Synthesis of foamed geopolymers by substituting fly ash with tailing slurry for the highly efficient removal of heavy metal contaminants: Behavioral and mechanistic studies

Abstract

This study aimed to synthesize porous geopolymers from tailing slurry, a byproduct of bauxite mining, for use as potential materials for groundwater remediation. The effects of various factors, such as foaming agents, liquid-solid (L/S) ratio, and foam stabilizers, on the geopolymers’ pore structure and adsorption properties were investigated. Batch experiments and characterization methods were conducted to evaluate the adsorption capacity and mechanism of the geopolymers on binary heavy metals (Pb²⁺ and Cu²⁺). The results showed that adjusting the foaming behavior resulted in a porous geopolymer with porosity of 81.4%, connectivity of 17.2%, and water absorption rate of 122.9%. The presence of closed pores and capillaries hindered the removal performance of heavy metals. In contrast, optimizing foaming behavior could increase the adsorption capacity of Pb²⁺ from 7.49 mg/g to 24.95 mg/g by improving pore connectivity. The main removal mechanisms include physical sealing, chemical precipitation of heavy metal ions with —OH, and the formation of chemical bonds T (Si, Al)—O—M (Pb, Cu). Tailing slurry-based porous geopolymers (TPGs) demonstrated excellent heavy metal removal performance and exhibited great potential in remediating mine-polluted groundwater.

Keywords

porous geopolymer / tailing slurry / permeable reactive barrier / pore characterization / heavy metal removal

References

[1] ZhouL, GouM, HouW, et al. . Effect of thermal activation and particle size on cementitious activity of bauxite tailings [J]. Environmental Science and Pollution Research, 2022, 29(52): 78960-78972

[2] LuoS, LiuM, YangL, et al. . Utilization of waste from alumina industry to produce sustainable cement-based materials [J]. Construction and Building Materials, 2019, 229: 116795

[3] PengY, OuX, ChenX, et al. . Utilization of discarded bauxite tailings into eco-friendly foamed mixture lightweight soil [J]. Journal of Cleaner Production, 2022, 333130167

[4] LiC, LiM, ZengJ, et al. . Migration and distribution characteristics of soil heavy metal(loid)s at a lead smelting site [J]. Journal of Environmental Sciences (China), 2024, 135600-609

[5] SariY A, KumralM. A landfill based approach to surface mine design [J]. Journal of Central South University, 2018, 25(1): 159-168

[6] HeF, YangZ, ZhaoF, et al. . Unveiling the dual roles of the intercalation of [MoS₄]²⁻ clusters in boosting heavy metal capture by Ca-Al layered double hydroxide [J]. Environmental Science: Nano, 2023, 10(1): 190-202

[7] QinF, WeiC, ZhongS, et al. . Soil heavy metal(loid)s and risk assessment in vicinity of a coal mining area from southwest Guizhou, China [J]. Journal of Central South University, 2016, 23(9): 2205-2213

[8] JiangJ, LuoH, WangS, et al. . A two-dimensional analytical model for heavy metal contaminants transport in permeable reactive barrier [J]. Water Science and Technology: a Journal of the International Association on Water Pollution Research, 2023, 87(2): 393-406

[9] WeiB, XueZ, YangY, et al. . Preparation of tungsten slag-bentonite particle adsorbent and its adsorption performance for lead ion from wastewater [J]. Journal of Central South University, 2023, 30(6): 1841-1855

[10] XieH, YuM, YanH, et al. . Analytical model for the design of permeable reactive barriers considering solute transport in a dual-domain system [J]. Journal of Environmental Engineering, 2023, 149(9): 04023046

[11] LiH, LiuQ-mei. Reaction medium for permeable reactive barrier remediation of groundwater polluted by heavy metals [J]. Frontiers in Environmental Science, 2022, 10: 968546

[12] SinghR, ChakmaS, BirkeV. Performance of field-scale permeable reactive barriers: An overview on potentials and possible implications for in situ groundwater remediation applications [J]. Science of the Total Environment, 2023, 858158838

[13] ZhangY, WangF, CaoB, et al. . Simultaneous removal of Pb and MTBE by mixed zeolites in fixed-bed column tests [J]. Journal of Environmental Sciences (China), 2022, 12241-49

[14] Amoako-NimakoG K, YangX, ChenF. Denitrification using permeable reactive barriers with organic substrate or zero-valent iron fillers: Controlling mechanisms, challenges, and future perspectives [J]. Environmental Science and Pollution Research, 2021, 28(17): 21045-21064

[15] HaoN, YeJ, ZhaoL, et al. . Evaluating iron remediation with limestone using spectral induced polarization and microscopic techniques [J]. The Science of the Total Environment, 2021, 800149641

[16] NadiaN F J, GharzouniA, Nait-AliB, et al. . Comparative study of laterite and metakaolin/hematite-based geopolymers: Effect of iron source and alkalization [J]. Applied Clay Science, 2023, 233106824

