EUROPEAN POLYMER JOURNAL
·
2021
·
IF 4.598
Wenjian Guo,Shuxin Bai,Yicong Ye
Although numerous efforts have been focused on the high-value-added reutilization of resin matrix in abandoned composites, the evidence chain of whether high-value-added resin pyrolysis oil can be reused has not been comprehensively presented. Herein, the epoxy resin (EP) matrix in composite wastes was pyrolyzed into EP pyrolytic oil (EPO), and its detailed composition and effects on the microstructure, strength, and ablation of remanufactured carbon fiber (CF) composites were analyzed and evaluated. According to the results, more than half (57.8 wt%) of the EP matrix was converted into EPO, which mainly included phenol and its derivatives. Given that EPO contains a certain amount of phenol derivatives, the viscosity and wettability of EPO-formaldehyde (EPOF) prepolymer with CF was slightly poorer than that of industrial grade phenol formaldehyde (PF). In addition, CF reinforced EPOF (CF/EPOF) composites with strengths and ablation rates comparable to those of CF/PF composites were fabricated successfully, owing to good process performance of the EPOF prepolymer. The present work provides a comprehensive feasibility data support and basis for high-value-added reutilization of an abandoned resin matrix composite for the manufacture of composites.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Jiaxin Zhu,Zekun Liu,Yihua Chen,Zhiqiang Chen,Hang Ma,Jian Sun,Liao Meng,Tongzhou Liu
The discharge of widely used fluorinated aromatics (FAs) leads to their notoriously high persistence and toxicity in natural environments. Defluorination is the key step for FAs pollutants detoxification. Due to its easy operation and mild reaction conditions, hydrodefluorination (HDF), especially electrochemical HDF, is a promising approach for FAs detoxification. A comprehensive and detailed investigation of the effective cathode and mechanism insights are contributable for the development of effective FAs defluorination techniques. In this study, 4-fluorophenol (4-FP) was selected as a model compound to optimize the electrochemical HDF process and understand the reaction mechanism. Cathode coating material investigation revealed that Rh outperformed Pd due to its higher reactivity towards C F bond cleavage. The Rh coating was primarily elemental and in Rh(1 1 1) crystalline form which helped store the generated atomic hydrogen (H*). Reaction conditions optimizations showed 4-FP degradation favored acidic > alkaline > neutral environment and a cell potential higher than −3 V was required for efficient 4-FP degradation. Dissolved oxygen (DO) negatively affected 4-FP degradation and the rapid 4-FP decay only occurred after DO depleted in the solution. Based on quenching experiments and ESR analysis, H* was determined as the main reactive species. In situ Raman characterization suggested that electrochemical 4-FP degradation was initiated by 4-FP adsorption through R···F···Rh bridging and H* generation/adsorption on Rh coated cathode, resulting in phenol generation. The generated phenol further experienced hydrogenation to yield cyclohexanone and cyclohexanol with lower toxicity and better biodegradation potential, demonstrating that electrochemical treatment of 4-FP simultaneously achieved defluorination along with detoxification. The outcomes of this work provide support for electrocatalyst technology development towards efficient FAs treatment while providing in-depth observation of the electrochemical HDF process.
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ENVIRONMENTAL POLLUTION
·
2023
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IF 8.9
Tao Pei,Feng Shi,Can Liu,Yi Lu,Xu Lin,Defa Hou,Shunxiong Yang,Jirong Li,Zhifeng Zheng,Yunwu Zheng
In this study, a novel nitrogen-doped magnetic Fe–Ca codoped biochar for phenol removal was successfully fabricated via a hydrothermal and coactivation pyrolysis method. A series of adsorption process parameters (K 2 FeO 4 to CaCO 3 ratio, initial phenol concentration, pH value, adsorption time, adsorbent dosage and ion strength) and adsorption models (kinetic models, isotherms and thermodynamic models) were determined using batch experiments and various analysis techniques (XRD, BET, SEM-EDX, Raman spectroscopy , VSM, FTIR and XPS) to investigate the adsorption mechanism and metal-nitrogen-carbon interaction. The biochar with a ratio of Biochar: K 2 FeO 4 : CaCO 3 = 3:1:1 exhibited superior properties for adsorption of phenol and had a maximum adsorption capacity of 211.73 mg/g at 298 K, C 0 = 200 mg/L, pH = 6.0 and t = 480 min. These excellent adsorption properties were due to superior physicomechanical properties (a large specific surface area (610.53 m 2 /g) and pore volume (0.3950 cm 3 /g), a well-developed pore structure (hierarchical), a high graphitization degree (I D /I G = 2.02), the presence of O/N-rich functional groups and Fe-Ox,Ca-Ox, N-doping, as well as synergistic activation by K 2 FeO 4 and CaCO 3 ). The Freundlich and pseudo-second-order models effectively fit the adsorption data, indicating multilayer physicochemical adsorption. Pore filling and π-π interactions were the predominant mechanisms for phenol removal, and H-bonding interactions, Lewis-acid-base interactions, and metal complexation played an important role in enhancing phenol removal. A simple, feasible approach with application potential to organic contaminant/pollutant removal was developed in this study.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
