Design of hydrotalcite and biopolymers entrapped tunable cerium organic cubic hybrid material for superior fluoride adsorption.

The excess fluoride in drinking water is serious risk which leads to fluorosis. The adsorption method is facile route for defluoridation studies. Hybrid adsorbent possesses unique advantages like high surface area and high stability has been employed for water treatment. In the present work, hydrotalcite (HT) fabricated Ce-metal organic frameworks (MOFs) bridged with biopolymers (alginate and chitosan) namely HT-CeMOFs@Alg-CS cubic hybrid beads was developed and employed towards fluoride removal in batch mode. The fabricated HT-CeMOFs@Alg-CS beads were analyzed by DTA, FTIR, SEM, EDAX, TGA and XRD studies. Besides, FTIR and EDAX proved the affinity of HT-CeMOFs@Alg-CS cubic hybrid beads on fluoride was majorly attributed by electrostatic interaction, ion-exchange and complexation mechanism. To include detail insight into adsorption route; the kinetics, thermodynamic and isotherm studies were investigated for fluoride adsorption. The equilibrium data of HT-CeMOFs@Alg-CS cubic hybrid beads for fluoride adsorption was fitted with Langmuir isotherm model. Thermodynamic investigation results demonstrated that the fluoride adsorption was spontaneous with endothermic nature. The regeneration and field investigation results revealed that the developed HT-CeMOFs@Alg-CS cubic hybrid beads are reusable and more apt at field environment.

Rationally designed and hierarchically structured functionalized aluminium organic frameworks incorporated chitosan hybrid beads for defluoridation of water.

In this present investigation, aluminium (Al3+) fabricated 2-aminobenzene-1,4-dicarboxylic acid (ABDC) namely Al@ABDC metal organic frameworks (MOFs) was developed for defluoridation studies. The unique advantages of developed MOFs possess high selectivity, high porosity and enhanced surface area but the developed powder form of Al@ABDC MOFs has several limitations in field applications like slow filtration and column blockage. To prevail over these troubles, biopolymer namely chitosan (CS) supported Al@ABDC MOFs namely Al@ABDC-CS beads were developed for effective fluoride adsorption from water. The synthesized Al@ABDC-CS beads were employed for the retention of fluoride in batch level. The defluoridation capacities (DCs) of Al@ABDC MOFs and Al@ABDC-CS beads were found to be 4880 and 4900 mgF- kg-1 respectively. The influencing parameters of adsorption method namely agitation time, adsorbent dosage, initial fluoride concentration, pH, co-existing anions and temperature were exploit to get utmost defluoridation capacity (DC) of Al@ABDC-CS beads. The experimental data of Al@ABDC-CS beads have been evaluated utilizing Langmuir, Fruendlich and Dubinin-Radushkevich (D-R) isotherms. The defluoridation nature of Al@ABDC-CS beads was determined by the thermodynamic parameters. The order of reaction of Al@ABDC-CS beads was studied using various kinetic models. The regeneration and field water studies of Al@ABDC-CS beads were also carried out to check their reusability and suitability at field conditions.

Development of triaminotriazine functionalized graphene oxide capped chitosan porous composite beads for nutrients remediation towards water purification.

The porous, definite and nitrogen rich triaminotriazine (TAT) grafted graphene oxide (GO) known as TATGO composite was developed for nutrients (NO3- and PO43-) retention. Additionally, the structural property of TATGO composite was improved with the use of chitosan (CS) to produce easily separable TATGO@CS hybrid beads which possess the significant NO3- and PO43- adsorption capacities of 58.46 and 61.38 mg/g respectively than their individual materials. The instrumentations such as SEM, TGA, FTIR, EDAX, XRD and BET studies were executed for adsorbents. The optimization of the parameters accountable for adsorption process was performed in batch scale. The effect of isotherms (Langmuir, Freundlich and Dubinin-Radushkevich (D-R)), kinetics (pseudo-first/second order and particle/intraparticle diffusion) and thermodynamic parameters (ΔG°, ΔH° and ΔS°) of the adsorption was explored. The removal mechanism of TATGO@CS hybrid beads was to be electrostatic attraction on NO3- and PO43-. The field applicability and reuse of TATGO@CS hybrid beads was also inspected.

Development of chitosan encapsulated tricalcium phosphate biocomposite for fluoride retention.

