@article { ISI:000257637000008, title = {Adsorption of fluoride ions by Zn-Al layered double hydroxides}, journal = {Applied Clay Science}, volume = {40}, number = {1-4}, year = {2008}, month = {JUN}, pages = {54-62}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

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.

}, keywords = {Adsorption, Anionic clay, Fluoride, Layered double hydroxide}, issn = {0169-1317}, doi = {10.1016/j.clay.2007.07.004}, author = {Mandal, Sujata and Mayadevi, S.} } @article { ISI:000257474100021, title = {Cellulose supported layered double hydroxides for the adsorption of fluoride from aqueous solution}, journal = {Chemosphere}, volume = {72}, number = {6}, year = {2008}, month = {JUN}, pages = {995-998}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

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.

}, keywords = {Adsorption, cellulose, Fluoride, Layered double hydroxide}, issn = {0045-6535}, doi = {10.1016/j.chemosphere.2008.03.053}, author = {Mandal, Sujata and Mayadevi, S.} } @article { ISI:000267267000126, title = {Defluoridation of water using as-synthesized Zn/Al/Cl anionic clay adsorbent: equilibrium and regeneration studies}, journal = {Journal of Hazardous Materials}, volume = {167}, number = {1-3}, year = {2009}, month = {AUG}, pages = {873-878}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

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.

}, keywords = {Adsorption, Anionic clay, Fluoride, Isotherm, kinetics, Regeneration}, issn = {0304-3894}, doi = {10.1016/j.jhazmat.2009.01.069}, author = {Mandal, Sujata and Mayadevi, S.} } @article { ISI:000305714200033, title = {Alginate and hydrotalcite-like anionic clay composite systems: synthesis, characterization and application studies}, journal = {Microporous and Mesoporous Materials}, volume = {158}, year = {2012}, month = {AUG}, pages = {241-246}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

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.

}, keywords = {Alginate, Anionic clay, Composite, Fluoride, Orange II dye}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2012.03.046}, author = {Mandal, Sujata and Patil, Varsha S. and Mayadevi, S.} }