Caprolactam is most commonly used in the production of Nylon 6 in industry and is generally produced from cyclohexanone by the Beckmann rearrangement. Orthophosphoric acid is generally used in fertilizer production and is produced through two processes: wet and dry. In this study, detailed characterization of CL-PA was carried out by synthesizing CL-PA ionic liquid from orthophosphoric acid (PA) and caprolactam (CL). FTIR, Raman and UV-Vis spectroscopic analyses reveal that a bond is formed between CL and PA. The thermal behavior of CL-PA ionic liquid was inspected by TGA and DSC. It has been observed that the decomposition temperature of CL-PA ionic liquid is different from that of the starting materials (CL and PA). It was disclosed by DSC analysis that CL-PA ionic liquid only has a glass transition temperature. The room-temperature CL-PA ionic liquid synthesized from solid CL with melting point of 70.34 ℃ and 85 wt.% PA did not show any melting or freezing point and the glass transition temperature was found to be −27 ℃. It was revealed that CL-PA ionic liquid was more thermally stable than CL which alone almost completely evaporated at about 197 ℃. As a result of FTIR analysis of CL-PA ionic liquid and its constituents, it was demonstrated that –NH peaks of CL disappeared in the CL-PA spectrum and the peak of C=O group shifted to a lower frequency (i.e., 1604 cm⁻1). In the Raman analysis of CL-PA and its constituents, it was observed that the asymmetric C=O bending vibration and C=O stretching vibration of CL disappeared in the CL-PA spectrum. In the UV spectrum, it was observed that the maximum absorbance of CL-PA ionic liquid varied with respect to that of CL.
Ashurst, P. R. (Ed.). (2016). Chemistry and Technology of Soft Drinks and Fruit Juices. Wiley. https://doi.org/10.1002/9781118634943
Bailey, J., Byrne, E. L., Goodrich, P., Kavanagh, P. and Swadźba-Kwaśny, M. (2024). Protic ionic liquids for sustainable uses. Green Chem., 26(3), 1092–1131. https://doi.org/10.1039/D3GC03297C
Bajpai, P. (2021). Deep Eutectic Solvents for Pretreatment of Lignocellulosic Biomass. Springer Singapore. https://doi.org/10.1007/978-981-16-4013-1
Cao, S., Ma, Y., Yang, L., Lin, L., Wang, J., Xing, Y., Lu, F., Cao, T., Zhao, Z. and Liu, D. (2023). Designing Low-Cost, Green, and Recyclable Deep Eutectic Solvents for Selective Separation and Recovery of Valuable Metals from Spent Li-Ion Batteries. ACS Sustain. Chem. Eng., 11(48), 16984–16994. https://doi.org/10.1021/acssuschemeng.3c04802
Celik, S., Albayrak, A. T., Akyuz, S., Ozel, A. E. and Sigirci, B. D. (2021). Synthesis, antimicrobial activity, molecular docking and ADMET study of a caprolactam-glycine cluster. J Biomol. Struct. Dyn., 39(7), 2376–2386. https://doi.org/10.1080/07391102.2020.1748112
Chen, H., Li, W., Wang, J., Xu, H., Liu, Y., Zhang, Z., Li, Y. and Zhang, Y. (2019). Adsorption of cadmium and lead ions by phosphoric acid-modified biochar generated from chicken feather: Selective adsorption and influence of dissolved organic matter. Bioresour. Technol., 292. https://doi.org/10.1016/j.biortech.2019.121948
