Mechanism Of Chemical Transformations Research Articles

<i>In situ</i> study of heterogeneous media combustion processes by time Resolved XRD

The use of in situ diagnostic methods is required to obtain data on the structure and composition of the material in real time when studying condensed substances in the course of chemical reactions and phase transformations. We present the results on the development and application of the time-resolved X-ray diffraction method for the diagnosis of fast processes in heterogeneous condensed media, including self-propagating high-temperature synthesis. An X-ray tube was used as a radiation source. The method is based on the use of high-speed registration of XRD patterns in a wide angular interval and provides obtaining in situ data on the evolution of the crystal structure of the reactants. A high-speed linear detector and reaction chambers, an effective analysis system with a time resolution in the range of 10–1 – 102 sec has been developed on the base of a powder diffractometer. A complex of object-oriented diffraction techniques has been developed to study the dynamics of phase transitions in self-propagating high-temperature synthesis of inorganic materials, combustion of energy systems and liquid solutions, crystallization of amorphous alloys, in the analysis of the phase composition of materials in the process of heat treatment. The results obtained can be used to identify the mechanism of structural and chemical transformations in condensed matter.

PREPARATION AND PROPERTIES OF NITRIDE-CONTAINING COMPOSITES DURING COMBUSTION OF THE «SILICON – ZIRCON» MIXTURE IN NITROGEN

Nitriding of silicon with the addition of zircon (10-70%) was performed by the self-propagating high-temperature synthesis (SHS) method. The nitriding potential and the combustion rate were studied versus the mixture composition, nitrogen pressure, and the sample diameter. The maximum nitriding potential is achieved with the addition of 40 – 50% zircon to the starting mixture. Nitriding of the «silicon – zircon» mixture by the SHS method occurs in the autoscillatory mode. The macrostructure of the burned samples was shown to be heterogeneous. Combustion was impossible for the «50% silicon – 50% zircon» mixture with a sample diameter less than 30 mm and a nitrogen pressure less than 1.5 MPa. Varying the synthesis parameters (nitrogen pressure 1.5-6 MPa, sample diameter 30-60 mm), the phase composition of the synthesized products consists of α,β-Si3N4, ZrO2, Si2N2O and ZrSi2. The high-temperature interaction of the «40% silicon – 60% zircon» mixture with gaseous nitrogen was studied using the complex DSC-TG- analysis. It was found that zircon does not undergo physical and chemical transformations involving a weight change under controlled heating conditions in the range of 20 – 1500 °С. Silicon in the «silicon – zircon – nitrogen» system exhibits the properties of both a nitride-forming agent (Si3N4, Si2N2O phases are identified in the synthesized products), and a reducing agent ZrO2 with the formation of ZrSi2. The mechanism of chemical transformations during SHS nitriding of silicon with zircon is presented. The properties of the nitride-containing composites were investigated depending on the zircon content in the mixture.

Formation of a system of concepts about a chemical reaction at the level of electronic representations

The article reveals the essence of this stage of training, which consists in clarifying the scope of the concept of “chemical reaction”, deepening knowledge about the essence of a chemical phenomenon, explaining the regularities of a chemical reaction in the light of the theory of atomic structure, and the appearance of initial ideas about the mechanism of chemical transformation.

Investigation of the chemical changes during the thermal treatment of acrylonitrile‐co‐methyl acrylate‐polymer (polyacrylonitrile‐precursor) focusing on the fate of the methyl acrylate moiety

AbstractSeventeen samples of acrylonitrile (AN)‐co‐methyl acrylate (MA)‐polymer (MA content 0–11 mol%) are examined. Several selective isotopic labelings are employed (d1‐MA, d2‐MA, 13CO‐MA, CD3‐MA, d1‐AN, d2‐AN, and 15N‐AN). The thermal treatment under inert atmosphere is investigated to gain insight into the chemical transformation mechanisms concerning the MA sub‐unit. The volatiles are determined by means of evolved gas analysis (EGA) (Fourier transform infrared [FTIR] and GC/MS). Methanol is found for the first time as one decisive volatile stemming from the MA sub‐unit, next to water and carbon dioxide. In addition, methylamines are proven to be formed by reaction of ammonia with the MA sub‐unit, while a similar reaction of hydrogen cyanide (HCN) yielding in acetonitrile could be ruled out. Several volatile compounds could even be quantified. The non‐volatile polymeric material is characterized by means of simultaneous thermal analysis (differential scanning calorimetry, thermogravimetric analysis), in‐situ‐FTIR spectroscopy and sophisticated solid‐state NMR methods. Selected defined model compounds are synthesized and analyzed for comparison. Detailed reaction mechanisms for the thermal transformation are concluded from the results, pointing in particular to the importance of ammonia for all processes as stoichiometric and/or catalytic reagent.

