The increasing CO2 concentration in the atmosphere has caused a lot of environmental problems. However, absorbents for highly efficient and reversible carbon capture, especially direct air capture, are still under development. Herein, a strategy of improving the CO2 absorption and desorption behavior of a kind of imidazole-based ionic liquid for reversible CO2 capture from ambient air via hydrogen bonding interaction was reported. By adding different hydrogen bond donors, the CO2 capacities and absorption enthalpies of imidazole-based IL ([N2224][Im]) were well tuned. Between them, [N2224][Im]-Car exhibited a relatively high CO2 capacity at the atmospheric CO2 concentration of 0.4 mbar at 30 °C up to 0.6 mol CO2 per mol IL and excellent reversibility. Compared with pure [N2224][Im], the regeneration performance of [N2224][Im]-Car was immensely enhanced, making it more promising for energy-efficient CO2 capture and practical application in direct air capture.
{"title":"Fine-tuning of imidazole-based ionic liquid for highly efficient and reversible direct air capture via hydrogen bonding interaction","authors":"Kaili Wang, Jiayi Bai, Zhenyu Zhao, Zhaowei Zhang, Weiqi Mao, Lili Jiang, Haoran Li, Congmin Wang","doi":"10.1016/j.seppur.2025.131790","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131790","url":null,"abstract":"The increasing CO<sub>2</sub> concentration in the atmosphere has caused a lot of environmental problems. However, absorbents for highly efficient and reversible carbon capture, especially direct air capture, are still under development. Herein, a strategy of improving the CO<sub>2</sub> absorption and desorption behavior of a kind of imidazole-based ionic liquid for reversible CO<sub>2</sub> capture from ambient air via hydrogen bonding interaction was reported. By adding different hydrogen bond donors, the CO<sub>2</sub> capacities and absorption enthalpies of imidazole-based IL ([N<sub>2224</sub>][Im]) were well tuned. Between them, [N<sub>2224</sub>][Im]-Car exhibited a relatively high CO<sub>2</sub> capacity at the atmospheric CO<sub>2</sub> concentration of 0.4 mbar at 30 °C up to 0.6 mol CO<sub>2</sub> per mol IL and excellent reversibility. Compared with pure [N<sub>2224</sub>][Im], the regeneration performance of [N<sub>2224</sub>][Im]-Car was immensely enhanced, making it more promising for energy-efficient CO<sub>2</sub> capture and practical application in direct air capture.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"131 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.seppur.2025.131787
Yang Hong, Yan Zhou, Jiaqi Chen, linqian Qin, Yongqi Li, Yang Li, Hongyan Jiang, Huiyang Zhao, Jinzhu Wu, Xiaohong Wu
Advances in carbon capture and storage (CCS) technologies are critical for mitigating global climate change due to their low cost and operational simplicity. Although zeolites hold promise for carbon capture, the development of advanced zeolite materials with optimized CO2 separation efficiency and diffusivity remains challenging. In this study, we present a quantum dot-regulated growth strategy, in which silicon quantum dots (SiQDs) act as heterogeneous seeds to not only initiate the growth of nanoscale zeolite units but also guide their assembly. The resulting 13X-SiQDs exhibit a distinct micrometer-scale hollow sphere structure composed of nanoscale zeolite units, which provide additional adsorption sites and mesopores, significantly enhancing adsorption and diffusion. The amino groups on the surface of the SiQDs further enable chemical adsorption with CO2, strengthening the binding force. The synergistic combination of thermodynamic and kinetic advantages enables 13X-SiQDs to achieve substantial improvements in CO2 adsorption capacity (132.20 cm3·g−1), CO2/N2 selectivity (561), and diffusion rate. This quantum dot-regulated synthesis strategy offers a promising approach for designing advanced adsorption materials with high performance, extending their potential applications beyond carbon capture.