Cheremisina, O. V., Sergeev, V. V., Chirkst, D. E. and Litvinova, T. E. (2015). Thermodynamic investigation into extraction of cerium(III) by tributyl phosphate from phosphoric acid solutions. Russ. J. Non-ferrous Metals, 56(6), 615–621. https://doi.org/10.3103/S1067821215060036
Cherkasova, E. V., Patrakov, Y. F., Tryasunov, B. G., Cherkasova, T. G. and Tatarinova, E. S. (2009). Thermal analysis of rare-earth metal(III) hexa(isothiocyanato)chromate(III) complexes with ε-caprolactam. Russ. J. Inorg. Chem., 54(10), 1625–1629. https://doi.org/10.1134/S0036023609100192
Chu, G., Zhao, J., Huang, Y., Zhou, D., Liu, Y., Wu, M., Peng, H., Zhao, Q., Pan, B. and Steinberg, C. E. W. (2018). Phosphoric acid pretreatment enhances the specific surface areas of biochars by generation of micropores. Environ. Pollut., 240, 1–9. https://doi.org/10.1016/j.envpol.2018.04.003
Fang, X., Wyatt, T., Shi, J. and Yao, D. (2018). Fabrication of high-strength polyoxymethylene fibers by gel spinning. J. Mater. Sci., 53(16), 11901–11916. https://doi.org/10.1007/s10853-018-2410-5
Frost, R. L., Xi, Y., Scholz, R., Belotti, F. M. and Cândido Filho, M. (2013). Infrared and Raman spectroscopic characterization of the borate mineral colemanite – CaB3O4(OH)3·H2O – implications for the molecular structure. J. Mol. Struct., 1037, 23–28. https://doi.org/10.1016/j.molstruc.2012.11.047
Gilmour, R. (2014). Phosphoric Acid: Purification, Uses, Technology, and Economics. CRC Press. https://doi.org/10.1201/b16187
Guo, B., Duan, E., Zhong, Y., Gao, L., Zhang, X. and Zhao, D. (2011). Absorption and oxidation of H2S in caprolactam tetrabutyl ammonium bromide ionic liquid. Energ. Fuel., 25(1), 159–161. https://doi.org/10.1021/ef1012006
Hao, L., Su, T., Hao, D., Deng, C., Ren, W. and Lü, H. (2018). Oxidative desulfurization of diesel fuel with caprolactam-based acidic deep eutectic solvents: Tailoring the reactivity of DESs by adjusting the composition. Cuihua Xuebao/Chinese J. Catal., 39(9), 1552–1559. https://doi.org/10.1016/S1872-2067(18)63091-8
House, J. E. (2020). Inorganic chemistry. Academic Press.
Ichihashi, H., Ishida, M., Shiga, A., Kitamura, M., Suzuki, T., Suenobu, K. and Sugita, K. (2003). The Catalysis of Vapor-Phase Beckmann Rearrangement for the Production of ε-Caprolactam. Catal. Surv. Asia, 7(4), 261–270. https://doi.org/10.1023/B:CATS.0000008165.80991.05
Kabo, G. J., Kozyro, A. A., Krouk, V. S., Sevruk, V. M., Yursha, I. A., Simirsky, V. V and Gogolinsky, V. I. (1992). Thermodynamic properties of 6-aminohexanoic lactam (-caprolactam). J. Chem. Thermodyn., 24(1), 1-13. https://doi.org/10.1016/S0021-9614(05)80249-6
Kalinová, J. P., Tříska, J., Vrchotová, N. and Novák, J. (2016). Uptake of caprolactam and its influence on growth and oxygen production of Desmodesmus quadricauda algae. Environ. Pollut., 213, 518–523. https://doi.org/10.1016/j.envpol.2016.03.024
Karibayev, M. and Shah, D. (2020). Comprehensive Computational Analysis Exploring the Formation of Caprolactam-Based Deep Eutectic Solvents and Their Applications in Natural Gas Desulfurization. Energ. Fuel., 34(8), 9894–9902. https://doi.org/10.1021/acs.energyfuels.0c01721
Lange, N. A. and Speight, J. G. (2005). Lange’s handbook of chemistry. McGraw-Hill.