A feasible processing-omics strategy for comprehensive evaluation of mechanisms of chemical transformation in processing Polygalae Radix

Traditional processing methods have been used to relieve toxicity and enhance a calming effect of Polygalae Radix (PR). However, up to now, there is no comprehensive study on the changes of saponins, aromatic acids, and so on (from relatively big molecules to small molecules). Here, a novel processing-omics (PO) strategy was reported. It cleverly integrated the non-targeted and targeted chemomics technology, and the simulated processing method of compounds for mining original markers, to rapidly and comprehensively evaluate mechanisms of chemical transformation among PR, PR with refined honey (HP), and PR with licorice (LP). In this strategy, the advanced ultra-high performance liquid chromatography coupled with quadrupole time-of-flight data-independent mass spectrometry (UHPLC-Q-TOF-MS E ) and HPLC platform were employed to study and collect chemical composition data of PR processing. And the combination of QI and UNIFI TM software was designed to analyze relatively big molecules for PR, HP and LP sequentially, avoiding a waste of time for the identification of extra non-markers. A total of 57 relatively big markers were identified. Six small aromatic acids were quantified by targeted chemomics, as critical markers. Importantly, the hydrolysis mechanisms of saponins, isomerization of xanthones and glycolipids, and intact mechanisms of transformation, were reported by a combination of above chemomics and the simulated processing method. This study provided a rapid and comprehensive guidance to further study on processing procedures, chemical mechanisms, and construction of quality standards. A feasible processing-omics (PO) strategy was cleverly integrated, including the non-targeted and targeted chemomics technology, and the simulated processing method of compounds for mining original markers, the mechanisms of transformation among Polygalae Radix (PR), PR with refined honey (HP) and PR with licorice (LP) were rapidly and comprehensively evaluated.

In situ/operando soft x-ray spectroscopy of chemical interfaces in gas and liquid environments

Many energy storage and energy conversion systems are based on the complexity of material architecture, chemistry, and interfacial interactions. To understand and thus ultimately control the energy applications calls for in situ/operando characterization tools. Over the years, in situ/operando soft x-ray spectroscopy has been developed for the studies of gas molecules, molecular liquids, catalytic, and electrochemical reactions. Soft x-ray spectroscopy offers electronic structure characterization of materials in energy conversion, energy storage, and catalysis regarding functionality, complexity of material architecture, and chemical interactions. It has been shown how to use the powerful in situ/operando soft x-ray spectroscopy characterization techniques of interfacial phenomena and how to reveal the mechanism of charge transfer and chemical transformation of solid/gas and solid/liquid interfaces of energy storage and catalytic materials in a realistic environment. It has been demonstrated how to overcome the challenge that soft x-rays cannot easily peek into the high-pressure catalytic or liquid electrochemical reactions. The unique design of in situ/operando soft x-ray spectroscopy instrumentation and fabrication principle and examples of experiments are presented.

Defect-Driven Oxide Transformations and the Electrochemical Interphase.

ConspectusThe redox reaction pathway is crucial to the sustainable production of the fuels and chemicals required for a carbon-neutral society. Our society is becoming increasingly dependent on devices using batteries and electrolyzers, all of which rely on a series of redox reactions. The overall properties of oxide materials make them very well suited for such electrochemical and catalytic applications due to their associated cationic redox properties and the static site-adsorbate interactions. As these technologies have matured, it has become apparent that defect-driven redox reactions, defect-coupled diffusion, and structural transformations that are both time- and rate-dependent are also critical materials processes. This change in focus, considering not only redox properties but also more complex, dynamic behaviors, represents a new research frontier in the molecular sciences as they are strongly linked to device operation and degradation and lie at the heart of various phenomena that take place at electrochemical interfaces. Fundamental studies of the structural, electronic, and chemical transformation mechanisms are key to the advancement of materials and technological innovations that could be implemented in various electrochemical systems.In this Account, we focus on recent studies and advances in characterizing and understanding the dynamic redox evolution and structural transformations that take place in model perovskites and layered oxides under reactive conditions and correlate them with degradation mechanisms and operations in electrolyzers and batteries. We show that the dynamic evolution of oxygen vacancies and cationic migration in the surface or bulk occurs at the solid-liquid interface, using a combination of different synchrotron-based X-ray spectroscopies and scattering probes. Detailed redox-structure-reactivity correlation studies show how defects and diffusion processes can be tailored to drive various physical and chemical transformations in electrolyzers and batteries. We also highlight a strong correlation between oxygen redox reactivity and structural reorganization in both model thin films and particles, helping to bridge the gap between fundamental studies of the reaction mechanism and device applications. On the basis of these findings, we discuss strategies to probe and tune the redox reactivity and structural stability of the redox-active oxide interphase toward devising efficient pathways for energy and chemical harvesting.

