Thiophenic Sulfur Research Articles

Desulfurization of simulated and commercial liquid fuel on nano-ZnO fabricated walnut shells.

The current investigation involved the development of activated carbon, juglans regia activated carbon (JRACs), from walnut shells, scientifically known as Juglans regia. The ZnO nanorods were loaded on the activated carbon and referred to as ZnO@JRACs. Desulfurization efficiency was assessed through batch adsorption and compared to commercial activated carbon known as DARCO. The materials were characterized using PXRD (powder X-ray diffraction), FTIR (Fourier-transform infrared spectroscopy), ICP-AES (inductively coupled plasma atomic emission spectroscopy), BET (Brunauer-Emmett-Teller) surface area analysis, TEM (transmission electron microscopy) imaging, and TGA (thermal gravimetric analysis). The findings indicated that the materials have oxygen functionalities, a porous morphology, and a substantial specific surface area (BET) of 1269.92 m2/g for ZnO@JRACs. Zn atom concentration in the ZnO@JRACs surface was determined to be 1.16 atomic percent using ICP-AES. Desulfurization experiments were conducted on three liquid fuels, namely a single component model fuel, MSF (multicomponent simulated fuel), and commercial fuel (kerosene), under optimized conditions (8g/L adsorbent dosage in 10mL of fuel, 15min of contact time at room temperature). The conditions effectively removed ~ 98.9% of dibenzothiophene (DBT) from the single component model fuel. The observed order for adsorption capacity is as follows: ZnO@JRACs (63.6mgg-1) > JRACs (46.3mgg-1) > DARCO (26.1mgg-1). The analysis of multicomponent simulated fuel (MSF) using gas chromatography-flame photometric detector (GC-FPD) revealed significant removal percentages for different types of thiophenic sulfur. Specifically, the removal percentages were ~ 46.2%, 97.6%, and 99.4% for benzothiophene, dibenzothiophene, and 4, 6-dimethyldibenzothiophene, respectively. Kinetic studies have shown that the adsorption process is governed by a pseudo second-order reaction. Additional thermodynamic studies were conducted to further investigate the mechanism of adsorption. The spent synthesized composite ZnO@JRACs were thermally regenerated and can be reused for up to four cycles.

Maximizing Thiophene–Sulfur Functional Groups in Carbon Catalysts for Highly Selective H2O2 Electrosynthesis

Maximizing Thiophene–Sulfur Functional Groups in Carbon Catalysts for Highly Selective H₂O₂ Electrosynthesis

Enhanced persulfate activation for sulfadiazine degradation by N, S self-doped biochar from sludge and sulfonated lignin: Emphasizing the roles of graphitic nitrogen and thiophene sulfur

Biochar derived from sludge is recognized for its sustainable and cost-effective role in advanced oxidation processes, yet its restricted catalytic capacity poses significant challenges. In this work, nitrogen (8.43 at%) and sulfur (1.39 at%) co-doped biochar (ML-SDBC) featuring a large surface area of 161.14 m2/g was synthesized by the pyrolysis of sewage sludge and sulfonated lignin without external dopants. In the synthesis of ML-SDBC, graphitic nitrogen and thiophene sulfur were efficiently integrated into the carbon framework. Furthermore, the resulting biochar notably outperformed sludge-derived biochar (SDBC) in activating peroxymonosulfate (PMS) for sulfadiazine (SDZ) degradation, achieving a 31.9% higher removal rate within 120 min and exhibiting a rate constant (kobs) of 1.73×10−2 min−1, effectively tripling the efficiency compared to that of SDBC-driven processes. The degradation rate consistently exceeded 85% across a wide pH range of 3–9. Mechanistic analysis exhibited that degradation processes involved radical and non-radical pathways, with 1O2 playing a prominent role. Furthermore, density functional theory (DFT) calculations revealed that the catalytic potential in ML-SDBC would benefit from the synergistic interaction between graphitic nitrogen and thiophene sulfur. This study presents a novel synthesis of heteroatom-doped biochar from waste, offering a sustainable solution to antibiotic pollution and waste management challenges.

