, including mass attenuation coefficients (MAC), were calculated using Phy-X and XCOM software for photon energies between 0.2835 MeV and 1.333 MeV. KB4 (Pb3O4) showed superior shielding performance with the highest linear attenuation coefficient (LAC) and the lowest half-value layer (HVL) and mean free path (MFP). Despite KB4's high density, KB3 (Bi2O3) is suggested as a more suitable candidate for radiation shielding applications due to its balanced combination of mechanical strength and γ-ray attenuation efficiency.

High transparent glass of germanate-borate-tellurite modified by different concentration of bismuth oxide for optical and radiation shielding applications

The current investigation studied one of the high-density heavy metal oxides (Bi2O3) having density = 8.9 g/cm³, which was utilized to improve structural and optical features of the B2O3–TeO2-GeO2-MgO glass system. Three high transparent glasses with a chemical formula of 35B2O3–20TeO2-10GeO2-35MgO-xBi2O3 (x = 5, 10, and 15 mol %) were fabricated by melting at 1100 °C for 20 min and annealing at 400 °C for 5 h. X-ray diffraction measurements for the Bi5 sample, containing 5 mol % Bi2O3, were obtained at the range of 10°–80° to inspect the structural characteristics of the made glasses. Optical absorption was employed and recorded for Bi5, Bi10, and Bi15 samples at wavelength range 300–1000 nm to examine the optical properties, including optical band gap. Using Makishima and Mackenzie methods, the mechanical features of the glass samples were assessed. Nuclear library ENDF/B-VI.8 is coupled to the MCNP-5 code and is used to study and simulate the prepared Bi glass sample shielding parameters. The ionizing absorption properties for the prepared Bi5, Bi10, and Bi15 samples were found to be changed because of many circumstances like the photon energy (Eγ, MeV), and chemical compositions (Bi2O3 content (mol. %). The increased layer thickness of glass between 25 and 200 mm enhances the RPE values at 0.6 MeV over the range of 16.31–50.93 % (Bi5 glass sample), 18.68–56.26 % (Bi10 glass sample), and 20.80–60.66 % (Bi15 glass sample).

Exploring the Radiation Shielding Efficiency of High-Density Aluminosilicate Glasses and Low-Calcium SCMs

A lot of work is now going into making low-calcium supplementary cementitious materials (SCMs) and aluminosilicate glasses so that they can be used as radiation shielding materials. These materials demonstrate superior performance in several aspects as compared to conventional concrete. The present investigation focuses on the radiation shielding characteristics of the evaluated materials, specifically their capacity to reduce the intensity of gamma rays and neutrons. Regarded for their exceptional density and ability to include heavy metal oxides, aluminosilicate glasses have remarkable shielding characteristics, especially when designed at the molecular scale. An evaluation of the performance of these materials in comparison to traditional concrete is carried out using Phy-X/PSD software. The goal is to determine the most important shielding properties, such as the mass attenuation coefficient, the linear attenuation coefficient, and the half-value layer. Our study findings suggest that some aluminosilicate glasses, such as GM, consistently demonstrate exceptional photon and neutron attenuation efficiency. The observation that GM performs better than other materials in tests like effective atomic number, rapid neutron removal cross section, and energy absorption accumulation factor supports this claim. There is evidence that using low-calcium glass-crystal materials (SCMs) with aluminosilicate glasses not only improves radiation protection but also makes solutions work better when space or weight are limited. The present investigation validates that these materials exhibit superior performance compared to conventional concrete in challenging environments such as nuclear waste storage, where safety is of utmost significance.

Gamma irradiation effects on photoluminescence and semiconducting properties of non-conventional heavy metal binary PbO–Bi2O3 glasses

Non-conventional heavy metal oxide glasses have attracted great interest owing to their unique optical properties and their radiation shielding behavior. Non-conventional glasses of main chemical composition (100 − x) PbO–xBi2O3 where x = 35, 30, 25, 20, 15, 10, and 5 were prepared through the conventional melting and annealing approach. X-ray diffraction measurements denoted the amorphous nature of the prepared glasses. The optical absorption in the UV–visible range recorded strong UV-near visible absorption spectra that correlated to trivalent Bi3+ ions. The optical band gap Eopt, Urbach energy ∆E, and the refractive index were identified for the prepared glasses employing the cognizant theories. The variations in the optical parameters have been associated with the increasing Bi2O3 and the doses of γ- irradiation. The photoluminescent properties of the prepared non-conventional binary Bi2O3–PbO glasses were recorded in the visible range after UV excitation and the color coordinates are located and distributed in the hue violet degree. FT-IR spectroscopic measurements before and after gamma irradiation were applied to investigate the structural changes in the binary heavy metal PbO–Bi2O3 glasses. FTIR data specified that the glass network is composed of different structural building units from BiO3/BiO6 and PbO3/PbO4 depending on the addition ratio between PbO and Bi2O3.