{"title":"Regulating the growth process of FAU zeolite via quantum dots for enhanced CO2/N2 separation","authors":"Yang Hong, Yan Zhou, Jiaqi Chen, linqian Qin, Yongqi Li, Yang Li, Hongyan Jiang, Huiyang Zhao, Jinzhu Wu, Xiaohong Wu","doi":"10.1016/j.seppur.2025.131787","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131787","url":null,"abstract":"Advances in carbon capture and storage (CCS) technologies are critical for mitigating global climate change due to their low cost and operational simplicity. Although zeolites hold promise for carbon capture, the development of advanced zeolite materials with optimized CO<sub>2</sub> separation efficiency and diffusivity remains challenging. In this study, we present a quantum dot-regulated growth strategy, in which silicon quantum dots (SiQDs) act as heterogeneous seeds to not only initiate the growth of nanoscale zeolite units but also guide their assembly. The resulting 13X-SiQDs exhibit a distinct micrometer-scale hollow sphere structure composed of nanoscale zeolite units, which provide additional adsorption sites and mesopores, significantly enhancing adsorption and diffusion. The amino groups on the surface of the SiQDs further enable chemical adsorption with CO<sub>2</sub>, strengthening the binding force. The synergistic combination of thermodynamic and kinetic advantages enables 13X-SiQDs to achieve substantial improvements in CO<sub>2</sub> adsorption capacity (132.20 cm<sup>3</sup>·g<sup>−1</sup>), CO<sub>2</sub>/N<sub>2</sub> selectivity (561), and diffusion rate. This quantum dot-regulated synthesis strategy offers a promising approach for designing advanced adsorption materials with high performance, extending their potential applications beyond carbon capture.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"25 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.seppur.2025.131783
Gequn Shu, Borui Liu, Hua Tian, Ligeng Li, Rui Sun, Xuan Wang
With the rising global demand for liquefied natural gas (LNG) in various fields, the need for LNG carriers has increased, which causes elevated CO2 emission. Thus, CO2 capture technology to achieve carbon neutrality on large LNG carriers has become a research concern. Besides, boil-off gas (BOG) is constantly generated which is due to the unavoidable heat leaks during the voyage resulting in the vaporization of several LNG. Therefore, a novel cryogenic on-board carbon capture (COCC) system making full use of LNG cold energy coupled with a BOG re-liquefaction (COCC-RL) system is firstly proposed, and the full operation conditions are considered. In this integrated system, superior thermal matching allows for CO2 capture in the exhaust, natural gas fuel vaporization and BOG re-liquefaction. It is astounding that the small capacity capture system could also produce a more competitive annual total profit (ATP) (4.13 × 104 $/ton) at a higher CO2 capture rate (56.69 %) compared to a high main load as design point. Therefore, a hitherto unexploited solution avenue has emerged, presenting a novel direction for designing a cryogenic on-board carbon capture system coupled with BOG re-liquefaction at variable engine loads and shows the potential of cryogenic CO2 capture technology in the shipping industry.
{"title":"A cryogenic CO2 capture system coupled with boil-off gas re-liquefaction for LNG carriers","authors":"Gequn Shu, Borui Liu, Hua Tian, Ligeng Li, Rui Sun, Xuan Wang","doi":"10.1016/j.seppur.2025.131783","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131783","url":null,"abstract":"With the rising global demand for liquefied natural gas (LNG) in various fields, the need for LNG carriers has increased, which causes elevated CO<sub>2</sub> emission. Thus, CO<sub>2</sub> capture technology to achieve carbon neutrality on large LNG carriers has become a research concern. Besides, boil-off gas (BOG) is constantly generated which is due to the unavoidable heat leaks during the voyage resulting in the vaporization of several LNG. Therefore, a novel cryogenic on-board carbon capture (COCC) system making full use of LNG cold energy coupled with a BOG re-liquefaction (COCC-RL) system is firstly proposed, and the full operation conditions are considered. In this integrated system, superior thermal matching allows for CO<sub>2</sub> capture in the exhaust, natural gas fuel vaporization and BOG re-liquefaction. It is astounding that the small capacity capture system could also produce a more competitive annual total profit (ATP) (4.13 × 10<sup>4</sup> $/ton) at a higher CO<sub>2</sub> capture rate (56.69 %) compared to a high main load as design point. Therefore, a hitherto unexploited solution avenue has emerged, presenting a novel direction for designing a cryogenic on-board carbon capture system coupled with BOG re-liquefaction at variable engine loads and shows the potential of cryogenic CO<sub>2</sub> capture technology in the shipping industry.