Larkin, P. (2011). Infrared and Raman Spectroscopy. Elsevier. https://doi.org/10.1016/C2010-0-68479-3
Li, J., Zhang, C. and Luo, J. (2011). Superlubricity behavior with phosphoric acid-water network induced by rubbing. Langmuir, 27(15), 9413–9417. https://doi.org/10.1021/la201535x
Li, W.-C., Lu, A.-H., Palkovits, R., Schmidt, W., Spliethoff, B. and Schüth, F. (2005). Hierarchically Structured Monolithic Silicalite-1 Consisting of Crystallized Nanoparticles and Its Performance in the Beckmann Rearrangement of Cyclohexanone Oxime. J. Am. Chem. Soc., 127(36), 12595–12600. https://doi.org/10.1021/ja052693v
Liu, B., Zhao, J. and Wei, F. (2013). Characterization of caprolactam based eutectic ionic liquids and their application in SO2 absorption. J. Mol. Liq., 180, 19–25. https://doi.org/10.1016/j.molliq.2012.12.024
Malek, M. A. and Chong, C. S. (2000). FTIR study of H2O in polyallyl diglycol carbonate. Vib. Spectrosc., 24, 181-184. https://doi.org/10.1016/S0924-2031(00)00071-0
Benvenuto, M. A. and Plaumann, H. (2021). Industrial Catalysis. Walter de Gruyter GmbH, Berlin/Boston.
Mather, R. R. and Wardman, R. H. (2015). The chemistry of textile fibres, 2nd Edition, The Royal Society of Chemistry. https://doi.org/10.1039/9781782626534
Maxwell, G. R. (2005). Synthetic Nitrogen Products. Kluwer Academic Publishers. https://doi.org/10.1007/b106641
McGraw-Hill Concise Encyclopedia of Science and Technology FIFTH EDITION. (2005). McGraw-Hill Companies, Inc.
Naiyl, R. A., Kengara, F. O., Kiriamiti, K. H. and Ragab, Y. A. (2021). Synthesis and Characterization of Caprolactam- based Ionic Liquids as Green Solvents. Asian J. Appl. Chem. Res., 74–87. https://doi.org/10.9734/ajacr/2021/v8i430201
Naiyl, R. A., Kengara, F. O., Kiriamiti, K. H. and Ragab, Y. A. (2022). Lipid extraction from microalgae using pure caprolactam-based ionic liquids and with organic co-solvent. PeerJ Anal. Chem., 4, e13. https://doi.org/10.7717/peerj-achem.13
Płotka-Wasylka, J., de la Guardia, M., Andruch, V. and Vilková, M. (2020). Deep eutectic solvents vs ionic liquids: Similarities and differences. Microchem. J., 159, 105539. https://doi.org/10.1016/j.microc.2020.105539
Ren, C., Wang, Z., Gao, Q., Li, J., Jiang, S., Huang, Q., Yang, Y., Zhang, J., Wang, Y., Hu, Y., Liu, Z. and Guo, X. (2023). Novel Brønsted Acidic Ionic Liquids as High Efficiency Catalysts for Liquid-Phase Beckmann Rearrangement. Catalysts, 13(6). https://doi.org/10.3390/catal13060978
Sato, M., Ikushima, Y., Hatakeda, K. and Ikeshoji, T. (2005). Acceleration of Chemical Reactions Using a Supercritical Water Microreaction System. Int. J. Chem. React. Eng., 3(1). https://doi.org/10.2202/1542-6580.1294
Shiflett, M. B. (Ed.). (2020). Commercial Applications of Ionic Liquids. Springer International Publishing. https://doi.org/10.1007/978-3-030-35245-5
Sun, Q., Lin, D., Khayatnezhad, M. and Taghavi, M. (2021). Investigation of phosphoric acid fuel cell, linear Fresnel solar reflector and Organic Rankine Cycle polygeneration energy system in different climatic conditions. Process Saf. Environ., 147, 993–1008. https://doi.org/10.1016/j.psep.2021.01.035
Sun, S., Liu, S., Yu, F., Zhang, J., Xing, W. and Yu, S. (2022). Reusable Deep Eutectic Solvents for Clean ϵ-Caprolactam Synthesis under Mild Conditions. ACS Sustain. Chem. Eng., 10(4), 1675–1688. https://doi.org/10.1021/acssuschemeng.1c07613
Wang, H., Qin, M., Wu, Q., Cheng, D. G., Meng, X., Wang, L. and Xiao, F. S. (2023). Zeolite Catalysts for Green Production of Caprolactam. Ind. Eng. Chem. Res., 62(5), 2217–2224. https://doi.org/10.1021/acs.iecr.2c01693
Wang, L. K. (2006). Waste treatment in the process industries. CRC/Taylor and Francis.
