01450nas a2200205 4500008004100000022001400041245006700055210006600122260007300188300001000261490000700271520075900278653001501037653001701052653001301069653002901082100001901111700001701130856009701147 2008 eng d a0169-131700aAdsorption of fluoride ions by Zn-Al layered double hydroxides0 aAdsorption of fluoride ions by ZnAl layered double hydroxides aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUN a54-620 v403 a

Zn-Al layered double hydroxides (LDHs) with different molar ratios Zn/Al (0, 0.17, 0.34, 0.97, 3.47, proportional to) were prepared by the co-precipitation of chlorides, characterized and evaluated for their fluoride adsorption at room temperature from aqueous solutions. The fluoride adsorption of the as-synthesized LDHs was influenced by the chemical composition of the LDHs and ZA-11 (Zn/Al = 0.97) had the highest capacity for fluoride adsorption (1.14-4.16 mg/g). The adsorption increased after calcination of the LDH up to 500 degrees C. The equilibrium data were fitted to the Freundlich, Langmuir, and Temkin equations. The kinetics of fluoride adsorption followed the pseudo-second order model. (C) 2007 Elsevier B.V All rights reserved.

10aAdsorption10aAnionic clay10aFluoride10aLayered double hydroxide1 aMandal, Sujata1 aMayadevi, S. uhttp://library.ncl.res.in/content/adsorption-fluoride-ions-zn-al-layered-double-hydroxides-001753nas a2200205 4500008004100000022001400041245010300055210006900158260010600227300001200333490000700345520096500352653001501317653001401332653001301346653002901359100001901388700001701407856012301424 2008 eng d a0045-653500aCellulose supported layered double hydroxides for the adsorption of fluoride from aqueous solution0 aCellulose supported layered double hydroxides for the adsorption aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJUN a995-9980 v723 a

Cellulose supported layered double hydroxides (CSLDHs) were synthesized and tested for adsorption of fluoride in aqueous medium. Three samples of cellulose supported LDHs were synthesized by varying the LDH loading on cellulose. The raw cellulose, unsupported LDH and cellulose supported LDHs were characterized by XRD, SEM and BET surface area. Batch adsorption as well as fixed-bed column experiments were performed for determining the fluoride adsorption characteristics of CSLDHs. The fluoride adsorption properties of CSLDHs were found to be superior to that of reported adsorbents, including activated alumina and carbon nanotubes. Defluoridation capacity of the CSLDHs was 2-4 times higher than that of unsupported LDH. The cellulose supported LDH, CSLDH-50, having an LDH loading of 27% showed maximum fluoride uptake capacity (5.29 mg g(-1) of CSLDH, 25.18 mg g(-1) of LDH) in fixed-bed column study. (C) 2008 Elsevier Ltd. All rights reserved.

10aAdsorption10acellulose10aFluoride10aLayered double hydroxide1 aMandal, Sujata1 aMayadevi, S. uhttp://library.ncl.res.in/content/cellulose-supported-layered-double-hydroxides-adsorption-fluoride-aqueous-solution-001795nas a2200229 4500008004100000022001400041245011900055210006900174260007300243300001200316490000800328520098000336653001501316653001701331653001301348653001301361653001301374653001701387100001901404700001701423856012501440 2009 eng d a0304-389400aDefluoridation of water using as-synthesized Zn/Al/Cl anionic clay adsorbent: equilibrium and regeneration studies0 aDefluoridation of water using assynthesized ZnAlCl anionic clay  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG a873-8780 v1673 a

Zn/Al/Cl anionic clay has been synthesized by co-precipitation method and applied for adsorption of fluoride in aqueous medium. Equilibrium adsorption data were fitted to Langmuir, Freundlich, Temkin, and Generalized isotherm equations. Thermodynamic parameters like Delta G and Delta H values show the feasibility and exothermic nature of the adsorption process. Influence of solution pH and presence of other anions on fluoride adsorption by the clay has also been studied. Presence of carbonate in water was found to have an adverse effect on fluoride adsorption by the clay. pH(pzc) of the clay has been found to be 8.97. A two-step 1st order kinetic model was used to explain the fluoride adsorption kinetics of the as-synthesized clay. It was possible to regenerate the adsorbent with an aqueous solution of 0.01 M NaOH and the effect of regeneration on fluoride adsorption was reported up to five regeneration cycles. (C) 2009 Elsevier B.V. All rights reserved.

10aAdsorption10aAnionic clay10aFluoride10aIsotherm10akinetics10aRegeneration1 aMandal, Sujata1 aMayadevi, S. uhttp://library.ncl.res.in/content/defluoridation-water-using-synthesized-znalcl-anionic-clay-adsorbent-equilibrium-and-002245nas a2200277 4500008004100000022001400041245011100055210006900166260007300235300001000308490000800318520125700326653001501583653002101598653002501619653001301644653002101657100002301678700002401701700002401725700002001749700002601769700002401795700002601819856012201845 2010 eng d a0011-916400aAdsorption of fluoride from aqueous solution by alumina of alkoxide nature: batch and continuous operation0 aAdsorption of fluoride from aqueous solution by alumina of alkox aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC a15-230 v2643 a

