聚羧酸减水剂对水泥浆结合氯离子性能的影响
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摘要
从氯离子等温吸附、吸附动力学及吸附热力学3个方面,研究聚羧酸减水剂对水泥浆结合氯离子性能的影响,同时应用XRD微观测试技术研究其作用机理。结果表明:掺入聚羧酸减水剂使水泥浆体结合氯离子能力减弱,且水灰比越小,这种影响作用则越大;掺入聚羧酸减水剂的水泥浆体对氯离子的固化过程,短期内符合准一级动力学方程,表现为物理吸附,长期内符合准二级动力学方程,表现为化学结合,其中随着聚羧酸减水剂掺量的增大,吸附速率逐渐减小;聚羧酸减水剂使水泥浆结合氯离子过程中的自由能变、焓变和熵变都减小,且这个过程是自发、放热的;掺入聚羧酸减水剂主要影响水泥浆体对氯离子的物理吸附,对化学结合没有明显影响。
Through the isothermal adsorption of chloride ion, the adsorption kinetics and the adsorption thermodynamics,the influence of polycarboxylate superplasticizer on the chloride binding in cement paste has been investigated. Besides,the influencing mechanism was examined by the X-ray powder diffractometer( XRD). It has been found that the polycarboxylate superplasticizer reduces the chloride binding,and the smaller the water-cement ratio is,the greater the effect is. Chloride binding onto cement paste with polycarboxylate superplasticizer in a short time conforms to pseudo-first-order kinetic equation,indicating the physical adsorption of chloride ions. In a long time,it conforms to pseudo-second-order kinetic equation,indicating the chemical adsorption of chloride ions. With the increase of content of polycarboxylate superplasticizer,the adsorption rate decreases. The free energy,enthalpy and entropy of chloride binding are decreased with the increase of polycarboxylate superplasticizer,and this process is spontaneous and exothermic. The influence of polycarboxylate superplasticizer on the chloride binding is mainly attributed to the physical adsorption,not chemical combination of chloride ions.
Through the isothermal adsorption of chloride ion, the adsorption kinetics and the adsorption thermodynamics,the influence of polycarboxylate superplasticizer on the chloride binding in cement paste has been investigated. Besides,the influencing mechanism was examined by the X-ray powder diffractometer( XRD). It has been found that the polycarboxylate superplasticizer reduces the chloride binding,and the smaller the water-cement ratio is,the greater the effect is. Chloride binding onto cement paste with polycarboxylate superplasticizer in a short time conforms to pseudo-first-order kinetic equation,indicating the physical adsorption of chloride ions. In a long time,it conforms to pseudo-second-order kinetic equation,indicating the chemical adsorption of chloride ions. With the increase of content of polycarboxylate superplasticizer,the adsorption rate decreases. The free energy,enthalpy and entropy of chloride binding are decreased with the increase of polycarboxylate superplasticizer,and this process is spontaneous and exothermic. The influence of polycarboxylate superplasticizer on the chloride binding is mainly attributed to the physical adsorption,not chemical combination of chloride ions.
引文
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[20]范荣玉,郑细鸣.铅(Ⅱ)离子印迹复合膜对重金属离子的吸附热力学与吸附动力学[J].化工学报,2013,64(5):1651-1659.(FAN Rongyu,ZHENG Ximing. Adsorption thermodynamics and adsorption kinetics of heavy metal ions by lead(II)ion imprinted composite membrane[J]. CIESC Journal,2013,64(5):1651-1659.(in Chinese))
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[22]王宝贝,蒲洋,林丽芹,等.离子交换树脂对D-甘油酸的吸附热力学和动力学[J].化工学报,2016,67(11):4671-4677.(WANG Baobei,PU Yang,LIN Liqing,et al. Thermodynamics and kinetics of D-glyceric acid adsorption on ion exchange resin[J]. CIESC Journal,2016,67(11):4671-4677.(in Chinese))
[2]孙成,李洪锡,张淑泉,等.钢筋混凝土腐蚀研究综述[J].材料导报,2000,14(5):27-28.(SUN Cheng,LI Hongxi,ZHANG Shuquan,et al. Review of research on reinforced concrete corrosion[J]. Materials Review,2000,14(5):27-28.(in Chinese))
[3]XU Jinxia,JIANG Linhua,WANG Jingxiang. Influence of detection methods on chloride threshold value for the corrosion of steel reinforcement[J]. Construction and Building Materials,2009,23(5):1902-1908.
[4]蒋林华,白舒雅,徐金霞,等.钢筋锈蚀氯离子临界浓度研究进展[J].水利水电科技进展,2015,35(5):77-82.(JIANG Linhua,BAI Shuya,XU Jinxia,et al. Research progress of critical chloride concentration in steel corrosion[J]. Advances in Science and Technology of Water Resources,2015,35(5):77-82.(in Chinese))
[5]LUO R,CAI Y B,WANG C Y,et al. Study of chloride binding and diffusion in GGBS concrete[J]. Cement and Concrete Research,2003,33(1):1-7.