Wang, S., Liu, G., Wan, W., Li, X., Li, J. and Wang, C. (2024). Acetamide-Caprolactam Deep Eutectic Solvent-Based Electrolyte for Stable Zn-Metal Batteries. Adv. Mater., 36(5). https://doi.org/10.1002/adma.202306546
Wei, H., Wang, T., Zhang, Q., Jiang, Y. and Mo, C. (2020). Study of composition and structure of aluminum phosphate binder. J. Chin. Chem. Soc., 67(1), 116–124. https://doi.org/10.1002/jccs.201900008
Xu, C., Zhang, W., Li, P., Zhao, S., Du, Y., Jin, H., Zhang, Y., Wang, Z. and Zhang, J. (2019). High-performance aluminum-ion batteries based on AlCl3/caprolactam electrolytes. Sustain. Energ. Fuels, 4(1), 121–127. https://doi.org/10.1039/c9se00941h
Xu, L., Yin, J., Luo, Y., Liu, H., Li, H., Zhu, L., He, J., Jiang, W., Zhu, W. and Li, H. (2022). Rational Design of Caprolactam-Based Deep Eutectic Solvents for Extractive Desulfurization of Diesel Fuel and Mechanism Study. ACS Sustain. Chem. Eng., 10(14), 4551–4560. https://doi.org/10.1021/acssuschemeng.1c08413
Yang, H., Jiang, B., Sun, Y., Hao, L., Huang, Z. and Zhang, L. (2016). Synthesis and oxidative desulfurization of novel lactam-based Brønsted-Lewis acidic ionic liquids. Chem. Eng. J., 306, 131–138. https://doi.org/10.1016/j.cej.2016.07.044
Yankova, R. and Tankov, I. (2021). Hydrogen bonding effect on the thermal behavior of acidic ionic liquids. J. Mol. Struct., 1238, 130416. https://doi.org/10.1016/j.molstruc.2021.130416
You, K., Mao, L., Yin, D., Liu, P. and Luo, H. (2008). Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam catalyzed by sulfonic acid resin in DMSO. Catal. Commun., 9(6), 1521–1526. https://doi.org/10.1016/j.catcom.2008.01.011
Zhang, Y., Cui, P., Luo, G., Chen, L., Li, X., Chao, Y. and Zhu, W. (2023). One-step selective separation and efficient recovery of valuable metals from spent lithium batteries by phosphoric acid-based deep eutectic solvent. Green Chem. Eng., 5(3), 390-398. https://doi.org/10.1016/j.gce.2023.10.002
Zhou, Q., Yu, Y., Liu, Q., Zhuang, Y., Lv, Y., Song, N. and Ni, L. (2020). Morphology evolution and thermodynamic behavior of the “soft core hard shell” structure formed by reactive amino triblock in epoxy resin. J. Mater. Sci., 55(35), 16846–16859. https://doi.org/10.1007/s10853-020-05258-2
Zhu, Z., Luo, X., Sokolov, A. P., Sokolov, A. P. and Paddison, S. J. (2020). Proton Transfer in Phosphoric Acid-Based Protic Ionic Liquids: Effects of the Base. J. Phys. Chem. A, 124(20), 4141–4149. https://doi.org/10.1021/acs.jpca.0c02863
Year 2024,
Volume: 7 Issue: 2, 165 - 174, 04.10.2024
Ashurst, P. R. (Ed.). (2016). Chemistry and Technology of Soft Drinks and Fruit Juices. Wiley. https://doi.org/10.1002/9781118634943
Bailey, J., Byrne, E. L., Goodrich, P., Kavanagh, P. and Swadźba-Kwaśny, M. (2024). Protic ionic liquids for sustainable uses. Green Chem., 26(3), 1092–1131. https://doi.org/10.1039/D3GC03297C
Bajpai, P. (2021). Deep Eutectic Solvents for Pretreatment of Lignocellulosic Biomass. Springer Singapore. https://doi.org/10.1007/978-981-16-4013-1
