Uptake Fluoride from Water by Starch Stabilized Layered Double Hydroxide

Abstract

A novel starch stabilized Mg/Al LDHs material (S-LDH) was prepared in a facile approach and its fluoride ion removal performance was developed. Characterization of S-LDH was employed by using XRD, FTIR and particle size distribution. The adsorption property was studied through the assessment of adsorption isotherms, kinetic models, thermal dynamics and pH influence. The result shows that a low loading of starch of 10 mg onto LDH could obviously improve fluoride removal rate. The S-LDH had 3 times higher adsorption capacity to fluoride than that of Mg/Al LDH to fluoride. The particle size was smaller and the particle size distribution was narrower for S-LDH than that for Mg/Al LDH. Langmuir adsorption isotherm model and pseudo-second-order kinetic model fitted well with the experimental data. In thermodynamic parameters, the enthalpy (△H 0 ) value was 35.63 kJ mol -1 and the entropy (△S 0 ) value was 0.0806 kJ mol -1 K -1 . The values of △G 0 were negative, implying the adsorption process is spontaneous. S-LDH reveals stable adsorption property in a wide pH range from 3 to 9. The mechanism for fluoride adsorption on S-LDH included surface adsorption and interaction ion exchange.

The Relationship between Fluoride Exposure and Cognitive Outcomes from Gestation to Adulthood—A Systematic Review

“…A total of 31 out of the 46 included studies reported their cognitive outcomes using mean IQ scores alone. Of these, 25 [22,27,29,30,[32][33][34][35]37,39,[42][43][44][45][47][48][49]51,53,58,[61][62][63][64]67] concluded that the mean IQ levels of children exposed to fluoride at more than or equal to 2 mg/L were significantly lower than those exposed to <2 mg/L, while the remaining 6 studies reported no significant association between the fluoride exposure and the mean IQ of participants [40,41,46,54,65,66].…”

“…We report results using a subgroup analysis according to (1) study design; (2) age group; (3) fluoride level; and (4) study quality (Table 1). ≥2 mg/L 26 [22,23,25,27,28,30,31,34,37,39,[41][42][43][44][45][46][47][49][50][51]53,56,58,63,64,67] 24 (92) [22,23,25,27,28,30,31,34,37,39,[42][43][44][45]47,[49][50][51]53,56,58,63,64,67] Not reported 9…”

“…Out of the seven studies [35,43,54,56,59,62,66] which were classified as good quality, two longitudinal studies [54,56] and three cross-sectional studies [35,43,62] showed a significant negative relationship between fluoride and cognition. Among the 14 studies [23,24,26,29,33,37,39,42,45,[47][48][49]51,67] that scored "fair", 13 studies [23,26,29,33,37,39,42,45,[47][48][49]51,67] had a significant negative association, and from the 20 studies [22,27,28,[30][31][32]34,36,38,41,…”

Enamel Remineralisation with a Novel Sodium Fluoride-Infused Bristle Toothbrush

“…The decline in dental caries accompanied by the rise in the prevalence of fluorosis in communities with both fluoridated and non-fluoridated water have raised public concern about the necessity and efficiency of water fluoridation [18]. Concerns have also been raised about the safety of water fluoridation [19,20]; studies have even related fluoridation with various medical conditions, such as child development impairment [21], an increase in hypothyroidism risk [22], neurotoxicity, and cancer [23,24]. However, adverse effects have been seen with ingestion/water fluoridation doses over the recommended limits.…”