Unveiling the biomedical potential of thiophene‐derived Schiff base complexes: A comprehensive study of synthesis, spectral characterization, antimicrobial efficacy, antioxidant activity, and computational insights

In our pursuit of designing potent bioactive compounds, we synthesized six novel tellurium (IV) complexes through the condensation of 5‐methyl‐2‐thiophene carboxaldehyde and p‐nitroaniline. These compounds underwent rigorous investigation using various analytical techniques (TGA, SEM, EDAX, and powder XRD) and spectral analyses (NMR, mass spectrometry, UV–Vis, and FTIR). Spectroscopic analysis suggested an octahedral geometry for the complexes, revealing chelation through the thiophene sulfur and azomethine nitrogen atoms. Thermal analysis indicated a three‐step degradation process, ultimately leaving behind metal oxide as the end product. We conducted in‐vitro antimicrobial screening using the broth micro‐dilution method, highlighting the significant antimicrobial and antioxidant properties of complexes 3c and 3d, as well as the potent antimicrobial activity of 3b and 3f against various bacterial strains, including Candida albicans. To further substantiate our findings, we performed advanced computational analyses, including molecular docking, pharmacophore modeling, DFT, MESP, and ADMET studies. Molecular docking validated our antimicrobial results, whereas pharmacophore models enhanced our understanding of molecular interactions with proteins, potentially identifying novel bioactive compounds. Furthermore, DFT and MESP investigations underscored the superior biological efficacy of tellurium (IV) complexes over thiophene‐derived ligands, emphasizing their potential as therapeutic agents. ADMET analysis revealed their favorable profile as precursors for drug development with minimal adverse effects. In summary, our research seamlessly integrates experimental and theoretical aspects, offering innovative insights into drug design and potential applications in pharmaceuticals. This study represents a significant milestone, paving the way for future advancements in the field of pharmaceutical science.

Structural Characterization and Molecular Model Construction of Lignite: A Case of Xianfeng Coal

The object of the study is lignite. Analytical testing techniques, such as elemental analysis, 13C nuclear magnetic resonance (13C NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM), were used to acquire information on the structural parameters of lignite. The aromaticity of Xianfeng lignite is 43.57%, and the aromatic carbon structure is mainly naphthalene and anthracene/phenanthrene. The aliphatic carbon structure is dominated by cycloalkanes, alkyl side chains, and hydrogenated aromatics. Oxygen is mainly present in ether oxygen, carboxyl, and carbonyl groups. Nitrogen is mainly in the form of pyrrole nitrogen and quaternary nitrogen. Sulfur is mainly thiophene sulfur. According to the analysis results, the molecular structure model of XF lignite was constructed. The molecular formula is C184H172O39N6S2. The 2D structure was converted to a 3D structure using computer simulation software and optimized. The optimized model has a remarkable stereoconfiguration, and the aromatic lamellae are irregularly arranged in space. The aromatic rings were mainly connected by methylene, hypomethylene, methoxy, and aliphatic rings. In addition, the simulated 13C NMR spectra are in good agreement with the experimental spectra. This shows the rationality of the 3D chemical structure model.

Synergistic Boosting Capture Ability of Thiophene Sulfur with a Novel Dual-Amino-Functionalized MOF-on-MOF Adsorbent.

