Abstract：Flotation technology offers an effective method for separating microplastics (MPs) from water. The process involves the adhesion of fine air bubbles and MP particles, forming bubble-particle combinations with a lower apparent density than water, which results in their floatation to the surface. This study examines the principles, methods, and characteristics of flotation, traces its classification and application, provides a systematic explanation of the interactions between bubbles and MP particles during flotation, compares the differences in the efficiency of removing MPs between traditional air flotation and enhanced air flotation, discusses the effects of the properties of air bubbles and MPs on flotation based on the principle of flotation, and elucidates how environmental conditions of water affect the separation efficiency of MPs.
[1] Li J, Song Y, Cai Y B. Focus topics on microplastics in soil: Analytical methods, occurrence, transport, and ecological risks [J]. Environmental Pollution, 2020,257:113570. [2] 于颖,赵奕锦,董志强,等.水厂与污水厂对水体中微塑料的去除处理技术研究进展[J]. 净水技术, 2023,42(6):45-56. Yu Y, Zhao Y J, Dong Z Q, et al. Research progress of treatment technologies for removal of microplastics from water bodies in WTPs and WWTPs [J]. Water Purification Technology, 2023,42(6):45-56. [3] Auta H S, Emenike C U, Fauziah S H. Distribution and importance of microplastics in the marine environment: A review of the sources, fate, effects, and potential solutions [J]. Environment International, 2017, 102:165-176. [4] Weis J S. Aquatic microplastic research-A critique and suggestions for the future [J]. Water, 2020,12(5):1475. [5] Jeong C B, Won E J, Kang H M, et al. Microplastic size-dependent toxicity, oxidative stress induction, and p-JNK and p-p38activation in the monogonont rotifer (Brachionus koreanus) [J]. Environmental Science & Technology, 2016,50(16):8849-8857. [6] Esterhuizen M, Buchenhorst L, Kim Y J, et al. In vivo oxidative stress responses of the freshwater basket clam Corbicula javanicus to microplastic fibres and particles [J]. Chemosphere, 2022,296:134037. [7] Zhou G Y, Wang Q G, Li J, et al. Removal of polystyrene and polyethylene microplastics using PAC and FeCl3coagulation: Performance and mechanism [J]. Science of the Total Environment, 2021,752:141837. [8] 项晓方,谢显传,刘振中.混凝对附着生物膜的微塑料的去除效能[J].中国给水排水, 2024,40(1):1-7. Xiang X F, Xie X C, Liu Z Z. Effect of coagulation on the removal of microplastics attached to biofilm [J]. China Water & Wastewater, 2024,40(1):1-7. [9] 刘贝贝,郭康鹰,高悦,等.混凝去除微塑料的研究现状与展望[J].环境科学学报, 2023,43(12):112-124. Liu B B, Guo K Y, Gao Y, et al. Coagulation process for removing microplastics: Current research status and perspectives [J]. Acta Scientiae Circumstantiae, 2023,43(12):112-124. [10] Arenas L R, Gentile S R, Zimmermann S, et al. Fate and removal efficiency of polystyrene nanoplastics in a pilot drinking water treatment plant [J]. Science of the Total Environment, 2022,813: 152623. [11] Tadsuwan K, Babel S. Microplastic abundance and removal via an ultrafiltration system coupled to a conventional municipal wastewater treatment plant in Thailand [J]. Journal of Environmental Chemical Engineering, 2022,10(2):107142. [12] Reimonn G, Lu T F, Gandhi N, et al. Review of microplastic pollution in the environment and emerging recycling solutions [J]. Journal of Renewable Materials, 2019,7(12):1251-1268. [13] Swart B, Pihlajamaki A, Chew Y M J, et al. Microbubble-microplastic interactions in batch air flotation [J]. Chemical Engineering Journal, 2022,449:137866. [14] Esfandiari A, Mowla D. Investigation of microplastic removal from greywater by coagulation and dissolved air flotation [J]. Process Safety and Environmental Protection, 2021,151:341-354. [15] Wei F, Xu C L, Chen C, et al. Distribution of microplastics in the sludge of wastewater treatment plants in chengdu, China [J]. Chemosphere, 2022,287(4):132357. [16] Sun J, Dai X H, Wang Q L, et al. Microplastics in wastewater treatment