The performance of calcined serpentine to simultaneously remove fluoride, iron and manganese

To solve the problem of high fluoride, iron and manganese concentrations in groundwater, serpentine (Srp) was modified by metal salt impregnation, acid-base activation and calcination, and the effects of these three modifications on removal performance of Srp were compared. Specifically, the effects of the calcined serpentine (Csrp) dose, reaction time, pH, and temperature on the removal performance of F−, Fe2+ and Mn2+ on Csrp were analysed. An isothermal adsorption model and adsorption kinetic equation were established and confirmed through SEM, EDS, XRD and FTIR spectroscopy to analyse the mechanism of removing F−, Fe2+ and Mn2+ by Csrp. The results show that when 3 g/L Csrp was used to treat water samples with 5 mg/L F−, 20 mg/L Fe2+, and 5 mg/L Mn2+ (pH of 6, reaction temperature of 35 °C, and time of 150 min), the removal rates of F−, Fe2+, and Mn2+ were 94.3%, 99.0%, 98.9%, respectively. The adsorption of F−, Fe2+ and Mn2+ on Csrp follows the quasi-second-order kinetic equation and Langmuir isotherm adsorption model. After 5 cycles of regeneration of Csrp, Csrp can still maintain good properties of fluoride,iron and manganese removal.

Prospects for the Role of Ferroptosis in Fluorosis

As a strong oxidant, fluorine can induce oxidative stress resulting in cellular damage. Ferroptosis is an iron-dependent type of cell death caused by unrestricted lipid peroxidation (LPO) and subsequent plasma membrane rupture. This article indicated a relationship between fluorosis and ferroptosis. Evidence of the depletion of glutathione (GSH) and increased oxidized GSH can be found in a variety of organisms in high fluorine environments. Studies have shown that high fluoride levels can reduce the antioxidant capacity of antioxidant enzymes, while increasing the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), resulting in oxidative stress and fluoride-induced oxidative stress, which are related to iron metabolism disorders. Excessive fluorine causes insufficient GSH, glutathione peroxidase (GSH-Px) inhibition, and oxidative stress, resulting in ferroptosis, which may play an important role in the occurrence and development of fluorosis.

The cognitive impairment and risk factors of the older people living in high fluorosis areas: DKK1 need attention

Objective To evaluate cognitive impairment and risk factors of elders in high fluoride drinking water areas and investigate whether DKK1 is involved in this disorder. Methods MoCA-B and AD-8 were used to measure the cognitive functions of 272 and 172 subjects over the age of 60 came from the high and normal fluoride drinking water areas respectively, general information and peripheral blood were collected, the level of SOD, GSH and MDA were measured, mRNA level of DKK1, the concentration of blood fluoride and the polymorphism of APOE were tested. Results The blood fluoride concentration, mRNA level of DKK1 and ratio of abnormal cognitive function of subjects in high fluorine drinking water areas were higher than those in normal areas. The level of SOD of subjects in high fluorine drinking water was low compared with those in normal areas. The level of MDA and GSH had no difference between the two crowds in different fluorine drinking water areas. There were differences in cigarette smoking, education, dental status, hypertension, hyperlipidaemia and APOE results between the two crowds in different fluorine drinking water areas. The mRNA level of DKK1 and the level of cognitive function showed a positive correlation and DKK1 was one of five risk factors involved in cognitive impairment of older people living in high fluorosis areas. Conclusions The cognitive functions could be impaired in the older people living in high fluoride drinking water areas, and DKK1 may as a potential intervention point of this brain damage process need attention.

Fluorine Speciation in Loess in The Shaanxi Loess Plateau, Related Quality Assessment And Exposure Risks Implication

In this study, distributing characteristics of five fluorine (F) species in loess in the Shaanxi Loess Plateau (SLP) were determined including unextractable residual F (Fre), extractable water-soluble F (Fws), exchangeable F (Fex), F bound to Fe-Mn oxides (Ffm), and F bound to organics (For). The results show that unextractable Fre represents most percentage of Ftf in loess. Of the four extractable F species, the content of Fws is higher than the other three extractable F species in most loess samples. The loess in the southeast SLP has the highest Fws content while the loess in the southwest has the highest Ftf content. And the loess in the north SLP contains the lowest overall concentrations of Ftf and Fws. Similar to Fws, the respective content of Fex, Ffm, and For in the loess is also very low. However, the total of them and Fws cannot be negligible for F mobility in loess. Overall, the loess in the SLP can be assessed as inferior quality in terms of F as a result of high Fws content in most samples. Based on the F speciation in the loess, F exposure to grazing animals and humans, in fact to children, was assessed, indicating that F in the loess in the southwest SLP might pose a much greater risk to grazing animals than in other part of SLP as the loess contains more Ftf. However, there is no concern for the children’s exposure to loess F via ingestion in the study area in the present condition. As for the loess F risk to groundwater, it can be concluded that not only Fws but also the other extractable F including Fex, Ffm and For in loess may be responsible for the F enrichment in local groundwater in the area with the aid of the characteristics of F speciation in loess and distribution of local high-fluoride groundwater.

Fast Fluoride Ion Conduction in Molecular Cation-Containing Compounds, NH4(Mg1-xLix)F3-x and (NH4)2(Mg1-xLix)F4-x

Aiming development of the fast anion conductors, we proposed a new material design using flexible molecular cation as a host cation, and demonstrated it with fluoride ion conduction in NH4(Mg1-xLix)F3-x and (NH4)2(Mg1-xLix)F4-x. Relatively high fluoride ion conductivities of 4.8×10-5 S cm-1 and 8.4×10-6 S cm-1 were achieved at 323 K in (NH4)2(Mg0.85Li0.15)F3.85 and NH4(Mg0.9Li0.1)F2.9, respectively. Our findings suggest molecular cation-containing compounds can be attractive material groups for fast anion conductors.