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"1 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The photocatalytic reduction of CO2 and H2O to form formic acid (HCOOH) holds promise for meeting the carbon–neutral target. However, the reduced efficiency of carrier separation and the material’s vulnerability to photo-corrosion significantly impede its practical application. Herein, a 0D/1D Cu2O/W18O49 S-scheme heterostructure is prepared by in situ growing Cu2O nanocrystals on W18O49 ultrathin nanorods via the wet chemistry method. In situ irradiation X-ray photoelectron spectroscopy characterization uncovered the formation of a stable internal electric field (IEF) at the heterojunction interface between W18O49 and Cu2O, which facilitates the separation of photon-generated carriers through an effective interfacial S-scheme transmission mechanism. Small-sized Cu2O (5–10 nm) anchored on the ultrathin W18O49 nanorods exposes abundant active sites and enhances carrier separation while inducing electrons generated from W18O49 to consume the holes in Cu2O, thus preventing the oxidation of Cu2O. The W18O49/Cu2O S-scheme heterostructure with the optimized composite ratio (40 % Cu:W) exhibited excellent performance in HCOOH production (56.42 μmol g−1h−1, 23.2-fold enhancement compared to pristine Cu2O) and 100 % selectivity for CO2 photoreduction in water without any sacrificial reagents. This work provides a rational method for improving the stability of the catalyst and regulating charge carrier migration for highly selective CO2 photoreduction in water.
{"title":"Regulation of charge carrier migration in Cu2O/W18O49 S-scheme heterostructure for highly selective photocatalytic reduction of CO2 to HCOOH in water","authors":"Xiaoxue Liu, Ailin Gao, Tao Dong, Jiaming Li, Jian Liu, Changchao Jia","doi":"10.1016/j.seppur.2025.131791","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131791","url":null,"abstract":"The photocatalytic reduction of CO<sub>2</sub> and H<sub>2</sub>O to form formic acid (HCOOH) holds promise for meeting the carbon–neutral target. However, the reduced efficiency of carrier separation and the material’s vulnerability to photo-corrosion significantly impede its practical application. Herein, a 0D/1D Cu<sub>2</sub>O/W<sub>18</sub>O<sub>49</sub> S-scheme heterostructure is prepared by <em>in situ</em> growing Cu<sub>2</sub>O nanocrystals on W<sub>18</sub>O<sub>49</sub> ultrathin nanorods <em>via</em> the wet chemistry method. <em>In situ</em> irradiation X-ray photoelectron spectroscopy characterization uncovered the formation of a stable internal electric field (IEF) at the heterojunction interface between W<sub>18</sub>O<sub>49</sub> and Cu<sub>2</sub>O, which facilitates the separation of photon-generated carriers through an effective interfacial S-scheme transmission mechanism. Small-sized Cu<sub>2</sub>O (5–10 nm) anchored on the ultrathin W<sub>18</sub>O<sub>49</sub> nanorods exposes abundant active sites and enhances carrier separation while inducing electrons generated from W<sub>18</sub>O<sub>49</sub> to consume the holes in Cu<sub>2</sub>O, thus preventing the oxidation of Cu<sub>2</sub>O. The W<sub>18</sub>O<sub>49</sub>/Cu<sub>2</sub>O S-scheme heterostructure with the optimized composite ratio (40 % Cu:W) exhibited excellent performance in HCOOH production (56.42 μmol g<sup>−1</sup>h<sup>−1</sup>, 23.2-fold enhancement compared to pristine Cu<sub>2</sub>O) and 100 % selectivity for CO<sub>2</sub> photoreduction in water without any sacrificial reagents. This work provides a rational method for improving the stability of the catalyst and regulating charge carrier migration for highly selective CO<sub>2</sub> photoreduction in water.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"28 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sulfadiazine (SDZ), a potent antibiotic resistant to conventional biological treatment, presents considerable environmental risks if discharged untreated. Electro-Fenton (EF) is a promising technology in SDZ removal. However, oxygen reduction reaction (ORR) performance deterioration caused by iron deposition and the diverse optimal operating conditions for ORR and ferric reduction reaction (FRR) significantly affect the durability and the SDZ removal efficiency in EF system. In this study, a dual-stage spatiotemporal separation heterogeneous EF system was constructed, employing an air-breathing cathode (ABC) in the first stage and a Fe0-Fe3O4/CF cathode in the second stage, which effectively addresses the inherent limitations of EF systems by separating the ORR, H2O2 activation, and FRR spatiotemporally. A novel K2FeO4 etching method was employed to fabricate the Fe0-Fe3O4/CF cathode, ensuring uniformly dispersed active sites within pores. Under optimal operating conditions, the system achieved complete SDZ degradation in 10 min and 80.42 % total organic carbon (TOC) removal. High Fe(II) retention (55.12 %) on Fe0-Fe3O4/CF25 after reaction was observed due to effective FRR. Mechanism studies confirmed that ·OH generated from heterogeneous Fenton dominated SDZ degradation, with DFT analysis confirming electron transfer from SDZ to ·OH. The system demonstrated high durability and low energy consumption, maintaining the ability to completely degrade SDZ in 30 min after six uses, with an energy consumption of 8.48 kWh (kg SDZ)-1 and 0.26 kWh (g TOC)-1. These findings provide ideas for constructing EF systems with higher SDZ removal efficiency and durability.
