Fluoride is one of the anionic contaminants which is found in excess in surface or groundwater because of geochemical reactions or anthropogenic activities such as the disposal of industrial wastewaters. Among various methods used for defluoridation of water such as coagulation, precipitation, membrane processes, electrolytic treatment, ion-exchange, the adsorption process is widely used. It offers satisfactory results and seems to be a more attractive method for the removal of fluoride in terms of cost, simplicity of design and operation. Various conventional and non-conventional adsorbents have been assessed for the removal of fluoride from water. In this review, a list of various adsorbents (oxides and hydroxides, biosorbents, geomaterials, carbonaceous materials and industrial products and by-products) and its modifications from literature are surveyed and their adsorption capacities under various conditions are compared. The effect of other impurities on fluoride removal has also been discussed. This survey showed that various adsorbents, especially binary and trimetal oxides and hydroxides, have good potential for the fluoride removal from aquatic environments.

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Background Down syndrome (DS) is the most common genetic disorder. To date, the scientific literature regarding micronutrient status in children and adolescents with DS has not been systematically reviewed. Therefore, our aim was to provide a systematic review and meta-analysis on this topic. Methods We identified all relevant case-control studies published by 1 January 2022, by searching the PubMed and Scopus databases for original English-language articles analysing the micronutrient status of individuals with DS. Forty studies were included in the systematic review and 31 in the metaanalysis.Results Statistically significant differences between individuals with DS (cases) and non-DS (controls) (P ≤ 0.05) were obtained for zinc, selenium, copper, vitamin B12, sodium and calcium. Serum, plasma and whole blood analyses showed lower zinc levels in cases than controls {standardised mean difference [SMD] serum [95% confidence interval (CI)] = À2.32 [À3.22, À1.41], P < 0.00001; SMD plasma [95% CI] = À1.29 [À2.26, À0.31], P < 0.01; SMD blood [95% CI] = À1.59 [À2.29, À0.89], P < 0.00001}. Similarly, plasma and blood selenium concentrations were significantly lower in cases than controls (SMD plasma [95% CI] = À1.39 [À2.26, À0.51], P = 0.002; SMD blood [95% CI] = À1.86 [À2.59, À1.13], P < 0.00001). Intraerythrocytic copper and serum B12 were higher in cases than controls (SMD Cu [95% CI] = 3.33 [2.19, 4.46], P < 0.00001; SMD B12 [95% CI] = 0.89 [0.01, 1.77], P = 0.048). Blood calcium was lower in cases than controls (SMD Ca [95% CI] = À0.77 [À1.34, À0.21], P = 0.007).Conclusions This study provides the first systematic overview of micronutrient status in children and adolescents with DS and has shown that relatively little consistent research has been executed in this field. There is a clear need for more well-designed, clinical trials to study the micronutrient status and effects of dietary supplements in children and adolescents with DS.

Humic acid (HA) impairs water quality due to its reactivity with many substances present in water. During the drinking-water treatment process and water distribution via water supply system, HA present in water may react with chlorine and other disinfects <br /> producing harmful disinfection by-products (DBPs), which are categorized by the International Agency for Research on Cancer (IARC) in groups 2A (probably carcinogenic to humans) or 2B (possibly carcinogenic to humans). Several studies have investigated and reported increased HA removal by iron-coated sorbents. Therefore, the aim of this study was to examine the removal of HA from water by two commercially available bituminous coal-based activated carbons (ACs), Cullar D (Cm) and Hydraffin 30N (Hm). Prior to testing the chosen adsorbents were chemically modified according to two protocols: (1) oxidation by acid mixture (m1), and (2) oxidation with acid mixture followed by iron-ions impregnation (m2). The batch adsorption tests were used to test their efficiency in HA removal under various values of process parameters (initial HA concentration, pH, contact time, adsorbent mass, and temperature). The results showed that up to 96 % of HA removal can be obtained by Cullar D modification Cm1, while maximum uptake of HA by Hydraffin 30N modification was achieved with Hm1 (62.1 %). After surface saturation with Fe3+ –ions (m2), both activated carbons showed similar and lower performances in HA removal (Cm2 up to 66.5 %, and Hm2 up to 50.3 %). FTIR analysis confirmed differences in modified AC structures, as well as favorable structure of Cm1 for HA adsorption.