plants: Detection, occurrence and removal [J]. Water Research, 2019,152:21-37. [17] Moosai R, Dawe R A. Gas attachment of oil droplets for gas flotation for oily wastewater cleanup [J]. Separation and Purification Technology, 2003,33(3):303-314. [18] Zhao Y, Li Y P, Huang J, et al. Rebound and attachment involving single bubble and particle in the separation of plastics by froth flotation [J]. Separation and Purification Technology, 2015,144:123-132. [19] Buchmann M, Oktem G, Rudolph M, et al. Proposition of a bubble-particle attachment model based on DLVO van der Waals and electric double layer interactions for froth flotation modelling [J]. Physicochemical Problems of Mineral Processing, 2022,58(5):154812. [20] Reddy M S, Kurose K, Okuda T, et al. Selective recovery of PVC-free polymers from ASR polymers by ozonation and froth flotation [J]. Resources Conservation and Recycling, 2008,52(6):941-946. [21] Zhang Y S, Chen S J, Wang H, et al. Separation of polyvinylchloride and acrylonitrile-butadiene-styrene combining advanced oxidation by S2O82-/Fe2+ system and flotation [J]. Waste Management, 2019,91:80-88. [22] Truc N T T, Lee B K. Sustainable and selective separation of PVC and ABS from a WEEE plastic mixture using microwave and/or mild-heat treatment with froth flotation [J]. Environmental Science & Technology, 2016,50(19):10580-10587. [23] Shen H T, Forssberg E, Pugh R J. Selective flotation separation of plastics by chemical conditioning with methyl cellulose [J]. Resources Conservation and Recycling, 2002,35(4):229-241. [24] Zisman W A. Relation of the equilibrium contact angle to liquid and solid constitution [J]. Contact Angle, Wettability and Adhesion, 1964, 43(1):1-51. [25] Shen H T, Forssberg E, Pugh R J. Selective flotation separation of plastics by particle control [J]. Resources Conservation and Recycling, 2001,33(1):37-50. [26] Saththasivam J, Loganathan K, Sarp S. An overview of oil-water separation using gas flotation systems [J]. Chemosphere, 2016,144: 671-680. [27] Shen W H, Mukherjee D, Koirala N, et al. Microbubble and nanobubble-based gas flotation for oily wastewater treatment: A review [J]. Environmental Reviews, 2022,30(3):359-379. [28] Han Y L, Zhu J B, Shen L, et al. Bubble size distribution characteristics of a jet-stirring coupling flotation device [J]. Minerals, 2019,9(6):369. [29] Priyanka M, Saravanakumar M P. A sustainable approach for removal of microplastics from water matrix using colloidal gas aphrons: New insights on flotation potential and interfacial mechanism [J]. Journal of Cleaner Production, 2022,334:130198. [30] Zlokarnik M. Separation of activated sludge from purified waste water by Induced Air Flotation (IAF) [J]. Water Research, 1998,32(4):1095-1102. [31] Ye Q, Xia F J, Zhu N W. Study on the treatment of oil-bearing wastewater by induced gas floatation and micro-power filter [J]. Industrial Water Treatment, 2008,28(3):45-47. [32] Zhang Y S, Jiang H R, Wang H, et al. Separation of hazardous polyvinyl chloride from waste plastics by flotation assisted with surface modification of ammonium persulfate: Process and mechanism [J]. Journal of Hazardous Materials, 2020,389:121918. [33] Jameson G J. Hydrophobicity and floc density in induced-air flotation for water treatment [J]. Colloids and Surfaces a-Physicochemical and Engineering Aspects, 1999,151(1/2):269-281. [34] Zhang J, Liu J H, Yu S J, et al. Bubble growth and floating behavior during degassing process of molten steel/(N2, H2) system [J]. ISIJ International, 2020,60(3):470-480. [35] Hassas B V, Jin J Q, Dang L X, et al. Attachment, coalescence, and spreading of carbon dioxide nanobubbles at pyrite surfaces [J]. Langmuir, 2018,34(47):14317-14327. [36] Sandoval M A, Fuentes R, Thiam A, et al. Arsenic and fluoride removal by electrocoagulation process: A general review [J]. Science of the Total Environment, 2021,753:142108. [37] Garcia-Segura S, Eiband M M S G, Melo J V D, et al. Electrocoagulation and advanced