{"title":"Spatiotemporally optimized dual-stage electro-Fenton system with etched Fe⁰-Fe3O4/CF cathode for efficient sulfadiazine degradation","authors":"Yanshi Zheng, Jinyan Yang, Mei Li, Jiayu Liang, Dehai Yu, Ziyao Wang, Xiao Shan, Gaofeng Pan, Jianchuan Pei","doi":"10.1016/j.seppur.2025.131756","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131756","url":null,"abstract":"Sulfadiazine (SDZ), a potent antibiotic resistant to conventional biological treatment, presents considerable environmental risks if discharged untreated. Electro-Fenton (EF) is a promising technology in SDZ removal. However, oxygen reduction reaction (ORR) performance deterioration caused by iron deposition and the diverse optimal operating conditions for ORR and ferric reduction reaction (FRR) significantly affect the durability and the SDZ removal efficiency in EF system. In this study, a dual-stage spatiotemporal separation heterogeneous EF system was constructed, employing an air-breathing cathode (ABC) in the first stage and a Fe<sup>0</sup>-Fe<sub>3</sub>O<sub>4</sub>/CF cathode in the second stage, which effectively addresses the inherent limitations of EF systems by separating the ORR, H<sub>2</sub>O<sub>2</sub> activation, and FRR spatiotemporally. A novel K<sub>2</sub>FeO<sub>4</sub> etching method was employed to fabricate the Fe<sup>0</sup>-Fe<sub>3</sub>O<sub>4</sub>/CF cathode, ensuring uniformly dispersed active sites within pores. Under optimal operating conditions, the system achieved complete SDZ degradation in 10 min and 80.42 % total organic carbon (TOC) removal. High Fe(II) retention (55.12 %) on Fe<sup>0</sup>-Fe<sub>3</sub>O<sub>4</sub>/CF<sub>25</sub> after reaction was observed due to effective FRR. Mechanism studies confirmed that ·OH generated from heterogeneous Fenton dominated SDZ degradation, with DFT analysis confirming electron transfer from SDZ to ·OH. The system demonstrated high durability and low energy consumption, maintaining the ability to completely degrade SDZ in 30 min after six uses, with an energy consumption of 8.48 kWh (kg SDZ)<sup>-1</sup> and 0.26 kWh (g TOC)<sup>-1</sup>. These findings provide ideas for constructing EF systems with higher SDZ removal efficiency and durability.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"74 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.seppur.2025.131775
Yu Zhang, Rui Wang
Reinforcing the development of efficient catalysts is crucial for addressing the challenges associated with NOx removal technologies. Herein, we present a unique method for the in situ production of halogen-doped NiCoMoOx catalysts utilizing a crystallization-thermal decomposition mechanism and the use of such catalysts for the selective catalytic reduction of NOx with NH3 (NH3-SCR). The formation of lattice defect (oxygen vacancies) and surface acid sites on Br-doped NiCoMoOx catalyst was considerably enhanced compared with that on pure NiCoMoOx, resulting in highly efficient reduction of NOx and a broader temperature operating range. The 2Br-NiCoMoOx catalyst achieved the highest NOx conversion of 97.2 % at 250°C, while NiCoMoOx was only 83 %, and the NOx conversion was always above 80 % in a wide temperature window of 200 to 350 °C. Through comprehensive characterization, it was also revealed that the introduction of Br enhanced the low temperature redox performance and the adsorption and activation of NO and NH3 on the catalyst surface, which played a crucial role in facilitating the reaction between NO and NH3. Furthermore, we achieved broad temperature window NOx reduction by ingeniously utilizing a tandem catalyst system composed of V2O5-WO3/TiO2 and 2Br-NiCoMoOx, with the optimal mass ratio of the two phases being 1:3. This research presents novel design approaches that offer a new approach to the creation of high-performance SCR catalysts.
