Search Results (40)

Municipal solid waste incineration fly ash (MSWI FA) represents a significant environmental challenge due to its high content of toxic heavy metal (HM) and large-scale generation. This study demonstrates the feasibility pathway for converting hazardous MSWI FA into well-crystallized layered double hydroxide nanosheets (LDH-FA). Sodium dimethyl dithiocarbamate (SDD) was incorporated as a chelating stabilizer to enable synergistic HM immobilization during acid leaching and crystallization. High-resolution transmission electron microscopy (HRTEM) confirmed the characteristic two-dimensional nanosheet morphology with interlayer spacings consistent with LDH structures, while elemental mapping revealed homogeneous distribution of Pb and Zn within the nanosheet matrix. SDD dosages higher than 1.0 wt% effectively suppressed HM leaching, and Pb concentrations were controlled below 0.1 mg/L and Zn maintained at minimal levels. BCR sequential extraction analysis further demonstrated that SDD treatment effectively transformed HMs from bioavailable acid-soluble fractions to stable forms. This investigation establishes an innovative approach to MSWI FA resource utilization and provides mechanistic insights into HM stabilization within LDH nanostructures, offering a scientific basis for safer applications of waste-derived nanomaterials. Full article

This study addresses the issue of insufficient product purity caused by the co-deposition of three major impurity ions—zinc, nickel, and lead—during the electrodeposition process of high-purity manganese. A targeted deep purification method for manganese sulfate electrolyte was developed using dithiocarbamate chelating agents (sodium dimethyldithiocarbamate, SDD). By optimizing key process parameters such as precipitant concentration, reaction temperature, reaction time, and solution pH, combined with density functional theory (DFT) calculations, to elucidate the selective impurity removal mechanism at the molecular level, a novel process for the efficient synergistic removal of Zn²⁺, Ni²⁺, and Pb²⁺ was established. The results showed that under the conditions of precipitant concentration of 1 g/L, solution pH of 6.5, reaction temperature of 55 °C, and reaction time of 2 h, the residual concentrations of Zn, Ni, and Pb in the electrolyte were all below 0.2 mg/L. DFT calculations revealed that SDD coordinates with metal ions through four sulfur atoms, and the absolute values of binding energies follow the order Ni²⁺ > Pb²⁺ > Zn²⁺ > Mn²⁺, indicating thermodynamically preferential capture of impurity ions. After purification, the manganese metal obtained by electrodeposition from the manganese sulfate solution achieved a purity exceeding 99.999%, with Zn, Ni, and Pb contents of 0.11 mg/kg, 0.038 mg/kg, and 0.05 mg/kg, respectively, meeting the raw material requirements for semiconductor-grade copper–manganese alloy targets. Full article

To address the challenge of removing copper from copper–ammonia complex wastewater in the printed circuit board (PCB) industry, this study employed natural chitosan (CTS) as the base material. Dithiocarbamate (DTC) groups were grafted onto CTS, followed by further carboxylation (-COOH) to produce two novel adsorbents: DTC-CTS and DTC-CTS-COOH. The materials were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), SEM, and related techniques. The effects of solution pH, adsorption isotherms, kinetics, and regeneration performance were systematically investigated. Characterization results confirmed the successful introduction of DTC and carboxyl (-COOH) groups. Adsorption experiments demonstrated that DTC-CTS-COOH exhibited superior Cu²⁺ adsorption performance across pH 5–8, achieving a removal efficiency of (97.67 ± 1.3)% at pH 7. Its adsorption behavior followed the Langmuir model, with a maximum adsorption capacity (Q_m) of 234.8 mg·g⁻¹ at 318.15 K, significantly higher than that of DTC-CTS (183.6 mg·g⁻¹). Adsorption kinetics conformed to a pseudo-second-order model, indicating rapid adsorption rates. After five adsorption-desorption cycles, DTC-CTS-COOH maintained a Cu²⁺ removal rate above 68.41%. The synergistic interaction between -COOH and DTC functional groups enhanced the adsorbent’s capacity, rate, and pH adaptability, demonstrating that DTC-CTS-COOH holds strong potential for application in the treatment of complex copper–ammonia wastewater. Full article