electrocoagulation processes: A general review about the fundamentals, emerging applications and its association with other technologies [J]. Journal of Electroanalytical Chemistry, 2017,801:267-299. [38] Elkhatib D, Oyanedel-Craver V, Carissimi E. Electrocoagulation applied for the removal of microplastics from wastewater treatment facilities [J]. Separation and Purification Technology, 2021,276: 118877. [39] Vasudevan S, Oturan M A. Electrochemistry: as cause and cure in water pollution-An overview [J]. Environmental Chemistry Letters, 2014,12(1):97-108. [40] Akarsu C, Deniz F. Electrocoagulation/electroflotation process for removal of organics and microplastics in laundry wastewater [J]. Clean-Soil Air Water, 2021,49(1):2000146. [41] Chou W L, Wang C T, Huang K Y. Investigation of process parameters for the removal of polyvinyl alcohol from aqueous solution by iron electrocoagulation [J]. Desalination, 2010,251(1):12-19. [42] 王金鑫,刘盛,肖安明,等.电絮凝-气浮法去除水中聚乙烯颗粒研究[J]. 环境科学与技术, 2021,44(9):81-85. Wang J X, Liu S, Xiao A M, et al. Removal of polyethylene particles in water by electrocoagulation-flotation [J]. Environmental Science & Technology, 2021,44(9):81-85. [43] Akarsu C, Kumbur H, Kideys A E. Removal of microplastics from wastewater through electrocoagulation-electroflotation and membrane filtration processes [J]. Water Science and Technology, 2021,84(7): 1648-1662. [44] Zhang Y S, Li C, Wang L, et al. Application of froth flotation in the separation of polyvinyl chloride and polycarbonate for recycling of waste plastic based on a novel surface modification [J]. Waste Management, 2020,110:43-52. [45] Wang J C, Liu W Q, Wang H, et al. Separation of acrylonitrile-butadiene-styrene and polystyrene waste plastics after surface modification using potassium ferrate by froth flotation [J]. Waste Management, 2018,78:829-840. [46] Wang J C, Wang H. Fenton treatment for flotation separation of polyvinyl chloride from plastic mixtures [J]. Separation and Purification Technology, 2017,187:415-425. [47] Zhang Y S, Jiang H R, Bian K, et al. Is froth flotation a potential scheme for microplastics removal? Analysis on flotation kinetics and surface characteristics [J]. Science of the Total Environment, 2021, 792:148345. [48] Wang Y L, Li Y N, Tian L P, et al. The removal efficiency and mechanism of microplastic enhancement by positive modification dissolved air flotation [J]. Water Environment Research, 2021,93(5): 693-702. [49] Kökklç O, Mohammadi-Jam S, Chu P B, et al. Separation of plastic wastes using froth flotation-An overview [J]. Advances in Colloid and Interface Science, 2022,308:102769. [50] Zhang M, Guiraud P. Surface-modified microbubbles (colloidal gas aphrons) for nanoparticle removal in a continuous bubble generation-flotation separation system [J]. Water Research, 2017,126:399-410. [51] 李亚男,田立平,王丰科,等.强化气浮除藻及其联用工艺研究进展[J]. 净水技术, 2020,39(10):102-108. Li Y N, Tian L P, Wang F K, et al. Research progress of enhanced dissolved air floatation and the combined processes for algae removal [J]. Water Purification Technology, 2020,39(10):102-108. [52] Wang H, Chen X L, Bai Y, et al. Application of dissolved air flotation on separation of waste plastics ABS and PS [J]. Waste Management, 2012,32(7):1297-1305. [53] Zhang M, Yang J H, Kang Z, et al. Removal of micron-scale microplastic particles from different waters with efficient tool of surface-functionalized microbubbles [J]. Journal of Hazardous Materials, 2021,404(Part A):124095. [54] Wang J C, Wang H, Kang Z, et al. Insights into mechanism of hypochlorite-induced functionalization of polymers toward separating BFR-containing components from microplastics [J]. Acs Applied Materials & Interfaces, 2020,12(32):36755-36767. [55] Perren W, Wojtasik A, Cai Q. Removal of microbeads from wastewater using electrocoagulation [J]. ACS Omega, 2018,3(3): 3357-3364. [56] Alter H. The recovery of plastics from waste with reference to froth flotation [J]. Resources, Conservation and