Combination of the endophytic manganese-oxidizing bacterium Pantoea eucrina SS01 and biogenic Mn oxides: An efficient and sustainable complex in degradation and detoxification of malachite green

Recently, Mn oxides (MnOxs) have been attracting considerable interest in the oxidation of organic pollutants. However, the reduction of MnOx in these reactions leads to the deactivation of the catalyst, which must be frequently regenerated. We evaluated the application of a manganese-oxidizing bacterium (MOB) and MnOx in removing toxic dyes. We studied the co-function of a plant-endophytic MOB, Pantoea eucrina SS01, with its bio-generated MnOx and evaluated the detoxification activity and chemical transformation mechanisms of the complex in malachite green (MG) degradation. We found a synergistic effect between MnOx and the strain. Particularly, strain SS01 could adsorb MG but could not degrade it, whereas the addition of Mn(II) promoted MG degradation by the formation of a complex containing the bacterium and MnOx aggregates (SS01-bio-MnOx), with distinct morphology characteristics. The complex showed a marked sustainability in the degradation of MG into less toxic or non-toxic metabolites. In this process, strain SS01 might have enhanced the regeneration of MnOx, accelerating MG degradation. Our data not only contribute to understanding the mechanism of MG removal by the SS01-bio-MnOx complex, but also provide a scientific basis for the future application of MOB and MnOx.

A comprehensive evaluation protocol for sulfur fumigation of ginseng using UPLC-Q-TOF-MS/MS and multivariate statistical analysis

Ginseng (Panax ginseng), a tonic and functional food in Asia and among the ten top-selling herbal remedies worldwide, is often sulfur-fumigated (SF) during post-harvest handling. In this study, a practical protocol was developed using ultra-high performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) and multivariate statistical analysis to identify characteristic SF markers, dissect chemical transformation mechanism, and control the quality of SF ginseng. The result showed that sulfur fumigation significantly altered the holistic chemical profile of ginseng by triggering chemical transformation of certain original components, 14 ginsenosides and its metabolites together with 2 potential sulfur-contained ginsenoside sulfates were screened out to be the most characteristic markers for distinguishing non-fumigated (NF) and SF ginseng. Moreover, the transformation mechanism of the sulfates of ginsenoside Rg1, Rh1 and 24(R)-pseudoginsenoside Rt5 was inferred, and which showed that in addition to hydrolysis, esterification and dehydration reaction occurred in the process of sulfur fumigation. This study shows that the comprehensive evaluation protocol-based chemical profiles and discriminated markers can be applied to quality evaluation of NF and SF ginseng and other edible or medical materials.

Environmental evaluation study of toxic elements (F, Zn, Be, Ni, Ba, U) in the underground coal gasification (UCG) residuals

Underground coal gasification (UCG) is considered to be an important means of coal utilization. However, the stability of underground coal gasification residuals has always been the focus of people’s attention. In this paper, based on the sequential chemical extraction and thermodynamic equilibrium calculation, the chemical forms and transformation mechanism of the toxic elements (TEs) were investigated. Moreover, the risk level of toxic elements to underground environment was also studied in this paper. Results showed that Zn and Ni are thiophilic elements and favored to react with S to generate ZnS and NiS in the UCG pyrolysis stage. In the 900–1300 °C reduction ash, the toxic elements (Zn, Be, Ni, Ba, and U) in the residual speciation (F4) have the large percentage. For the oxidation residuals, Be and U are intimately related with the Fe–Si–Al–O–Be–U mineral system, and F exists in the form of CaF2. According to the risk assessment code (RAC), the harmful degree of toxic elements to the underground environment decreases with rises of reaction temperature. When the reaction temperature reaches 1200 °C, the harmful degree of toxic elements to the underground environment is range in the Low risk, indicating that the underground residuals have reached the stability. The results can provide suggestions for future handing of the underground coal gasification residuals.

