Chlorination Reaction Research Articles

Sustainable synthesis of fine chemicals and polymers using industrial chlorine chemistry.

To achieve sustainable resource circulation, preparation of reactive species from stable compounds is unavoidable. Chlorine chemistry is an eco-friendly methodology to address this demand. Chlorine is industrially produced from sodium chloride (NaCl), an abundant natural resource in oceans. Chlorine provides various chemical products, including polymers, through chlorination and subsequent conversion reactions. In these reactions, the byproducts are usually hydrogen chloride, which is commercially utilized as hydrochloric acid and is finally neutralized to NaCl after use. Therefore, chlorine chemistry enables fine chemical production from NaCl with almost no wastage. This review provides an overview of the synthesis of fine chemicals and polymers using chlorine chemistry and discusses them from the perspective of sustainability.

Unveiling the Critical Pathways of Hydroxyl Radical Formation in Breakpoint Chlorination: The Role of Trichloramine and Dichloramine Interactions.

Chlorination of ammonia or chloramine-containing waters induces breakpoint chlorination reactions, producing a hydroxyl radical (•OH), but enhances the formation of undesirable N-nitrosamines. The prevailing view attributes •OH formation to a nitrosyl intermediate derived from the hydrolysis of dichloramine, but this pathway is unlikely at neutral or acidic pH. This study reveals a novel mechanism where •OH is generated via interactions between trichloramine (NCl3) and dichloramine (NHCl2), which also form nitrosation agents. Our experiments demonstrated that the NCl3-NHCl2 interaction degrades micropollutants with kinetics 2-3 times faster than breakpoint chlorination. Using electron paramagnetic resonance, we detected •OH in the NCl3-NHCl2 reaction. Micropollutant removal was unimpaired under low dissolved oxygen (O2(aq)) conditions, aligning with negligible O2(aq) changes during the NCl3-NHCl2 reaction and suggesting O2(aq) does not participate in •OH formation. Using benzene as a probe in 18O-labeled H2O, we confirmed water contributes to the oxygen source of •OH in NCl3-NHCl2 interactions, through which parallel reactions occur, leading to the formation of one mole of •OH alongside 1.92 mol of N2. A kinetic model developed in this study accurately predicted •OH and N2 and demonstrated the NCl3-NHCl2 interaction as the primary pathway for •OH formation in breakpoint chlorination, providing new insights into breakpoint chemistry.

Unveiling the Geometric Site Dependence of Co‐Based Spinel Oxides in the Halogen Evolution Reaction

AbstractCobalt‐based spinel oxides, such as Co3O4, have emerged as promising electrocatalysts for chlorine and bromine evolution reactions (CER and BrER) in recent years. However, the role of Co valence in determining the exceptional performance of Co3O4 for both CER and BrER remains ambiguous due to the coexistence of both octahedrally coordinated Co3+ (Co3+Oh) and tetrahedrally coordinated Co2+ (Co2+Td) sites, despite their high catalytic activity and stability. Herein, combining experiment results and electrochemical data analysis, the Co3+Oh site functions as the primary active site for CER is demonstrated. In contrast, for BrER, both Co3+Oh and Co2+Td sites exhibit good catalytic activity, with Co3+Oh sites displaying better BrER catalytic performance than Co2+Td sites. To further enhance the CER catalytic activity of the Co3+Oh site, inert Co2+Td is replaced with Cu2+ cations. As expected, CuCo2O4 featuring an optimized Co3+Oh site demonstrates an overpotential of 24 mV at a current density of 10 mA cm−2 while exhibiting exceptional stability for ≈60 h, surpassing the performance of the majority of non‐noble and even noble metal‐based electrocatalysts reported to date. Therefore, the study elucidates the significance of geometric configuration‐dependent activity in electrocatalytic halogen evolution reactions.