Cao, S., Ma, Y., Yang, L., Lin, L., Wang, J., Xing, Y., Lu, F., Cao, T., Zhao, Z. and Liu, D. (2023). Designing Low-Cost, Green, and Recyclable Deep Eutectic Solvents for Selective Separation and Recovery of Valuable Metals from Spent Li-Ion Batteries. ACS Sustain. Chem. Eng., 11(48), 16984–16994. https://doi.org/10.1021/acssuschemeng.3c04802
Celik, S., Albayrak, A. T., Akyuz, S., Ozel, A. E. and Sigirci, B. D. (2021). Synthesis, antimicrobial activity, molecular docking and ADMET study of a caprolactam-glycine cluster. J Biomol. Struct. Dyn., 39(7), 2376–2386. https://doi.org/10.1080/07391102.2020.1748112
Chen, H., Li, W., Wang, J., Xu, H., Liu, Y., Zhang, Z., Li, Y. and Zhang, Y. (2019). Adsorption of cadmium and lead ions by phosphoric acid-modified biochar generated from chicken feather: Selective adsorption and influence of dissolved organic matter. Bioresour. Technol., 292. https://doi.org/10.1016/j.biortech.2019.121948
Cheremisina, O. V., Sergeev, V. V., Chirkst, D. E. and Litvinova, T. E. (2015). Thermodynamic investigation into extraction of cerium(III) by tributyl phosphate from phosphoric acid solutions. Russ. J. Non-ferrous Metals, 56(6), 615–621. https://doi.org/10.3103/S1067821215060036
Cherkasova, E. V., Patrakov, Y. F., Tryasunov, B. G., Cherkasova, T. G. and Tatarinova, E. S. (2009). Thermal analysis of rare-earth metal(III) hexa(isothiocyanato)chromate(III) complexes with ε-caprolactam. Russ. J. Inorg. Chem., 54(10), 1625–1629. https://doi.org/10.1134/S0036023609100192
Chu, G., Zhao, J., Huang, Y., Zhou, D., Liu, Y., Wu, M., Peng, H., Zhao, Q., Pan, B. and Steinberg, C. E. W. (2018). Phosphoric acid pretreatment enhances the specific surface areas of biochars by generation of micropores. Environ. Pollut., 240, 1–9. https://doi.org/10.1016/j.envpol.2018.04.003
Fang, X., Wyatt, T., Shi, J. and Yao, D. (2018). Fabrication of high-strength polyoxymethylene fibers by gel spinning. J. Mater. Sci., 53(16), 11901–11916. https://doi.org/10.1007/s10853-018-2410-5
Frost, R. L., Xi, Y., Scholz, R., Belotti, F. M. and Cândido Filho, M. (2013). Infrared and Raman spectroscopic characterization of the borate mineral colemanite – CaB3O4(OH)3·H2O – implications for the molecular structure. J. Mol. Struct., 1037, 23–28. https://doi.org/10.1016/j.molstruc.2012.11.047
Gilmour, R. (2014). Phosphoric Acid: Purification, Uses, Technology, and Economics. CRC Press. https://doi.org/10.1201/b16187
Guo, B., Duan, E., Zhong, Y., Gao, L., Zhang, X. and Zhao, D. (2011). Absorption and oxidation of H2S in caprolactam tetrabutyl ammonium bromide ionic liquid. Energ. Fuel., 25(1), 159–161. https://doi.org/10.1021/ef1012006
Hao, L., Su, T., Hao, D., Deng, C., Ren, W. and Lü, H. (2018). Oxidative desulfurization of diesel fuel with caprolactam-based acidic deep eutectic solvents: Tailoring the reactivity of DESs by adjusting the composition. Cuihua Xuebao/Chinese J. Catal., 39(9), 1552–1559. https://doi.org/10.1016/S1872-2067(18)63091-8
House, J. E. (2020). Inorganic chemistry. Academic Press.