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IF 8.6
Yangke Long,Shixin Huang,Shiyin Zhao,Guicong Xiao,Jianlin Sun,Dan Peng
The practical application of periodate-based advanced oxidation technologies (PI-AOTs) for wastewater treatment requires efficient and cost-effective activators. Pyrolyzed Fe–N/C materials are potential candidates, however, their actual active sites and activation mechanisms are yet to be fully understood. Herein, a series of Fe–N/C samples (denoted as Fe@NC- X ) with differing structures and iron components were delicately synthesized. Experimental studies on the structure–activity relationship and density functional theory (DFT) computations revealed that Fe–N x species serve as the dominant active site for periodate activation, while the inactive iron-based particles (i.e., Fe 0 and Fe 3 C) optimized the binding affinity of surrounding carbon layers with periodate, resulting in enhanced activity. In-depth exploration of the oxidative mechanism revealed that Fe@NC- X activated periodate through an electron transfer regime. Our results also showed that the optimal Fe@NC-0.2/periodate system was highly effective in catalyzing the oxidation of 4-CP, outperforming many reported activators. These findings provide an indispensable foundation for the rational development of advanced Fe–N/C activators and offer vital insights into the mechanism underlying pollutant destruction through PI-AOTs.
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MACROMOLECULES
·
2023
·
IF 5.5
Nan Li,Shengfu Yang,Kan Zhang
The future development of benzoxazine thermosetting resins as advanced polymeric materials depends on designing more attractive chemical structures and reaching a deeper understanding of the structure–property relationship at the molecular level. Herein, we synthesized a new series of benzoxazines containing the thiophenecarboxamide or thiopheneacetamide functionality at the ortho- and para-positions with respect to oxygen in the oxazine ring. Successful syntheses of thiophene-rich benzoxazine monomers and their corresponding molecular characterizations were confirmed by Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and high-resolution mass spectroscopy. Ring-opening polymerization processes of benzoxazines and thermal properties of their resulting polybenzoxazines were studied by differential scanning calorimetry, in situ FT-IR spectroscopy, and thermogravimetric analysis. In addition, a combined experimental and computational study using both 1D and 2D NMR as well as density functional theory calculations provided kinetic insights into the effects of structural and hydrogen bonding on the polymerization mechanism. With the designed varieties of hydrogen bonds in these novel benzoxazines, it has been found that oxygen in the oxazine ring involved in stronger hydrogen bonding can generate a relatively weaker O–CH2 bond, leading to the reduced ring-opening polymerization temperature. The fundamental investigations presented in the current work provide us a deeper understanding of the hydrogen bonding interaction in benzoxazine as well as its role in polymerization behavior. Moreover, these newly obtained thiophene-rich benzoxazines also give us ample opportunities to develop high-performance polybenzoxazine thermosets with promising applications.
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JOURNAL OF MOLECULAR LIQUIDS
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2023
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IF 6
Ziyue Zhou,Yu Cao,Kai Zong,Dongshun Deng
In chemical industry, efficient absorption of ammonia (NH 3 ) from industrial exhaust remains a challenge and significant issue for resource utilization and pollution control. Present study proposed a new strategy to design non-ionic deep eutectic solvents (DESs) using phenolic analogues. Several phenol-based DESs with multiple acidic sites were constructed by paring catechol (Cat) or resorcinol (Res) with phenol (PhOH) and investigated as feasible NH 3 absorbents from physical property, NH 3 absorption performance, and mechanism analysis. Among the as-obtained DESs, Res/PhOH (1:3) demonstrated attractive NH 3 absorption capacity at 303.15 K (11.862 mol/kg at 101.3 kPa, and 6.391 mol/kg at 5.0 kPa), surpassing most DESs and ionic liquids (ILs) reported in the literatures. Meanwhile, it displayed good reversibility, satisfactory thermal stability, and high NH 3 /CO 2 selectivity. The mechanism of NH 3 absorption was further elucidated using FTIR and NMR spectra, and Quantum chemistry calculation, and inferred as the strong and multiple interaction between NH 3 and weakly acidic sites of DESs.
