Arabian Journal of Chemistry
·
2020
·
IF 4.762
Zefeng Yu,Weifeng Song,Jiayao Li,Qiuhua Li
In this paper, a metakaolin-based mesoporous geopolymer (GP-CTAB) was used as adsorbent for Cu(II) and Cr(VI) through a novel and simple synthetic route using cetyltrimethylammonium bromide (CTAB) as an organic modifier. The application of GP-CTAB for the simultaneous removal of metal anions and cations in aqueous solution was studied for the first time. The results of X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Brunauer, Emmett and Teller (BET), and Barrett, Joyner, and Halenda (BJH) methods indicate that GP-CTAB is still geopolymer even in the presence of quaternary ammonium salt cations. The material was tested to simultaneously adsorb Cu(II) and Cr(VI) from an aqueous solution. The results show that GP-CTAB can adsorb anions simultaneously without sacrificing the adsorption properties of heavy metal cations, which is superior to conventional geopolymers. The maximum theoretical adsorption capacity of GP-CTAB for Cu(II) and Cr(VI) was 108.2 mg/g and 95.3 mg/g in the binary system, respectively. It was also found that the presence of Cu(II) in the solution promoted the adsorption of Cr(VI). Given this characteristic of GP-CTAB, it has shown great application prospects in the prevention and control of heavy metal pollution.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NON-CRYSTALLINE SOLIDS
·
2024
·
IF 3.2
Qikun Wang,Xiaohong Li,Siqi Ma,Hualong Yang,Wei Shi,Qibing Chang,Yongqing Wang,Haize Jin
There is a limited understanding of the mechanical activation mechanisms that enhance the geopolymerization reactivity of aluminosilicate materials. For this purpose, this paper systematically investigates the microstructures of metakaolin with varying reactivities, along with the geopolymers prepared from them. The findings indicate that the mechanical activation mechanism of metakaolin encompasses several processes: a reduction in particle size, an increase in specific surface area, the transformation of multilayer lamellar stacked structures into monolayer lamellar structures, the amorphization of potassium mica crystals, the dissociation of the aluminosilicate network structure on the particle surface, and the enrichment of Al at the particle surface. In comparison to geopolymers prepared with untreated metakaolin, those made with metakaolin mechanically activated for 4 h exhibited a 28.7 % increase in compressive strength after a setting time of 7 days, and a 53.0 % increase in early compressive strength after a setting time of 8 h.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2025
·
IF 8
Zhendong Liu,Longguan Zhu,Yulan Hu,Bingjian Zhang
The limestone cultural relics within the West Lake World Cultural Heritage Site in Hangzhou, China, have suffered severe material loss and deep cracks due to prolonged natural and anthropogenic erosion. This necessitates the urgent development of highly efficient and compatible stone-mimicking restoration materials for their repair and preservation. This study systematically investigates the effects of varying metakaolin (MK) additions on the performance and microstructure of magnesium phosphate cement (MPC). Using mercury intrusion porosimetry, X-ray diffraction (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC), and scanning electron microscopy (SEM), it was found that MK significantly enhances the mechanical properties of MPC by filling pores and forming aluminum phosphate gel, while also prolonging the setting time of the paste. Based on these findings, MPC with 30 % MK addition (F-MPC) was selected as the binder, and commonly used materials in cultural heritage restoration—hydraulic lime (F-NHL), Portland cement (F-OPC), and epoxy resin (F-EP)—were employed as comparative materials. Calcite particles and iron oxide pigments were incorporated to create stone-mimicking restoration materials. Results showed that the mechanical strength of F-NHL and F-OPC was significantly lower than that of the limestone substrate, whereas F-EP exhibited much higher strength but severely compromised the substrate's breathability. In contrast, F-MPC demonstrated excellent compatibility with limestone in terms of mechanical properties while maintaining good breathability. This study provides theoretical support and practical guidance for the innovative application of magnesium phosphate in limestone restoration, highlighting its significant value and broad prospects in the field of cultural heritage conservation.