Energy conservation and efficiency enhancement necessitate continuous advancement in the development and preparation of multifunctional, high-performance lubricant additives. This paper reports three novel ashless, phosphorus-free, multifunctional nitrogen-containing heterocyclic dialkyl dithiocarbamate derivative additives (Py-2-DBDTC, PDM-DBDTC, and BZT-DBDTC). Thermal stability, oxidation resistance, and tribological properties were investigated for the synthesized additives. All three additives demonstrated excellent thermal stability and oxidation resistance. Furthermore, their extreme-pressure properties improved by 116.33% or more compared to the base oil, while wear reduction rates also exceeded 58.32%. Under both point-to-point and point-on-flat friction conditions, the friction-reducing performance of all three additives was equally outstanding. Across a broad temperature range (25 °C–150 °C), all additives maintained their friction-reducing properties. Analysis of the worn surface morphology reveals that all three additives undergo tribochemical reactions during the friction process, forming tribofilms containing sulfur elements. Research indicates that introducing different nitrogen-containing heterocyclic structures into dialkyl dithiocarbamates can effectively enhance the adsorption capacity of the additives on metal surfaces and promote the formation of tribofilms at the friction interface, thereby significantly improving tribological performance. These systematic investigations not only provide important guidance for the molecular design and industrial application of multifunctional lubricant additives but also further advance the development of sustainable lubrication technologies. Full article

Based on the need for safe disposal of hazardous waste incineration fly ash (HFA), this study evaluated the solidification/stabilization (S/S) performance of silicate cement, sodium dihydrogen phosphate (NaH₂PO₄), and sodium dimethyl dithiocarbamate (SDD) used individually and in combination. The raw HFA failed the leaching test for Pb, Zn, Cd, and Ni, with their concentrations exceeding the GB16889-2024 limits by factors of 3.1, 2.45, 1.67, and 1.1, respectively. While cement (150% dosage) effectively immobilized Pb, and Cd with >90% leaching reduction, it resulted in significant volume expansion (2.7-fold). NaH₂PO₄ excelled in Pb stabilization (100% efficiency at 20% dosage) via insoluble phosphate formation but required high doses. SDD effectively chelated Zn (63.4% efficiency at 5% dosage) but was less effective for Pb and costly. A synergistic combination of 5% cement, 15% SDD, and 10% NaH₂PO₄ was identified as the possible optimal formulation, successfully immobilizing all heavy metals within regulatory limits. This combined approach minimized dosage, controlled volume expansion ratio (R_VE) (~1.31), and reduced cost. The low initial dioxin content (7.6 ng TEQ/kg) was unaffected by S/S treatments and remained compliant. Mechanistic analyses (XRD, FTIR, SEM-EDS) confirmed the formation of C-S-H gels from cement, insoluble phosphates from NaH₂PO₄, and metal chelates from SDD, collectively transforming the HFA into a compact, low-porosity matrix conducive to safe disposal. This stabilization and solidification strategy not only achieves the safe disposal of hazardous waste incineration fly ash but also contributes to the goals of sustainable waste management by reducing the environmental footprint of treatment processes and minimizing the final disposal volume. Full article

This review provides a comprehensive analysis of the role of chemical agents in enhancing the performance of geopolymers for the stabilization and adsorption of heavy metals. Geopolymers, synthesized from aluminosilicate sources activated under alkaline conditions, are recognized for their versatile structural and environmental benefits, including low carbon emissions and high chemical resistance. Their unique Si-O-Al framework supports both stabilization/solidification (S/S) and adsorption processes, making them an ideal polymeric matrix for the immobilization of hazardous heavy metals in contaminated environments. The review categorizes the heavy metal immobilization mechanisms into physical encapsulation, ion exchange, hydroxide precipitation, and chemical complexation, depending on the specific metal species and geopolymer formulation. The introduction of chemical stabilizing agents, such as dithiocarbamate, sodium sulfide, and trimercaptotriazine, significantly improves the encapsulation efficacy of geopolymers by promoting targeted reactions and stable metal complexes. These agents enable the effective S/S of metals, such as lead, cadmium, and chromium, reducing their leachability and environmental impact. In addition to solid waste management applications, geopolymers have shown promising adsorption capabilities for aqueous contaminants, with chemical modifications further increasing their affinity for specific heavy metals. This review evaluates the impact of different agents and synthesis conditions on the overall performance of geopolymers in heavy metal immobilization, highlighting advances in environmental applications and future research directions for sustainable hazardous waste treatment. Full article

