Coal pitch-based nanosheets enhance the electronic and ionic transport of flow electrode capacitive deionization

Abstract

High-salinity wastewater treatment has always been a challenging issue. In this study, coal tar pitch was used as the carbon source and melamine as the nitrogen source to prepare coal tar pitch-based nanosheets (CPN-9) using a salt-template method. The desalination performance of CPN-9 was evaluated using flow-electrode capacitive deionization technology. The results showed that CPN-9 has a high specific surface area (466.34 m²/g), a rich pore structure (micro-/meso-pore volume was 0.28), excellent rheological properties, and hydrophilicity (contact angle of 20.44°), thereby accelerating ion transport. Electrochemical results indicated that CPN-9 exhibits a significant double-layer ion storage mechanism, with a specific capacitance of 176.66 F/g at a current density of 0.5 A/g. CPN-9 has a very low charge transfer resistance. The synergistic effect of aromatic carbon and nitrogen doping (the content of pyrrole and pyridine nitrogen was 36.40% and 35.83%, respectively) in coal tar pitch accelerates electron transfer in CPN-9. The good ion diffusion performance and low impedance of CPN-9 accelerate the ion exchange rate, resulting in outstanding desalination performance. At 1.2 V and 3% mass loading, with a CPN-9 to conductive carbon black ratio of 4:1, the average desalination rate, charge efficiency, and energy consumption reached 0.039 mg/(cm²·min), 48.47%, and 0.012 kWh/mol, respectively. In summary, this study optimized the structure of CPN-9 from the perspective of electronic and ionic transport, enhancing its desalination performance and providing theoretical support for the deionization of high-salinity wastewater.

Keywords

Flow electrode capacitor deionization / Coal pitch / Mine water / Desalination

Acknowledgments

This research was financially supported by National Natural Scie nce Foundation of China (Nos. 52374286 and 52274279); the National Key Research and Development Program of China (No. 202 1YFC2902604).

Supplementary material

Supplementary data to this article can be found online at https://doi.org/10.1016/j.ijmst.2025.03.008.

References

[1] Witecki K, Polowczyk I, Kowalczuk PB. Chemistry of wastewater circuits in mineral processing industry: A review. J Water Process Eng 2022; 45:102509.

[2] Opitz J, Bauer M, Alte M, Peiffer S. Development of a novel sizing approach for passive mine water treatment systems based on ferric iron sedimentation kinetics. Water Res 2023; 233:119770.

[3] Song HQ, Xu JJ, Fang J, Cao ZG, Yang LZ, Li TX. Potential for mine water disposal in coal seam goaf: Investigation of storage coefficients in the Shendong mining area. J Clean Prod 2020; 244:118646.

[4] Zhang SY, Wang H, He XW, Guo SQ, Xia Y, Zhou YX, Liu K, Yang S. Research progress, problems and prospects of mine water treatment technology and resource utilization in China. Crit Rev Environ Sci Technol 2020; 50(4):331-83.

[5] Liu PY, Yan TT, Shi LY, Park HS, Chen XC, Zhao ZG, Zhang DS. Graphene-based materials for capacitive deionization. J Mater Chem A 2017; 5(27):13907-43.

[6] Zhao XY, Wei HX, Zhao HC, Wang YF, Tang N. Electrode materials for capacitive deionization: A review. J Electroanal Chem 2020; 873:114416.

[7] Yang F, He YF, Rosentsvit L, Suss ME, Zhang XR, Gao T, Liang P. Flow-electrode capacitive deionization: A review and new perspectives. Water Res 2021; 200:117222.

[8] Wang RH, Sun KW, Zhang YH, Qian CF, Bao WZ. Dimensional optimization enables high-performance capacitive deionization. J Mater Chem A 2022; 10 (12):6414-41.

[9] Ma J, Chen LL, Yu F. Environmental applications and perspectives of flow electrode capacitive deionization (FCDI). Sep Purif Technol 2024; 335:126095.

[10] Ma JX, He C, He D, Zhang CY, Waite TD. Analysis of capacitive and electrodialytic contributions to water desalination by flow-electrode CDI. Water Res 2018; 144:296-303.