Effect of bromide on the degradation kinetics of antibiotic resistance genes during water chlorination

Degradation of antibiotic resistance genes (ARGs) in water chlorination can be influenced by bromide (Br−), a common component in water matrices; however, detailed kinetic information on this process is limited. This study investigated the degradation kinetics tetA and blaTEM-1 genes, contained within the plasmid pWH1266, when exposed to bromine, chlorine, and chlorine with varying concentrations of Br− across a pH range of 7.0–8.5. The degradation of four ARG amplicons, measured using quantitative polymerase chain reaction, was observed to pursue second-order kinetics with bromine, exhibiting k of 4.0 × 102 − 1.6 × 103 M−1 s−1 at pH 7.0 and 2.6 × 102 − 9.6 × 102 M−1 s−1 at pH 8.5. These k values increased linearly with the length of the ARG sequences (209–1136 bps), yielding sequence-independent k of 1.2 and 7.4 × 10−1 (M AT + GC)−1 s−1 at pH 7.0 and 8.5, respectively. The degradation rate of ARGs during chlorination increased with rising Br− concentration due to the bromine formation through the reaction between chlorine with Br−, which subsequently degrades ARGs more rapidly than chlorine. This behavior was successfully simulated using a kinetic model derived from the reaction kinetics of bromine and chlorine reactions with ARGs. The existence of dissolved organic matter extracts only marginally decreased the enhanced degradation of ARGs with Br−, while ammonia significantly inhibited this process during chlorination, both with and without Br−, due to the low reactivity of NH2Cl and NH2Br toward ARGs. These findings highlight the importance of Br− in ARG degradation during water chlorination and the need for further studies in diverse water matrices.

Enhancing hot corrosion resistance of N-doping NiCoCr-based superalloy coatings fabricated by directed energy deposition in mixed molten salts

Here, a NiCoCr-based superalloy coating has been developed in ultra-supercritical environments. However, optimizing the coating composition to enhance the anti-corrosion performance remains a formidable challenge. This research introduced an innovative N-doping strategy to enhance the hot corrosion resistance of the coating by utilizing directed energy deposition. The hot corrosion behavior at 700 °C of the coating with N-doping reinforcement was investigated. Detailed characterizations of the microstructural evolution and corrosion products were conducted. The results showed that the improvement of hot corrosion resistance was attributed to the continuous protective film retained in the N-doping reinforced coating, which inhibited the inward diffusion of corrosive media to retard the chlorination and sulfuration reaction. This work provides new insight into the design of corrosion-resistant superalloys and highlights the potential of N-doping superalloy coating in extreme environments.

Reactivity, Pathways, and Iodinated Disinfection Byproduct Formation during Chlorination of Iodotyrosines Derived from Edible Seaweed.

Iodine derived from edible seaweed significantly enhances the formation of iodinated disinfection byproducts (I-DBPs) during household cooking. Reactions of chlorine with monoiodotyrosine (MIT) and diiodotyrosine (DIT) derived from seaweed were investigated. Species-specific second-order rate constants (25 °C) for the reaction of hypochlorous acid with neutral and anionic MIT were calculated to be 23.87 ± 5.01 and 634.65 ± 75.70 M-1 s-1, respectively, while the corresponding rate constants for that with neutral and anionic DIT were determined to be 12.51 ± 19.67 and 199.12 ± 8.64 M-1 s-1, respectively. Increasing temperature facilitated the reaction of chlorine with MIT and DIT. Based on the identification of 59 transformation products/DBPs from iodotyrosines by HPLC/Q-Orbitrap HRMS, three dominant reaction pathways were proposed. Thermodynamic results of computational modeling using density functional theory revealed that halogen exchange reaction follows a stepwise addition-elimination pathway. Among these DBPs, 3,5-diiodo-4-hydroxy-benzaldehyde and 3,5-diiodo-4-hydroxy-benzacetonitrle exhibited high toxic risk. During chlorination of MIT and DIT, iodinated trihalomethanes and haloacetic acids became dominant species at common cooking temperature (80 °C). These results provide insight into the mechanisms of halogen exchange reaction and imply important implications for the toxic risk associated with the exposure of I-DBPs from household cooking with iodine-containing food.