Thallium is an accumulative highly toxic metal, that can be present in environmental samples due to industrial pollution and is dangerous for living organisms. Thus, its determination at trace levels is necessary. The lab-in-syringe (LIS) is considered to be a simple, functional, and versatile, technique that combines operational concepts and flow and sequential injection analysis. In this study, a liquid-phase microextraction LIS system was developed as a front-end to flame atomic absorption spectrometry (FAAS) for the determination of thallium in water samples. The proposed approach is based on the formation of Tl(III) ammonium–pyrrolidine–dithiocarbamate complex followed by its extraction using di-isobutyl-ketone. These procedures take place within the syringe barrel of the LIS system. The limit of detection of the developed method was 2.1 µg L⁻¹ with a linear range from 7.0 to 400 µg L⁻¹. The relative standard deviation (RSD) was 3.9% (at 50.0 µg L⁻¹ Tl(I)), demonstrating good precision. Moreover, good method accuracy was obtained since the relative recovery values were within the range of 93.4–101.2%. Finally, reliable method applicability and green merits were demonstrated using the blue applicability grade index and green analytical procedure index, respectively. The proposed method was used for the analysis of environmental water samples. Full article

Heavy metals in flue gas desulfurization (FGD) gypsum from coal-fired power plants are at risk of releaching during the processes of stockpiling and resource utilization. In this study, the effects of organosulfur chelators dithiocarbamate (DTC) and trisodium trithiocyanate-15 (TMT-15) on the solidification characteristics of heavy metals in desulphurized gypsum under different mass fractions, pH values, water contents and reaction times were investigated. The chemical composition and morphology were analyzed by inductively coupled plasma atomic emission spectrometer (ICP-AES) and scanning electron microscope (SEM). The experiments showed that both DTC and TMT-15 were effective at stabilizing the heavy metals in the FGD gypsum, with more than a 50% curing effect for all the heavy metals except Pb. DTC showed a better stabilization for Pb, Hg, Cu, Zn, and Cr, and TMT-15 showed a better curing effect for Cd. The solidified gypsum had good heavy metal stability in low-water-content environments. Increasing the mass fraction, reaction time, and pH decreased the heavy metal leaching, and the mass fraction had the greatest effect on the total heavy metal leaching concentration, followed by the reaction time and pH value. Full article

Tribofilms, resulting from tribochemical reactions involving lubricants, additives, and metal surfaces, are pivotal in reducing friction, preventing adhesion, and minimizing wear. This study investigates the tribological characteristics of textured surfaces in boundary lubrication, emphasizing the impact of surface texturing on tribofilm formation. Untextured surfaces manifest high friction coefficients and low wear owing to the development of thick tribofilms. However, debris accumulation impedes further tribochemical reactions, necessitating more energy for sliding and resulting in higher friction coefficients. Additionally, molybdenum dialkyl dithiocarbamate-derived MoS₂ oxidation diminishes the expected lubrication effect. Textured surfaces exhibit lower friction coefficients and higher wear because the structure aids debris removal, promoting the formation of thinner tribofilms. Despite increased wear from solid-to-solid contact, textured surfaces facilitate an early fluid lubrication transition and enhance cavitation capacity, leading to reduced friction coefficients. We also consider the impact of sliding direction angles on friction coefficients, revealing that lower angles parallel to the grooves heighten friction, whereas higher angles enhance cavitation capacity. Unexpectedly, a 90° sliding direction angle increases the friction coefficients, attributed to MoS₂ distribution in the tribofilms. These results provide crucial insights for optimizing lubrication strategies and enhancing wear resistance in boundary lubrication scenarios. Full article