A single metal-organic framework (MOF) exhibits some drawbacks in deep adsorptive desulfurization such as insufficient functional active sites, water instability, low surface area, etc. Herein, a dual-amino-functionalized (ZIF-8-NH2)-PVP-(Cu-BTC-NH2) core-shell dual MOF adsorbent was first synthesized by the hydrothermal growth method. The adsorption performance of thiophene sulfur (ThS) is systematically investigated and evaluated at mild temperatures through batch tests. The (ZIF-8-NH2)-PVP-(Cu-BTC-NH2) exhibits good adsorption ability toward ThS, which is attributed to the associative effects of dual MOFs with structure features such as hydrogen bond, open metal active sites, suitable pore sizes and π-π conjugation, etc. Meanwhile, the (ZIF-8-NH2)-PVP-(Cu-BTC-NH2) embedded 25 wt % water still remains crystal intact and good adsorption desulfurization performance, which is attributed to the NH2- functional groups. After five recycles, more than 90% ThS uptake onto (ZIF-8-NH2)-PVP-(Cu-BTC-NH2) could be recovered, exhibiting good reuse performance. This study presents a new strategy for grafting MOF-on-MOF with specific functional groups to improve the abilities of desulfurization and water resistance.

Development of Dual N, S‐Heteroatom Doped Hollow Carbon Spheres as an Alternative Electrocatalyst for Oxygen Reduction Reaction in Alkaline Medium

AbstractHollow heteroatom‐doped mesoporous carbons were found to be an efficient non‐noble metal catalyst to enhance the oxygen reduction reaction (ORR) in fuel cells. Here, we use dopamine hydrochloride (DHC) and dibenzyl disulfide (DBS) as the nitrogen and sulfur precursors to infiltrate N and S into the HCS in a single‐step process. Dibenzyl disulfide is less explored in literature as a sulfur dopant. Due to its high sulfur content and high boiling point, dibenzyl disulfide acts as an excellent sulfur dopant and can withstand the carbonization process. Among them, NSMHCS‐0.2 obtained by adding 0.2 g of dibenzyl disulfide at 31 h intervals to the polydopamine (PDA) loaded silica leads to the ideal N, S dual hetero‐atom doping in NSMHCS. Notably, it has a high shell thickness (45 nm), high BET surface area (637 m2 g−1), high pyridinic nitrogen (13.54 %), and thiophene sulfur (89.8 %) concentration. Such property tuning paved the way to reach a high positive onset potential (0.86 V vs RHE) and a limiting current density of 3.64 mA cm−2 at 0.4 V vs RHE. Additionally, NSMHCS‐0.2 has shown superior methanol tolerance and strong electrochemical stability when compared to Pt/C 20 %.

Facile tuning Non-radical/Radical oxidation by nitrogen doping on Fe-S doped carbonaceous catalysts for peroxymonosulfate activation

In this paper, iron-sulfur-nitrogen co-doped carbonaceous materials (Fe@SxNyC) was prepared by doping N during the preparation of iron-sulfur co-doped carbonaceous material (Fe@SC), which was used to activate PMS and effectively modulate the radical and non-radical oxidation pathways in the catalytic system to achieve efficient degradation of sulfamerazine (SMR). N doping introduced multiple N sites (graphitic N, pyridinic N and pyrrolic N) in the Fe@SxNyC while promoting the generation of thiophene sulfur of the pristine active sites. Meanwhile, N doping introduced more defects in Fe@S4NC and thus exhibited better catalytic activity than Fe@SC, promoting the decomposition of PMS with a maximum k value (0.1721 min−1). Notably, the involvement of nitrogen shifted the cooperative oxidation reaction from a non-radical (1O2) to a radical-dominated (SO4·–) oxidation pathway with more oxidative intensity, resulting in deeper mineralization of organic pollutants. Moreover, compared with Fe@SC/PMS system, the radical-dominated Fe@S4NC/PMS system had better cycling stability, and the efficiency of SMR degradation could still reach 85 % after 4 cycles. The prepared Fe@S4NC catalytic ceramic membrane exhibited stable water flux and exceptional catalytic activity, demonstrating that Fe@S4NC had good potential for practical applications. This work elucidated the improvement of the catalytic mechanism of iron-carbon based materials by doping with various heteroatoms and provided a theoretical basis to design Fenton-like heterogeneous catalysts suitable for different water matrix.

