Alkali Metal Research Articles

Experimental and theoretical investigation on pre-deposited precursor as growth sites for monolayer MoS2 growth by supercritical fluid deposition

The assistance of promoters, Molybdates or alkali metal salts can regulate the nucleation site of MoS2 in chemical vapor deposition. However, the introduction of impurities inevitably reduces the MoS2 quality. Here, we present the growth of monolayer MoS2 by supercritical fluid deposition to pre-deposit Mo(CO)6 precursors as nucleation sites, replacing difficult to clean conventional promoters. Domain-limited homogeneous and heterogeneous reactions occur at nucleation sites, and through optimization of sulfurization parameters, high-quality monolayer MoS2 with about 20 μm domain size can be obtained by growing at 760 °C and 40 sccm argon for 20 min. Monolayer MoS2 coverage ranged from 2.6 % to 39.1 % by regulating dissolution mass in range of 100–400 mg, utilizing the highly soluble Mo(CO)6 in supercritical CO2. Density functional theory calculations show that decarbonylated Mo(CO)6 possesses higher sulfide reactivity. This study provides new insights into the impurity-free controlled site growth of two-dimensional materials.

Optical and electronic properties of RENiO3 doped with alkali earth metals (Be, Mg, Ca, Sr and Ba): Combining first principles calculations and machine learning

The perovskite rare earth nickelate (RENiO3) has attracted significant attention owing to its peculiar physical properties and promising potential for diverse applications. It is reported that introducing H or Li might change the electronic and optical properties of RENiO3. However, little is known about multi-electrons doping in RENiO3. In this study, the bandgaps, optical and electronic properties were investigated in RENiO3 with alkaline earth metal (AEM) elements (Be, Mg, Ca, Sr and Ba) doping. For the atomic configurations of doped RENiO3, the interstitial sites of RENiO3 are more likely to be occupied by Be, Mg and Ca atoms, whereas Sr and Ba atoms tend to replace RE atoms in RENiO3. The band gap of RENiO3 decreases after AEM doping. Moreover, the machine learning results found that the formation energy of the AEM, the relative atomic mass of the AEM, and the doping position significantly influence the band gap. Furthermore, the infrared light blocking capability, the visible light transmission, and the electronic conductivity are enhanced in AEM doped RENiO3. This study may contribute to the experimental modulation of the optical and electronic properties of RENiO3 through AEM doping.

Ash Interaction with Two Cu-Based Magnetic Oxygen Carriers during Biomass Combustion by the Chemical Looping with Oxygen Uncoupling Process.

Chemical-looping combustion (CLC) stands out as a promising method for carbon capture and storage for the purpose of mitigating climate change. The process involves the conversion of fuel facilitated by an oxygen carrier, with the resulting CO2 inherently separated from other air components. Notably, when applied to biomass combustion this process offers a pathway to achieving negative CO2 emissions. However, a significant challenge for CLC, particularly in its application to biomass, is the management of interactions between ash and oxygen carriers. Biomass-derived ashes typically contain substantial quantities of reactive ash-forming substances, such as alkaline and alkali earth elements. These interactions can impact the performance and longevity of the oxygen carrier, necessitating careful consideration and mitigation strategies in CLC systems utilizing biomass feedstocks. This study examined the interaction between biomass ash components and two recently developed oxygen carriers, Cu30MnFekao7.5 and Cu30MnFe, during combustion in a 1.5 kWth continuous unit. Both oxygen carriers achieved 100% combustion efficiency and a CO2 capture efficiency of 95% at 900 °C. Although the copper in both oxygen carriers did not exhibit any noticeable interaction with ash components, the accumulative presence of potassium and magnesium in Cu30MnFekao7.5 was identified by inductively coupled plasma and scanning electron microscopy with energy dispersive X-ray analysis, indicating an increase in the amount of both elements in the particles after combustion operation. No problems of agglomeration or fluidization were observed in any of the experiments.