研究领域:
文物保护
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建筑材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Building Engineering
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2022
·
IF 7.144
Ren Luo,Huai Liu,Ping Duan,Jiayuan Ye,Wei Chen,Zuhua Zhang,Aiguo Wang
As an alternative to the ordinary Portland cement (OPC), it is imperative to improve the performance of geopolymer under harsh conditions (such as sulfate/seawater attack). Sulfate attack is one of the reasons which cause deterioration and damages of geopolymer structures. Thus, the strategy of sulfate resistance attracts attention of researchers. As a reinforcement for geopolymer, the cellulose nanofiber (from waste bamboo powder) facilitates the utilization of waste bamboo powder. High-purity cellulose nanofiber (CNF) was obtained by using alkali, bleaching and acid hydrolysis treatments on waste bamboo powder. The purification effect and environmental impact of CNF were compared by different bleaching methods. The optimal conditions (containing 5 wt% H 2 O 2 , 0.04 wt% MgSO 4 and 0.05 wt% TAED) for CNF purification were determined. This work aims to investigate the effect of CNF and wollastonite (WS) on the sulfate resistance of metakaolin (MK) geopolymer. The deterioration mechanism of geopolymer reinforced by natural fiber (CNF and WS) exposed to sulfate environment was revealed by employing XRD , SEM and MIP . The influence of extreme sulfate environment on mechanical properties and microstructure was investigated. The analysis results of microstructure, mass loss rate and mechanical properties were also combined to evaluate the sulfate resistance. The outcomes show that the bleaching method of H 2 O 2 can effectively remove impurities and enhance the purification effect of CNF. The optimum mix proportion of MK geopolymer reinforced by natural fiber (formulated as 2% of CNF, 10% of WS and 88% of MK) is obtained. The compressive and flexural strengths are increased by up to 76.1% and 135.5% (compared to the control group), respectively. The deterioration of geopolymer is related to the concentration of Na 2 SO 4 and the immersion time. The degradation mechanism is attributed to the incomplete geopolymerization and the destruction of the pore structure due to sulfate attack exposure. The deterioration processes of geopolymer can be slowed down by introducing WS and CNF. It improves the sulfate resistance of the matrix from the structural aspect.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2020
·
IF 4.605
Xiaohai Liu,Baoguo Ma,Hongbo Tan,Li Gao,Pian Chen
Metakaolin (MK) is a widely used admixture in chloride immobilization which is conducive to the durability of reinforced concrete. In this study, triisopropanolamine (TIPA) was added into cement-MK system to improve the chloride immobilization by expediting the pozzolanic reaction of MK. The effect of TIPA on hydration of binder composed of 90% Portland cement and 10% MK was investigated, and the hydration behavior was characterized by thermogravimetric analysis , X-ray diffraction, nuclear magnetic resonance spectroscopy , and mercury intrusion porosimetry , based on the evaluation of pozzolanic reaction of MK by ion dissolution. Results indicated that TIPA promoted the hydration of both MK and cement, and chloride immobilization was also improved. The mechanism for the improvement was involved in three aspects: a) TIPA facilitated the dissolution of aluminum from MK to obtain more chloroaluminate salts, strengthening chemical binding; b) TIPA accelerated hydration of cement and MK for more C-S-H gel, conducive to the physical adsorption; c) TIPA increased the amount of hydrates to refine the pore structure , hindering the migration of chloride ion. This investigation provided one new method for improving the pozzolanic reaction of MK to enhance chloride immobilization of cement-MK system.