Recycling, 2005,43(2):119-132. [57] Shen H T, Pugh R J, Forssberg E. Floatability, selectivity and flotation separation of plastics by using a surfactant [J]. Colloids and Surfaces A-Physicochemical and Engineering Aspects, 2002,196(1):63-70. [58] Negari M S, Movahed S O, Ahmadpour A. Separation of polyvinylchloride (PVC), polystyrene (PS) and polyethylene terephthalate (PET) granules using various chemical agents by flotation technique [J]. Separation and Purification Technology, 2018,194:368-376. [59] Basarová P, Bartovská L, Kořínek K, et al. The influence of flotation agent concentration on the wettability and flotability of polystyrene [J]. Journal of Colloid and Interface Science, 2005,286(1):333-338. [60] Wang C Q, Wang H, Fu J A, et al. Effects of additives on PVC plastics surface and the natural flotability [J]. Colloids and Surfaces A-Physicochemical and Engineering Aspects, 2014,441:544-548. [61] Güney A, Özdilek C, Kangal M O, et al. Flotation characterization of PET and PVC in the presence of different plasticizers [J]. Separation and Purification Technology, 2015,151:47-56. [62] Jiang H R, Zhang Y S, Wang C Q, et al. A clean and efficient flotation towards recovery of hazardous polyvinyl chloride and polycarbonate microplastics through selective aluminum coating: Process, mechanism, and optimization [J]. Journal of Environmental Management, 2021,299:113626. [63] Zhao Y, Mishra P J, Han F R, et al. Surface micro-alcoholysis treatment: A novel approach towards froth flotation based separation for binary mixtures of polyethylene terephthalate and polyvinyl chloride [J]. Journal of Cleaner Production, 2019,232:848-857. [64] Mallampati S R, Lee B H, Mitoma Y, et al. Selective sequential separation of ABS/HIPS and PVC from automobile and electronic waste shredder residue by hybrid nano-Fe/Ca/Ca assisted ozonisation process [J]. Waste Management, 2017,60:428-438. [65] Okuda T, Kurose K, Nishijima W, et al. Separation of polyvinyl chloride from plastic mixture by froth flotation after surface modification with ozone [J]. Ozone-Science & Engineering, 2007, 29(5):373-377. [66] Reddy M S, Okuda T, Kurose K, et al. Surface ozonation of polyvinyl chloride for its separation from waste plastic mixture by froth floatation [J]. Journal of Material Cycles and Waste Management, 2010,12(4):326-331. [67] Wang H, Wang J C, Zou Q P, et al. Surface treatment using potassium ferrate for separation of polycarbonate and polystyrene waste plastics by froth flotation [J]. Applied Surface Science, 2018,448:219-229. [68] Matsui Y, Fukushi K, Tambo N. Modeling, simulation and operational parameters of dissolved air flotation [J]. Journal of Water Services Research and Technology-Aqua, 1998,47(1):9-20. [69] Albijanic B, Ozdemir O, Nguyen A V, et al. A review of induction and attachment times of wetting thin films between air bubbles and particles and its relevance in the separation of particles by flotation [J]. Advances in Colloid and Interface Science, 2010,159(1):1-21. [70] Chen Y X, Zhuang L, Zhang Z J. Effect of particle shape on particle-bubble interaction behavior: A computational study using discrete element method [J]. Colloids and Surfaces A-Physicochemical and Engineering Aspects, 2022,653:130003. [71] Basařová P, Machoň V, Hubička M, et al. Collision processes involving a single rising bubble and a larger stationary spherical particle [J]. International Journal of Mineral Processing, 2010,94(1/2): 58-66. [72] Dai Z, Fornasiero D, Ralston J. Particle–bubble collision models-a review [J]. Advances in Colloid and Interface Science, 2000,85(2): 231-256. [73] Waldschläger K, Schüttrumpf H. Effects of particle properties on the settling and rise velocities of microplastics in freshwater under laboratory conditions [J]. Environmental Science & Technology, 2019, 53(4):1958-1966. [74] Wang Y, Jin X, Yang S J, et al. Interactions between flocs and bubbles in the separation zone of dissolved air flotation system [J]. Science of