{"title":"Series of halogen engineered well-mixed oxides derived from layered double hydroxides for highly efficient NH3-SCR catalysts: Improvement of the oxygen vacancies","authors":"Yu Zhang, Rui Wang","doi":"10.1016/j.seppur.2025.131775","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131775","url":null,"abstract":"Reinforcing the development of efficient catalysts is crucial for addressing the challenges associated with NO<sub>x</sub> removal technologies. Herein, we present a unique method for the in situ production of halogen-doped NiCoMoO<sub>x</sub> catalysts utilizing a crystallization-thermal decomposition mechanism and the use of such catalysts for the selective catalytic reduction of NO<sub>x</sub> with NH<sub>3</sub> (NH<sub>3</sub>-SCR). The formation of lattice defect (oxygen vacancies) and surface acid sites on Br-doped NiCoMoO<sub>x</sub> catalyst was considerably enhanced compared with that on pure NiCoMoO<sub>x</sub>, resulting in highly efficient reduction of NO<sub>x</sub> and a broader temperature operating range. The 2Br-NiCoMoO<sub>x</sub> catalyst achieved the highest NO<sub>x</sub> conversion of 97.2 % at 250°C, while NiCoMoO<sub>x</sub> was only 83 %, and the NO<sub>x</sub> conversion was always above 80 % in a wide temperature window of 200 to 350 °C. Through comprehensive characterization, it was also revealed that the introduction of Br enhanced the low temperature redox performance and the adsorption and activation of NO and NH<sub>3</sub> on the catalyst surface, which played a crucial role in facilitating the reaction between NO and NH<sub>3</sub>. Furthermore, we achieved broad temperature window NO<sub>x</sub> reduction by ingeniously utilizing a tandem catalyst system composed of V<sub>2</sub>O<sub>5</sub>-WO<sub>3</sub>/TiO<sub>2</sub> and 2Br-NiCoMoO<sub>x</sub>, with the optimal mass ratio of the two phases being 1:3. This research presents novel design approaches that offer a new approach to the creation of high-performance SCR catalysts.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"22 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.seppur.2025.131764
Xin He, Zhongxin Zhong, Yixuan Ouyang, Jianbo Wang
With the global dramatic increase in e-waste, recycling thermoplastics in e-waste through tribo-electrostatic separation has become essential. In this study, the internal and external functional group distribution of four typical thermoplastics including polyvinyl chloride (PVC), high impact polystyrene (HIPS), polypropylene (PP) and acrylonitrile–butadiene–styrene (ABS) were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). A certain degree of oxidation, mainly exhibited as –OH, existed in all thermoplastics. For the first time, atomic force microscopy (AFM) was employed to assess surface potentials of thermoplastics, and their total electronegativity was calculated by integrating the content and electronegativity of various functional groups. The order of surface potential and total electronegativity in four thermoplastics is consistent: PVC (−4.08 V, 2.74) > HIPS (−8.36 V, 2.59) > PP (−9.18 V, 2.57) > ABS (−11.30 V, 2.56). Both content and electronegativity of functional groups in thermoplastics significantly influence surface potential levels. The variations in volume resistivity and relative dielectric constant (RDC) of thermoplastics under different environmental conditions suggested that low relative humidity and low temperature (particularly lower temperature) are more conducive to separation. Effective separation and recycling of binary mixed thermoplastics could be accomplished via tribo-electrostatic method. Thermoplastics with higher surface potential are more inclined to gain electrons and negatively charged, finally enriched in positive electrode. The greater the surface potential difference between two thermoplastics, the higher purity of their separation products. For instance, both positive and negative product purities of the ABS-PVC exceeded 97 % (surface potential difference of 7.22 V).