Internal stress-induced recrystallization and diffusive transport in CaTiO3-PbTiO3 solid solutions: A new transport mechanism in geomaterials and its implications for thermobarometry, geochronology, and geospeedometry

AbstractWe conducted a series of high-temperature experiments where single crystals of CaTiO3 were embedded in PbTiO3 powder for durations of 4 to 502 h at temperatures between 753 and 1207 °C. Combined with results from a previous study (Beyer et al. 2019), these experiments allow us to explore the influence of chemical potential gradients on the mechanisms of incorporation of Pb in CaTiO3. Unlike in the previous study where Pb diffused into CaTiO3, here we find that the rims of the CaTiO3 crystals recrystallize to form a polycrystalline aggregate of [PbxCa(1–x)]TiO3 solid solutions. The width of the recrystallized front increases with run duration, and the contact to the single crystal becomes progressively wavy. The concentration of Pb decreases within the recrystallized front toward the interior of the single crystal, and the newly formed crystals are of different chemical compositions and orientations and are themselves chemically zoned. There is a discontinuous jump in Pb-concentration at the contact of the recrystallized front with the single crystal (termed “the migrating interface”). The development of chemical concentration gradients, combined with the fact that the width of the front grows as the square-root of time indicates a role of diffusion in the process; the formation of new crystals with different composition and no orientation relation to the precursor, and the jump in concentration at the boundary between the newly formed crystals and the single crystal indicates a dissolution-precipitation type process. Thus, this is a novel mechanism where diffusion, as well as dissolution-precipitation (in the sense that the structure of the single crystal is destroyed and replaced by new crystals), occurs simultaneously in a coupled manner and neither is rate-determining. The observations in this experimental study provide several insights into the mechanisms of chemical transformation in such non-metallic materials: (1) chemical differences can trigger mechanical deformation, which in turn can control chemical fluxes; (2) newly formed crystals, even at the high temperatures of the experiments, evolve continuously in chemistry and are not of an equilibrium composition; (3) the activation energy of the overall process (~70 kJ/mol) is lower than that for diffusion and provides a more effective means of chemical transformation, even though diffusion plays a central role in the process; and (4) it underscores the role of surface/interface free energy in the evolution of the transformation process. These results have important consequences for the reading of the petrological and geochemical signatures of the rock record—notably, in addition to knowing when a phase becomes chemically stable, it is also important to know when a particular crystal of the phase begins to exist. Some possible implications for thermobarometry, isotopic dating, and geospeedometry/diffusion chronometry are discussed.

Investigation of the tribological properties of nano-scaled ZrO2 and CuO additive in automotive lubricants

To improve the fuel efficiency and the lifetime of the internal combustion engines, the lubricants and their additives have to be developed further. One of the possible future engines lubricants can be the nano-sized ceramic particles, which can provide positive tribological properties also in the presence of non-metallic surface materials. This paper presents the results of investigations with the help of ZrO2 and CuO nano-sized ceramic particles. To define the tribological properties of these additives, lubricant samples with different additive-concentrations were prepared and tribologically analysed. The frictional losses of these lubricant samples were analysed by a ball-on-disk sliding friction machine. The worn surface on the test specimens was analysed by different high-resolution microscopes. To define the functional mechanisms of the nano-additives, the worn surfaces were investigated by high resolution scanning electron microscopes. The ZrO2 additive has experimentally shown an excellent wear reduction property (over 40% wear reduction compared with the neat Group 3 base oil) at the optimum mixing concentration of 0.4wt%. Both frictional and wear reduction properties could be determined at the application of CuO additive (15-15% friction coefficient and wear scar diameter reduction) at its optimum concentration (0.5wt%). A copper-yellow layer can be seen on the worn surface of the disc specimens with CuO, which indicates the mechanism of chemical transformation to elementary copper from the cupric-oxide nanoparticle and this elementary copper can be melted on the surface, because of the applied high temperature and high loads during the experiments.