the Total Environment, 2021,761:143222. [75] Hubička M, Basařová P, Vejražka J. Collision of a small rising bubble with a large falling particle [J]. International Journal of Mineral Processing, 2013,121:21-30. [76] Wang L J, Wang Y H, Yan X K, et al. A numerical study on efficient recovery of fine-grained minerals with vortex generators in pipe flow unit of a cyclonic-static micro bubble flotation column [J]. Chemical Engineering Science, 2017,158:304-313. [77] Edzwald J K. Dissolved air flotation and me [J]. Water Research, 2010,44(7):2077-2106. [78] Kim M S, Han M, Kim T I, et al. Effect of nanobubbles for improvement of water quality in freshwater: Flotation model simulation [J]. Separation and Purification Technology, 2020,241: 116731. [79] Xing Y, Gui X, Pan L, et al. Recent experimental advances for understanding bubble-particle attachment in flotation [J]. Advances in Colloid and Interface Science, 2017,246:105-132. [80] Krasowska M, Malysa K. Kinetics of bubble collision and attachment to hydrophobic solids: I. Effect of surface roughness [J]. International Journal of Mineral Processing, 2007,81(4):205-216. [81] Yang L W, Zhao Y, Yang J J, et al. Visualized study on the interaction between single bubbles and curved solid surface in flotation separation process [J]. Water Science and Technology, 2014,70(4):627-633. [82] Chubarenko I, Bocherikova I, Esiukova E, et al. Microplastics in sea ice: A fingerprint of bubble flotation [J]. Science of the Total Environment, 2023,892:164611. [83] Chau T T, Bruckard W J, Koh P T L, et al. A review of factors that affect contact angle and implications for flotation practice [J]. Advances in Colloid and Interface Science, 2009,150(2):106-115. [84] Pita F, Castilho A. Separation of plastics by froth flotation. The role of size, shape and density of the particles [J]. Waste Management, 2017, 60:91-99. [85] Wang Z, An C J, Lee K, et al. Overlooked role of bulk nanobubbles in the alteration and motion of microplastics in the ocean environment [J]. Environmental Science & Technology, 2023,57(30):11289-11299. [86] Wang J, Wang Z H, Pei F Y, et al. Enrichment of microplastic pollution by micro-nanobubbles [J]. Chinese Physics B, 2022,31(11):118104. [87] Jiang H R, Bu J Q, Bian K, et al. Surface change of microplastics in aquatic environment and the removal by froth flotation assisted with cationic and anionic surfactants [J]. Water Research, 2023,233:119794. [88] Wang H N, Yang W Q, Yan X K, et al. Regulation of bubble size in flotation: A review [J]. Journal of Environmental Chemical Engineering, 2020,8(5):104070. [89] Han M Y. Modeling of DAF: The effect of particle and bubble characteristics [J]. Journal of Water Supply Research and Technology-Aqua, 2002,51(1):27-34. [90] Leppinen D M. Trajectory analysis and collision efficiency during microbubble flotation [J]. Journal of Colloid and Interface Science, 1999,212(2):431-442. [91] Nirmalkar N, Pacek A W, Barigou M. On the existence and stability of bulk nanobubbles [J]. Langmuir, 2018,34(37):10964-10973. [92] Michailidi E D, Bomis G, Varoutoglou A, et al. Bulk nanobubbles: Production and investigation of their formation/stability mechanism [J]. Journal of Colloid and Interface Science, 2020,564:371-380. [93] 王永磊,刘威,田立平,等.气浮工艺中微纳米气泡应用特性与检测技术研究[J]. 工业水处理, 2020,40(4):18-23. Wang Y L, Liu W, Tian L P, et al. Research progress on micro-nano bubble characteristics detection method and its application in air floatation process [J]. Industrial Water Treatment, 2020,40(4):18-23. [94] Ahmadi R, Khodadadi D A, Abdollahy M, et al. Nano-microbubble flotation of fine and ultrafine chalcopyrite particles [J]. International Journal of Mining Science and Technology, 2014,24(4):559-566. [95] Li C, Wang L G. Improved froth zone and collection zone recoveries of fine mineral particles in a flotation column with oscillatory air supply [J]. Separation and Purification Technology, 2018,193:311-316. [96] Ding S H, Xing Y W, Zheng X, et al. New