Enhanced health risk of soil heavy metal exposure following an extreme rainstorm under climate change

Widespread concerns raised in changes in the health risk of soil heavy metals exposure due to extreme rainstorm under climate change. However, the impacts of extreme rainstorm on human exposure risk and the underlying mechanisms are still unclear. In this study, soil properties, speciation distribution and bioaccessibility of Ni, Cu, Zn, Cd and Pb in soil samples, which were collected before and after extreme rainstorm, were measured, subsequently the soil oral exposure risk of heavy metals was assessed based on bioaccessibility. Results indicate that extreme rainstorm can significantly enhance the accumulated non-carcinogenic and carcinogenic exposure risk by 10.1–188.3 %, with lowland soil posing 1.3–1.7 times higher risk than highland soil. The increase in exposure risk varies among elements in highland and lowland soil. Specifically, the exposure risk for Cd and Pb increased by 2.5–9.7 times, whereas that for Cu decreased by 43.2 % - 60.6 %. The risk of Zn and Ni exposure exhibits complex trends, with an increase of 37.2 %–104.8 % in lowland soil but a decrease of 9.4 %–46.5 % in highland soil. Bioaccessibility variations are the primary risk factors for soil heavy metal exposure during extreme rainstorms, not total concentration. Mechanistically, the extreme rainstorm directly increases soil moisture content and reduce organic matter concentration, leading to an increment in the proportion of bio-utilization speciation and decrement in the speciation bounding to Fe/Mn oxides of soil heavy metals. Furthermore, the bioaccessibility of soil heavy metal positively correlates with their bio-utilization speciation and negatively correlates with their speciation bounding to Fe/Mn oxides, which ultimately increasing exposure risk. Our study suggests the necessity that attentions should be paid to the enhanced health risk associated with soil heavy metal exposure following extreme rainstorm, particularly for population residing in lowland areas.

Di-tert-butyl Peroxide (DTBP)-Promoted Heterocyclic Ring Construction

Abstract: Di-tert-butyl peroxide (DTBP) is one of the most widely used organic peroxides in a variety of oxidative transformations. The main factors contributing to the increasing use of DTBP are its affordability, minimal environmental impact, great effectiveness, and capacity to substitute scarce or dangerous heavy metal oxidants. We have reviewed critically and succinctly the noteworthy applications of DTBP in heterocyclic ring constructions from 2014 onwards in this decennial update. The main components of this evaluation are the pros and cons of its use, the scope of a synthetic organic transformation, and mechanistic logistics.

Engineering of Co/MgO interface with combination of ultrathin heavy metal insertion and post-oxidation for voltage-controlled magnetic anisotropy effect

The voltage-controlled magnetic anisotropy (VCMA) effect in ferromagnet/insulator junctions provides an effective way to manipulate electron spins, which can form the basis of future magnetic memory technologies. Recent studies have revealed that the VCMA effect can be strongly tuned by a process of “interface engineering” exploiting ultrathin heavy metal layers and an electron depletion effect. To further decrease the numbers of electrons, chemical reactions, such as surface oxidation of ferromagnets, may also be an effective way to achieve this depletion. However, the knowledge of combined effect of heavy metal layers and oxidation is still lacking. Here, we demonstrate that dual interfacial engineering using an insertion of heavy metals (Pt or Re) and a post-oxidation process can have a remarkable effect on the perpendicular magnetic anisotropy and the VCMA effect. Interestingly, a strong enhancement of the perpendicular magnetic anisotropy is observed by dual interfacial engineering with Pt insertion, although it does not occur with Pt insertion or surface oxidation alone. Furthermore, even a sign reversal of the additional VCMA effect due to the ultrathin heavy metal layers is observed by utilizing dual interfacial engineering. These findings provide another degree of freedom for designing voltage-controlled spintronic devices and pave the way to interfacial spin–orbit engineering for the VCMA effect.

