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Applications of Particulate Dispersions and Composites
Published in Rajinder Pal, Rheology of Particulate Dispersions and Composites, 2006
Toothpaste is a particulate dispersion [55–57]. The dispersed phase of a toothpaste consists of solid particles of some mildly abrasive agent (usually dicalcium phosphate) to help remove stains and polish teeth. The weight percentage of solids in the dispersion is about 10 to 50. The continuous phase is an aqueous solution consisting of water, humectant (moisture controller to prevent the toothpaste from becoming dry and firm) such as glycerol, a binder or thickener such as sodium carboxymethylcellulose to prevent the solid particles of the polishing agent from settling out, detergent or surfactant such as lauryl sulphate to provide foaming action and to enhance the cleaning ability of the toothpaste, therapeutic agents such as sodium monofluorophosphate to prevent tooth decay, and minor amounts of flavors, preservatives, and coloring agents.
Bridge Management Objectives and Methodologies
Published in J.E. Harding, G.E.R. Parke, M.J. Ryall, Bridge Management 3, 2014
The principle of the MFP method is to replace the demolition of carbonated or chloride contaminated sound concrete by a deep impregnation of a solution of sodium monofluorophosphate (MFP) to rebar level. This product has two main actions, it increases the resistance of steel to corrosion [3], and it reacts with concrete itself to reinforce it:
Fluoride and human health: Systematic appraisal of sources, exposures, metabolism, and toxicity
Published in Critical Reviews in Environmental Science and Technology, 2020
Humayun Kabir, Ashok Kumar Gupta, Subhasish Tripathy
Many dental products available on the market, such as toothpaste, dentifrices, and mouth rinses, are systematically available sources of F− and contribute to overall exposure levels. The concentrations of F− in toothpastes and mouth rinses range from 1000 to 1500 and 230 to 900 mg L−1, respectively (Murray, 1986). These products contain F− in the form of sodium fluoride (NaF), stannous fluoride (SnF2), and sodium monofluorophosphate (Na2PFO3). Fluoride treatment gels contain acidulated or neutral phosphate F− with an F− ion concentration as high as 19,400 mg L−1 (Whitford, 1996). Use of F− containing dental products by children increases daily F− intake. Inadequate control of the swallowing reflex by preschool aged children results in a higher amount of F− ingestion (Levy, 1994). The F− exposure level from these products varies among individuals, depending on the frequency, amount of use, type of F− salt, F− concentration, and individual response. The amount of F− from toothpaste ingested by children consuming optimally fluoridated water, who have good control in swallowing and brush their teeth twice per day is approximately equal to the daily F− intake from drinking water, food, and beverages (Whitford, Allmann, & Shahed, 1987). Fluoride present in dental products interacts with saliva and forms CaF2. The formation of easily dissolvable CaF2 promotes uptake and incorporation into the crystalline lattice (Prabhu et al., 2017).
Rhamnolipids as an eco-friendly corrosion inhibitor of rebars in simulated concrete pore solution: evaluation of conditioning and addition methods
Published in Corrosion Engineering, Science and Technology, 2020
Varvara Shubina Helbert, Laurent Gaillet, Thierry Chaussadent, Vincent Gaudefroy, Juan Creus
Corrosion inhibitors used in civil engineering are divided into two main families, inorganics based on nitrites and organic compounds such as alkanolamine. Based on their ways of action, they can also be classified as anodic, cathodic or mixed inhibitors [10]. Inhibitors are generally introduced as additives during the preparation of concrete or applied to the concrete surface. More rarely, they are applied directly on rebars as in this article. The inorganic inhibitors, based on nitrites (sodium and calcium), were the first inhibitors implemented and are effective and represent a large part of the market. Nevertheless, they have proven to be toxic to humans and their use in Europe is being questioned [16]. Among the inorganic cathodic type inhibitors, monofluorophosphates are also widely used including sodium monofluorophosphate applied to the concrete surface. There are still some questions about their exact mechanism of inhibition of corrosion and its toxicity [17–19]. Organic inhibitors such as amines and alkanolamines are considered as a specific inhibitor class. Their mechanism of action is mix and consists of a surface absorption on steel with the formation of a covalent bond blocking the arrival of other species on this surface [20–23]. To improve the effectiveness of corrosion inhibitors, hybrid corrosion inhibitors have been developed such as the addition of quaternary ammonium salts or phosphates to organic compounds. They exhibit good resistance to corrosion, but their production and mechanisms of action are more complex [24,25]. The various chemical molecules that compose these inorganic and organic inhibitors can be toxic to the environment and humans. They are not biodegradable and can be expensive to use. To overcome this, the latest generation of so-called biological inhibitors uses biomolecules.