[6]李梅,温勇,张广泰,等.矿物掺合料对混凝土抗氯离子渗透性的影响综述[J].材料导报,2013,27(11):107-110.(LI Mei,WEN Yong,ZHANG Guangtai,et al. Review of the influence of mineral admixtures on chloride ion permeability of concrete[J].Materials Review,2013,27(11):107-110.(in Chinese))
[7]勾密峰,管学茂.水泥基材料固化氯离子的研究现状与展望[J].材料导报,2010,24(11):124-127.(GOU Mifeng,GUAN Xuemao. Research status and prospect of chloride ion curing by cement based materials[J]. Materials Review,2010,24(11):124-127.(in Chinese))
[8]ISHIDA T,MIYAHARA S,MARUYA T. Chloride binding capacity of mortars made with various portland cements and mineral admixtures[J]. Journal of Advanced Concrete Technology,2008,6(2):287-301.
[9]SONG Zijian,JIANG Linhua,ZHANG Ziming,et al. Distance-associated chloride binding capacity of cement paste subjected to natural diffusion[J]. Construction and Building Materials,2016,112:925-932.
[10]DE W K,COLOMBO A,COPPOLA L,et al. Impact of the associated cation on chloride binding of Portland cement paste[J].Cement and Concrete Research,2015,68:196-202.
[11]XU Jinxia,FENG Wei,JIANG Linhua,et al. Influence of surfactants on chloride binding in cement paste[J]. Construction and Building Materials,2016,125:369-374.
[12]LI Shun,YU Qijun,WEI Jiangxiong. Effect of molecular structure of polycarboxylate water reducers on hydration of cement[J].Journal of the Chinese Silicate Society,2012,40(4):613-619.
[13]TOLEDANO P M,LORENZO P M,GONZALEZO F B,et al. Effect of polycarboxylate superplasticizers on large amounts of fly ash cements[J]. Construction and Building Materials,2013,48:628-635.
[14]TANG L,NILSSON L O. Chloride binding capacity and binding isotherms of OPC pastes and mortars[J]. Cement and Concrete Research,1993,23(2):247-253.
[15]周良春,孟祥光,李建梅,等.β-环糊精修饰的壳聚糖对氯酚吸附的动力学和热力学[J].物理化学学报,2010,28(7):1615-1622.(ZHOU Liangchun,MENG Xiangguang,LI Jianmei,et al. Kinetics and thermodynamics of adsorption of chlorop Henols ontoβ-cyclodextrin modified chitosan[J]. Acta PHysico-Chimica Sinica,2010,28(7):1615-1622.(in Chinese))
[16]WU Jian,ZHANG Liang,LONG Chao,et al. Adsorption characteristics of pentane,hexane,and heptane:comparison of hydrop Hobic hypercrosslinked polymeric adsorbent with activated carbon[J]. Journal of Chemical and Engineering Data,2017,57(57):3426-3433.
[17]MARTIN-PEREZ B,ZIBARA H,HOOTONR D,et al. A study of the effect of chloride binding on service life predictions[J].Cement and Concrete Research,2000,30(8):1215-1223.
[18]BOPARAI H K,JOSEPH M,O’CARROLL D M. Kinetics and thermodynamics of cadmium ion removal by adsorption onto nano zerovalent iron particles[J]. Journal of Hazardous Materials,2011,186(1):458-465.
[19] YU Y G,ZHANG Y X. Coupling of chemical kinetics and thermodynamics for simulations of leaching of cement paste in ammonium nitrate solution[J]. Cement and Concrete Research,2017,95:95-107.
[20]范荣玉,郑细鸣.铅(Ⅱ)离子印迹复合膜对重金属离子的吸附热力学与吸附动力学[J].化工学报,2013,64(5):1651-1659.(FAN Rongyu,ZHENG Ximing. Adsorption thermodynamics and adsorption kinetics of heavy metal ions by lead(II)ion imprinted composite membrane[J]. CIESC Journal,2013,64(5):1651-1659.(in Chinese))
[21]WU Z J,JOO H,LEE K. Kinetics and thermodynamics of the organic dye adsorption on the mesoporous hybrid xerogel[J].Chemical Engineering Journal,2005,112(1/2/3):227-236.
[22]王宝贝,蒲洋,林丽芹,等.离子交换树脂对D-甘油酸的吸附热力学和动力学[J].化工学报,2016,67(11):4671-4677.(WANG Baobei,PU Yang,LIN Liqing,et al. Thermodynamics and kinetics of D-glyceric acid adsorption on ion exchange resin[J]. CIESC Journal,2016,67(11):4671-4677.(in Chinese))