研究领域:
建筑材料学
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化学工程
✓ 已验证
DOI
高影响因子
APPLIED CLAY SCIENCE
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2024
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IF 5.3
Shiqin Long,Jiangxin Xiang,Hongbo Li,Shoushu Wei,Qingze Chen,Runliang Zhu
Rare earth elements (REEs) as emerging soil contaminants have attracted increasing concerns. Efficient, economical, and eco-friendly soil amendments for REEs-contaminated farmland in-situ remediation are exigently needed. Herein, phosphorus-modified metakaolin (MK-P) was synthesized as a soil amendment to immobilize REEs in soil and reduce their bioaccumulation in water spinach ( Ipomoea aquatica Forssk. ). MK-P was developed by the combination of mechanochemical and thermal treatments using metakaolin and KH 2 PO 4 as raw materials. Our results indicated that the aluminum potassium phosphate and active Al–O–P sites were generated within MK-P, facilitating the immobilization of REEs and the controlled release of phosphorus. The application of 3% MK-P significantly reduced the content of available REEs in soil by 76.7%–99.2% and reduced the REE contents in the shoots (edible parts) of water spinach by 43.0%–57.3%. Correlation analysis suggested that the enhancement for REE immobilization using MK-P could be ascribed to the increase of soil pH and available P. Furthermore, the application of MK-P led to the amelioration of soil fertility, which subsequently increased plant yield by 14.8%–20.1% under MK-P treatment. These findings suggest that MK-P can be used as a promising soil amendment to minimize REE bioavailability in REEs-contaminated soil and improve soil quality.
研究领域:
环境科学
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土壤学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2019
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IF 3.89
Xiang Hu,Zhu Shu,Hui Guo,Jun Zhou,Tiantian Li,Yigen Tan,Zihao Liao,Wenbin Wang,Zhengliang Zhao
Nanostructure-tailoring and composite-construction are two effective strategies to optimize polymeric carbon nitride (PCN) for advanced photocatalysis . Herein, a vapor deposition process was adopted to grow PCN nanosheets on the surface of the cheap mineral metakaolin , achieving both the nano-structuring of PCN and the synchronous construction of metakaolin/nano-PCN composite. It showed a substantially improved photocatalytic H 2 evolution activity 3.8 times higher than the traditional bulk PCN under visible light. Performance gains benefit from the natural electronegativity of metakaolin and the nanosizing of PCN, which synergistically facilitate the separation and utilization of photoinduced charge carriers. This work may inspire not only the utilization of various clay minerals but also the nano-tailoring and composite-construction of PCN.
研究领域:
材料科学
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环境科学
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化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Weifu Sun,Yaru Sun
In this work, meta-kaolinite has been successfully multidimensionally modified by growing melamine-phytate nanoflakes within the interlayer and on the surface of metakaolinite via facile and green supramolecular self-assembly technology . Then, multidimensionally modified metakaolinite (Mul-K 0 ) along with intumescent flame retardant (IFR) has been incorporated into polyurea (PUA)The incorporation of Mul-K 0 together with IFR into PUA has simultaneously enhanced both the fire safety and mechanical property. Flame retardancy and smoke suppression of Mul-K 0 based PUA/IFR composite have been evaluated by oxyacetylene ablation test, limiting oxygen index, UL-94 vertical burning and conventional or modified cone calorimeter tests. The underlying mechanism of Mul-K 0 responsible for enhancing the fire safety and mechanical properties were explored. This work offers a new strategy for improving the flame-retardancy efficiency utilizing the synergistic effect of IFR and modified meta-kaolinite and provides a promising opportunity for fabricating long-life flame retardant PUA composites.
研究领域:
材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2025
·
IF 5.8
Shu Jiang,Jinhua Wang,Jiaqi Chen,Xiaotong Huo,Yongkang Cao
Choosing proper cementitious material for the restoration of stone relics with high strength is challenging. In this study, a novel chemically bonded phosphate ceramics (CBPCs) was prepared based on acid-base reaction adopting metakaolin (MK) and monocalcium phosphate monohydrate (Ca(H 2 PO 4 ) 2 ·H 2 O, MCPM). The reaction products mainly consist of brushite (CaHPO 4 ·2H 2 O) and phosphorus‑aluminum silicate gel phase. In which, the appropriate amount of brushite can fill the gap in the gel phase, favoring more densified microstructure and higher mechanical performance. Notably, the activated alumina in metakaolin is the key reaction component, and the P/Al molar ratios affect the compositions and properties. Besides, the physicochemical properties of the product are comparable to stone matrix. Further, the concentration of the undesirable soluble salt ions is less than 7 % of ordinary Portland cement, which can effectively avoid salt damage and guarantee the applicational safety of the stone relics.