Transition metal inserted NbS₂ (T_xNbS₂) compounds receive great attention due to their intriguing and diverse magnetic and electric transport properties. Typically, these compounds are prepared by high-temperature synthesis from the elements, which is time and energy-consuming and yields highly crystalline products. So far, no route for preparing these compounds from precursors by thermal decomposition has been reported. Herein, we report the synthesis of a dithiocarbamate of niobium Nb₂S₄(CS₂NH₂)₄ as a precursor for the synthesis of NbS₂ by this preparative strategy. Furthermore, we demonstrate that a co-decomposition with dithiocarbamates of transition metals (here, Co and Pd) is a viable route for the synthesis of T_xNbS₂-type compounds. This is a promising route for the exploration of these compounds’ properties in the form of, e.g., nanocrystalline or thin film samples. Full article

Copper (Cu) is an essential trace metal and its concentration in body plasma is tightly regulated. An increase in Cu concentration in body fluids is observed in numerous pathological conditions, including infections caused by microorganisms. Evidence shows that Cu ions can impact the activity of antibiotics by increasing efficiency or diminishing/neutralizing antibiotic activity, forming complexes which may lead to antibiotic structure degradation. Herein, we represent the evidence available on Cu–antibiotic interactions and their possible impact on antimicrobial therapy efficiency. So far, in vitro studies described interactions between Cu ions and the majority of antibiotics in clinical use: penicillins, cephalosporins, carbapenems, macrolides, aminoglycosides, tetracyclines, fluoroquinolones, isoniazid, metronidazole. In vitro-described degradation or lower antimicrobial activity of amoxicillin, ampicillin, cefaclor, ceftriaxone, and meropenem in the presence of Cu ions suggest caution when using prescribed antibiotics in patients with altered Cu levels. On the other hand, several Cu-dependent compounds with antibacterial activity including the drug-resistant bacteria were discovered, such as thiosemicarbazones, disulfiram, dithiocarbamates, 8-hydroxiquinoline, phenanthrolines, pyrithione. Having in mind that the development of new antibiotics is already marked as inadequate and does not meet global needs, the potential of Cu–antibiotic interactions to change the efficiency of antimicrobial therapy requires further investigation. Full article

The discovery of cisplatin has influenced scientists to study the anticancer properties of other metal complexes. Organotin(IV) dithiocarbamate compounds are gaining attention as anticancer agents due to their potent cytotoxic properties on cancer cells. In this study, a series of organotin compounds were assessed for their toxic effects on the Jurkat E6.1 cell line. WST-1 assay was used to determine the cytotoxic effect of the compounds and showed that six out of seven organotin(IV) dithiocarbamate compounds exhibited potent cytotoxic effects toward T-lymphoblastic leukemia cells, Jurkat E6.1 with the concentration of IC₅₀ ranging from 0.67–0.94 µM. The apoptosis assay by Annexin V-FITC/PI staining showed that all tested compounds induced cell death mainly via apoptosis. Cell cycle analysis assessed using RNase/PI staining showed that organotin(IV) dithiocarbamate compounds induced cell cycle arrest at different phases. In conclusion, the tested organotin(IV) dithiocarbamate compounds demonstrated potent cytotoxicity against Jurkat E6.1 cells via apoptosis and cell cycle arrest at low IC₅₀ value. However, further studies on the mechanisms of action are required to probe the possible potential of these compounds on leukemia cells before they can be developed into anti-leukemic agents. Full article