insights into the role of surface nanobubbles in bubble-particle detachment [J]. Langmuir, 2020,36(16):4339-4346. [97] Ndikubwimana T, Chang J Y, Xiao Z Y, et al. Flotation: A promising microalgae harvesting and dewatering technology for biofuels production [J]. Biotechnology Journal, 2016,11(3):315-326. [98] Reis A S, Filho A M R, Demuner L R, et al. Effect of bubble size on the performance flotation of fine particles of a low-grade Brazilian apatite ore [J]. Powder Technology, 2019,356:884-891. [99] Ma F Y, Zhang P, Tao D P. Surface nanobubble characterization and its enhancement mechanisms for fine-particle flotation: A review [J]. International Journal of Minerals Metallurgy and Materials, 2022, 29(4):727-738. [100] Sobhy A, Tao D. Nanobubble column flotation of fine coal particles and associated fundamentals [J]. International Journal of Mineral Processing, 2013,124:109-116. [101] Zhou W G, Wu C N, Lv H Z, et al. Nanobubbles heterogeneous nucleation induced by temperature rise and its influence on minerals flotation [J]. Applied Surface Science, 2020,508:145282. [102] Ishida N, Inoue T, Higashitani K. Nano bubbles on a hydrophobic surface in water observed by tapping-mode atomic force microscopy [J]. Langmuir, 2000,16(16):6377-6380. [103] Hampton M A, Nguyen A V. Nanobubbles and the nanobubble bridging capillary force [J]. Advances in Colloid and Interface Science, 2010,154(1):30-55. [104] Kharraz J A, Jia M Y, et al. Determination of microplastic pollution in marine ecosystems and its effective removal using an advanced nanobubble flotation technique [J]. Journal of Water Process Engineering, 2024,57:104637. [105] Sakr M, Mohamed M, Jung J. A critical review of the recent developments in micro-nano bubbles applications for domestic and industrial wastewater treatment [J]. Alexandria Engineering Journal, 2022,61(8):6591-6612. [106] Takahashi M. ζ-potential of microbubbles in aqueous solutions: Electrical properties of the gas-water interface [J]. The Journal of Physical Chemistry B, 2005,109(46):21858-21864. [107] Ushikubo F Y, Furukawa T, Nakagawa R, et al. Evidence of the existence and the stability of nano-bubbles in water [J]. Colloids and Surfaces A-Physicochemical and Engineering Aspects, 2010,361(1-3): 31-37. [108] Ma X T, Li M B, Pfeiffer P, et al. Ion adsorption stabilizes bulk nanobubbles [J]. Journal of Colloid and Interface Science, 2022, 606:1380-1394. [109] 周春地,隋铭皓.环境水体中腐殖酸与共存物的相互作用[J]. 化学进展, 2023,35(7):1018-1029. Zhou C D, Sui M H. Interaction between humic acid and co-existing substances in aquatic environments [J]. Progress in Chemistry, 2023, 35(7):1018-1029. [110] Bui T T, Nguyen D C, Han M. Average size and zeta potential of nanobubbles in different reagent solutions [J]. Journal of Nanoparticle Research, 2019,21(8):173. [111] Ahmed A K A, Sun C Z, Hua L, et al. Colloidal properties of air, oxygen, and nitrogen nanobubbles in water: Effects of ionic strength, natural organic matters, and surfactants [J]. Environmental Engineering Science, 2018,35(7):720-727. [112] Calgaroto S, Wilberg K Q, Rubio J. On the nanobubbles interfacial properties and future applications in flotation [J]. Minerals Engineering, 2014,60:33-40. [113] Cui X, Shi C, Zhang S, et al. Probing the effect of salinity and pH on surface interactions between air bubbles and hydrophobic solids: Implications for colloidal assembly at air/water interfaces [J]. Chemistry-An Asian Journal, 2017,12(13):1568-1577. [114] Jiang H R, Zhang Y S, Bian K, et al. Insight into the effect of aqueous species on microplastics removal by froth flotation: Kinetics and mechanism [J]. Journal of Environmental Chemical Engineering, 2022, 10(3):107834. [115] Ma G X, Xia W C. Detachment behavior of single-curved/nonCurved particles from ultrasound-assisted oscillation bubbles [J]. ACS Omega, 2020,5(6):2718-2724. [116] Perren W, Wojtasik A, Cai Q. Removal of microbeads from wastewater using electrocoagulation [J]. ACS Omega, 2018,3(3): 3357-3364.