Unraveling the influence of deposited layers on Ti/RuO2 anodes to define the electroactivity of oxygen evolution and active chlorine reactions

Ti/RuO2 were synthesized using Pechini method with 4, 8 and 16-RuO2 layers, to account for the influence of their physical properties upon their behavior towards reactive oxygen evolution (OER) and active chlorine reaction (CER). Rietveld refinement conducted using X-Ray diffraction (XRD) measurements confirmed the formation of TiO2 (P42/mnm) and RuO2 (P42/mnm, poor rutile-type), which grew on a thin native TiO2 layer forming a solid solution. This analysis corroborated that the smaller RuO2 crystallite size was obtained using 4-layers, unlike the trend of increasing sizes with more layer’s numbers. This situation is not conducive to accessing reactive sites and electronic conduction issues. Interestingly, exchange current densities (j0) in NaCl(aq) presence were higher than Na2SO4(aq) for 4 and 8-layers, evidencing an inhibition of OER to catalyze CER due to RuO2. This behavior is not related to the electroactive area, since this property decreased by rising the number of layers. The 4-layers anode showed the largest production of CER after 20 min of electrolysis, but the lower accelerated lifetime (ALT). Thus, the stacking of more RuO2 layers creates a higher resistance for charge transfer. Likewise, Ti substrate is important to define the CER catalysis, whence a low coverage of RuO2 will be more catalytic than a high coverage of this oxide. The electrode activity was assessed through the removal of 132 µmol L−1 Acetaminophen (ACM), revealing that 93, 80, and 50 % was removed using 4, 8 and 16-layers of RuO2 coating respectively, at 10 mA and 0.1 molL−1 NaCl. Density functional theory (DFT) and high-performance liquid chromatograph coupled to a mass spectrometer (HPLC-MS) were used to propose a reaction mechanism for ACM degradation. Four byproducts with m/z ACM-I-1 (C8H5Cl4NO3) 304, ACM-I-2 (C8H6Cl3NO3) 274, ACM-I-3 (C6H4Cl3NO2) 227, and ACM-I-4 (C6H3Cl3O3) 229 were identified corresponding to the addition of chlorine in the amide group and aromatic ring, as a susceptible site to electrophilic attack.

Biomimetic and Concise Total Syntheses of Prenylated and Bicyclo[2.2.2]diazaoctane-Containing Indole Alkaloids Including Taichunamide A, Notoamide N and Versicolamide B.

Total syntheses of the title prenylated indole alkaloids together with seven others are reported. Biogenetic considerations have been employed in devising the reaction sequences leading to these targets with, in the opening stages, electrochemically-derived indole-3-carboxaldehyde 15 being subject to an aldol-type condensation reaction involving diketopiperazine derivative 19. This led, after prototopic shifts, intramolecular Diels-Alder cycloaddition and hydrolysis/deprotection steps, to the racemic forms of the bicyclo[2.2.2]diazaoctane-containing natural product stephacidin A (2) and its C6 epimer 3. Epoxidation of the last compound afforded, following rearrangement of the primary oxidation products, a mixture of (±)-taichunamide A [(±)-4] and (±)-versicolamide B [(±)-7]. Related protocols allowed for the conversion of (±)-stephacidin A [(±)-2] into (±)-notoamide B [(±)-5]. Analogous aldol condensation, nucleophilic reduction, and epoxidation steps led to the formation of (-)-notoamide E and its conversion into notoamide C as well as the indole fragmentation product amoenamide E. A late-stage chlorination reaction applied to (±)-stephacidin A provided access to the spirocyclic oxindole (±)-notoamide N [(±)-6].

Hydrophobic TaOx Species Overlayer Tuning Light-Driven Methane Chlorination with Inorganic Chlorine.