Self-protected Chlorella@Mn catalyst with excellent resistance to alkali/alkaline earth metal for NOx reduction by NH3

In the selective catalytic reduction of NOx by NH3 (NH3-SCR), conventional Mn-based denitration catalysts often suffered from susceptibility to poisoning by alkali and alkaline earth metals, this paper presented an innovative self-protected Chlorella@Mn denitration catalyst. Remarkably, in the presence of high concentrations (2 wt%) of alkali and alkaline earth metal oxides, the Chlorella@Mn catalyst sustained a NOx conversion exceeding 96 % at 175 °C. At an even higher concentration (4 wt%), NOx conversion above 90 % at 175 °C, surface analysis revealed that POMn sites acted as sacrificial sites, binding to the alkali and alkaline earth metals, the Chlorella@Mn catalyst surface naturally carried a spectrum of acidic species (such as SO42−, PO3−, SiO32−), proficient in capturing alkali/alkaline earth metal effectively, elements such as S, P, and Si formed bonds with K, Na, Ca, and Mg. The synergistic protection of the active sites and the surface elements avoided the deactivation of the catalyst. The detrimental effects of high concentrations of alkali and alkaline earth metals were primarily due to promoting an excessively high valence state of Mn on the catalyst surface and the reduction or loss of NH3 adsorption and activation at Brønsted acid sites. This research provided valuable insights for advancing the development of low-temperature denitration catalysts with improved resistance to alkali and alkaline earth metal poisoning.

Surface Chemical Effects on Fischer–Tropsch Iron Oxide Catalysts Caused by Alkali Ion (Li, Na, K, Cs) Doping

Among the alkali metals, potassium is known to significantly shift selectivity toward value-added, heavier alkanes and olefins in iron-based Fischer–Tropsch synthesis catalysts. The aim of the present contribution is to shed light on the mechanism of action of alkaline promoters through a systematic study of the structure–reactivity relationships of a series of Fe oxide FTS catalysts promoted with Group I (Li, Na, K, Cs) alkali elements. Reactivity data are compared to structural data based on in situ, synchrotron-based XRD and XPS, as well as temperature-programmed studies (TPR-H2, TPC-CO, TPD-CO2, and TPD-H). It has been observed that the alkali elements induced higher carburization rates, higher basicities, and lower adsorbed hydrogen coverages. Catalyst stability followed the trend Na-Fe > unpromoted > Li-Fe > K-Fe > Cs-Fe, being consistent with the ability of the alkali (Na) to prevent active site loss by catalyst reoxidation. Potassium was the most active in promoting high α hydrocarbon formation. It is active enough to promote CO dissociative adsorption (and the formation of FeCx active phases) and decrease the surface coverage of H-adsorbed species, but it is not so active as to cause premature catalyst deactivation by the formation of a carbon layer resulting in the blocking active sites.

Ammonothermal Synthesis of Luminescent Imidonitridophosphate Ba4P4N8(NH)2:Eu2.

The structural variability of a compound class is an important criterion for the research into phosphor host lattices for phosphor-converted light-emitting diodes (pc-LEDs). Especially, nitridophosphates and the related class of imidonitridophosphates are promising candidates. Recently, the ammonothermal approach has opened a systematic access to this substance class with larger sample quantities. We present the successful ammonothermal synthesis of the imidonitridophosphate Ba4P4N8(NH)2:Eu2+. Its crystal structure is solved by X-ray diffraction and it crystallizes in space group Cc (no.9) with lattice parameters a=12.5250(3), b=12.5566(4), c=7.3882(2)Å and β=102.9793(10)°. For the first time, adamantane-type (imido)nitridophosphate anions [P4N8(NH)2]8- are observed next to metal ions other than alkali metals in a compound. The presence of imide groups in the structure and the identification of preferred positions for the hydrogen atoms are performed using a combination of quantum chemical calculations, Fourier-transform infrared, and solid-state NMR spectroscopy. Eu2+ doped samples exhibit cyan emission (λmax=498nm, fwhm=50nm/1981cm-1) when excited with ultraviolet light with an impressive internal quantum efficiency (IQE) of 41%, which represents the first benchmark for imidonitridophosphates and is promising for potential industrial application of this compound class.