Ichihashi, H., Ishida, M., Shiga, A., Kitamura, M., Suzuki, T., Suenobu, K. and Sugita, K. (2003). The Catalysis of Vapor-Phase Beckmann Rearrangement for the Production of ε-Caprolactam. Catal. Surv. Asia, 7(4), 261–270. https://doi.org/10.1023/B:CATS.0000008165.80991.05
Kabo, G. J., Kozyro, A. A., Krouk, V. S., Sevruk, V. M., Yursha, I. A., Simirsky, V. V and Gogolinsky, V. I. (1992). Thermodynamic properties of 6-aminohexanoic lactam (-caprolactam). J. Chem. Thermodyn., 24(1), 1-13. https://doi.org/10.1016/S0021-9614(05)80249-6
Kalinová, J. P., Tříska, J., Vrchotová, N. and Novák, J. (2016). Uptake of caprolactam and its influence on growth and oxygen production of Desmodesmus quadricauda algae. Environ. Pollut., 213, 518–523. https://doi.org/10.1016/j.envpol.2016.03.024
Karibayev, M. and Shah, D. (2020). Comprehensive Computational Analysis Exploring the Formation of Caprolactam-Based Deep Eutectic Solvents and Their Applications in Natural Gas Desulfurization. Energ. Fuel., 34(8), 9894–9902. https://doi.org/10.1021/acs.energyfuels.0c01721
Lange, N. A. and Speight, J. G. (2005). Lange’s handbook of chemistry. McGraw-Hill.
Larkin, P. (2011). Infrared and Raman Spectroscopy. Elsevier. https://doi.org/10.1016/C2010-0-68479-3
Li, J., Zhang, C. and Luo, J. (2011). Superlubricity behavior with phosphoric acid-water network induced by rubbing. Langmuir, 27(15), 9413–9417. https://doi.org/10.1021/la201535x
Li, W.-C., Lu, A.-H., Palkovits, R., Schmidt, W., Spliethoff, B. and Schüth, F. (2005). Hierarchically Structured Monolithic Silicalite-1 Consisting of Crystallized Nanoparticles and Its Performance in the Beckmann Rearrangement of Cyclohexanone Oxime. J. Am. Chem. Soc., 127(36), 12595–12600. https://doi.org/10.1021/ja052693v
Liu, B., Zhao, J. and Wei, F. (2013). Characterization of caprolactam based eutectic ionic liquids and their application in SO2 absorption. J. Mol. Liq., 180, 19–25. https://doi.org/10.1016/j.molliq.2012.12.024
Malek, M. A. and Chong, C. S. (2000). FTIR study of H2O in polyallyl diglycol carbonate. Vib. Spectrosc., 24, 181-184. https://doi.org/10.1016/S0924-2031(00)00071-0
Benvenuto, M. A. and Plaumann, H. (2021). Industrial Catalysis. Walter de Gruyter GmbH, Berlin/Boston.
Mather, R. R. and Wardman, R. H. (2015). The chemistry of textile fibres, 2nd Edition, The Royal Society of Chemistry. https://doi.org/10.1039/9781782626534
Maxwell, G. R. (2005). Synthetic Nitrogen Products. Kluwer Academic Publishers. https://doi.org/10.1007/b106641
McGraw-Hill Concise Encyclopedia of Science and Technology FIFTH EDITION. (2005). McGraw-Hill Companies, Inc.