Halogenated methane serves as a universal platform molecule for building high-value chemicals. Utilizing sodium chloride solution for photocatalytic methane chlorination presents an environmentally friendly method for methane conversion. However, competing reactions in gas-solid-liquid systems leads to low efficiency and selectivity in photocatalytic methane chlorination. Here, an in situ method is employed to fabricate a hydrophobic layer of TaOx species on the surface of NaTaO3. Through in-situ XPS and XANES spectra analysis, it is determined that TaOx is a coordination unsaturated species. The TaOx species transforms the surface properties from the inherent hydrophilicity of NaTaO3 to the hydrophobicity of TaOx/NaTaO3, which enhances the accessibility of CH4 for adsorption and activation, and thus promotes the methane chlorination reaction within the gas-liquid-solid three-phase system. The optimized TaOx/NaTaO3 photocatalyst has a good durability for multiple cycles of methane chlorination reactions, yielding CH3Cl at a rate of 233 µmol g-1 h-1 with a selectivity of 83%. In contrast, pure NaTaO3 exhibits almost no activity toward CH3Cl formation, instead catalyzing the over-oxidation of CH4 into CO2. Notably, the activity of the optimized TaOx/NaTaO3 photocatalyst surpasses that of reported noble metal photocatalysts. This research offers an effective strategy for enhancing the selectivity of photocatalytic methane chlorination using inorganic chlorine ions.

Long-term straw return enhanced the chlorine reactivity of soil DOM: Highlighting the molecular-level activity and transformation trade-offs

Chemical properties and molecular diversity of dissolved organic matter (DOM) in agricultural soils are important for soil carbon dynamics and chlorine activity. Yet the chlorine reactivity of soil DOM at the molecular level under agricultural management practices remains unidentified. Here, we investigated the chlorine reactivity of soil DOM under long-term straw return and the molecular activities and transformations during chlorination. The 9-year straw return enhanced the chlorine reactivity of soil DOM, leading to increases in the production of traditional disinfection byproducts (DBPs) and decreases in the formation of emerging high molecular weight DBPs. C17HnOmCl1–2 and C22HnNmOzCl were the highest relative abundances of emerging DBPs. The emerging DBPs were primarily generated through chlorine substitution reactions, with their precursors exhibiting higher H/Cwa (1.47) and O/Cwa (0.41) ratios under straw return. The molecular transformation ability and inactive molecules of soil DOM under long-term straw return were reduced after chlorination, resulting in increased DOM instability. Chlorination led to a shift in the thermodynamic processes of soil DOM molecules from thermodynamically limited to thermodynamically favorable processes, and lignin-like compounds displayed higher potentials for transformation into protein/amino sugar-like compounds. C19H26O6 was identified as a sensitive formula for tracing chlorine reactivity under straw return, and a network illustrating the generation of DBPs from C19H26O6 was established. Overall, these results highlighted the strong chlorine reactivity of soil DOM under long-term straw return.

Br-to-Cl Transformation Guided the Formation of Polyhalogenated Dibenzo-p-dioxins/Dibenzofurans.

Polyhalogenated dibenzo-p-dioxins/dibenzofurans (PXDD/Fs) are commonly released into the environment as byproducts of combustion processes, accompanied by flue gases. Chlorinated (Cl) and brominated (Br) precursors play crucial roles in forming PXDD/Fs. However, the specific contributions of Cl-precursors and Br-precursors to PXDD/Fs formation have not been fully elucidated. Herein, we demonstrate that the formation of Br-precursors can increase the fraction of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) congeners substituted at specific positions, such as 1,2,3,4,6,7,8-HpCDD, OCDD, 2,3,4,7,8-PeCDF, and 2,3,4,6,7,8-HxCDF. This is attributed to the electrophilic chlorination reaction of the Br-precursors, which includes the Br-to-Cl transformation pathway, following the principle of regioselectivity. The observed formation of polybrominated/chlorinated dibenzo-p-dioxins/benzofurans (PBCDD/Fs) from 1,2-dibromobenzene (1,2-DiBBz) as a Br precursor provides direct evidence supporting the proposed Br-to-Cl transformation. Quantum chemical calculations are employed to discuss the principle of regioselectivity in the Br-to-Cl transformation, clarifying the priority of the position for electrophilic chlorination. Additionally, the concentration of PCDD/Fs formed from 1,2-DiBBz is 1.6 μg/kg, comparable to that of polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) (2.4 μg/kg), highlighting the potential of brominated organic pollutants as precursors for PCDD/Fs formation. This study provides three potential pathways for PCDD/Fs formation from Br-precursors, establishing a theoretical foundation for elucidating the formation mechanism of PXDD/Fs in the coexistence of Cl and Br.