研究领域:
材料科学
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文物保护
✓ 已验证
DOI
高影响因子
Journal of Cleaner Production
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2022
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IF 11.072
Shuangjian Yang,Liyun Yang,Mengdan Gao,Hao Bai,Tetsuya Nagasaka
Zeolite-geopolymer composites synthesized using industrial solid waste have mechanical strength, high specific surface area and cation exchange ability. This self-supporting adsorbent can replace natural heulandite zeolite to remove metal ions . In this study, a zeolite-geopolymer composite with a high zeolite content was synthesized by a simple two-step process using fly ash and metakaolin as raw materials. The compressive capacity, pore structure and adsorption ability for Pb(II) in the solution of the composite were analyzed and compared with natural heulandite zeolite. Through the two-step synthesis, the dynamic conditions of zeolite crystallization and geopolymer solidification were determined, and the zeolite-geopolymer composite with 57.5% zeolite A content and 6.42 MPa compressive strength was successfully prepared. The composite had hierarchical pore sizes, including microporous, mesoporous and macroporous pores, and its specific surface area was larger than that of natural heulandite zeolite. The Pb(II) adsorption capacity of the composite could reach 446.73 mg/g through ion exchange and hydroxyl reactions in solution, which was higher than the value of 323.37 mg/g for natural heulandite zeolite. Therefore, zeolite-geopolymer composites with high zeolite content synthesized by the simple two-step method can be used as self-supporting adsorbents to replace natural heulandite zeolites for removing metal ions from water.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Colloid and Interface Science Communications
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2021
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IF 4.914
Haize Jin,Youyou Zhang,Qikun Wang,Qibing Chang,Cuixia Li
Ongoing researches about adsorption removal of heavy metal ions and dyes are targeted to improve adsorption efficiency and recycle to solve environmental problems. Geopolymer as an adsorbent for wastewater treatment exhibits a good application potential. Here, a rapid removal strategy for methylene blue (MB) and nickel ions based on metakaolin-based geopolymer (MG) is provided. The adjustment of pH allows the MG to expose more negative charge adsorption sites, resulting in rapid removal of MB and Ni 2+ . The adsorption data fitted well by the pseudo-second-order model and Langmuir model, indicating the chemisorption of MG for MB and Ni 2+ . The decrease of pH of wash solution is conducive to the desorption of Ni 2+ . However, the desorption of MB-loading MG proved to be very difficult. This study provides a universal reference and possibility for rapid removal of cationic dyes and heavy metal ions under relatively mild conditions.
研究领域:
环境科学
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材料科学
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化学工程
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水处理
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2023
·Vol. 30
·期 16
·47025-47037
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IF 5.8
Wang Tianyu,Yang Lang,Rao Feng,Jiang Kaixi,Byrynnai Choduraa
Adding organics in the process of geopolymer synthesis can combine the functional groups of organics with the three-dimensional structure of geopolymer, thus changing the properties of geopolymer such as compressive strength, flexural strength, and acid resistance. In this work, excellent mechanical properties and acid resistance of metakaolin-blast furnance slag (Mk-BFS)-based geopolymer were synthesized by the incorporation of chitosan. The formation of sodium-alumino-silicate-hydrate (N-A-S–H) gel and calium-alumino-silicate-hydrate (C-A-S–H) gel in geopolymerization were characterized by 29 Si nuclear magnetic resonance (NMR). At 5% of chitosan, the compressive strength of Mk-BFS-based geopolymer could reach to 33.7 MPa. The results could be ascribed to that chitosan reacts with geopolymer to generate new C-O-Si structure meanwhile adhesion produced by the combination of positively charged cations and negatively charged ions makes the structure of geopolymer denser. After 7 days of sulfuric acid immersion, the reduction of compressive strength is less than 3 MPa, demonstrating its great acid resistance. The acid resistance of Mk-BFS-based geopolymer could attribute to that the free amino groups in chitosan preferentially react with acid solution and weakened the erosion of sulfuric acid. This study optimizes the compressive strength and acid resistance of geopolymer by adding appropriate amount of chitosan.
研究领域:
材料科学
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硅酸盐化学
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无机非金属材料
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功能复合材料
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建筑材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）