{"title":"Investigation of tribo-electrostatic separation mechanism for thermoplastics in e-waste based on functional group distribution and surface potential","authors":"Xin He, Zhongxin Zhong, Yixuan Ouyang, Jianbo Wang","doi":"10.1016/j.seppur.2025.131764","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131764","url":null,"abstract":"With the global dramatic increase in e-waste, recycling thermoplastics in e-waste through tribo-electrostatic separation has become essential. In this study, the internal and external functional group distribution of four typical thermoplastics including polyvinyl chloride (PVC), high impact polystyrene (HIPS), polypropylene (PP) and acrylonitrile–butadiene–styrene (ABS) were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). A certain degree of oxidation, mainly exhibited as –OH, existed in all thermoplastics. For the first time, atomic force microscopy (AFM) was employed to assess surface potentials of thermoplastics, and their total electronegativity was calculated by integrating the content and electronegativity of various functional groups. The order of surface potential and total electronegativity in four thermoplastics is consistent: PVC (−4.08 V, 2.74) > HIPS (−8.36 V, 2.59) > PP (−9.18 V, 2.57) > ABS (−11.30 V, 2.56). Both content and electronegativity of functional groups in thermoplastics significantly influence surface potential levels. The variations in volume resistivity and relative dielectric constant (RDC) of thermoplastics under different environmental conditions suggested that low relative humidity and low temperature (particularly lower temperature) are more conducive to separation. Effective separation and recycling of binary mixed thermoplastics could be accomplished via tribo-electrostatic method. Thermoplastics with higher surface potential are more inclined to gain electrons and negatively charged, finally enriched in positive electrode. The greater the surface potential difference between two thermoplastics, the higher purity of their separation products. For instance, both positive and negative product purities of the ABS-PVC exceeded 97 % (surface potential difference of 7.22 V).","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"38 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.seppur.2025.131779
Yonghai Gan, Le Qu, Zihao Cang, Xinhe Ding, Jun Luo, Zhe Li, Zheng Wang, Chengcheng Ding, Yibin Cui, Bin Xu, Bingdang Wu
Arsenic-fluoride (As-F) co-existence pollution seriously threatened the drinking water safety of residents using groundwater as water sources. At present, coagulation technology was widely used in the removal of arsenic and fluoride due to its economic efficiency and simple operation. While traditional aluminum (Al) and iron (Fe) coagulants could not remove fluoride and As(III) simultaneously, and high metal residues would bring additional risks. Based on the hydrolysis properties and pollution removal performance of zirconium (Zr) and titanium (Ti) salts, here we developed a new bimetallic composite xerogel coagulant (ZTXC) for simultaneous deep purification of fluoride and As(III). The characterization of physicochemical properties showed that ZTXC was a high-polymerization amorphous hydroxide similar to titanium xerogel coagulant (TXC) and zirconium xerogel coagulant (ZXC). ZTXC with a Zr/Ti molar ratio of 4:1 could effectively purify fluoride and As(III) at the same time, reducing fluoride and As(III) to 0.45 mg/L and 9.07 μg/L at pH 5.0 with dosage of 0.4 mM, respectively. Combining the advantages of Zr and Ti salts, ZTXC showed better coagulation performance and lower metal residues than PAC and PFS. Through the analysis of hydrolysis precipitation species and charge differences, fluoride removal mainly relied on the electrostatic attraction by positively charged hydrolysates, while neutral As(III) was mainly removed through hydroxyl coordination. This study could provide reference and theoretical guidance for the development and application of materials and technologies for As-F co-contaminated drinking water treatment.