Atmospheric chemistry of CF3CHFCF2OCH3 (HFE-356mec3) and CHF2CHFOCF3 (HFE-236ea1) initiated by OH and Cl and their contribution to global warming.

The kinetic study of the gas-phase reactions of hydroxyl (OH) radicals and chlorine (Cl) atoms with CF3CHFCF2OCH3 (HFE-356mec3) and CHF2CHFOCF3 (HFE-236ea1) was performed by the pulsed laser photolysis/laser-induced fluorescence technique and a relative method by using Fourier Transform infrared (FTIR) spectroscopy as detection technique. The temperature dependences of the OH-rate coefficients (kOH(T) in cm3s-1) between 263 and 353K are well described by the following expressions: 9.93 × 10-13exp{-(988 ± 35)/T}for HFE-356mec3 and 4.75 × 10-13exp{-(1285 ± 22)/T} for HFE-236ea1. Under NOx-free conditions, the rate coefficients kCl at 298K and 1013mbar (760Torr) of air were determined to be (2.30 ± 1.08) × 10-13 cm3s-1and (1.19 ± 0.10) × 10-15 cm3s-1, for HFE-356mec3 and HFE-236ea1, respectively. Additionally, the relative kinetic study of the Cl + CH2ClCHCl2 reaction was investigated at 298K, as it was used as a reference reaction in the kinetic study of the Cl-reaction with HFE-356mec3 and discrepant rate coefficients were found in the literature. The global atmospheric lifetimes were estimated relative to CH3CCl3 at the tropospheric mean temperature (272K) as 1.4 and 8.6years for HFE-356mec3 and HFE-236ea1, respectively. These values combined with the radiative efficiencies for HFE-356mec3 and HFE-236ea1 derived from the measured IR absorption cross sections(0.27 and 0.41 W m-2 ppv-1) yield global warming potentials at a 100-yrs time horizon of 143 and 1473, respectively. The contribution of HFE-356mec3 and HFE-236ea1 to global warming of the atmosphere would be large if they become widespread increasing their atmospheric concentration.

Recent Advances in Direct Regioselective C-H Chlorination at Aromatic and Aliphatic.

Direct installation of key functionalities in a molecule through C-H bond activation is one of the thrust areas as well as challenging task in organic synthesis. Particularly, introduction of chlorine in a molecule imparts additional benefits for further functionalizations as well as improves the electronic behaviour such as lipophilicity and polarity towards drug development process. The chlorinated molecules have also been established as efficient biologically relevant scaffolds. Current manuscript has been focused on the direct installation of the chlorine atom at various aromatic and aliphatic positions to produce functional molecules. The key highlight of the manuscript belongs to the site selectivity (regioselectivity) for the installation of chlorine functionality. Manuscript describes the advanced methods developed for the direct C-H chlorination reactions and further simplified for the chlorination reactions at various positions including aromatic (o-, m-, and p-), benzylic, heteroaromatic, and aliphatic positions. Directing groups (DGs) and the coordination with the catalyst is the key for the enhancement of regioselectivities during direct C-H chlorination reactions.

Optimization of process parameters for selective chlorination and volatilization in FeO-Cu2O-CaCl2 system