Enhancing Aniline Condensation Reaction Efficiency Using Alkali and Rare Earth Element Modified USY Zeolite Catalyst: Synergistic Effects and Mechanistic Insights

Enhancing Aniline Condensation Reaction Efficiency Using Alkali and Rare Earth Element Modified USY Zeolite Catalyst: Synergistic Effects and Mechanistic Insights

Effect of CaCO3, SrCO3 and BaCO3 additions on the microstructure and electrical characteristics of SnO2-based varistor ceramics

The ceramic varistors SnO2–Co3O4–Nb2O5–Cr2O3 with the addition of CaCO3, SrCO3 or BaCO3 were sintered at temperatures 1250 and 1350°C, then their structures and electrical properties were studied. In all samples, the SnO2 cassiterite phase with a rutile-type structure and the Co2SnO4 phase with a spinel-type structure were observed. All materials exhibited a highly nonlinear dependence of the current density on the electric field with the nonlinearity coefficient 24–50. When alkaline earth metal carbonates were added, the grain size of all samples decreased and the electric field E1 increased. The addition of CaCO3 lead to the decrease of the low-field electrical conductivity of varistors. The lowest low-field conductivities 4·10-13 and 6·10-13 Ω-1 cm-1 were found in the samples with CaCO3 addition baked at 1250 and 1350°C, respectively. The observed effect is due to the increase of the potential barrier height at the SnO2 grain boundaries by 7 and 13%, respectively, and the decrease of the grain size by 26 and 28% compared to SnO2-based varistor ceramics without CaCO3 addition.

Effectively Sieving Alkali Metal Ions Using Functionalized Graphene Oxide Membranes by Exploiting Water-Repellent Interactions.

Sieving membranes capable of discerning different alkali metal ions are important for many technologies, such as energy, environment, and life science. Recently, two-dimensional (2D) materials have been extensively explored for the creation of sieving membranes with angstrom-scale channels. However, because of the same charge and similar hydrated sizes, mostly laminated membranes typically show low selectivity (<10). Herein, we report a facile and scalable method for functionalizing graphene oxide (GO) laminates by dually grafting cations and water-repellent dimethylsiloxane (DMDMS) molecules to achieve high selectivities of ∼50 and ∼20 toward the transport of Cs+/Li+ and K+/Li+ ion pairs, surpassing many of the state-of-the-art laminated membranes. The enhanced selectivity for alkali metal ions can be credited to a dual impact: (i) strong hydrophobic interactions between the incident cations' hydration shells and the water-repellent DMDMS; (ii) the efficient screening of electrostatic interactions that hamper selectivity.

Alkali metal cation adsorption–induced surface polarization in polymeric carbon nitride for enhanced photocatalytic hydrogen peroxide production

Photocatalytic hydrogen peroxide (H2O2) generation on the catalyst surface from oxygen is an electron-demanding process, making the construction of an electron-rich surface highly advantageous. In this study, a localized electric field was observed on the surface of polymeric carbon nitride (g-C3N4) when alkali metal cations were adsorbed onto it. These fields effectively inhibited surface carrier recombination and extended their lifespan, thereby enhancing H2O2 production. As a result, g-C3N4 achieved a superior H2O2 yield of 2.25 mM after 1 h in a 0.25 M K+ solution, which was 2.06 times greater than that (1.09 mM) achieved in a pure solvent. Notably, the increase in photocatalytic efficiency showed a remarkable dependence on ion species. At low concentrations, H2O2 generation efficiency was in the order of Li+ < Na+ < K+ < Rb+ < Cs+. However, after optimizing the ion concentration, the highest H2O2 production was achieved in a solution containing K+ instead of Cs+. Molecular dynamics simulations and temperature-dependent photocatalysis experiments revealed that the synergistic interaction between adsorption energy and adsorption distance was crucial in governing the extent to which alkali metal cation adsorption enhanced g-C3N4 photocatalytic H2O2 production. This study provides theoretical insights for the design of materials for electron-demanding photocatalysis and aids in understanding variations in photocatalytic behavior in natural waters.

Photoluminescence studies of Sr3P4O13: Eu3+ phosphor prepared by wet chemical method: Structural properties, charge compensation via alkali metal ions and Judd-Ofelt analysis

The Sr3P4O13:Eu3+ phosphors co-doped with alkali metal ions (A+ = Li+, Na+ and K+) were prepared by wet chemical method. The comparison with standard JCPDS data confirmed the formation of a triclinic crystalline phase with P-1(2) space group for the Eu3+ doped Sr3P4O13 phosphor and co-doped with alkali metal ions. The Li+ co-doped Sr3P4O13:Eu3+ phosphor has comparatively sharp and intense XRD patterns. The scanning electron microstructural analysis confirmed the formation of the particles size of 5 -50 μm. The comparative study of photoluminescence properties depicted that the peak positions were similar for all the prepared samples. The photoluminescence analysis of Sr3P4O13:Eu3+ phosphors show the emission in the red-orange region under the excitation of 394 nm (7F0→5L6) wavelength. Further, the charge compensation using alkali metal ions shows the larger photoluminescence intensity observed in the case of the Li+ co-doped Sr3P4O13:Eu3+ phosphors suggesting that the Li+ ion is better charge compensator among the studied alkali metal ions. Further, Judd-Ofelt (J-O) parameters were estimated for the Sr3P4O13:Eu3+ phosphors and co-doped with alkali metal ions in a series of samples. The comparison of Sr3P4O13:Eu3+ phosphors co-doped with alkali metal ions alongwith the J-O estimated parameters have been presented in the article.