[11] Zornitta RL, Ruotolo LAM. Simultaneous analysis of electrosorption capacity and kinetics for CDI desalination using different electrode configurations. Chem Eng J 2018; 332:33-41.

[12] Tauk M, Folaranmi G, Cretin M, Bechelany M, Sistat P, Zhang CY, Zaviska F. Recent advances in capacitive deionization: A comprehensive review on electrode materials. J Environ Chem Eng 2023; 11(6):111368.

[13] Zhang XY, Dutta J. X-Fe (X=Mn, Co, Cu) Prussian blue analogue-modified carbon cloth electrodes for capacitive deionization. ACS Appl Energy Mater 2021; 4(8):8275-84.

[14] Mourshed M, Niya SMR, Ojha R, Rosengarten G, Andrews J, Shabani B. Carbon-based slurry electrodes for energy storage and power supply systems. Energy Storage Mater 2021; 40:461-89.

[15] Zhu ZT, Xiong JJ, Chen MJ, Mu LW, Lu XH, Zhu JH. Insights into the particle hydrophilicity and electrical conductivity for the construction of a highly efficient electrical percolation network in flow electrode capacitive deionization. Ind Eng Chem Res 2023; 62(43):17721-30.

[16] Qin FF, Tian XD, Guo ZY, Shen WZ. Asphaltene-based porous carbon nanosheet as electrode for supercapacitor. ACS Sustainable Chem Eng 2018; 6 (11):15708-19.

[17] Wang LP, Zhou Y, Qiu JS. Influence of pore structures on the electrochemical performance of asphaltene-based ordered mesoporous carbons. Microporous Mesoporous Mater 2013; 174:67-73.

[18] Hoheisel T, Schrettl S, Dr RS, Prof HF. Nanostructured carbonaceous materials from molecular precursors. Angew Chem Int Ed 2010; 49(37):6496-515.

[19] Qu WH, Guo YB, Shen WZ, Li WC. Using asphaltene supermolecules derived from coal for the preparation of efficient carbon electrodes for supercapacitors. J Phys Chem C 2016; 120(28):15105-13.

[20] Luo KY, Niu QY, Zhu Y, Song B, Zeng GM, Tang WW, Ye SJ, Zhang J, Duan MB, Xing WL. Desalination behavior and performance of flow-electrode capacitive deionization under various operational modes. Chem Eng J 2020; 389:124051.

[21] Zhang ZH, Yang WM, Cheng LS, Cao WY, Sain M, Tan J, Wang A, Jia HB. Carbon fibers with high electrical conductivity: laser irradiation of mesophase pitch filaments obtains high graphitization degree. ACS Sustainable Chem Eng 2020; 8(48):17629-38.

[22] Zhai YP, Dou YQ, Zhao DY, Fulvio PF, Mayes RT, Dai S. Carbon materials for chemical capacitive energy storage. Adv Mater 2011; 23(42):4828-50.

[23] Zhu YW, Murali S, Stoller MD, Ganesh KJ, Cai WW, Ferreira PJ, Pirkle A, Wallace RM, Cychosz Katie A, Thommes M, Su D, Stach Eric A, Ruoff Rodney S. Carbon-based supercapacitors produced by activation of graphene. Science 2011; 332 (6037):1537-41.

[24] Chen H, Liu T, Mou JR, Zhang WJ, Jiang ZJ, Liu J, Huang JL, Liu ML. Free-standing N-self-doped carbon nanofiber aerogels for high-performance all-solid-state supercapacitors. Nano Energy 2019; 63:103836.

[25] Zhang R, Jing XX, Chu YT, Wang L, Kang WJ, Wei DH, Li HB, Xiong SL. Nitrogen/ oxygen Co-doped monolithic carbon electrodes derived from melamine foam for high-performance supercapacitors. J Mater Chem A 2018; 6(36):17730-9.

[26] Fu GS, Li Q, Ye JL, Han JJ, Wang JQ, Zhai L, Zhu YW. Hierarchical porous carbon with high nitrogen content derived from plant waste (pomelo peel) for supercapacitor. J Mater Sci Mater Electron 2018; 29(9):7707-17.

