摘要
以水玻璃、矿渣粉为材料,基于逆Leidenfrost效应制备了多孔地聚合物微球,研究了其孔结构及pH缓冲性能.结果表明:改变水玻璃掺量和水固比可以调控多孔地聚合物微球的孔结构和pH缓冲性能;当水固比为1.0、水玻璃掺量由4%增大至8%时,微球的孔隙率、中位孔径和孔比表面积均减小,pH值波动范围为1.50~1.90;当水玻璃掺量为4%、水固比由1.0增大至1.2时,微球的孔隙率、中位孔径和孔比表面积均增大,pH值波动范围超过2.00;与双氧水直接发气法制备的多孔地聚合物相比,基于逆Leidenfrost效应制备的多孔地聚合物具有更好的pH缓冲性能和更高的O
地聚合物具有早期强度高、耐化学腐蚀和高温稳定性好等优
逆Leidenfrost效
本研究基于逆Leidenfrost效应,通过碱激发矿渣粉制备多孔地聚合物微球,研究材料组成对地聚合物孔结构的调控作用以及孔结构对pH值与O
矿渣粉采用S95级粒化高炉矿渣粉(GBFS),由山东盈润智能新材料有限公司提供,比表面积为550
SiO2 | CaO | Al2O3 | Fe2O3 | SO3 | MgO | K2O | Na2O | Other |
---|---|---|---|---|---|---|---|---|
31.40 | 39.75 | 13.84 | 0.52 | 2.66 | 9.44 | 0.57 | 0.41 | 1.32 |
采用逆Leidenfrost效应制备多孔地聚合物微球的具体步骤如

图1 采用逆Leidenfrost效应制备多孔地聚合物微球的示意图
Fig.1 Schematic diagram of preparation of porous geopolymer microspheres based on inverse Leidenfrost effect
Sample | mW/mS | wWG/% |
---|---|---|
R1.0S4 | 1.0 | 4 |
R1.0S6 | 1.0 | 6 |
R1.0S8 | 1.0 | 8 |
R1.2S4 | 1.2 | 4 |
采用双氧水发气制备多孔地聚合物的过程如下:按水固比为0.53、水玻璃掺量为8%称取矿渣粉、水和水玻璃,混合后慢速搅拌4 min;加入3%(以矿渣质量分数计)的双氧水(市售,质量分数为30%),再快速搅拌1 min;将浆料倒入尺寸为70.7 mm×70.7 mm×70.7 mm的模具中,室温发气,脱模后蒸汽养护24 h;用精密切割机将样品切成与微球体积相近的正方体,用于后续pH缓冲测试.
pH缓冲测试:称取5 g蒸汽养护后的样品浸于60 mL去离子水中,浸泡1 d后使用pH计测试浸出液的pH值.测试后更换去离子水,重复上述操作23 d.
热分析所用仪器为Netzsch STA 182 449C型同步热分析仪.测试样品为冷冻干燥后,磨细过筛的粉末样品.测试条件为N2气氛,升温速率为10 ℃/min,温度由30 ℃升至1 000 ℃.
采用Auto pore IV 9500型压汞仪(MIP)测试样品中100 μm以下的孔径分布,称取0.8 g冷冻干燥3 d后的样品进行测试.对于双氧水直接发气法制备的样品,先通过体视显微镜观察并获取图片,再利用Image‑Pro Plus软件进行处理,统计样品中100 μm以上的宏观孔分布.
采用Zeiss EVO18型扫描电子显微镜(SEM)对样品进行微观形貌的观测.测试前,样品冷冻干燥3 d,测试电压为10 kV.
物相结果使用X'Pert PRO型多晶X射线衍射仪(XRD)获得.样品在测试前先经冷冻干燥处理,研磨后再过0.15 mm(100目)筛.测试设备靶材为铜靶,电流为40 mA、电压为40 kV、步长为0.033°,采集时间为10 s,扫描范围为5°~90°.
当水固比为1.0,水玻璃掺量分别为4%、6%、8%时,微球的孔结构特征如

图2 不同水玻璃掺量下微球样品MIP测试结果
Fig.2 MIP results of microsphere samples with different water glass contents(mW/mS=1.0)
Sample | Porosity(by volume)/% | Median pore radius/μm | Specific surface area/( |
---|---|---|---|
R1.0S4 | 39.1 | 1.17 | 10.7 |
R1.0S6 | 34.5 | 0.47 | 7.8 |
R1.0S8 | 31.8 | 0.12 | 6.2 |
R1.2S4 | 44.1 | 1.89 | 13.2 |
当wWG=4%,水固比为1.0和1.2时,微球的孔结构特征如