Despite the globally increasing use of platinum-based cytostatic drugs in the treatment of several types of cancer, only limited attention has been paid to developing a treatment for contaminated liquid samples originating from hospitals, laboratories and manufacturing facilities before and after their administration. In this work, we assess the efficiency of a low-cost adsorbent material, a dithiocarbamate-functionalized silica, in removing cisplatin from a solution containing it in the 0.5–150 mg L⁻¹ concentration range. The advantage of having a surface-functionalized silica is that adsorption can occur by either non-covalent interaction or surface complexation. In the latter case platinum(II) is de-complexed and the original drug is no longer present. Adsorption occurs through a first rapid step, followed by a second slower process. This is likely due to the fact that in our operating conditions (0.9% w/v NaCl), only the original compound is present, for which ligand substitution is known to proceed slowly. The interesting performance, even at low metal concentration, and facile synthesis of the material mean it could be adapted for other applications where the recycling of platinum can be realized. Full article

Herein, dithiocarbamate-modified biochar (BC-HDTC) was successfully synthesized with nitric acid (HNO₃), thionyl chloride (SOCl₂), branched PEI and carbon disulfide (CS₂). The effective anchoring of amine and dithiocarbamate groups onto the surface of the biochar was proven by SEM, FTIR, XPS, N2 adsorption–desorption experiment. The batch experiments demonstrated BC-HDTC can selectively remove 98% Pb(II) within multi-metals solution when pH = 5, T = 30 °C. The impact of variations on the BC-HDTC were researched (pH, contact duration, Pb(II) original concentration).The sorption kinetics (pseudo-first-order, pseudo-second-order, intra-particle diffusion model) and isotherm modeling (Langmuir, Freundlich, and tempkin models) of Pb(II) on BC-HDTC were investigated. The adsorption process was depicted to attain equilibrium in less than 20 min and to fit the Langmuir isotherms and pseudo-2nd-order kinetics satisfactorily. The complexation of functional groups of HDTC (amine/imine and dithiocarbamate) with Pb(II) as well as the ion exchange between Na(I) and Pb(II) are the main adsorption mechanisms. Pb(II) onto BC-HDTC was endothermic and spontaneous, according to thermodynamic parameters. After 4 consecutive adsorption-desorption cycles, Pb removal efficiency of BC- HDTC remained over 90%. This work revealed the significant potential for Pb(II) contamination of BC-HDTC, a valuable and reusable adsorbent. Full article

The photocatalytic reduction of hexavalent chromium, Cr(VI), to the trivalent species, Cr(III), has continued to inspire the synthesis of novel photocatalysts that are capable of achieving the task of converting Cr(VI) to the less toxic and more useful species. In this study, a novel functionalized graphitic carbon nitride (Cu_3.21Bi_4.79S₉/gC₃N₄) was synthesized and characterized by using X-ray diffraction (XRD), thermogravimetry analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), and scanning electron microscope (SEM). The composite was used for the photocatalytic reduction of hexavalent chromium, Cr(VI), under visible light irradiation. A 92.77% efficiency of the reduction was achieved at pH 2, using about 10 mg of the photocatalyst and 10 mg/L of the Cr(VI) solution. A pseudo-first-order kinetic study indicated 0.0076 min⁻¹, 0.0286 min⁻¹, and 0.0393 min⁻¹ rate constants for the nanoparticles, pristine gC₃N₄, and the nanocomposite, respectively. This indicated an enhancement in the rate of reduction by the functionalized gC₃N₄ by 1.37- and 5.17-fold compared to the pristine gC₃N₄ and Cu_3.21Bi_4.79S₉, respectively. A study of how the presence of other contaminants including dye (bisphenol A) and heavy-metal ions (Ag(I) and Pb(II)) in the system affects the photocatalytic process showed a reduction in the rate from 0.0393 min⁻¹ to 0.0019 min⁻¹ and 0.0039 min⁻¹, respectively. Finally, the radical scavenging experiments showed that the main active species for the photocatalytic reduction of Cr(VI) are electrons (e⁻), hydroxyl radicals (·OH⁻), and superoxide (·O₂⁻). This study shows the potential of functionalized gC₃N₄ as sustainable materials in the removal of hexavalent Cr from an aqueous solution. Full article