[27] Wang SY, Wang G, Wu TT, Li CP, Wang YW, Pan X, Zhan F, Zhang YQ, Wang SF, Qiu JS. Membrane-free hybrid capacitive deionization system based on redox reaction for high-efficiency NaCl removal. Environ Sci Technol 2019; 53 (11):6292-301.

[28] Sun YR, Cheng YJ, Yu F, Ma J. Enhanced salt removal performance using graphene-modified sodium vanadium fluorophosphate in flow electrode capacitive deionization. ACS Appl Mater Interfaces 2021; 13(45):53850-8.

[29] Hatzell KB, Hatzell MC, Cook KM, Boota M, Housel GM, McBride A, Kumbur EC, Gogotsi Y. Effect of oxidation of carbon material on suspension electrodes for flow electrode capacitive deionization. Environ Sci Technol 2015; 49 (5):3040-7.

[30] Chen KY, Shen YY, Wang DM, Hou CH. Carbon nanotubes/activated carbon hybrid as a high-performance suspension electrode for the electrochemical desalination of wastewater. Desalination 2022; 522:115440.

[31] Li BF, Xiao ZH, Cao YT, Yu ZQ, Sun YK, Li ZC, Wang YX, Gao ZF, Xu CM. Mesopore-dominated porous carbon derived from confinement-region activation strategy toward high capacitive desalination performance. Fuel 2023; 352:129112.

[32] Yu F, Yin HY, Bai XT, Pan JY, Zhang XC, Ma J. Cu@Cu2O/carbon for efficient desalination in capacitive deionization. Chin Chem Lett 2023; 34(12):108362.

[33] Huang QR, Hu LY, Chen XC, Cai WJ, Wang L, Wang B. Metal-organic framework-derived N-doped carbon with controllable mesopore sizes for low-Pt fuel cells. Adv Funct Mater 2023; 33(44):2302582.

[34] Cai YM, Zhao XT, Wang Y, Ma DY, Xu SC. Enhanced desalination performance utilizing sulfonated carbon nanotube in the flow-electrode capacitive deionization process. Sep Purif Technol 2020; 237:116381.

[35] Liang P, Sun XL, Bian YH, Zhang HL, Yang XF, Jiang Y, Liu PP, Huang X. Optimized desalination performance of high voltage flow-electrode capacitive deionization by adding carbon black in flow-electrode. Desalination 2017; 420:63-9.

[36] Li DP, Ning XN, Yang CH, Chen XH, Wang Y. Rich heteroatom doping magnetic carbon electrode for flow-capacitive deionization with enhanced salt removal ability. Desalination 2020; 482:114374.

[37] Vengatesan MR, Fahmi Darawsheh IF, Govindan B, Alhseinat E, Banat F. Ag-Cu bimetallic nanoparticle decorated graphene nanocomposite as an effective anode material for hybrid capacitive deionization (HCDI) system. Electrochim Acta 2019; 297:1052-62.

[38] Wei Q, Hu YD, Wang J, Ru Q, Hou XH, Zhao LZ, Yu DYW, San HK, Yan DL, Hui KN, Chen FM. Low energy consumption flow capacitive deionization with a combination of redox couples and carbon slurry. Carbon. 2020; 170:487-92.

[39] Ma JX, He D, Tang WW, Kovalsky P, He C, Zhang CY, Waite TD. Development of redox-active flow electrodes for high-performance capacitive deionization. Environ Sci Technol 2016; 50(24):13495-501.

[40] Zhu Y, Wang H, Zhang BS, Hu B, Wang YW, Li M, Yang JM, Liu JY. Carbon-covered Fe-pillared bentonite electrode boosting capacitive deionization. Desalination 2024; 577:117391.

[41] He QQ, Peng HS, Meng Z, Miao ZY, Wan KJ, Xu E, Gao MQ, Huang SM. Dual activation of porous nitrogen-doped carbon materials for highly efficient mine water desalination by flow electrode capacitive deionization. J China Coal Soc 2024; 0509:1-17.