In this investigation, we report the adsorption potential of alkoxide origin alumina for defluoridation of drinking water using batch and continuous mode of operations. The effects of different operating parameters such as adsorbent dose, initial fluoride concentration, pH of the solution and interfering ions (usually present in groundwater) were studied with a view to understand the adsorption behavior of the material under various conditions. A thermodynamic study shows that the adsorption of fluoride by alkoxide origin alumina is an exothermic and spontaneous process. The kinetic results showed that the fluoride sorption follows pseudo-second-order kinetics. The applicability of adsorbent in the field is also tested through column breakthrough studies. It has been observed that with an increase in the flow rate and initial fluoride concentration, the breakthrough curve becomes sharper and the breakthrough time and adsorbed fluoride ion concentration decrease. The breakthrough curve also becomes steeper as the bed height increases. The alkoxide origin alumina based adsorbent media can be used directly for field applications since it is also commercially available in granular form. (C) 2010 Elsevier B.V. All rights reserved.

10aAdsorption10aAlkoxide alumina10aBreakthrough studies10aFluoride10aKinetic modeling1 aKamble, Sanjay, P.1 aDeshpande, Gunavant1 aBarve, Prashant, P.1 aRayalu, Sadhana1 aLabhsetwar, Nitin, K.1 aMalyshew, Alexander1 aKulkarni, Bhaskar, D. uhttp://library.ncl.res.in/content/adsorption-fluoride-aqueous-solution-alumina-alkoxide-nature-batch-and-continuous-001728nas a2200229 4500008004100000022001400041245011900055210006900174260007300243300001200316490000800328520090100336653001301237653001701250653001401267653001301281653001801294100001901312700002201331700001701353856012801370 2012 eng d a1387-181100aAlginate and hydrotalcite-like anionic clay composite systems: synthesis, characterization and application studies0 aAlginate and hydrotalcitelike anionic clay composite systems syn aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG a241-2460 v1583 a

Hydrotalcite-like anionic clays (Zn/Al and Mg/Al) were intercalated with sodium alginate to form organic-inorganic composite adsorbents for water treatment applications. The synthesized composites were characterized using different characterization techniques viz. XRD, DRIFTS, SEM and surface area/porosity analysis. The adsorption potential of the alginate-clay composites was examined for removal of fluoride ions and Orange II dye from water by adsorption. Our studies revealed that these composites had high adsorption capacity for the adsorption of fluoride and Orange II dye from aqueous solutions. The adsorption capacity of the composites was considerably higher than that of either alginate or clay, used individually. The results indicated that these materials might be useful sorbents for groundwater purification/effluent treatment. (C) 2012 Elsevier Inc. All rights reserved.

10aAlginate10aAnionic clay10aComposite10aFluoride10aOrange II dye1 aMandal, Sujata1 aPatil, Varsha, S.1 aMayadevi, S. uhttp://library.ncl.res.in/content/alginate-and-hydrotalcite-anionic-clay-composite-systems-synthesis-characterization-and-002360nas a2200265 4500008004100000022001400041245013200055210006900187260000900256300001200265490000700277520148200284653001501766653001301781653000901794653001301803653000801816100002501824700001801849700002601867700002701893700001801920700002801938856012801966 2020 eng d a1060-132500aRemoval of fluoride from aqueous solution by mesoporous silica nanoparticles functionalized with chitosan derived from mushroom0 aRemoval of fluoride from aqueous solution by mesoporous silica n cSEP  a619-6270 v573 a

In the present study, chitosan functionalized mesoporous silica nanoparticles have been synthesized. Chitosan derived from an edible mushroom, Agaricus bisporus was used during synthesis of chitosan functionalized silica nanoparticles. The functionalized silica nanoparticles were subjected to fluoride sorption using a batch method which subsequently showed removal efficiency of 95% with maximum sorption capacity, 58.8 mg/g. The characterization of nanoparticles was carried out by SEM, EDAX, XRD and FTIR analysis respectively. EDAX analysis suggested that oxygen, 51.83% and silica 37.24% was main constituent of the functionalized nanomaterials. XRD yielded characteristic diffraction pattern corresponding to the lattice planes (100), (110), (112), (120), (200) and (220) respectively. Sorption data was used to study equilibrium isotherm namely Langmuir and Freundlich model. The adsorption capacity increased with temperature while kinetics studies revealed that the adsorption process followed a pseudo-second-order rate equation. The enthalpy change (Delta H) and entropy change (Delta S) was found to be -31.36 kJmol(-1) and -7.75 Jmol(-1) K-1, showing endothermic and spontaneous nature of the fluoride adsorption. Data suggested that the nature of adsorption belonged to chemisorptions. The overall results suggested that the synthesized nanoparticles showed strong and specific affinity for fluoride and could be excellent adsorbents for defluoridation.

10aAdsorption10aChitosan10aEDAX10aFluoride10aSEM1 aSrivastava, Anushree1 aKumari, Madhu1 aRamanathan, Alagappan1 aSelvaraj, Kaliaperumal1 aPrasad, Bablu1 aPrasad, Kumar, Suranjit uhttp://library.ncl.res.in/content/removal-fluoride-aqueous-solution-mesoporous-silica-nanoparticles-functionalized-chitosan