图3 不同水固比下微球样品的MIP测试结果
Fig.3 MIP results of microsphere samples with different water‑solid ratios(wWG=4%)

图4 微球样品R1.0S4和R1.2S4的SEM图
Fig.4 SEM images of microsphere sample R1.0S4 and R1.2S4
多孔地聚合物微球浸出液pH值随时间的变化如

图6 多孔地聚合物微球浸出液pH值随时间的变化
Fig.6 pH value of the leached solution of porous geopolymer microspheres changed with time
然而,pH值的变化并不能完全衡量样品的pH缓冲性能.计算多孔地聚合物微球中O
(1) |
(2) |
式中:Li为第i天时O

图7 多孔地聚合物微球中O
Fig.7 Cumulative leaching amount and ratio of O
pH缓冲测试后样品的孔径分布如

图8 pH缓冲测试后样品的孔径分布
Fig.8 Pore size distribution of samples after pH buffering test

图9 pH缓冲测试前后样品的测试结果
Fig.9 Thermal analysis results of samples before and after pH buffering test
本研究对比了双氧水直接发气法与基于逆Leidenfrost效应制备的多孔地聚合物的pH缓冲性能.双氧水直接发气法制备的多孔地聚合物中0.01~100 µm的孔径分布如

图10 双氧水直接发气法制备的多孔地聚合物中0.01~100.00 µm的孔径分布
Fig.10 Pore size distribution of 0.01-100.00 μm pores for porous geopolymer prepared by direct gassing with hydrogen peroxide

图11 双氧水直接发气法制备的多孔地聚合物中100~4 000 µm的累积孔分布情况
Fig.11 Cumulative pore size distribution of 100-4 000 μm pores for porous geopolymers prepared by direct gassing with hydrogen peroxide