Performance of Iron Phosphate Glass Containing Various Heavy Metal Oxides for Particulate Nuclear Radiation Shielding.

Employees may be exposed to different kinds of ionizing radiation at work. When ionizing radiation interacts with human cells, it can cause damage to the cells and genetic material. Therefore, one of the scientists' primary objectives has always been to create the best radiation-shielding materials. Glass could offer promising shielding material resulting from the high flexibility of composition, simplicity of production, and good thermal stability. The melt-quenching technique was used to create a glass having the following formula: 50% P2O5+20% Na2O+20% Fe2O3+10% X, where X = As2O3, SrO, BaO, CdO, and Sb2O3 mol %. The impact of the different heavy metal additions on the structure of the glass networks was studied using FTIR spectroscopy. Glass's ability to attenuate neutrons and/or charged particles has been theoretically investigated. The performance of the developed glass as a shield was examined by a comparison against commercial glass (RS 253 G18), ordinary concrete (OC), and water (H2O). For charged particle radiations (Electrons, Protons, and Alpha), the shielding parameters like the mass stopping power, the projected range, and the effective atomic number were evaluated, where S5/Sb glass achieves the best performance. In the case of Neutrons, the results values reveal that S3/Ba glass ( ΣR = 0.105) is the best-modified glass for neutron shielding. Among all the investigated glasses, S5/Sb glass composition has a smaller range and provides superior protection against charged particles. In contrast, the S3/Ba glass composition is a superior choice for shielding against neutron radiation.

Recycling of secondary aluminum dross to make alumina by hydrometallurgy: A review

Secondary aluminum (Al) dross (SAD) is a hazardous waste discharged from Al production, processing and recycling. Over 6.7 million tons of SAD was discharged on the planet in 2023. SAD is consisted of 40–60 wt% of alumina (Al2O3), 10–30 wt% of AlN, 5–15 wt% of salts and 3–10 wt% of heavy metal oxides. Currently, recycling of SAD to make Al2O3 by hydrometallurgy is a promising method for disposal of SAD. Hydrometallurgy method is mainly divided into acid leaching and alkali leaching. In acid leaching, Al, AlN and Al2O3 react with acid to form aluminum sulfate and aluminum chloride. In alkali leaching, Al, AlN and Al2O3 react with alkali to form sodium aluminate. High-purity Al2O3 is obtained after precipitation, washing, drying and calcination from the leachate. Resource consumption and emission was calculated to evaluate the economic and environmental benefits. About 147.9 and 172.6 dollars was earned after making Al2O3 from a ton of SAD by alkali and acid leaching process, respectively. And carbon emissions of a ton of Al2O3 was risen about 596.5 and 2216.0 kg CO2, respectively, compared with the Bayer process with bauxite. We proposed a calcination pre-treatment with quicklime on SAD to reduce the carbon emission. The Al and AlN are oxidized into Al2O3 after calcination, and the Al2O3 reacts with CaO to form CaO·Al2O3. The Al in CaO·Al2O3 can be leached out easily with a low concentration of alkali. This review provides a guidance for the recycling of SAD by hydrometallurgy, and proposes a novel idea for the energy and consumption reduction in alumina (Al₂O₃) production.

The effects of submicron particles of metal oxides on the production of hydrogen peroxide and the activity of oxidative enzymes of <i>Aspergillus niger</i> and <i>Penicillium chrysogenum</i>

The submicron particles effect of heavy metal oxides WO3, CsTeMoO6 и RbTe1.5W0.5O6 with photocatalytic activity on the content of hydrogen peroxide and the activity of extracellular oxidoreductases (catalase, peroxidase) in the cultivation medium of the Aspergillus niger and Penicillium chrysogenum fungi was studied. Addition of the studied compounds to the cultivation medium reduced the H2O2 content for both fungi. An ambiguous effect of the studied compounds on the activity of extracellular catalase and peroxidase was noted. In most cases, these compounds caused an increase in the activity of the studied enzymes both under light and in the dark. A significant decrease in activity was shown only for exocatalases of both fungi under the influence of WO3 and under the influence of CsTeMoO6 in P. chrysogenum.