Crystallographic evidence of Watson–Crick connectivity in the base pair of anionic adenine with thymine

Utilizing an ionic liquid strategy, we report crystal structures of salts of free anionic nucleobases and base pairs previously studied only computationally and in the gas phase. Reaction of tetrabutylammonium ([N4444]+) or tetrabutylphosphonium ([P4444]+) hydroxide with adenine (HAd) and thymine (HThy) led to hydrated salts of deprotonated adenine, [N4444][Ad]·2H2O, and thymine, [P4444][Thy]·2H2O, as well as the double salt cocrystal, [P4444]2[Ad][Thy]·3H2O·2HThy. The cocrystal includes the anionic [Ad-(HThy)] base pair which is a stable formation in the solid state that has previously not even been suggested. It exhibits Watson-Crick connectivity as found in DNA but which is unusual for the free neutral base pairs. The stability of the observed anionic bases and their supramolecular formations and hydrates has also been examined by electronic structure calculations, contributing to more insight into how base pairs can bind when a proton is removed and highlighting mechanisms of stabilization or chemical transformation in the DNA chains.

Conversion of heavy crude oil with carbonate rock in the medium of water superheated steam

A series of experiments with heavy crude oil were carried out by modeling hydrothermal effects involving mineral compounds of carbonate rocks. Depending on the thermodynamic parameters of exposure, various mechanisms of chemical transformations of heavy crude hydrocarbons predominate, affecting its composition and properties. In this paper, samples of crude and converted oil were analyzed by various instrumental methods. The work on the aquathermolysis of oil was carried out in a laboratory batch unit under isothermal conditions at of 290-375°C and pressures of 1-13.5 MPa. In this work, component composition, chromatographic analysis, rheology, X-ray analysis of heavy crude and converted oil were carried out. In converted crude oil the content of light fractions boiling up to 200°C increased with increasing in the specific surface of mineral compounds under hydrothermal influence. The results of X-ray structural analysis showed the presence of chemisorption processes on the surface of mineral particles as a result of hydrothermal influence on crude oil.

Hydrothermal influence of heavy oil in the presence of minerals of carbonate rock

A series of experiments with heavy crude oil was carried out modeling hydrothermal effects involving mineral compounds of carbonate rocks. Depending on the thermodynamic parameters of exposure, various mechanisms of chemical transformations of heavy crude hydrocarbons predominate, affecting its composition and properties. In this paper, samples of crude and converted oil were analyzed by various instrumental methods. The work on the aquathermolysis of oil was carried out in a laboratory batch unit under isothermal conditions at of 290-375°C and pressures of 1-13.5 MPa. In this work, component composition, chromatographic analysis, rheology, X-ray analysis of heavy crude and converted oil was carried out. In converted crude oil the content of light fractions boiling up to 200 °C increased with increasing in the specific surface of mineral compounds under hydrothermal influence. The results of X-ray structural analysis showed presence the of chemisorption processes on the surface of mineral particles as a result of hydrothermal influence on crude oil.

Enhancing Catalytic Activity and Selectivity by Plasmon-Induced Hot Carriers.

SummaryPlasmon-assisted chemical transformation holds great potential for solar energy conversion. However, simultaneous enhancement of reactivity and selectivity is still challenging and the mechanism remains mysterious. Herein, we elucidate the localized surface plasmon resonance (LSPR)-induced principles underlying the enhanced activity (∼70%) and selectivity of photoelectrocatalytic redox of nitrobenzene (NB) on Au nanoparticles. Hot carriers selectively accelerate the conversion rate from NB to phenylhydroxylamine (PHA) by ∼14% but suppress the transformation rate from PHA to nitrosobenzene (NSB) by ∼13%. By adding an electron accepter, the as-observed suppression ratio is substantially enlarged up to 43%. Our experiments, supported by in situ surface-enhanced Raman spectroscopy and density functional theory simulations, reveal such particular hot-carrier-induced selectivity is conjointly contributed by the accelerated hot electron transfer and the corresponding residual hot holes. This work will help expand the applications of renewable sunlight in the directional production of value-added chemicals under mild conditions.

Indirect photodegradation of fludioxonil by hydroxyl radical and singlet oxygen in aquatic environment: Mechanism, photoproducts formation and eco-toxicity assessment.