Efficient room-temperature oxidation of dibenzothiophene over mesoporous WO3@ZrO2-TiO2 composites derived from polymer-oriented self-assembly strategy

Deep removal of thiophenic sulfur compounds in fuel oil remains an enormous challenge to achieve ultra-clean diesel production. Herein, a polyoxometalate-based inorganic-organic hybrid derived mesoporous WO3@ZrO2-TiO2 composites has been prepared by a simple polymer-oriented self-assembly strategy using polyethyleneimine (PEI) as the structure-directing agent. It exhibits that the existence of mesoporous pore channels, Zr doped TiO2 matrix, and highly dispersed WO3 active sites on the ZrO2-TiO2 framework can facilitate the adsorption-oxidation process of thiophene-type sulfide and provide more accessible active sites. The as-prepared mesoporous WO3@ZrO2-TiO2 composite shows good catalytic activity for dibenzothiophene (DBT) at room temperature, removing 500 ppm of DBT from simulated oil within 80 min, making it a suitable alternative catalyst for deep oxidative desulfurization.

Adsorptive desulfurization of thiophenic sulfur compounds using nitrogen modified graphene

In this study, nitrogen modified graphene was investigated for adsorptive desulfurization of thiophene, benzothiophene and dibenzothiophene. For these compounds, graphene (257 m2/g and 0.48 cm3/g) showed adsorptive removal of 70.1, 65.4 and 61.2%, respectively. Nitrogen modification enhanced separation of graphene layers, resulting in increase of surface area and pore volume. With increase in nitrogen content, both properties were further enhanced. The highest surface area (301 m2/g) and pore volume (1.12 cm3/g) were obtained for 14-N-GR with highest nitrogen content of 13.8 wt%. Adsorptive removal was thereby, highest for 14-N-GR, with 97.3, 92.8 and 88.4%, respectively for thiophene, benzothiophene and dibenzothiophene. The pyrrolic-N and pyridinic-N within carbon matrix contributed significantly to π-π interactions between carbon matrix and sulfur compounds. The order of adsorptive removal efficiency for sulfur compounds was also associated with their molecular size. The adsorptive desulfurization was best described by pseudo-second-order kinetics and best represented by Langmuir adsorption model. The monolayer model agreed with major contribution of π-π interactions between adsorbate and adsorbent surface. The spent adsorbents regenerated using thermal process showed cyclic and thermal stability. After five adsorption-regeneration cycles, percentage removal decreased only up to 14%, without any major morphological change of adsorbent.

PEDOT wrapped biomimetic recognition system for selective determination of carcinogenic phenacetin content in drug samples

A molecular imprinted polymeric (MIP) recognition system comprising of PEDOT swaddled CoWO4 nanocapsules has been developed for the electrochemical detection of carcinogenic phenacetin drug. Facile hydrothermal route was employed to synthesize CoWO4 whereas, EDOT was wrapped around under chemical polymerization at room temperature. A series of characterizations revealed that electrostatic interactions generated between thiophene sulfur of PEDOT and metal atoms of CoWO4 have prompted the homogeneously wrapped molecularly imprinted nanocomposite. The obtained peak potential plotted against the CV scan rate revealed involvement of 2 electrons in the electroxidation detection process of phenacetin. The values of charge transfer coefficient α (0.69) and charge transfer rate constant ks (2.24 s−1) at electrode-electrolyte interface during the detection procedure were also evaluated. The nanoarchitecture of the designed MIP exhibited abundant imprinted sites to selectively bind the template molecule in terms of shape, size and functionalities resulted in significant augmentation in sensitivity (0.14 µA nM−1 cm−2) and a very low detection limit (0.091 nM). Phenacetin content in homeopathic and allopathic drug samples were successfully quantified with more than 95 % accuracy by employing the MIP modified electrode. The present research introduces new possibilities for identification of carcinogenic phenacetin used as adulterants in various narcotic drug samples.