Alkali Metal‐Doped Fullerenes as Hydrogen Storage—A Quantum Chemical Investigation

AbstractThe quest for alternative energy sources has been spurred by the drawbacks and environmental risks of fossil fuels, with hydrogen emerging as a viable contender. But finding materials that can effectively store hydrogen with the best adsorption energy is a major obstacle to building a hydrogen‐based economy. As a result, a significant amount of research has been conducted worldwide to examine fullerene's (C60) potential for hydrogen adsorption. The results of extensive DFT calculations are presented here, pertaining to the adsorption of hydrogen molecules onto fullerenes doped with alkali metals, namely Rubidium (Rb), Ceasium (Cs), and Fransium (Fr). The study analyzes a number of parameters, such as global properties, electronic, optical, and surface annihilation energy. These analyses are performed using the Gaussian 09 simulation package with the 6–31G/B3LYP level of theory DFT methodology. The findings show that an exothermic process is involved in the adsorption of hydrogen onto fullerene doped alkali elements, as evidenced by the negative adsorption energy. The attractive interactions between the polarized dipole of hydrogen molecules and the surface dipole of doped fullerenes can be the cause of this exothermicity. These results imply that fullerenes decorated with alkali metals are promising as likely hydrogen storage media.

Flame Photometry: For the Determination of Alkali Metals in Commercially Sold Fireworks

The alkali and alkaline earth metals such as potassium, sodium, barium and strontium are generally used as oxidizer in fireworks. The arbitrary use of these chemicals in fireworks is an acute issue responsible for higher emissions. Hence, efforts are underway to monitor these chemicals in fireworks. This work reports the precise determination of potassium and sodium in fireworks samples by flame photometry. The average deviation by flame photometry analysis was 7 to 8 % and 3 to 4 % for potassium and sodium, respectively, when the concentration of the respective metal nitrates in fireworks composition was less than 50%. The effect of different components in fireworks mixture, such as nitrate and metal precursor, were also studied to understand their impact on results. A brief study in terms of limit of detection (LOD), limit of quantification (LOQ) and dynamic range was also performed, which showed 0.42 and 3.26 mg/L as LOD and 1.29 and 9.88 mg L-1 as LOQ for the analysis of sodium and potassium, respectively. In summary, the study proved the prospective of flame photometry for determining sodium and potassium in fireworks samples.

Base-acid tandem catalytic upgrading of coal pyrolysis volatiles: the effects of alkaline earth oxides and modified HZSM-5 zeolites

Catalytic upgrading of coal pyrolysis volatiles is a promising technology to bolster the production of value-added chemicals from coal. To optimize product distribution and mitigate catalyst deactivation, this work investigated tandem catalysts combining the upper alkaline earth oxides (CaO or MgO) with the lower modified HZSM-5 (mesopore creation and Ga loading). The pre-cracking of volatiles over CaO or MgO lowered the average molecule size of tar components. The diffusion properties and aromatization of these pre-cracking-derived intermediates were improved, facilitating the secondary upgrading over HZSM-5-based catalysts, promoting the formation of aromatics. The experimental results showed that tandem CaO-HZSM-5 catalysts presented better synergy to improve the tar components as compared to MgO-HZSM-5, considering the formation of aromatics in tar. In this context, the mesopore and metal Ga were introduced into HZSM-5 to further upgrade the tar quality. The mesoporous structure for HZSM-5-meso and Ga/HZSM-5-meso promoted the conversion of aliphatic hydrocarbons into aromatics. Simultaneous introduction of mesopores and Ga synergistically increased the aromatic content in tar to 41.6% and reduced the carbon deposition to 0.88wt.%. In summary, this work elucidated the mechanism of tandem CaO-modified HZSM-5 catalysis for the upgrading of volatiles from coal pyrolysis.

