Subbaiah Muthu Prabhu

Novel one-pot synthesis of dicarboxylic acids mediated alginate–zirconium biopolymeric complex for defluoridation of water

The present investigation explains the fluoride removal from aqueous solution using alginate-zirconium complex prepared with respective dicarboxylic acids like oxalic acid (Ox), malonic acid (MA) and succinic acid (SA) as a medium. The complexes viz., alginate-oxalic acid-zirconium (Alg-Ox-Zr), alginate-malonic acid-zirconium (Alg-MA-Zr) and alginate-succinic acid-zirconium (Alg-SA-Zr) were synthesized and studied for fluoride removal. The synthesized complexes were characterized by FTIR, XRD, SEM with EDAX and mapping images. The effects of various operating parameters were optimized. The result showed that the maximum removal of fluoride 9653mgF(-)/kg was achieved by Alg-Ox-Zr complex at acidic pH in an ambient atmospheric condition. Equilibrium data of Alg-Ox-Zr complex was fitted well with Freundlich isotherm. The calculated values of thermodynamic parameters indicated that the fluoride adsorption is spontaneous and endothermic in nature. The mechanism of fluoride removal behind Alg-Ox-Zr complex has been proposed in detail. The suitability of the Alg-Ox-Zr complex has been tested with the field sample collected in a nearby fluoride endemic area.

A dendrimer-like hyper branched chitosan beads toward fluoride adsorption from water☆

The present study reports a novel approach for the preparation of polyamidoamine grafted chitosan beads (PAAGCB) via Michael addition followed by protonation of PAAGCB to get protonated PAAGCB (H(+)-PAAGCB). Various metal ions viz., Al(3+), Ce(3+), La(3+) and Zr(4+) have been loaded onto the PAAGCB in order to get respective Al-PAAGCB, Ce-PAAGCB, La-PAAGCB and Zr-PAAGCB. All these sorbents were used to remove the fluoride ions from aqueous solution. Ethylenediamine is used for amination purpose of chitosan beads through Michael addition. The results showed that Zr-PAAGCB was more selective with the maximum defluoridation capacity of 17.47 mg/g than the other metal ion loaded chitosan beads. The sorbents were characterized using FTIR, XRD, SEM and EDAX. The fluoride sorption was reasonably explained using Freundlich and Langmuir isotherm models. The mechanism concerned in the adsorption of fluoride ions is by physisorption on heterogeneous materials according to the results obtained by fitting the data to various isotherm models. Temperature study carried out at 303, 313 and 323K revealed that the adsorption process was spontaneous and endothermic in nature. The applicability of the sorbents studied has been tested with field sample collected from fluoride endemic area.

Effect of metal ions loaded onto iminodiacetic acid functionalized cation exchange resin for selective fluoride removal

AbstractIn the present work, Duolite (DLE) C 466 (Sodium form of iminodiacetic acid functionalized macroporous cross-linked polystyrene), a commercially available resin has been modified by loading various metal ions like Fe3+, Al3+, Ce3+, and La3+ to enhance the fluoride removal capacity of the resin. The effect of pH, dose of adsorbent, contact time, co-ions, and temperature on fluoride removal efficiency was studied. In order to establish the structural modifications, metals loaded DLE resins were characterized by FTIR and SEM−EDAX studies. The sorption data were subjected to Langmuir and Freundlich isotherms, and the sorption process follows Freundlich isotherm. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° indicated that the nature of fluoride sorption is spontaneous and endothermic. Dynamic adsorption data indicated that the pseudo-second-order rate equation is the suitable model for the sorption reaction.

Defluoridation of water using chitosan assisted ethylenediamine functionalized synthetic polymeric blends.

In this paper, a new kind of approach undertakes for the synthesis of novel chitosan (CS) blended with ethylenediamine (ED) functionalized synthetic polymers viz., acrylonitrile/divinylbenzene/vinylbenzyl chloride (CS@AN/DVB/VBC-ED) and styrene/divinylbenzene/vinylbenzyl chloride (CS@ST/DVB/VBC-ED) for defluoridation of water. Under batch mode, various influencing parameters like shaking time, pH, competitor ions and temperature were optimized. The fluoride removal was reasonably explained using Freundlich, Langmuir and D-R isotherms. The thermodynamic parameters viz., ΔG°, ΔH° and ΔS° indicates the nature of the fluoride sorption with the sorbents. The FT-IR, XRD and SEM with EDAX analysis were used to study the fluoride adsorption of CS@AN/DVB/VBC-ED and CS@ST/DVB/VBC-ED blends. The thermal stability of both the sorbents was tested using TGA/DSC analysis. Studies were also conducted to test the potential application of the prepared polymeric blends for fluoride removal from field water collected from the nearby fluoride endemic area.

Defluoridation of water using dicarboxylic acids mediated chitosan-polyaniline/zirconium biopolymeric complex

The present investigation describes the preparation of hydrogen bonded chitosan-polyaniline/zirconium biopolymeric matrix by grafting method under dicarboxylic acid medium for the removal of fluoride, first time. Herein, the dicarboxylic acids, oxalic acid, malonic acid, succinic acid were used as medium. The synthesized complex was characterized by usual analytical techniques like FTIR, XRD, SEM and EDAX analysis. From the batch equilibrium experiments, the maximum defluoridation capacity (DC) was found to be 8.713 mg/g at room temperature with the minimum contact time of 24 min at 100mg of the sorbent dosage. The temperature study results of adsorption kinetics showed the adsorption behavior could be better described by the pseudo-second-order equation than pseudo-first-order kinetic model. The adsorption isotherm was well fitted by the Freundlich equation rather than Langmuir and D-R isotherms. The mechanism of fluoride removal was ligand exchange at neutral pH and electrostatic attraction at acidic pH of the medium. Regeneration studies were carried out to identify the best regenerant which makes the process cost-effective. Conclusions of this work demonstrate the potential applicability of the dicarboxylic acid mediated chitosan-polyaniline/zirconium complex as an effective adsorbent for fluoride removal from water.