Selective chlorination and volatilization is an effective approach for element separation in non-ferrous metallurgical processes, and has also been used for the separation of iron oxide and copper oxide within steel industry. In this work, to determine and optimize the conditions for copper and iron separation in FeO-Cu2O-CaCl2 system, a series of orthogonal experiments were carried out to investigate the effects of reaction temperature, holding time, mole ratio of CaCl2 to Cu2O (n(CaCl2)/n(Cu2O)), and gas flow rate on the separation efficiency. Results demonstrated that both reaction temperature and n(CaCl2)/n(Cu2O) take significant effects on the final copper volatilization ratio. In contrast, the gas flow rate and holding time shows a negligible influence on the effect of separation between copper and iron. By increasing the reaction temperature and n(CaCl2)/n(Cu2O), the copper volatilization ratio significantly increases, while the iron volatilization ratio remains at a low level. When the reaction temperature was 1273 K, the holding time was 90 min, n(CaCl2)/n(Cu2O) was 2.0, and the gas flow rate was 100 mL·min−1, the copper volatilization ratio reached 51.08 % and the iron volatilization ratio was only 6.52 %. The chlorination reaction rate of copper was controlled by chemical reaction and the apparent activation energyEa was 57.17 kJ/mol.

Metal Chloride‐Induced Hydrogen Transfer Enables Efficient Conversion of Aromatic Hydrocarbons for Sodium Storage

AbstractThe cost‐effective synthesis of high‐performance hard carbons (HCs) is a key step of sodium‐ion batteries toward practical applications. Considering the rich resource of low‐value aromatic hydrocarbons (e.g., pitch), there is tremendous interesting in its conversion into value‐added HCs. Unfortunately, it still lacks an efficient way for the synthesis, in addition to the time‐consuming oxygen contamination of the carbon framework. Herein, a universal strategy is reported that enables the efficient synthesis of HCs from pitch by modulating hydrogen transfer using metal chlorides. CuCl2 is selected as the model modulator and the effect of different metal chlorides (FeCl3, AlCl3, ZnCl2, and MgCl2) are further explored. Based on material characterizations and density functional theory calculation employing 1‐methylnaphthalene as the model molecule, it shows that the hydrogen capture and chlorination reactions mediated by CuCl2 and FeCl3 are thermodynamically favored, which promote the crosslinking of pitch to form HCs. After optimization, the derived HC exhibits superior performance of reversible capacity of 304.8 mAh g−1 and a high initial Columbic efficiency of 88.4%. These discoveries provide new insights into the synthesis of HCs from aromatic hydrocarbons, facilitating their utilization in electrochemical energy storage.

Complexation with Metal Ions Affects Chlorination Reactivity of Dissolved Organic Matter: Structural Reactomics of Emerging Disinfection Byproducts.

Metal ions are liable to form metal-dissolved organic matter [dissolved organic matter (DOM)] complexes, changing the chemistry and chlorine reactivity of DOM. Herein, the impacts of iron and zinc ions (Fe3+ and Zn2+) on the formation of unknown chlorinated disinfection byproducts (Cl-DBPs) were investigated in a chlorination system. Fe3+ preferentially complexed with hydroxyl and carboxyl functional groups, while Zn2+ favored the amine functional groups in DOM. As a consequence, electron-rich reaction centers were created by the C-O-metal bonding bridge, which facilitated the electrophilic attack of α-C in metal-DOM complexes. Size-reactivity continuum networks were constructed in the chlorination system, revealing that highly aromatic small molecules were generated during the oxidation and decarbonization of metal-DOM complexes. Molecular transformation related to C-R (R represents complex sites) loss was promoted via metal complexation, including decarboxylation and deamination. Consequently, complexation with Fe3+ and Zn2+ promoted hydroxylation by the C-O-metal bonding bridge, thereby increasing the abundances of unknown polychlorinated Cl-DBPs by 9.6 and 14.2%, respectively. The study provides new insights into the regulation of DOM chemistry and chlorine reactivity by metal ions in chlorination systems, emphasizing that metals increase the potential health risks of drinking water and more scientific control standards for metals are needed.

ClSO and ClSO2 photochemistry: Implications for the Venusian atmosphere.