Study on molecular structure characteristic and optimization of molecular model construction of coal with different metamorphic grade

To investigate the structural properties of coal molecules with different degrees of metamorphism, in this study, we used Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and solid-state nuclear magnetic resonance carbon spectroscopy (13C NMR) to investigate the structural properties of three coal molecules with different degrees of metamorphism and finally constructed and optimized the coal molecular model. The experimental results showed that with the deepening of the deterioration degree, the proportion of oxygen-containing functional groups in the coal molecules was gradually reduced, the long fatty chains were shortened and reduced, and the aromaticity was enhanced. With increasing coalification, pyridine nitrogen and thiophene sulfur are becoming important components of the nitrogen- and sulfur-containing organic matter in coal. Coal metamorphism promotes the aromatization and condensation degree increase of coal molecular structure, which makes the coal molecular structure evolve into a microcrystalline structure with higher order degree. With this increase of coal rank, the carbon ratio around the bridge (XBP) increased from 0.12 to 0.47. The low-rank coal was dominated by benzene rings with low polymerization degree, and the high rank coal was dominated by aromatic structures, such as tetracene with a high degree of polymerization. The molecular formula of lignite finally constructed was C219H159O21N3, that of coking coal was C235H164O7N4S, and that of anthracite was C286H108O5N4S. The coal molecules constructed in this study provide a theoretical basis for the study of the molecular structure properties of coal with different degrees of metamorphism.

Controlling the metal-support interaction of Cu/ZnO sorbent to improve its ultra-deep desulfurization performance for thiophene in coke oven gas

The deep removal of thiophene sulfur from coke oven gas (COG) is an important aspect for the subsequent production of COG to natural gas via methanation. In this process, copper-based sorbents exhibit excellent desulfurization activity. However, the activity of the sorbent depends largely on the interaction between Cu and Zn in the sorbent, which is often used to stabilize metal particles and regulate the activity and stability of the sorbent. Despite a large number of studies on metal-support interaction, there is still a lack of understanding of the effects of metal-support interaction of different strengths on the structure and performance of sorbents. In this work, Cu/ZnO sorbents with different strengths of metal-support interaction were successfully synthesized to elucidate the effect of the interaction between Cu and Zn on the performance of thiophene removal. The reconstruction process of the sorbent (different component ratios) changed the CuZn interaction. For weakly interacting sorbents, the reconstruction process enhanced the interaction between the two components, which is conducive to electron transfer and overall activity improvement. On the contrary, for sorbents with strong interaction, the reconstruction process was hindered.

Effect of extracts of petroleum ether, dichloromethane and methanol on thiophenic sulfur release during coal pyrolysis

The existing forms and thermal transformation of sulfur in high sulfur coal directly influence the efficiency of coal clean utilization by the staged pyrolysis conversion. Low molecular compounds distributed in coal are very different from the macromolecular structure of coal and play an important role during coal pyrolysis. In order to investigate the effects of low molecular compounds on the release of typical thiophenic sulfur species during coal pyrolysis by Py-GC/MS, petroleum ether, dichloromethane, and methanol were used for sequential ultrasonic extraction of Linfen coal (LFC). The compositions of extracts were detected by GC×GC/MS. Results show that three primary kinds of thiophenic sulfur species (2-methyl thiophene, benzothiophene, and dibenzothiophene) were released during coal pyrolysis and they are mainly derived from the cracking of macromolecular skeleton containing thiophenic sulfur in coal. The amounts of thiophenic sulfur released during raw coal and residues pyrolysis both increase with temperature. Besides, extracts with different compositions have different effects on the release of thiophenic sulfur during pyrolysis. In detail, the cyclization of aliphatic compounds could provide active hydrogen. On the one hand, the active hydrogen promotes the break of bridge bonds around thiophenic sulfur. On the other hand, active hydrogen may attack sulfur atoms of thiophenic sulfur, reducing the energy barriers of thiophenic sulfur decomposition. Aromatic compounds polymerize with sulfur-containing groups converting to benzothiophene and dibenzothiophene with larger molecular weight. In addition, thiophenic sulfur may be oxidized by esters to sulfones or sulfoxides, which further decompose, resulting in the inhibition effect on thiophenic sulfur formation during coal pyrolysis.