Tert‐Butyl Hydroperoxide (TBHP): Recent Progress in C−H Functionalization and Heteroatom‐Heteroatom Bond Formations

Abstracttert‐Butyl hydroperoxide (tBuOOH, TBHP) is a commonly used hydroperoxide in many oxidation processes. The primary factors contributing to the increasing usefulness of TBHP include its affordability, eco‐friendliness, exceptional efficacy, and capacity to substitute harmful or rare heavy metal oxidants. In this sexennial update, we thoroughly and critically examined the most noteworthy applications of TBHP in C−H functionalization and heteroatom‐heteroatom bond formation reactions from 2018 till the present. The review has been subdivided based on the nature of the bonds being formed. The review focuses on the advantages and disadvantages of using synthetic organic transformations, as well as the breadth of their use and the underlying mechanisms involved.

Optical, physical, mechanical, structural, and radiation shielding investigations of B2O3–TeO2-GeO2-MgO-PbO for ionizing protection and optical transmission application

This study aims to investigate a new heavy glass system's potential use in the radiation shielding and optical transmission applications. Glass former like borate is replaced in this work by heavy metal oxides like lead oxide in the following glass system: (35-x) B2O3–20TeO2-10GeO2-35MgO-xPbO (where x = 2.5, 5, 7.5, and 10 mol%). Through the melt-annealing process, four transparent glasses were synthesized. A number of physical properties were reported, namely the boron–boron separation x 10−8 m, field strength x 1018 (cm2), inter nuclear distance x 10−8 m, ion concentration (N) x 1023 (ion cm3), molar volume (cm3/mol), molecular weight (g/mol), and polaron radius x 10−9 m. Moreover, the following mechanical and structural properties of the synthesized glasses were explored: bulk modulus (B, GPa), dissociation energy (kcal/cm3), fractal bond connectivity (d), longitudinal modulus (L, GPa), hardness (H, GPa), oxygen packing density, packing density (Vt), oxygen molar volume, packing factor (Vi), shear modulus (S, GPa), Poisson radius (σ), and Young modulus (Y, GPa). To study the bulk glasses' nature, the X-ray diffraction was examined. Optical absorption along with optical transmission profile have been recorded to extract various optical properties, as well as the direct and indirect band gap. The transmittance spectra of the prepared glass samples' FTIR were investigated within the 400–2000 cm−1 range. This allowed for the examination of molecular structural groups and vibrational modes. Radiation shielding parameters have been calculated and studied using XCOM software and MCNP-5 algorithm.

Ferroelectric Control of Spin‐Orbitronics

AbstractSpin‐orbit coupling refers to the relativistic interaction between the spin and orbital motions of electrons. This interaction leads to numerous intriguing phenomena, including spin‐orbit torques, spin–momentum locking, topological spin textures, etc., that have recently gained prominence in the field of spin‐orbitronics. In particular, the emerging ferroelectric control is recognized and validated as an effective means to enhance energy efficiency across a broad spectrum of spin‐orbitronic devices. Here, cutting‐edge research on ferroelectric control of spin‐orbitronics (FECSO) by means of spontaneous polarization, reversible ferroelectric switching, and multiferroic coupling, are comprehensively reviewed. Two fascinating topics are mainly discussed: topological spin texture and spin‐charge interconversion. The classification of control mechanisms for different interactions in FECSO is summarized first. Then, from the perspective of material classification, the ferroelectric‐controlled spin‐orbit coupling with tunable topological spin texture in oxide systems, magnetic metal multilayers, and 2D van der Waals materials is reviewed. Subsequently, the ferroelectric‐tunable spin‐charge interconversion on heavy metal layers, oxide interfaces, and ferroelectric Rashba semiconductors is highlighted. In the end, the challenges and forthcoming prospects of FECSO are discussed. This work may provide pertinent and forward‐thinking guidance to accelerate the ongoing advancement of this field.

