Fluoride removal from natural volcanic underground water by an electrocoagulation process: Parametric and cost evaluations.

Excessive fluoride content in groundwater can cause serious risks to human health, and sources of groundwater intended for human consumption should be treated to reduce fluoride concentrations down to acceptable levels. In the particular case of the island of Tenerife (Canary Islands, Spain), the water supply comes mainly from aquifers of volcanic origin with a high content of fluorides that make them unacceptable for human consumption without prior conditioning treatment. The treatments that generate a high rejection of water are not acceptable because water is a scarce natural resource of high value. An electrocoagulation process was investigated as a method to treat natural groundwater from volcanic soils containing a hazardously high fluoride content. The operating parameters of an electrocoagulation reactor model with parallel plate aluminum electrodes were optimized for batch and continuous flow operations. In the case of the batch operation, acidification of the water improved the removal efficiency of fluoride, which was the highest at pH 3. However, operation at the natural pH of the water achieved elimination efficiencies between 82 and 92%, depending on the applied current density. An optimum current density of 5 mA/cm2 was found in terms of maximum removal efficiency, and the kinetics of fluoride removal conformed to pseudo-second-order kinetics. In the continuous-flow operation, with the optimal residence time of 10 min and a separation of 0.5 cm between the electrodes, it was observed that the current density that would be applied would depend on the initial concentration of fluoride in the raw water. Thus, an initial fluoride concentration of 6.02 mg/L required a current density >7.5 mA/cm2 to comply with the legal guidelines in the product water, while for an initial concentration of 8.98 mg/L, the optimal current density was 10 mA/cm2. Under these operating conditions, the electrocoagulation process was able to reduce the fluoride concentration of natural groundwater to below 1.5 mg/L according to WHO guidelines with an operating cost between 0.20 and 0.26 €/m3 of treated water.

Health care applications based on mobile phone centric smart sensor network.

This paper presents the MIMOSA architecture and development platform to create Ambient Intelligence applications. MIMOSA achieves this objective by developing a personal mobile-device centric architecture and open technology platform where microsystem technology is the key enabling technology for their realization due to its low-cost, low power consumption, and small size. This paper focuses the demonstration activities carried out in the field of health care. MIMOSA project is a European level initiative involving 15 enterprises and research institutions and universities.

Micellar enhanced spectrofluorometric determination of chlorophyll a and chlorophyll b in fresh waters.

The enhancement of the fluorescence of chlorophyll a and chlorophyll b in a non-ionic micellar media is used for the establishment of a new analytical method for the determination of these pigments. After optimization of the variables, including concentration of surfactant, pH, temperature and percentage of organic solvent, the analytical figures of merit are determined. High recovery percentages are found when the method is applied to the simultaneous determination of chlorophyll a and b in synthetic mixtures. Finally, the method is used for the determination of both chlorophylls in local fresh waters, finding excellent agreement with the results obtained by an HPLC/fluorescence method.

Kinetic spectrofluorimetric determination of silver, based on its catalytic effect on the oxidation of pyrocatechol-1-aldehyde 2-pyridylhydrazone by peroxodisulphate in the presence of 1,10-phenanthroline as activator.

A kinetic fluorimetric method for the determination of silver is described, based on its catalytic effect on the oxidation of pyrocatechol-1-aldehyde 2-pyridylhydrazone by peroxodisulphate. In aqueous solution silver concentrations of 0.2-0.8 mug ml can be determined, and 10-80 ng ml in the presence of 1,10-phenanthroline as activator. The fluorescent species obtained (lambda(ex) 357 nm, lambda(em) 445 nm) results from oxidation of the reagent. The kinetic parameters and the interferences are reported, and the method is applied to the determination of silver in developed panchromatic plates.