{"title":"Simultaneous deep purification of fluoride and trivalent arsenic by a bimetallic composite xerogel coagulant","authors":"Yonghai Gan, Le Qu, Zihao Cang, Xinhe Ding, Jun Luo, Zhe Li, Zheng Wang, Chengcheng Ding, Yibin Cui, Bin Xu, Bingdang Wu","doi":"10.1016/j.seppur.2025.131779","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131779","url":null,"abstract":"Arsenic-fluoride (As-F) co-existence pollution seriously threatened the drinking water safety of residents using groundwater as water sources. At present, coagulation technology was widely used in the removal of arsenic and fluoride due to its economic efficiency and simple operation. While traditional aluminum (Al) and iron (Fe) coagulants could not remove fluoride and As(III) simultaneously, and high metal residues would bring additional risks. Based on the hydrolysis properties and pollution removal performance of zirconium (Zr) and titanium (Ti) salts, here we developed a new bimetallic composite xerogel coagulant (ZTXC) for simultaneous deep purification of fluoride and As(III). The characterization of physicochemical properties showed that ZTXC was a high-polymerization amorphous hydroxide similar to titanium xerogel coagulant (TXC) and zirconium xerogel coagulant (ZXC). ZTXC with a Zr/Ti molar ratio of 4:1 could effectively purify fluoride and As(III) at the same time, reducing fluoride and As(III) to 0.45 mg/L and 9.07 μg/L at pH 5.0 with dosage of 0.4 mM, respectively. Combining the advantages of Zr and Ti salts, ZTXC showed better coagulation performance and lower metal residues than PAC and PFS. Through the analysis of hydrolysis precipitation species and charge differences, fluoride removal mainly relied on the electrostatic attraction by positively charged hydrolysates, while neutral As(III) was mainly removed through hydroxyl coordination. This study could provide reference and theoretical guidance for the development and application of materials and technologies for As-F co-contaminated drinking water treatment.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"20 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The comprehensive recovery of spent lithium iron phosphate powder (LFP/C) remains challenging in industry due to the difficulty in impurity removal. Specifically, the impact of fluorine impurity on the recovery process is unclear. In this work, the specific effects of fluorine on the removal of aluminum impurities and the subsequent recovery of FePO4·2H2O from spent LFP/C were investigated, and an acid-assisted pyrolysis process was proposed to transfer fluorine species into the gas phase for fluorine removal. The results indicate that due to the coordination reactions between F- with Al3+ and Fe2+/Fe3+, the presence of F- in increased the difficulty of aluminum removal and reduced the precipitation efficiency of FePO4·2H2O. Additionally, F- accelerated the aging of LFP/C cathode materials, increasing resistance to lithium-ion migration, which ultimately resulted in an irreversible decline in electrochemical performance. The acid-assisted pyrolysis process achieved a fluorine removal rate of approximately 98 % under the optimal condition (pyrolysis temperature 600-700°C, reaction time 4.0h, H3PO4 dosage 1.2 times of theoretic amount, and solid/liquid ratio 4.0), reducing the fluorine content from 1.69 wt% to 0.05 wt%. This work presents a potential strategy for fluorine removal, contributing to the comprehensive recovery of valuable elements from spent LFP/C.
{"title":"Impact and removal of fluorine impurity in the comprehensive recovery of spent LiFePO4/C","authors":"Yang Jiang, Changhong Peng, Kanggen Zhou, Hao Zhou, Tangmiaoqin Chen, Guopeng Zhang, Wei Chen","doi":"10.1016/j.seppur.2025.131766","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131766","url":null,"abstract":"The comprehensive recovery of spent lithium iron phosphate powder (LFP/C) remains challenging in industry due to the difficulty in impurity removal. Specifically, the impact of fluorine impurity on the recovery process is unclear. In this work, the specific effects of fluorine on the removal of aluminum impurities and the subsequent recovery of FePO<sub>4</sub>·2H<sub>2</sub>O from spent LFP/C were investigated, and an acid-assisted pyrolysis process was proposed to transfer fluorine species into the gas phase for fluorine removal. The results indicate that due to the coordination reactions between F<sup>-</sup> with Al<sup>3+</sup> and Fe<sup>2+</sup>/Fe<sup>3+</sup>, the presence of F<sup>-</sup> in increased the difficulty of aluminum removal and reduced the precipitation efficiency of FePO<sub>4</sub>·2H<sub>2</sub>O. Additionally, F<sup>-</sup> accelerated the aging of LFP/C cathode materials, increasing resistance to lithium-ion migration, which ultimately resulted in an irreversible decline in electrochemical performance. The acid-assisted pyrolysis process achieved a fluorine removal rate of approximately 98 % under the optimal condition (pyrolysis temperature 600-700°C, reaction time 4.0h, H<sub>3</sub>PO<sub>4</sub> dosage 1.2 times of theoretic amount, and solid/liquid ratio 4.0), reducing the fluorine content from 1.69 wt% to 0.05 wt%. This work presents a potential strategy for fluorine removal, contributing to the comprehensive recovery of valuable elements from spent LFP/C.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"51 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143020963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-23DOI: 10.1016/j.seppur.2025.131763