Fludioxonil has been proven valuable as a broad-spectrum fungicide. However, there are concerns about its risk posed to non-target organisms in aquatic environments. In this paper, the mechanism, photoproducts transformation and eco-toxicity of fludioxonil during •OH/1O2-initiated process were systematically studied using quantum chemistry and computational toxicology. The results indicate that the two favorable pathways of •OH/1O2-initiated reactions are both occurred in pyrrole ring. It can conclude that the rate constants of •OH and 1O2 are 1.23×1010 and 3.69×107M-1s-1 at 298K, respectively, which results in half-lives of <2 days in surface waters under sunlit near-surface conditions. Based on toxicity assessments, these photoproducts showed a decreased aquatic toxicity but the majority products are still toxic. This study gives more insight into the chemical transformation mechanism of fludioxonil in aquatic environments.

An automated predictor for identifying transition states in solids

The minimum energy path (MEP) and transition state are two key parameters in the investigation of the mechanisms of chemical reactions and structural phase transformations. However, determination of transition paths in solids is challenging. Here, we present an evolutionary method to search for the lowest energy path and the transition state for pressure-induced structural transformations in solids without any user input or prior knowledge of possible paths. Instead, the initial paths are chosen stochastically by connecting randomly selected atoms from the initial to final structure. The MEP of these trials paths were computed and ranked in order of their energies. The matrix particle swarm optimization algorithm is then used to generate improved transition paths. The procedure is repeated until the lowest energy MEP is found. This method is validated by reproducing results of several known systems. The new method also successfully located the MEP for the direct low-temperature pressure induced transformation of face centered-cubic (FCC) silicon to the simple hexagonal(sh) phase and FCC lithium to a complex body centered-cubic cI16 high-pressure phase. The proposed method provides a convenient, robust, and reliable approach to identify the MEP of phase transformations. The method is general and applicable to a variety of problems requiring the location of the transition state.

Effects of speciation on uranium removal efficiencies with polyamine-functionalized silica composite adsorbent in groundwater

Uranium (Ⅵ) exists as many species in natural water systems. In the recent years, its contamination to groundwater has been reported more frequently. To investigate the effects of speciation on the removal of uranium, this work investigated the uranium adsorption behaviors of a polyamine-grafted silica composite named SAER at the concentration level of μg/L in the alkaline carbonate solutions with other four resins. Results suggested that the change of uranium speciation had minor effect on the adsorption efficiencies of SAER, except the addition of calcium. This was resulted from that the protonated tetraethylenepentamine had a much higher affinity to the electronegative uranyl-carbonate species, leading to the complete removal of uranium through the simultaneous anion exchange and chemical transformation mechanisms; Column experiments confirmed that merely a small portion of calcium while no magnesium cations were involved in the uranium adsorption in the simulated groundwater. Finally, the integrated removal mechanisms were proposed. Overall, this work demonstrated the feasibility of a novel adsorbent for the effective removal of uranium from different water matrices as well as the mechanisms underlying the interaction of uranium and the functional groups on the adsorbents. Furthermore, it enhanced the understanding of uranium removal under environmentally relevant conditions.

Research progress on formation characteristics and inhibition mechanism of dioxins during direct thermal desorption of soil

Based on the existing researches related to thermal desorption technology and dioxins, this paper provides a comprehensive review on the technological process, influencing factors of dioxins formation, and the mechanisms and measures of dioxins inhibition during the direct thermal desorption remediation of organic contaminated soil. Firstly, dioxins may be produced during different technological processes: dioxins present in contaminated soil are desorbed by heating; the organic pollutants in soil undergo molecular deconstruction and recombination, thus causing the generation of dioxins during the heating process of rotary kiln; dioxins are generated by heterogeneous catalytic reactions (including precursor and de-novo synthesis reactions) at each cooling stage in the exhaust gas purification process. Secondly, thermal desorption process parameters can also affect dioxins formation, such as heating temperature, heating time, flowing rate of carrier gas, reaction atmosphere and so on. Thirdly, the presence of metal compounds, water, carbon and chlorine source in contaminated soil can catalyze the formation of dioxins. Additionally, the characteristics of site pollution also have a certain impact on dioxins production. The addition of alkaline, sulfur, ammonium/nitrogen or sulfur-nitrogen containing compounds can inhibit the formation of dioxins during thermal desorption. At the end of the paper, the challenges of dioxin inhibition during thermal desorption are summarized, including the unclear chemical transformation mechanisms of various pollutants, the development of high-efficiency and practical inhibitors, etc. In addition, some future research directions are prospected.