Naiyl, R. A., Kengara, F. O., Kiriamiti, K. H. and Ragab, Y. A. (2021). Synthesis and Characterization of Caprolactam- based Ionic Liquids as Green Solvents. Asian J. Appl. Chem. Res., 74–87. https://doi.org/10.9734/ajacr/2021/v8i430201
Naiyl, R. A., Kengara, F. O., Kiriamiti, K. H. and Ragab, Y. A. (2022). Lipid extraction from microalgae using pure caprolactam-based ionic liquids and with organic co-solvent. PeerJ Anal. Chem., 4, e13. https://doi.org/10.7717/peerj-achem.13
Płotka-Wasylka, J., de la Guardia, M., Andruch, V. and Vilková, M. (2020). Deep eutectic solvents vs ionic liquids: Similarities and differences. Microchem. J., 159, 105539. https://doi.org/10.1016/j.microc.2020.105539
Ren, C., Wang, Z., Gao, Q., Li, J., Jiang, S., Huang, Q., Yang, Y., Zhang, J., Wang, Y., Hu, Y., Liu, Z. and Guo, X. (2023). Novel Brønsted Acidic Ionic Liquids as High Efficiency Catalysts for Liquid-Phase Beckmann Rearrangement. Catalysts, 13(6). https://doi.org/10.3390/catal13060978
Sato, M., Ikushima, Y., Hatakeda, K. and Ikeshoji, T. (2005). Acceleration of Chemical Reactions Using a Supercritical Water Microreaction System. Int. J. Chem. React. Eng., 3(1). https://doi.org/10.2202/1542-6580.1294
Shiflett, M. B. (Ed.). (2020). Commercial Applications of Ionic Liquids. Springer International Publishing. https://doi.org/10.1007/978-3-030-35245-5
Sun, Q., Lin, D., Khayatnezhad, M. and Taghavi, M. (2021). Investigation of phosphoric acid fuel cell, linear Fresnel solar reflector and Organic Rankine Cycle polygeneration energy system in different climatic conditions. Process Saf. Environ., 147, 993–1008. https://doi.org/10.1016/j.psep.2021.01.035
Sun, S., Liu, S., Yu, F., Zhang, J., Xing, W. and Yu, S. (2022). Reusable Deep Eutectic Solvents for Clean ϵ-Caprolactam Synthesis under Mild Conditions. ACS Sustain. Chem. Eng., 10(4), 1675–1688. https://doi.org/10.1021/acssuschemeng.1c07613
Wang, H., Qin, M., Wu, Q., Cheng, D. G., Meng, X., Wang, L. and Xiao, F. S. (2023). Zeolite Catalysts for Green Production of Caprolactam. Ind. Eng. Chem. Res., 62(5), 2217–2224. https://doi.org/10.1021/acs.iecr.2c01693
Wang, L. K. (2006). Waste treatment in the process industries. CRC/Taylor and Francis.
Wang, S., Liu, G., Wan, W., Li, X., Li, J. and Wang, C. (2024). Acetamide-Caprolactam Deep Eutectic Solvent-Based Electrolyte for Stable Zn-Metal Batteries. Adv. Mater., 36(5). https://doi.org/10.1002/adma.202306546
Wei, H., Wang, T., Zhang, Q., Jiang, Y. and Mo, C. (2020). Study of composition and structure of aluminum phosphate binder. J. Chin. Chem. Soc., 67(1), 116–124. https://doi.org/10.1002/jccs.201900008
Xu, C., Zhang, W., Li, P., Zhao, S., Du, Y., Jin, H., Zhang, Y., Wang, Z. and Zhang, J. (2019). High-performance aluminum-ion batteries based on AlCl3/caprolactam electrolytes. Sustain. Energ. Fuels, 4(1), 121–127. https://doi.org/10.1039/c9se00941h
Xu, L., Yin, J., Luo, Y., Liu, H., Li, H., Zhu, L., He, J., Jiang, W., Zhu, W. and Li, H. (2022). Rational Design of Caprolactam-Based Deep Eutectic Solvents for Extractive Desulfurization of Diesel Fuel and Mechanism Study. ACS Sustain. Chem. Eng., 10(14), 4551–4560. https://doi.org/10.1021/acssuschemeng.1c08413
Yang, H., Jiang, B., Sun, Y., Hao, L., Huang, Z. and Zhang, L. (2016). Synthesis and oxidative desulfurization of novel lactam-based Brønsted-Lewis acidic ionic liquids. Chem. Eng. J., 306, 131–138. https://doi.org/10.1016/j.cej.2016.07.044
Yankova, R. and Tankov, I. (2021). Hydrogen bonding effect on the thermal behavior of acidic ionic liquids. J. Mol. Struct., 1238, 130416. https://doi.org/10.1016/j.molstruc.2021.130416
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