Construction and optimization of macromolecular structure model of Tiebei lignite.

Mastering the molecular structure of coal is important for the effective utilization of coal. For a detailed study of the microstructural characteristics of Tiebei lignite, its molecular structure was characterized by elemental analysis, solid 13C nuclear magnetic resonance (13C NMR), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The results showed that the aromatic carbon content of Tiebei lignite was 51.98%, the aromatic carbon structure was mainly composed of benzene and naphthalene, and the ratio of aromatic bridgehead carbon to surrounding carbon Xbp was 0.14. Oxygen existed in phenol, ether, carbonyl, and carboxyl; nitrogen-containing structures mainly existed in the form of pyrrole and pyridine; sulfur mainly existed in thiophene sulfur; and aromatic substitution was mainly in the form of trisubstitution. The molecular formula of the macromolecular structure model of Tiebei lignite was C190H161O57N2, and the 13C NMR spectrum of the model was in good agreement with the experimental results, which fully verified the accuracy of the macromolecular structure model of Tiebei lignite. The construction of a macromolecular structure model of Tiebei lignite is essential to intuitively understand the molecular structure characteristics of Tiebei lignite and to provide theoretical support and guidance for the micromechanism research and prevention of lignite spontaneous combustion and other disasters.

Study on the in situ desulfurization and viscosity reduction of heavy oil over MoO3–ZrO2/HZSM-5 catalyst

Heavy oil is characterized by high viscosity. High viscosity makes it challenging to recover and transport. HZSM-5, MoO3/HZSM-5, ZrO2/HZSM-5 and MoO3–ZrO2/HZSM-5 catalysts were developed to promote in situ desulfurization and viscosity reduction of heavy oil. The physical and chemical properties of catalysts were characterized by XPS, XRD, TEM, NH3-TPD, etc. The effects of temperature, catalyst type and addition amount on viscosity and composition of heavy oil were evaluated. The results showed that the presence of MoO3–ZrO2/HZSM-5 nanoparticles during aquathermolysis could improve the oil quality by reducing the heavy fractions. It reduced viscosity by 82.56% after the reaction at 280 °C and catalyst addition of 1 wt%. The contents of resins and asphaltic in the oil samples were 5.69% lower than that in the crude oil. Sulfur content decreased from 1.45% to 1.03%. The concentration of H2S produced by the reaction was 2225 ppm. The contents of sulfur-containing functional groups sulfoxide and sulfone sulfur in the oil samples decreased by 19.92% after the catalytic reaction. The content of stable thiophene sulfur increased by 5.71%. This study provided a basis for understanding the mechanism of heavy oil desulfurization and viscosity reduction.

Sulfur and nitrogen co-doped biochar activated persulfate to degrade phenolic wastewater: Changes in impedance

In this research, sulfur and nitrogen co-doped biochar was prepared by co-pyrolysis method. The degradation law of phenol in simulated wastewater by activated potassium persulfate(PDS) was studied, and the effects of preparation conditions on the purification performance of phenol were also discussed. The results show that the phenol degradation rate by biochar with a doping ratio of 20% to activate PDS is up to 98.5%. In addition, the cycle performance of the doped biochar can still maintain 76% at the fifth cycle, indicating a good recycling performance. The results of density functional theory(DFT) calculations and various characterization techniques show that the sulfur and nitrogen exist in the form of thiophene sulfur and graphite nitrogen in the biochar, respectively. The electron density distribution of doped biochar become uneven, and the electrochemical impedance decreases from 32.88 to 10.53, prompting the reaction to proceed via non-radical path. Finally, the purification experiment results reveal that the S,NBC/PDS system possesses an excellent purification effect on simulated coal gasification wastewater, providing a reference for the industrial phenolic wastewater treatment.

