Adsorption Efficiency of Cement Impregnated Magnesium Oxide on the Removal of Fluoride

Presence of fluoride in drinking water above the prescribed limit may lead to a severe health complication. We present in this paper the fluoride removal capacity of cement impregnated MgO (MgO-cement) from drinking water. MgO-cement was prepared by adding magnesium oxide (MgO) into the cement slurry solution in the ratio of 1:10. Batch experiments were performed as a function of adsorbent dose, contact time, effect of pH and effect of co-ions. The percentage removal decreases with increasing initial fluoride concentration. Co-ions effect revealed that hydroxide ion was found to interfere more with fluoride removal followed by bicarbonate and least effect with sulphate. Reaction mechanism follows Freundlich isotherms. From the kinetic study we observed that uptake of fluoride ion is fast in the first sixty minutes and equilibrium time found to be independent of the initial fluoride concentration. Adsorption kinetics followed the pseudo second order model showing that the sorption of fluoride is a complex process. Surface as well as intraparticle diffusion contribute in the sorption process. No leaching of magnesium in the treated water was detected

A Modified Non Electrical Filter for Decontamination of Iron Rich Water for Rural Application

A non-electrical filter is designed to cater the need of providing iron free water in forward and rural areas. The features of the unit are equipped with the aeration system and activated sand chemically coated by iron oxide as catalytic and filtering media which can bring down iron concentration from 12 mg/L to desirable limit. It increases the pH of water from acidic to pH above 7. This is in contrast to some indigenous water filter which existed in the North Eastern India that tend to remove iron below 4 mg/L. The modified filter is effective in reducing excess total dissolved solids (TDS) from drinking water. All other physical parameters found to be within the prescribed limit. It can give iron free water with output capacity of 25L/hr. The added advantage of the unit is the provision for back washing of the filter media and collection point of the precipitated iron at the lower bottom of the tank for safe discharge

Aggregation and micellization of sodium dodecyl sulfate in the presence of Ce(III) at different temperatures: A conductometric study

Aggregation properties of sodium dodecyl sulfate (SDS) in the presence of cerium(III) chloride, at various temperatures (298.15-323.15 K) have been measured by the electrical conductance technique. The experimental data on aqueous solutions as a function of SDS concentration show the presence of two inflexion points indicating the presence of two distinct interaction mechanisms: the first, occurring at SDS concentrations below the critical micelle concentration of the pure surfactant, which can be explained by the formation of aggregates between dodecyl sulfate (DS-) and Ce(III), while the second one, at SDS concentrations around the critical micelle concentration (cmc) of the pure surfactant which is due to the SDS micellization. The aggregation between DS- and Ce(III) was confirmed by static light scattering. The binding ratio of DS-/Ce(III) changes from 6 to 4, shows a slight dependence on the Ce(III) concentration and is independent of the temperature. The thermodynamic micellization parameters, Gibbs energy, enthalpy and entropy of micellization were calculated on the basis of the experimental data for the aggregation concentration, and the degree of counterion dissociation of the micelles. The SDS micellization is energetically favoured by increasing either the concentration of CeCl3 or the temperature. Such behaviour is clearly dominated by a decrease of the micellization (exothermic) enthalpy. The entropy of micellization approaches zero as the cerium(III) chloride concentration and temperature increase.http://www.sciencedirect.com/science/article/B6WHR-4S6G90R-1/1/a864220de360ed7b600885de2f94b11