J. Vastyl, P. Lestinsky, P. Marsolek, J. Korpas, J. Koumar, M. Maxa, L. Obalova
Most of the world’s caprolactam production involves synthesizing caprolactam from cyclohexanone via the Beckmann rearrangement. Due to the presence of both polar and nonpolar impurities in crude caprolactam, purification traditionally includes forward extraction with a nonpolar solvent, such as trichloroethylene, followed by back-extraction with water and then multistage distillation. This study investigates mixed solvents containing 1-octanol or 1-heptanol combined with cyclohexane or n-heptane as safer, non-carcinogenic alternatives to trichloroethylene in caprolactam extraction. Cyclohexane and n-heptane were selected to adjust the solubility of the alcohols in the aqueous phase. Optimal alcohol concentrations in these mixed solvents were estimated through modeling based on Hansen solubility parameters and experimentally validated using a real crude caprolactam sample (70 wt% caprolactam in water). A 40 wt% 1-octanol in heptane mixture demonstrated a caprolactam distribution coefficient closely matching that of trichloroethylene. Liquid-liquid equilibrium data and key physical properties influencing mass transport (density, viscosity, and interfacial tension) for the chosen mixed solvents were experimentally determined and used to design Karr extraction columns for both forward and back-extraction processes. Literature correlations were applied to predict hydraulic characteristics, including Sauter drop diameter and dispersed phase hold-up. The model was further validated through performance trials with an actual extraction unit using trichloroethylene in caprolactam refining. A mixture of 60 wt% 1-octanol in cyclohexane was identified as optimal, offering a balance between column height, maximum caprolactam content in extract and mixed solvent consumption.
{"title":"Selection of mixed solvent for crude caprolactam extraction","authors":"J. Vastyl, P. Lestinsky, P. Marsolek, J. Korpas, J. Koumar, M. Maxa, L. Obalova","doi":"10.1016/j.seppur.2025.131763","DOIUrl":"https://doi.org/10.1016/j.seppur.2025.131763","url":null,"abstract":"Most of the world’s caprolactam production involves synthesizing caprolactam from cyclohexanone via the Beckmann rearrangement. Due to the presence of both polar and nonpolar impurities in crude caprolactam, purification traditionally includes forward extraction with a nonpolar solvent, such as trichloroethylene, followed by back-extraction with water and then multistage distillation. This study investigates mixed solvents containing 1-octanol or 1-heptanol combined with cyclohexane or n-heptane as safer, non-carcinogenic alternatives to trichloroethylene in caprolactam extraction. Cyclohexane and n-heptane were selected to adjust the solubility of the alcohols in the aqueous phase. Optimal alcohol concentrations in these mixed solvents were estimated through modeling based on Hansen solubility parameters and experimentally validated using a real crude caprolactam sample (70 wt% caprolactam in water). A 40 wt% 1-octanol in heptane mixture demonstrated a caprolactam distribution coefficient closely matching that of trichloroethylene. Liquid-liquid equilibrium data and key physical properties influencing mass transport (density, viscosity, and interfacial tension) for the chosen mixed solvents were experimentally determined and used to design Karr extraction columns for both forward and back-extraction processes. Literature correlations were applied to predict hydraulic characteristics, including Sauter drop diameter and dispersed phase hold-up. The model was further validated through performance trials with an actual extraction unit using trichloroethylene in caprolactam refining. A mixture of 60 wt% 1-octanol in cyclohexane was identified as optimal, offering a balance between column height, maximum caprolactam content in extract and mixed solvent consumption.","PeriodicalId":427,"journal":{"name":"Separation and Purification Technology","volume":"38 1","pages":""},"PeriodicalIF":8.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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