Interaction of liquid titanium with zirconates and titanates of some alkaline earth metals

Abstract The article presents the results of a study of the interaction of titanium melt with of zirconates BaZrO3 and SrZrO3, as well as titanate SrTiO3 under vacuum conditions and in an inert atmosphere at normal pressure. An original titanium heating method was used during the experiments. It eliminated the melt circulation at the interface between the solid and liquid phases. The method was based on resistive electrical heating of a Grade 2 titanium alloy rod or strip pressed into BaZrO3, SrZrO3 and SrTiO3 powders. Studied the structure, elemental, and phase composition of the products formed during various (up to 300 s) contact of titanium melt with surface zirconates and titaniums. The phase composition was compared with the products obtained by heating compacts from a mixture of titanium powders with BaZrO3, SrZrO3 and SrTiO3 powders. It was shown based on the results obtained that titanium, upon contact with these ceramic materials dissolves zirconium and oxygen and reduces barium and strontium to a metallic state. Barium and strontium evaporated due to the high vapor pressure at the experimental temperature, and caused the melt to splash or form a vapor layer that reduced the interaction rate of the melt with the ceramic. When a titanium melt interacted with BaZrO3 and SrZrO3 intermediate phases were not formed in quantities sufficient for their identification. The Sr3Zr2O7 phase was formed in small quantities during heating a mixture of Ti+SrZrO3 powders. When a titanium melt interacted with SrTiO3, a layer of an intermediate phase was formed, similar in composition to TiO2. Equations for the chemical reaction of the interaction of titanium with the indicated zirconates and titanate were compiled based on the experimental data obtained. It has been shown that titanium melt weted the surface of BaZrO3, SrZrO3 powders well and poorly weted the surface of SrTiO3 powder.

The roles of celestine and barite in modulating strontium and barium water column concentrations in the northeast Pacific Ocean

The water column distributions of the alkaline earth metals strontium (Sr) and barium (Ba) were studied along a transect from Hawaii to Alaska. Despite similarity in the chemical properties of Sr and Ba, we find that changes in their concentrations along the transect are governed by different chemical and biological processes, meaning that these elements can be treated as independent variables in modern and ancient environments. Alaskan margin sediments are a particularly important source of dissolved Ba to the North Pacific, likely through a combination of saline submarine groundwater discharge and reductive dissolution of manganese (Mn) oxides. Abyssal North Pacific sediments are also a source of Ba to the bottom waters but a sink for Sr. We find that over 90 % of the water column variability in Sr concentrations is driven by precipitation and dissolution of the celestine (SrSO4) skeletons of Acantharia. However, the high Ba content of Acantharia celestine accounts for only 5–8 % of the global ocean variability in Ba concentrations in the water column. Similarly, the effects of barite (BaSO4) precipitation and/or dissolution on the marine Sr cycle is negligible, accounting for <1 % of the water column concentration structure for Sr and ∼3 % of the sedimentary Sr burial. The Sr-Ba-PO4 concentration distributions in the North Pacific are inconsistent with significant export of barite to the deep ocean and sediment. This suggests most of the barite formed at intermediate depths dissolves at similar horizons to its formation. The Ba content of phytoplankton organic matter is too low to constitute a major source for particulate Ba in the mesopelagic North Pacific, which suggests Ba is concentrated in marine aggregates by heterotrophic micro-organisms.

Mitigating anodic corrosion in aluminum–air batteries: Effects of alkali metal cation size on electrochemical performance

Anodic corrosion limits the performance of aluminum–air batteries (AABs) by reducing discharge capacity and hindering energy density. This study proposes a strategy to mitigate anodic corrosion by controlling electrolyte cations to decrease the activity of free water molecules in the anodic corrosion process. Alkali metal cations (Na+, K+, Rb+) are introduced into a 1mol dm−3 KOH solution to examine their solvation properties and effects on free water molecule activity. Results show that larger cations (Na+ < K+ < Rb+) enhance anode discharge capacity by promoting more stable discharge reactions. Raman spectroscopy reveals that as cation radius increases, free water molecule activity decreases due to increased hydration. X-ray photoelectron spectroscopy analysis shows that larger cations favor the formation of corrosion-resistant aluminum compounds like Al2O3 and Al(OH)3, due to their higher concentration in the electric double layer, inhibiting anodic corrosion. This study highlights the critical role of cation solvation in enhancing electrochemical performance and corrosion resistance of AAB anodes.