图12 不同成孔方式下多孔地聚合物的O
Fig.12 Comparison of O
(1)当水固比为1.0、水玻璃掺量由4%增至8%时,基于逆Leidenfrost效应制备的多孔地聚合物微球的孔隙率、中位孔径和孔比表面积均减小,孔径大于1 μm孔的进汞量减小,2~500 nm孔的进汞量增加;当水玻璃掺量为4%、水固比由1.0增至1.2时,微球的孔隙率、中位孔径和孔比表面积均增大,累积进汞量也增加, 孔径2~500 nm的孔大幅度减少.由此可见,改变水玻璃掺量和水固比,可以调控多孔地聚合物微球的孔结构.
(2)当水固比为1.0、水玻璃掺量由4%增大至8%时,微球浸出液的pH值在0~7 d内快速下降,O
(3)pH缓冲测试过程中除了O
(4)与双氧水直接发气法相比,基于逆Leidenfrost效应制备的多孔地聚合物微球具有更高的比表面积,可供O
参考文献
BENITO P, LEONELLI C, MEDRI V, et al. Geopolymers: A new and smart way for a sustainable development[J]. Applied Clay Science, 2013, 73:1‑6. [百度学术]
SINGH B, ISHWARYA G, GUPTA M, et al. Geopolymer concrete:A review of some recent developments[J]. Construction and Building Materials, 2015, 85:78‑90. [百度学术]
丁兆洋,苏群,李明泽,等. 水玻璃模数对地聚物再生混凝土力学性能的影响[J]. 建筑材料学报,2023,26(1):61‑70. [百度学术]
DING Zhaoyang, SU Qun, LI Mingze, et al. Effect of modulus of water glass on mechanical properties of geopolymer recycled aggregate concrete[J]. Journal of Building Materials, 2023, 26(1):61‑70. (in Chinese) [百度学术]
REN B, ZHAO Y L, BAI H Y, et al. Eco‑friendly geopolymer prepared from solid wastes:A critical review[J]. Chemosphere, 2021, 267:128900. [百度学术]
曹瑞林,李保亮,贾子健,等. 锂渣在碱-水热环境下的溶出特性和反应产物[J]. 建筑材料学报,2023,26(2):163‑171. [百度学术]
CAO Ruilin, LI Baoliang, JIA Zijian, et al. Leaching characteristics and reaction products of lithium slag in alkali‑hydrothermal environment[J]. Journal of Building Materials, 2023, 26(2):163‑171. (in Chinese) [百度学术]
陈柯宇,吴大志,胡俊涛,等. 废弃玻璃替代河砂对地聚合物砂浆性能的影响[J]. 建筑材料学报,2022,25(6):577‑584. [百度学术]
CHEN Keyu, WU Dazhi, HU Juntao, et al. Impact of substitution of river sand by waste glass on properties of geopolymer mortar[J]. Journal of Building Materials, 2022, 25(6):577‑584. (in Chinese) [百度学术]
彭晖,李一聪,罗冬,等. 碱激发偏高岭土/矿渣复合胶凝体系反应水平及影响因素分析[J]. 建筑材料学报,2020,23(6):1390‑1397. [百度学术]
PENG Hui, LI Yicong, LUO Dong, et al. Analysis of rection level and factors of alkali activated metakaolin/GGBFS[J]. Journal of Building Materials, 2020, 23(6):1390‑1397. (in Chinese) [百度学术]
LLOYD R R, PROVIS J L, VAN DEVEVTER J S J. Pore solution composition and alkali diffusion in inorganic polymer cement[J]. Cement and Concrete Research, 2010, 40(9):1386‑1392. [百度学术]
ŠKVÁRA F, ŠMILAUER V, HLAVÁČEK P, et al. A weak alkali bond in (N, K)‑A‑S‑H gels:Evidence from leaching and modeling[J]. Ceramics‑Silikaty, 2012, 56(4):374‑382. [百度学术]
ZHANG Z H, PROVIS J L, REID A, et al. Fly ash‑based geopolymers:The relationship between composition, pore structure and efflorescence[J]. Cement and Concrete Research, 2014, 64:30‑41. [百度学术]
NAJAFI KANI E, ALLAHVERDI A, PROVIS J L. Efflorescence control in geopolymer binders based on natural pozzolan[J]. Cement and Concrete Composites, 2012, 34(1):25‑33. [百度学术]
XUE X, LIU Y L, DAI J G, et al. Inhibiting efflorescence formation on fly ash‑based geopolymer via silane surface modification[J]. Cement and Concrete Composites, 2018, 94:43‑52. [百度学术]
NOVAIS R M, BURUBERRI L H, SEABRA M P, et al. Novel porous fly ash‑containing geopolymers for pH buffering applications[J]. Journal of Cleaner Production, 2016, 124:395‑404. [百度学术]
CHEN N, LIU W F, HUANG J H, et al. Preparation of octopus‑like lignin‑grafted cationic polyacrylamide flocculant and its application for water flocculation[J]. International Journal of Biological Macromolecules, 2020, 146:9‑17. [百度学术]
PENG W J, LÜ S, CAO Y J, et al. A novel pH‑responsive flocculant for efficient separation and recovery of Cu and Mo from secondary resources via selective flocculation‑flotation[J]. Journal of Cleaner Production, 2023, 395:136463. [百度学术]
闫旭,李琦路,韩云平,等. pH对污水好氧处理过程N2O产生的影响[J]. 环境工程学报,2015,9(7):3240‑3246. [百度学术]
YAN Xu, LI Qilu, HAN Yunping, et al. Effect of pH value on N2O production in aerobic wastewater treatment process[J]. Chinese Journal of Environmental Engineering, 2015, 9(7):3240‑3246. (in Chinese) [百度学术]
ZHANG C S, SU H J, BAEYENS J, et al. Reviewing the anaerobic digestion of food waste for biogas production[J]. Renewable and Sustainable Energy Reviews, 2014, 38:383‑392. [百度学术]
王晴,康升荣,吴丽梅,等. 地聚合物凝胶体系中N‑A‑S‑H和C‑A‑S‑H结构的分子模拟[J]. 建筑材料学报,2020,23(1):184‑191. [百度学术]
WANG Qing, KANG Shengrong, WU Limei, et al. Molecular simulation N‑A‑S‑H and C‑A‑S‑H in geopolymer cementitious system[J]. Journal of Building Materials, 2020, 23(1):184‑191. (in Chinese) [百度学术]
LEIDENFROST J G. De aquae communis nonnullis qualitatibus tractatus[M]. Duisburg: Ovenius, 1756. [百度学术]
BUMANIS G. The effect of alkaline material particle size on adjustment ability of buffer capacity[J]. Materials Science‑Mediagotyra, 2015, 21(3):405‑409. [百度学术]
NOVAIS R M, SEABRA M P, LABRINCHA J A. Porous geopolymer spheres as novel pH buffering materials[J]. Journal of Cleaner Production, 2017, 143:1114‑1122. [百度学术]