Calcium Fluoride Precipitation and Deposition From 12 mmol/L Fluoride Solutions With Different Calcium Addition Rates.

IF 1.5 4区 工程技术
M Markovic, S Takagi, L C Chow, S Frukhtbeyn
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引用次数: 14

Abstract

The effects of different Ca-addition rates on calcium fluoride (CaF2) precipitation and deposition were investigated in 12 mmol/L sodium fluoride solutions to which 0.1 mol/L calcium chloride solution was continuously added at average rates of (5, 7.5, 10, 12.5, 15 or 20) mmol L(-1) min(-1). The changes in ionic fluoride and calcium concentrations, as well as turbidity, were continuously recorded by F and Ca electrodes, and a fiber optic based spectrophotometer, respectively. The F(-) concentration decreased and turbidity increased with time indicating precipitation of CaF2. For the systems with Ca-addition rates of (5, 7.5, 10, 12.5, 15, and 20) mmol L(-1) min(-1), the 1 min CaF2 depositions in the model substrate (cellulose filter paper, pores 0.2 µm) expressed as mean ± SD of deposited F per substrate surface area were (3.78 ± 0.31, 11.45 ± 0.89, 9.31 ± 0.68, 8.20 ± 0.56, 6.63 ± 0.43, and 2.09 ± 0.28) µg/cm(2), respectively (n = 10 for each group). The 1-min F depositions did not show positive correlation to Ca-addition rates. The lowest 1-min F deposition was obtained in the systems with the highest Ca-addition rate of 20 mmol L(-1) min(-1) for which CaF2 precipitation rate reached the maximum value of 0.31 mmol L(-1) s(-1) almost immediately after beginning of reaction (6 s). The largest 1-min F depositions were obtained from the systems with Ca addition rates of (7.5 to 12.5) mmol L(-1) min(-1) in which CaF2 precipitation rates continuously increased reaching the maximum values of (0.13 to 0.20) mmol L(-1) s(-1) after (18 to 29) s, respectively. The 1-min F depositions were greatly enhanced in comparison with the control F solutions that did not have continuous Ca-addition. This indicates that continuous Ca addition that controls the rate of CaF2 formation could be a critical factor for larger F depositions from F solutions. The efficacy of conventional F mouthrinses could be improved with addition of a substance that continuously releases Ca.

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不同加钙速率下12 mmol/L氟溶液中氟化钙的沉淀与沉积
在12 mmol/L氟化钠溶液中,以(5、7.5、10、12.5、15、20)mmol L(-1) min(-1)连续添加0.1 mol/L氯化钙溶液,研究了不同钙添加速率对氟化钙(CaF2)沉淀和沉积的影响。分别用F电极和Ca电极和光纤分光光度计连续记录氟离子浓度和钙离子浓度以及浊度的变化。随着时间的推移,F(-)浓度降低,浊度增加,表明CaF2有沉淀。对于ca添加速率为(5、7.5、10、12.5、15和20)mmol L(-1) min(-1)的体系,模型底物(纤维素滤纸,孔隙0.2µm)中1 min的CaF2沉积量分别为(3.78±0.31、11.45±0.89、9.31±0.68、8.20±0.56、6.63±0.43和2.09±0.28)µg/cm(2)(每组n = 10)。1 min F沉积与ca添加速率不呈正相关。最低(F沉积得到系统Ca-addition率最高的20更易与L(1)分(1)CaF2的降水率达到最大值0.31更易与L(1)(1)后几乎立即开始反应(6 s)。最大的(F口供与Ca除了从系统获得的(7.5 - 12.5)更易与L(1)分(1)CaF2的沉淀率不断增加达到最大值(0.13 - 0.20)更易与L (1) (1)分别在(18 ~ 29)s之后。与没有连续添加ca的对照F溶液相比,1 min F沉积得到了极大的增强。这表明,控制CaF2形成速率的连续Ca添加可能是F溶液中较大F沉积的关键因素。添加一种能持续释放钙的物质,可以提高常规含钙漱口水的功效。
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来源期刊
自引率
33.30%
发文量
10
期刊介绍: The Journal of Research of the National Institute of Standards and Technology is the flagship publication of the National Institute of Standards and Technology. It has been published under various titles and forms since 1904, with its roots as Scientific Papers issued as the Bulletin of the Bureau of Standards. In 1928, the Scientific Papers were combined with Technologic Papers, which reported results of investigations of material and methods of testing. This new publication was titled the Bureau of Standards Journal of Research. The Journal of Research of NIST reports NIST research and development in metrology and related fields of physical science, engineering, applied mathematics, statistics, biotechnology, information technology.
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