Preparation and characterization of strontium-doped bismuth borate glasses

Employing the melt quenching method, new bismuth borate glass compositions denoted as (40+x)Bi2O3–(60-x-y)B2O3–ySrO, with x and y ranging between 0 to 20 mol%, were synthesized. The X-ray Diffraction analyses confirmed the amorphous nature of all glass samples, indicating the absence of long-range order typically seen in crystalline materials. Concurrently, the Fourier-transform Infrared Spectroscopy examinations unveiled the existence of fundamental structural units within the glasses, including BO3 and BO4 trigonal and tetrahedral units, as well as BiO3 and BiO6 polyhedra, suggesting a complex network structure. Differential Thermal Analysis (DTA) and dilatometry assessed the glasses' thermal properties. DTA demonstrated the glasses' high thermal stability, with a stability value of up to 106°C, noting that stability improves with more SrO. Dilatometry analyses revealed these glasses exhibit a high thermal expansion coefficient, ranging from 8.69 to 10.7 ppm/°C, alongside relatively low glass transition temperatures between 362 and 432°C and dilatometric softening temperatures spanning from 380 to 447°C. Density measurements were conducted, followed by molar volume and oxygen packing density calculations, to glean further insights into the samples. Compared to other heavy-metal oxide glasses, the glasses examined in this study exhibited notably high-density values, ranging between 6.279 and 7.476 g/cm3 .

Recent advances in TBHP‐promoted heterocyclic ring construction via annulation/cyclization

AbstractOne of the most often utilized hydroperoxides in an array of oxidation strategies is tert‐butyl hydroperoxide (tBuOOH, TBHP). The key reasons for rising utility of TBHP are its low cost, environmental friendliness, high efficiency, and ability to replace hazardous or rare heavy metal oxidants. In this sexennial update, we concisely and critically discussed the applications of TBHP in heterocyclic ring formations starting from 2018 to date. Merits and demerits of its utility, scope of a synthetic organic transformation along with mechanistic logistics are the key features of this review.

Enhanced Thermoelectric Performance of Na0.55CoO2 Ceramics Doped by Transition and Heavy Metal Oxides

Using the solid-state reactions method Na0.55(Co,M)O2 (M = Cr, Ni, Zn, W, and Bi) ceramics were prepared and their crystal structure, microstructure, electrophysical, thermophysical, and thermoelectric properties were studied. Doping of Na0.55CoO2 by transition or heavy metal oxides led to the increase in the grain size of ceramics, a decrease in electrical resistivity and thermal diffusivity values, and a sharp increase in the Seebeck coefficient, which resulted in essential enhancement of their thermoelectric properties. The largest power factor (1.04 mW/(m·K2) at 1073 K) and figure of merit (0.702 at 1073 K) among the studied samples possessed the Na0.55Co0.9Bi0.1O2 compound, which also demonstrated the highest values of the Seebeck coefficient (666 μV/K at 1073 K). The obtained results show that the doping of layered sodium cobaltite by different metal oxides allows for improving its stability, microstructure, and functional properties, which proves the effectiveness of the doping strategy for developing new thermoelectric oxides with enhanced thermoelectric performance.

Advancing mechanical durability and radiation shielding properties in Silicon dioxide (SiO2) glasses through various incorporations: A comparative analysis

Silicon dioxide (SiO2) glasses, known for their high thermal stability, excellent optical transparency, and substantial mechanical strength, are crucial in numerous technological applications, including radiation shielding. This research explores the impact of compositional variations in SiO2-based glasses on their mechanical and radiation shielding properties, particularly focusing on the inclusion of heavy metal oxides (HMO) and rare earth elements (REE) like neodymium (Nd). Through the systematic investigation of fifteen distinct glass samples with varying concentrations of specific oxides and elements, we investigate the compositional changes and their influence on physical properties and their effectiveness in attenuating radiation. Our findings demonstrate that the incorporation of Nd significantly enhances the glass's radiation shielding capabilities. Glasses doped with Nd exhibited higher effective atomic numbers and electron densities, which translate to superior attenuation characteristics at lower photon energies. This is highlighted by the exceptional performance of the 20Nd sample, showing the lowest exposure build-up factors (EBF) at 10 mean free paths (mfp), indicating its potential as a premier candidate for shielding applications against various energy levels of radiation. Moreover, the variation in the Elastic Modulus of the glass samples underscores the significant impact of the glass matrix composition on its mechanical properties, suggesting a delicate balance between network formers and modifiers in determining the glass properties. It can be concluded that the neodymium-doped SiO2-based glasses may be considered as targeted compositions in fine-tuning material properties to meet specific application requirements. As the demand for efficient radiation shielding materials grows across medical, industrial, and space exploration sectors, our findings provide a solid foundation for the development of new glass formulations tailored for enhanced mechanical properties and superior radiation protection levels.