Redistribution of d-orbital in Fe-N4 active sites optimizing redox kinetics of the sulfur cathode

Redistributing the d-orbital of single Fe atom catalysts (SFeACs) has been challenging to optimize redox kinetics of lithium sulfur batteries (LSBs). Here, the Fe-N4/S2C with mounting energy level of dz2 and partial occupation of dxz is controllably fabricated. The increased dz2, originating from thiophene sulfur, upshifts d band center compared to the Fe-N4/C with planar symmetric structure. That promotes electron transfer between Fe-N4 and sulfur, enhancing conversion of polysulfides and solid products. The lower fill of dxz develops hybridization between Fe and S atoms via the form of bonding and antibonding, with alleviating the loss of sulfur. Thus, the sulfur cathode with Fe-N4/S2C delivers a high capacity of 749 mAh g−1 at 2.0 C, accompanied by excellent stability with a lower capacity decay of 0.07% per cycle. This work has developed a novel coordination configuration towards SFeACs and uncovered the intrinsic mechanism of facilitated redox kinetics with SFeACs for LSBs.

Synthesis and Conformational Analysis of N-Aromatic Acetamides Bearing Thiophene: Effect of Intramolecular Chalcogen–Chalcogen Interaction on Amide Conformational Stability

The conformations of aromatic amides bearing an N-(2-thienyl) or N-(3-thienyl) group were investigated in solution and in the crystal state. NMR spectral data indicate that the conformational preferences of these amides in solution are dependent not only on the relative π-electron densities of the N-aromatic moieties, but also on the three-dimensional relationship between carbonyl oxygen and the N-aromatic moieties. A comparison of the conformational preferences of N-(2-thienyl)amides and N-(3-thienyl)amides revealed that the Z-conformers of N-(2-thienyl)acetamides are stabilized by 1,5-type intramolecular S···O═C interactions between amide carbonyl and thiophene sulfur. The crystal structures of these compounds were similar to the solution structures. The stabilization energy due to 1,5-type intramolecular S···O═C interaction in N-aryl-N-(2-thienyl)acetamides and N-methyl-N-(2-thienyl)acetamide was estimated to be ca. 0.74 and 0.93 kcal/mol, respectively.

Effect of copper ions on transformation of organic sulfur in cationic exchange resins in Li2CO3–Na2CO3–K2CO3 molten-salt system

Cationic exchange resins (CERs) were applied for purification and clarifying process of radioactive wastewater in nuclear industry, which was a kind of sulfur-containing organic material. Molten-salt oxidation (MSO) method can be applied for the treatment of spent CERs and the absorption of acid gas (such as SO2). The experiments about the molten salt destruction of the original resin and Cu ions doped resin were conducted. The transformation of organic sulfur in Cu ions doped resin was investigated. Compared with the original resin, the content of tail gas (such as CH4, C2H4, H2S and SO2) released from the decomposition of Cu ions doped resin was relatively high at 323–657 °C. Sulfur elements in the form of sulfates and copper sulfides were fixed in spent salt through XRD analysis. The XPS result revealed that the portion of functional sulfonic acid groups (-SO3H) in Cu ions doped resin was converted into sulfonyl bridges (-SO2-) at 325 °C. With the enhancement of temperature, sulfonyl bridges (-SO2-) were further decomposed to sulfoxides sulfur (-SO-) and organic sulfide sulfur. The destruction of thiophenic sulfur to H2S and CH4 was prompted by copper ions in copper sulfide. Sulfoxide were oxidized to the sulfone sulfur in molten salt. Sulfones sulfur consumed by reduction of Cu ions at 720 °C was more than it produced by oxidation of sulfoxide through XPS analysis, and the relative proportion of sulfone sulfur was 16.51%.