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JOURNAL OF HAZARDOUS MATERIALS
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2023
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IF 13.6
Jun Wang,Hao Lv,Xiandong Tong,Wei Ren,Yi Shen,Lun Lu,Yang Zhang
In order to minimize the knowledge gap between single and binary pollutants degradation by persulfate-based advanced oxidation processes (PS-AOPs), iron-loaded N-doped carbon nanotubes (Fe-NCNT) and its acid-washing sample (Fe-NCNT-W) were synthesized as peroxymonosulfate (PMS) activator for simultaneous oxidation of acid orange 7 (AO7) and electron-rich (phenol/ibuprofen) or electron-deficient pollutants (nitrobenzene/benzoic acid). Mechanistic studies revealed that both radical (HO•, SO 4 •− ) and nonradical (electron-transfer, high-valent iron) pathways involved for organic oxidation in Fe-NCNT/PMS system, while electron-transfer pathway (ETP) and high-valent iron-oxo species accounted for pollutant degradation at the surface and inner space of Fe-NCNT-W, respectively. The oxidation performances in single or binary systems were systematically investigated. In comparison to benchmark radical-based (Fe 2+ /PMS), nonradical ETP (NCNT/PMS) and mixed (Fe-NCNT/PMS) systems, Fe-NCNT-W/PMS outperformed superior performance toward oxidation of binary pollutants with little inference from solution pH or background substances, which could also be fabricated into membrane reactor for actual dyeing sewage treatment . Such superiorities should be mainly ascribed to the particular selectivity and intensive treatment of nonradical pathways in Fe-NCNT-W/PMS system with nanoconfinement effect. This work affords novel insights into the treatment of combined pollution via PMS activation by engineered nanomaterials .
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Aihua Xu,Runshi Chen,Wenpei Zhao,Jiajin Lin,Rongrong Hu,Aimal Khan,Wei Li,Xiaoxia Li,Shuaiqi Zhao,Yongcai Qiu
Modifying the surface structure of catalysts is critical for facilitating peroxymonosulfate (PMS) activation. Here, we present a quenching approach to effectively modify the surface chemistry of LaMnO 3 nanocatalysts, in which the optimal catalyst obtained by quenching displays higher catalytic degradation performance for levofloxacin (LEVO). The experimental results demonstrates that the increased intrinsic catalytic activity is directly connected to the quenching-induced exposed facets transition and synergistic effect of Cu/Co ions. Meanwhile, density functional theory calculations (DFT) further reveal the aforementioned modifications to surface structure result in an upward shift of d-band centre, which optimizes the adsorption of PMS and makes it easier for the transfer of electron between Mn sites and PMS, thereby facilitating the reduction of Mn 4+ and enhancing catalytic activity for PMS activation and LEVO degradation. This study presents new ideas for controlling surface structure of perovskite metal oxide catalysts and broadens applicability of quenching chemistry in heterogeneous catalysis.
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Polymers
·
2023
·Vol. 15
·期 15
·3168
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IF 5
Ruixue Niu,Zhening Zheng,Xuedong Lv,Benqiao He,Sheng Chen,Jiaying Zhang,Yanhong Ji,Yi Liu,Liuchun Zheng
The introduction of long-chain branched structures into biodegradable polyesters can effectively improve the melt strength and blow-molding properties of polyesters. In this study, pentaerythritol (PER) was used as a branching agent to synthesize branched poly(butylene dodecanedioate) (PBD), and the resulting polymers were characterized by Nuclear Magnetic Resonance Proton Spectra (1H NMR) and Fourier Transform Infrared spectroscopy (FT-IR). It was found that the introduction of a small amount of PER (0.25–0.5 mol%) can generate branching and even crosslinking structures. Both impact strength and tensile modulus can be greatly improved by the introduction of a branching agent. With the introduction of 1 mol% PER content in PBD, the notched impact strength of PBD has been increased by 85%, and the tensile modulus has been increased by 206%. Wide-angle X-ray diffraction and differential scanning calorimetry results showed that PER-branched PBDs exhibited improved crystallization ability compared with linear PBDs. Dynamic viscoelastics revealed that shear-thickening behaviors can be found for all branched PBD under low shear rates.Keywords:biodegradable;polyester;poly(butylene dodecanedioate);branched;mechanical properties;rheological properties
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MOLECULES
·
2023
·Vol. 28
·期 16
·6063
·
IF 4.6
Yali Guo,Bing Wang,Lifei Gu,Guo Yin,Shuhong Wang,Meifang Li,Lijun Wang,Xie-An Yu,Tiejie Wang