Phase comparison and equation of state for Ta2O5

Tantalum pentoxide (Ta2O5) is among the most technologically useful heavy transition metal oxides. Unfortunately, its crystal structure is the subject of long-standing and unresolved disagreement. Among other consequences, this uncertainty has made it impossible to formulate a robust high pressure equation of state for Ta2O5. Here, we report the results of high pressure x-ray diffraction experiments indexed against a comprehensive list of proposed Ta2O5 phases. Five of the proposed phases produce good matches to experimental observations, and the compressibility parameters for these phases are all consistent within uncertainty. This means that regardless of the particular phase chosen, the Ta2O5 equation of state can be described with bulk modulus K0=138±3.68 GPa and pressure derivative K0′=1.82±0.45 . Combining these experimental results with new density-functional theory calculations allows us to identify the λ phase as the best structural model of Ta2O5 at ambient conditions.

Performance and oxidation mechanism of VUV photo–Fenton in simultaneous removal of Ni-EDTA and hypophosphite: decomplexation, low-valent phosphorous oxidation and DFT calculation

The photo–Fenton process offers a promising alternative for the oxidation of complex heavy metals. However, the potential influence of coexisting substrates may be overlooked. The •OH radicals generated in the photo–Fenton process ensure superior oxidation ability. In this study, we used a vacuum ultraviolet (VUV) light-assisted photo–Fenton (VPF) process to explore its performance in the synergistic oxidation of Ni-ethylenediaminetetraacetic acid (EDTA) and coexisting hypophosphite, typical pollutants in electroless nickel plating (ENP) wastewater. Based on electron spin resonance (ESR) and DMSO-probing results, •OH was the predominant reactive oxygen species, and VPF possessed the highest •OH concentration compared to other photochemical processes under identical conditions (pH, Fe, H2O2). Enhanced •OH generation in VPF was attributed to various photochemical reactions, including photo–Fenton, UV/H2O2, and VUV/H2O. Consequently, VPF exhibited efficient Ni-EDTA decomplexation and hypophosphite oxidation. Notably, the evolution and rate-limiting steps during hypophosphite oxidation were demonstrated by experimental results and density functional theory calculations. Hypophosphite was initially oxidized to phosphite, which subsequently oxidized to phosphate. The oxidation of phosphite could be considered the rate-limiting step as it exhibits higher energy barriers than hypophosphite oxidation. Adequate •OH generation in the VPF process could overcome this energy barrier, indicating its potential for application in pollutant removal and resource recovery from ENP wastewater.

Effective stabilization of heavy metals in solid waste and sludge pyrolysis using intercalated-exfoliated modified vermiculite: Experiment and simulation study

Pyrolysis is effective in reducing the volume of solid waste and sludge, and produces less pollutants than incineration and landfill, but the process still suffers from heavy metal pollution. Four types of intercalated-exfoliated modified vermiculite (UIV, DIV, TIV and 3IV) were prepared using urea, dimethylsulfoxide, tributyl phosphate and 3-aminopropyltriethoxysilane as intercalators for the control of Cd, Cr, Cu, Pb and Zn in municipal sewage sludge (MSL), paper mill sludge (PML), municipal domestic waste (MWA) and aged refuse (AFE). The larger the interlayer spacing of the vermiculite, the more favorable the retention of heavy metals. 3IV was the most effective additive, with an average retention of more than 75 % of all heavy metals at 450 ℃ for the four raw materials. Cr, Cu, Pb and Zn were all at low potential ecological risk (Pr), while Cd was moderate or considerable Pr, and the addition of 3IV reduced the Pr. Distribution of intercalators between vermiculite interlayers was haphazard, and interlayer spacing results were close to those of the experiment (except for tributyl phosphate). The reactive electrons mainly flowed from the Highest Occupied Molecular Orbital (HOMO) of vermiculite flakes to the Lower Unoccupied Molecular Orbital (LUMO) of heavy metal chlorides. In contrast, the reactive electrons mostly flowed from the HOMO of heavy metal oxides to the LUMO of vermiculite flakes. Heavy metal oxides were more readily adsorbed on vermiculite flakes than heavy metal chlorides, and the adsorption capacity of Cr and Zn was stronger than that of Cd, Pb and Cu.