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CuO nanorods can remove Pb(ii) from aqueous solution with a maximum sorption capacity of 3.31 mg g−1at 298 K.

Nano-sized magnesium oxide (nano-MgO) was investigated for adsorption of fluoride from water. The pure and fluoride adsorbed nano-MgO were characterised by Brunauer-EmmettTeller, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analyses. The surface area of the adsorbent was found to be 92.46 m 2 /g. Maximum (90%) fluoride removal was obtained with 0.6 g/L dosage of nano-MgO. Fluoride adsorption by nano-MgO was found to be less sensitive to pH variations. Fluoride sorption was mainly influenced by the presence of OH À ion. The presence of other ions studied did not affect the fluoride adsorption capacity of nano-MgO significantly. It has been observed that Freundlich model was better fitted as compared to Langmuir model which indicated the multilayer adsorption of the adsorbent following a pseudo-second order kinetics. Regeneration study showed that 1 M HCl was the best eluent with 95% desorption capacity towards fluoride removal followed by NaOH (2 M) with 25% regeneration of the adsorbent.

A novel and facile method for the synthesis of uniform stoichiometric powder form of non-magnetic iron oxide-hydroxide nanoparticles with spherical morphology and its application for defluoridation of drinking water is reported. X-ray powder diffraction analysis (XRD), BET surface area, FTIR, field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) images were used to characterize nanoscale iron oxide-hydroxide. Transmission electron microscopy (TEM) image revealed the formation of iron oxide-hydroxide nanoparticles with spherical morphology. The iron oxide-hydroxide nanoparticles showed an excellent ability to remove fluoride (F-) from contaminated water over a wide range of pH. The influences of temperature, stirring speed, pH, adsorbent dose and contact time were studied. The equilibrium data were tested with various isotherm models and finally, a calculation procedure was reported for the calculation of adsorbent requirement. The fluoride adsorbed nanoparticles was regenerated upto 70% using sodium hydroxide or hydrochloric acid solution. The iron oxide-hydroxide nanoparticles can be used as an effective and replicable adsorbent media for defluoridation of water in presence of competing anions like chloride, iodate, iodide and sulphate.

A method for removal of iron and arsenic (III) from contaminated water using iron oxide-coated sand and limestone has been developed for drinking water. For the intended use, sand was coated with ferric chloride and used as filtering media. Limestone was added onto the coated sand and the effect of limestone addition on removal efficiency of iron and arsenic was monitored. Both batch and column experiments were conducted to investigate the efficiency of coated sand and limestone as filtering media. Maximum removal of iron (99.8 %) was obtained with coated sand at a dose of 5 g/100 ml and by adding 0.2 g/ 100 ml of limestone at pH 7.3. Arsenic (III) removal efficiency increased with the increased dose of coated sand and was best removed at pH 7.12. The maximum adsorption capacity for arsenic (III) obtained from Langmuir model was found to be 0.075 mg/g and the kinetics data followed pseudo-first order better than pseudo-second order. Energy dispersive X-ray analysis and FT-IR study proved the removal of iron and arsenic. Column experiment showed removal of iron and arsenic (III) to\0.3 mg/l and 10 lg/l, respectively, from an initial concentration of 20 mg/l (iron) and 200 lg/l (arsenic).

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The specific conductivity of several oil-in-water (o/w) microemulsions (MEs) stabilized by sodium dodecyl sulfate and 1-butanol was measured at 25 °C as functions of the volume fraction of oil (φ0) and the molar ratio of water to surfactant (R). The oils used are octane, benzene, toluene, carbon tetrachloride, chloroform, cyclohexane, xylene, and nitrobenzene. The conductivity data were explained by the modified Bruggeman equation in the entire experimental range of φ0 in the case of octane and nitrobenzene and in a limited range of φ0 in the case of other oils. The value of the slope of this equation, f, is found to depend on (i) the concentration of surfactant or the R value, (ii) the nature of the oil, and (iii) the nature and number of substituents, if the oil is a substituted benzene. The specific conductivity data of o/w MEs of R ) 120 and 100 were also analyzed in the light of the mixed electrolyte model, and the values of aggregation number, counterion binding constant, and radius of droplet were computed.