The fraud phenomenon is currently widespread in the traditional Chinese medicine Radix Astragali (RA) market, especially where high-quality RA is substituted with low-quality RA. In this case, focused on polysaccharides from RA, the classification models were established for discrimination of RA from different growth patterns, origins, species, and growth years. 1H Nuclear Magnetic Resonance (H1-NMR) was used to establish the spectroscopy of polysaccharides from RA, which were used to distinguish RA via chemical pattern recognition methods. Specifically, orthogonal partial least squares discriminant analysis (OPLS-DA) and linear discriminant analysis (LDA) were used to successfully establish the classification models for RA from different growth patterns, origins, species, and growth years. The satisfactory parameters and high accuracy of internal and external verification of each model exhibited the reliable and good prediction ability of the developed models. In addition, the polysaccharide content and immunological activity were also tested, which was evaluated by the phagocytic activity of RAW 264.7. And the result showed that growth patterns and origins significantly affected the quality of RA. However, there was no significant difference in the aspects of origins and growth years. Accordingly, the developed strategy combined with chemical information, biological activity, and multivariate statistical method can provide new insight for the quality evaluation of traditional Chinese medicine.Keywords:Radix Astragali;immunomodulatory activity;polysaccharide content;chemical pattern recognition;quality evaluation
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ENVIRONMENTAL RESEARCH
·
2023
·
IF 8.3
Tong Wei,Xin-Sheng Zhu,Qi-Xue Wang,Ke-Ke Xu,Fu-Kai Tang,Ming-Zhu Zhang,Shi-Wen Lv,Feng Ge
It is of great significance to develop the effective technique to treat phenol-containing wastewater. Herein, Fe-based prussian blue analogues-derived zero valent iron (ZVI) was successfully synthesized by one-step calcination method. Owing to high specific surface area and rich active sites, ZVI-2 possessed excellent performance in charge transfer. Notably, in comparison with conventional ZVI and Fe 2+ , ZVI-2 can effectively activate peroxymonosulfate (PMS) for achieving rapid degradation of phenol, and the highest removal efficiency of phenol reached 94.9% within 24 min. More importantly, developed ZVI-2/PMS oxidation system with good stability displayed strong anti-interference capability. Interestingly, Fe 0 loaded on the surface of ZVI-2 can efficiently break the O–O bond of PMS to generate reactive oxygen species (i.e., SO 4 •− , OH • , O 2 •− and 1 O 2 ). As main adsorption sites of PMS, the existence of oxygen vacancy promote the formation of high-valent transition metal complexes (namely ZVI-2≡Fe 4+ =O). Under the combined action of reactive oxygen species and ZVI-2≡Fe 4+ =O, phenol can be eventually degraded into CO 2 and H 2 O. The possible degradation pathways of phenol were also investigated. Furthermore, proposed ZVI-2/PMS oxidation system displayed great potential for application in the field of wastewater treatment . All in all, current work provided a valuable reference for design and application of Fe-based catalysts in PS-AOPs.
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ACS ES&T Water
·
2023
·
IF 5.3
Jiayue Dong,Peizeng Yang,Gregory V. Korshin,Junhe Lu
Bromide (Br–) and nitrite (NO2–) can be transformed to brominated and nitrophenolic byproducts, respectively, in sulfate radical (SO4·–)-based oxidation processes, which has raised growing concern. In the present work, we examined the byproducts in the heat-activated persulfate oxidation system with the copresence of Br– and NO2–, finding that Br– acted as a catalyst to accelerate the NO2– transformation and nitrophenolic byproduct formation. Nitryl bromide (NO2Br) was the key intermediate in this process. It was generated by the reaction between NO2– and free bromine in situ formed as the product of the oxidation of Br– by SO4·–. As a strong nitrating agent, NO2Br reacted with natural organic matter directly, resulting in nitrophenolic byproducts. Alternatively, it reacted with excess NO2– to form N2O4, which hydrolyzed to NO3– ultimately. Both pathways were accompanied by releasing Br–. There was little Br– loss in the earlier reaction phase. Only after NO2– was completely transformed, brominated byproduct formation occurred. Thus, the transformations of Br– and NO2– are interweaved in SR-AOPs, which facilitates the formation of nitrophenolic byproducts but inhibits brominated byproducts. These new insights underscore the potential hazardous effects when SO4·– oxidation is applied under realistic environmental conditions.
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