The electronic structure and spectroscopy of ClSOx (x = 1 and 2) isomers were investigated using coupled cluster theory and multireference interaction methods. In this study, the equilibrium geometry and harmonic vibrational frequencies of these isomers in their ground electronic state were shown. Our analysis of the vertical excitation energy and potential energy surface showed the photochemical instability of ClSO for wavelengths below 280nm. Furthermore, the photodissociation of ClSO was unlikely to cause the formation of diatomic ClS. At the same time, ClSO could form atomic chlorine and SO as a result of photodissociation through the repulsive states. In the case of ClSO2, a novel weakly bound Cl-SO2 isomer was identified, indicating the potential influences on the chlorine and SO2 reactions. The potential energy surface of the most stable ClSO2 isomer also indicated the potential production of SO2 in both its ground and excited states. In addition, the electronic spectrum of ClSO2 was predicted to be broad, with numerous significant peaks in the near-UV‒Vis range. Valuable new insights into the chemical role of chlorine and sulfur in Venus's atmosphere were provided, along with a discussion of a potential mechanism contributing to the H2O and SO2 depletion in Venus's atmosphere.

Co-Extraction of Aluminum and Silicon and Kinetics Analysis in Carbochlorination Process of Low-Grade Bauxite.

Addressing the issue that the Bayer process is not suitable for low-grade bauxite, carbochlorination was proposed to recover aluminum and silicon from low-grade bauxite. This study focused on the behavior of aluminum and silicon during the carbochlorination process of low-grade bauxite. The impact of various process parameters on the chlorination efficiency was investigated, and the chlorination mechanism and kinetics of aluminum and silicon chlorination in bauxite were analyzed and discussed. Under optimal experimental conditions, the chlorination efficiency of Al2O3 and SiO2 reached 94.93% and 86.32%, respectively. The carbochlorination of aluminum and silicon in bauxite adhered to a shrinking, unreacted core model governed by gas diffusion within the product layer. This process can be bifurcated into two stages. Additionally, calculations were conducted to determine the apparent activation energy and reaction order of the chlorination processes involving Al2O3 and SiO2. Examining the chlorination mechanism revealed that the bauxite carbochlorination encompasses transformations among various minerals. Notably, the aluminum component prefers to participate in the carbothermal chlorination reaction over silicon.

Vicinal effect on chlorination of diols

The vicinal effect on chlorination reactions of diols was investigated by computational methods. Applying density functional theory (DFT) combined with polarizable continuum model (PCM) and explicit solvent molecules, we demonstrated the effect of hydration on the leaving and vicinal hydroxyl group in SN2 reactions of selected alcohols. Our results point out to the importance of intermolecular hydrogen bonds as a stabilizing factor in reaction pre-complexes and alcohols with vicinal hydroxyl groups, highlighting the importance of solute-solvent network formation. This indicates the significance of adequately describing the solvent in the study of reaction mechanisms, in special when the interaction with solute molecules and ions are strong. Also, we found a “vinical effect” on the reactivity, in other words, alcohols with vicinal hydroxyl groups exhibit higher activation energies when compared to related monoalcohols. Moreover, 1,3-propanediol and 1,3-butanediol present the highest activation energies.

Novel pathway of stabilized Cu2S volatilization by derivated CH3Cl

Stabilized heavy metals-containing phases and low chlorine utilization limit heavy metals chlorination reactions. The traditional method of adding chlorinating agents can promote heavy metals chlorination volatilization, but the limiting factor has not been resolved and more chlorides are emitted. Herein, a new reaction pathway to promote heavy metals chlorination volatilization through the transformation of stabilized heavy metals-containing phases and chlorine species by the addition of biomass at the sintering is first reported. The Cu volatilization efficiency increased sharply from 50.50% to 93.21% compared with the control, Zn, Pb, and Cd were nearly completely volatilized. Results show that the biomass carbonization process was more important for Cu chlorination volatilization. Stabilized heavy metals-containing phases were converted from Cu2S to CuO and Cu2O with the biochar and oxygen, increasing the activity of Cu. The chlorine species KCl reacted with CH3-containing groups to form CH3Cl, which reacted with CuO with a lower Delta G than HCl and Cl2, increasing the tendency for the conversion of CuO to CuCl. Cu chlorination volatilization process, following shrinking core kinetic model and controlled by chemical reactions. The outcomes fundamentally addresses the limiting step for heavy metals chlorination volatilization, supporting the incineration fly ash harmless treatment.