[17] ZeyadA M, MagboolH M, TayehB A, et al. . Production of geopolymer concrete by utilizing volcanic pumice dust [J]. Case Studies in Construction Materials, 2022, 16e00802

[18] TanT H, MoK H, LingT C, et al. . Current development of geopolymer as alternative adsorbent for heavy metal removal [J]. Environmental Technology & Innovation, 2020, 18100684

[19] CarvalheirasJ A, NovaisR M, LabrinchaJ A A. Metakaolin/red mud-derived geopolymer monoliths: Novel bulk-type sorbents for lead removal from wastewaters [J]. Applied Clay Science, 2023, 232106770

[20] BaiY, GuoW, WangX, et al. . Utilization of municipal solid waste incineration fly ash with red mud-carbide slag for eco-friendly geopolymer preparation [J]. Journal of Cleaner Production, 2022, 340130820

[21] GouM, ZhouL, ThenN W Y. Utilization of tailings in cement and concrete: A review [J]. Science and Engineering of Composite Materials, 2019, 26(1): 449-464

[22] JIANG Jie, LUO Hao-hao, OU Xiao-duo, et al. Long-term leaching characteristics of heavy metals from bauxite tailing slurry-based geopolymer backfill: Experimental and numerical simulation studies [J]. Environmental Technology, 2023. DOI: https://doi.org/10.1080/09593330.2023.2283410.

[23] RenY, RenQ, WuX, et al. . Mechanism of low temperature sintered high-strength ferric-rich ceramics using bauxite tailings [J]. Materials Chemistry and Physics, 2019, 238121929

[24] LuQ, HuY-hua. Synthesis of aluminum tripolyphosphate anticorrosion pigment from bauxite tailings [J]. Transactions of Nonferrous Metals Society of China, 2012, 22(2): 483-488

[25] YinZ, KhosoS A, SunW, et al. . Flocculation of flotation tailings in presence of silicate gel and polymer [J]. Journal of Central South University, 2018, 25(8): 1928-1937

[26] YeJ, ZhangW, ShiD. Properties of an aged geopolymer synthesized from calcined ore-dressing tailing of bauxite and slag [J]. Cement and Concrete Research, 2017, 10023-31

[27] YangN, GouL, BaiZ, et al. . A simple and mild synthesis of zeolite Y from bauxite tailings for lead adsorption: Reusable, efficient and highly selective [J]. Journal of Inorganic and Organometallic Polymers and Materials, 2022, 32(9): 3496-3507

[28] LanY, WangY, HuangC-bing. Removal of anionic ions from single material solution by bauxite tailings modified with FeCl₃·6H₂O [J]. Journal of Central South University of Technology, 2008, 15(5): 656-662

[29] ZhangQ, CaoX, SunS, et al. . Lead zinc slag-based geopolymer: Demonstration of heavy metal solidification mechanism from the new perspectives of electronegativity and ion potential [J]. Environmental Pollution, 2022, 293: 118509

[30] ZhangB, YuT, DengL, et al. . Ionadsorption type rare earth tailings for preparation of alkali-based geopolymer with capacity for heavy metals immobilization [J]. Cement and Concrete Composites, 2022, 134104768

[31] ChenW, YinS, ChenX, et al. . Study on comprehensive utilization of tailings by using bioleaching and microbial-cementation [J]. Case Studies in Construction Materials, 2023, 18e02190

[32] JiZ, SuL, PeiY-sheng. Characterization and adsorption performance of waste-based porous open-cell geopolymer with one-pot preparation [J]. Ceramics International, 2021, 47(9): 12153-12162

[33] SangM, ZhaoH, LiY, et al. . The adsorption properties of steel slag-based porous geopolymer for Cu²⁺ removal [J]. Minerals Engineering, 2023, 201108225

[34] LiuY, MengY, QiuX, et al. . Novel porous phosphoric acid-based geopolymer foams for adsorption of Pb(II), Cd(II) and Ni(II) mixtures: Behavior and mechanism [J]. Ceramics International, 2023, 49(4): 7030-7039

[35] YanS, HeP, JiaD, et al. . Synthesis of novel low-cost porous gangue microsphere/geopolymer composites and their adsorption properties for dyes [J]. International Journal of Applied Ceramic Technology, 2018, 15(6): 1602-1614

[36] SanguanpakS, WannagonA, SaengamC, et al. . Porous metakaolin-based geopolymer granules for removal of ammonium in aqueous solution and anaerobically pretreated piggery wastewater [J]. Journal of Cleaner Production, 2021, 297126643

[37] JiangJ, LuoH, WangS, et al. . Synthesis of tailing slurry-based geopolymers for the highly efficient immobilization of heavy metals: Behavior and mechanism [J]. Applied Clay Science, 2024, 247107199

[38] CheY, YangH-shan. Hydration products, pore structure, and compressive strength of extrusion-based 3D printed cement pastes containing nano calcium carbonate [J]. Case Studies in Construction Materials, 2022, 17e01590