Preferential Formation of Three-layered Host-Guest Complexes of a Planar Dinuclear Metallohost with Alkali Metal Ions.

We synthesized a planar macrocyclic dinuclear nickel(II) metallohost from the corresponding macrocyclic imine ligand containing two N2O2chelate coordination sites and an O6cation binding site like 18-crown-6 as well as peripheral hexyl groups. Due to the lipophilic nature of the hexyl groups, the metallohost was soluble in less polar media where its interaction with alkali metal ions was enhanced. The binding studies by NMR spectroscopy clearly showed its strong tendency to form multi-layered structures. The metallohost formed 2:1 and 1:1 (host/guest) complexes with Na+with the two-step binding constants of logK1= 6.6 and logK2= 3.0. In contrast, its complexation with larger alkali metal ions (K+, Rb+, Cs+) preferentially gave 3:2 (host/guest) complexes when 2/3 equiv of the guest was present. The three-layered structures of these 3:2 complexes were well characterized by mass spectrometry and 2D COSY/ROESY experiments as well as DFT calculations, elucidating their unique structural feature with three chemically different environments due to the oppositely curved two [Ni(saloph)] moieties of the metallohost. Therefore, the three-layered structures were preferentially formed when larger alkali metal ions (K+, Rb+, Cs+) were complexed with the metallohost.

Mn-Na2WO4/SiO2-tridymite with improved stability and selectivity for high-pressure oxidative coupling of methane

Elevated pressures are essential for industrial chemical processes. Oxidative coupling of methane (OCM) is also preferred to be operated at high pressures. This study investigates high-pressure OCM with operando temperature visualization over the Mn-Na2WO4/SiO2 and Mn-K2WO4/SiO2 catalysts (initially with cristobalite SiO2), which have potential applicability in the selective conversion of CH4 to olefins and paraffins frequently measured at ambient pressure. At high pressure condition of 0.9 MPa, we observed the decrease in C2-4 selectivity and stability with time. During the deactivation, the hotspot generated in the catalyst bed was found to shift towards the end of the bed and sintered the catalyst in the process. High-pressure OCM condition was necessary to cause a phase transformation from SiO2-cristobalite to SiO2-tridymite, resulting from high temperatures in the presence of high H2O pressure (>100 kPa) and was found to play a major part in loss of surface area of active site (Na and K). The hotspot’s influence was reduced by increasing the CH4/O2 ratio, and treatment to form SiO2-tridymite prior to the start of the reaction was found to significantly increase the high-pressure stability. After optimizing the reaction conditions and catalyst, the C2-4 selectivity decreased only from 77.0 % to 76.5 % with a CH4 conversion of 12.7 % over 100 h at a total pressure of 901 kPa and a furnace temperature of 775 °C with Mn(2 wt%)-Na2WO4(5 wt%)/SiO2-tridymite catalyst. In addition, a practical method is proposed to design SiO2-tridymite supported alkali metal catalyst. The insights obtained could be used to design new catalysts and minimize stability issues during high-pressure OCM reactions and in other catalyst systems.

Effects of different low-temperature pyrolysis treatments on the biotoxicity of biochar derived from tobacco stalks

The pyrolytic treatment of tobacco stalk (TS) waste results in the production of a large amount of biochar, which is usually used for environmental remediation. However, little attention has been given to the effects of different pyrolysis methods on the biotoxicity of TS biochar. This study examined the effects of three different pyrolysis methods at 350 °C (fast pyrolysis, slow pyrolysis, and low-temperature carbonization) on the biotoxicity of TS biochar (Escherichia coli (E. coli) growth and wheat germination). The results revealed that the dissolved organic matter (DOM) of the three types of biochar promoted the growth of E. coli, and the maximum growth of E. coli was ranked as DOM-F350 > DOM-S350 > DOM-350. However, the DOM inhibited the growth of the wheat seeds, with the growth index (below 0.8) of the wheat seeds ranked as DOM-350 > DOM-F350 > DOM-S350. The alkali metal content, pH and humus-like substance content of biochar may be responsible for the biotoxicity of biochar through various mechanisms. In addition, TS-S350 exhibited greater biotoxicity than did TS-F350 because of the greater content of toxic nitrogen-containing organic compounds. These findings can provide reliable theoretical guidance for the effective management and safe utilization of TS waste.