[39] PetrovićM, ŠoštarišT, StojanovišM, et al. . Removal of Pb²⁺ ions by raw corn silk (Zea mays L.) as a novel biosorbent [J]. Journal of the Taiwan Institute of Chemical Engineers, 2016, 58407-416

[40] DhasindrakrishnaK, PasupathyK, RamakrishnanS, et al. . Progress, current thinking and challenges in geopolymer foam concrete technology [J]. Cement and Concrete Composites, 2021, 116: 103886

[41] RamamurthyK, Kunhanandan NambiarE K, Indu Siva RanjaniG. A classification of studies on properties of foam concrete [J]. Cement and Concrete Composites, 2009, 31(6): 388-396

[42] ZhouH, XuZ, XieZ, et al. . Investigation on pore properties, thermal conductivity, and compressive behavior of fly ash/slag-based geopolymer foam [J]. International Journal of Applied Ceramic Technology, 2023, 20(6): 3517-3534

[43] LiuZ, ShaoN, QinJ, et al. . Strength and thermal behavior of low weight foam geopolymer using circulating fluidized bed combustion fly ash [J]. Journal of Central South University, 2015, 22(9): 3633-3640

[44] PuS, ZhuZ, SongW, et al. . A novel acidic phosphoric-based geopolymer binder for lead solidification/stabilization [J]. Journal of Hazardous Materials, 2021, 415125659

[45] SunY, ZhangP, LiZ, et al. . Iron-calcium reinforced solidification of arsenic alkali residue in geopolymer composite: Wide pH stabilization and its mechanism [J]. Chemosphere, 2023, 312(Pt2): 137063

[46] WanJ, ZhangF, HanZ, et al. . Adsorption of Cd²⁺ and Pb²⁺ by biofuel ash-based geopolymer synthesized by one-step hydrothermal method [J]. Arabian Journal of Chemistry, 2021, 148103234

[47] WangD, RepoE, HeF, et al. . Dual functional sites strategies toward enhanced heavy metal remediation: Interlayer expanded Mg-Al layered double hydroxide by intercalation with L-cysteine [J]. Journal of Hazardous Materials, 2022, 439129693

[48] TangQ, WangH, TangX, et al. . Removal of aqueous Ni(II) with carbonized leaf powder: Kinetics and equilibrium [J]. Journal of Central South University, 2016, 234778-786

[49] HaghsereshtF, LuG Q. Adsorption characteristics of phenolic compounds onto coal-reject-derived adsorbents [J]. Energy & Fuels, 1998, 12(6): 1100-1107

[50] LiuL, YangZ, ZhaoF, et al. . Manganese doping of hematite enhancing oxidation and bidentate-binuclear complexation during As(III) remediation: Experiments and DFT calculation [J]. Chemical Engineering Journal, 2023, 471144758

[51] PetrovićM, ŠoštarićT, StojanovićM, et al. . Mechanism of adsorption of Cu²⁺ and Zn²⁺ on the corn silk (Zea mays L.) [J]. Ecological Engineering, 2017, 9983-90

[52] ZhaoY, KangS, QinL, et al. . Self-assembled gels of Fe-chitosan/montmorillonite nanosheets: Dye degradation by the synergistic effect of adsorption and photo-Fenton reaction [J]. Chemical Engineering Journal, 2020, 379: 122322

[53] LvQ, WangZ, GuL, et al. . Effect of sodium sulfate on strength and microstructure of alkali-activated fly ash based geopolymer [J]. Journal of Central South University, 2020, 27(6): 1691-1702

[54] KränzleinE, HarmelJ, PöllmannH, et al. . Influence of the Si/Al ratio in geopolymers on the stability against acidic attack and the immobilization of Pb²⁺ and Zn²⁺ [J]. Construction and Building Materials, 2019, 227116634

[55] YangW, ZhangY, ZhengJ, et al. . Migration of spent grain-modified colloidal ferrihydrite: Implications for the in situ stabilization of arsenic, lead, and cadmium in co-contaminated soil [J]. Chemosphere, 2023, 344140310

[56] WangY, HanF, MuJ-qiu. Solidification/stabilization mechanism of Pb(II), Cd(II), Mn(II) and Cr(III) in fly ash based geopolymers [J]. Construction and Building Materials, 2018, 160818-827

[57] SimićM, PetrovićJ, ŠoštarićT, et al. . A mechanism assessment and differences of cadmium adsorption on raw and alkali-modified agricultural waste [J]. Processes, 2022, 10(10): 1957

[58] El-EswedB I, AldagagO M, KhaliliF I. Efficiency and mechanism of stabilization/solidification of Pb(II), Cd(II), Cu(II), Th(IV) and U(VI) in metakaolin based geopolymers [J]. Applied Clay Science, 2017, 140148-156

[59] LanT, LiP, RehmanF U, et al. . Efficient adsorption of Cd²⁺ from aqueous solution using metakaolin geopolymers [J]. Environmental Science and Pollution Research, 2019, 26(32): 33555-33567