The powder form of tricalcium phosphate (TCP) causes the significant pressure drop which limit its application under field conditions. To trounce such technological troubles and to enhance the defluoridation capacity (DC) of TCP, chitosan (CS) encapsulated TCP polymeric composite was prepared by dispersing TCP particles into chitosan polymeric matrix to produce tricalcium phosphate/chitosan (TCPCS) composite which could be made into any desirable form. The synthesized TCPCS composite possesses an enhanced DC of 1034 mgF-/kg than the individual components viz., TCP and chitosan which has got DC of 490 and 52 mgF-/kg respectively. The prepared adsorbents were characterized by FTIR, SEM and EDAX analysis. The various physico-chemical properties such as contact time, solution pH, co-anions and temperature were optimized to get maximum defluoridation. The equilibrium and kinetic experiments were conducted for TCPCS composite toward fluoride removal. The practical applicability of TCPCS composite was examined at field conditions.

Hydrothermal encapsulation of lanthanum oxide derived Aegle marmelos admixed chitosan bead system for nitrate and phosphate retention.

The potential of hydrothermal technology was utilized for the preparation of promising adsorbents in order to overcome the troubles of methemoglobinemia (blue baby syndrome) and eutrophication which is caused by excess nitrate (NO3-) and phosphate (PO43-) ions in water. Hence, in the present investigation, the chitosan (CS) encapsulated lanthanum oxide (La2O3) admixed Aegle marmelos(AM) (La2O3AM@CS) composite beads was prepared by both in situ precipitation (In situ) and hydrothermal (Hydro) methods for NO3- and PO43- adsorption. The hydro supported La2O3AM@CS composite beads hold an enhanced nitrate and phosphate sorption capacity (SC) of 27.84 and 34.91 mg/g than the other adsorbents prepared by in situ method. The characterization studies of the adsorbents such as FTIR, XRD, SEM and BET analysis were explored in detail. In batch scale, the adsorption affecting parameters such as contact time, pH, adsorbent dosage, initial adsorbate strength, competing anions and temperature was optimized. The fitted experimental data of various isotherms and thermodynamic parameters supports the feasible nature of NO3- and PO43- adsorption system. The field trial investigations and reuse of La2O3AM@CS composite beads were also executed.

Preparation and testing of a tetra-amine copper(II) chitosan bead system for enhanced phosphate remediation.

A tetra-amine copper(II) chitosan bead system (TAC@CS composite beads) was developed by grafting tetra-amine copper(II) (TAC) with chitosan (CS) and utilized for phosphate removal. The prepared TAC@CS composite beads possess enhanced phosphate sorption capacity (SC) of 41.42 ±â€¯0.071 mg/g than copper grafted chitosan (Cu@CS) composite, TAC and chitosan which were found to be 37.01 ±â€¯0.803, 33.20 ±â€¯0.650 and 7.24 ±â€¯0.059 mg/g respectively. In batch mode, various adsorption influencing parameters like contact time, initial phosphate concentration, solution pH, co-anions and temperature were optimized for maximum phosphate sorption. The prepared adsorbents were characterized by FTIR, XRD, UV-Visible, SEM and EDAX analysis. The adsorption isotherms and thermodynamic parameters of the adsorbent were studied. The feasible phosphate uptake mechanism of TAC@CS biocomposite beads was reported. The reusability studies of TAC@CS composite beads were carried out using NaOH as elutant. The suitability of TAC@CS composite beads at field conditions was tested with phosphate contaminated field water samples collected from nearby areas of Dindigul district.

Development of multivalent metal ions imprinted chitosan biocomposites for phosphate sorption.

In this present work, to overcome the problem of eutrophication due to phosphate an attempt was made to develop eco-friendly composite materials using chitosan and bentonite. To improve the properties of bentonite (bent) and chitosan (CS), chitosan supported bentonite (CSBent) composites were prepared and utilized for phosphate removal. To enhance the uptake capacity of CSBent, various multivalent metal ions like Zr4+, Fe3+ and Ca2+ were imprinted on CSBent composites namely Zr@CSBent, Fe@CSBent and Ca@CSBent biocomposites respectively. The synthesized Zr@CSBent, Fe@CSBent and Ca@CSBent biocomposites possess the efficient phosphate sorption capacities (SCs) of 40.86, 22.15 and 13.44mg/g than the individual CSBent composite. The systematic study for various adsorption influenced parameters such as agitation time, presence of co-existent anions, solution pH, temperature and initial phosphate concentration has been verified in batch mode. The prepared biocomposites was exemplified by FTIR, TEM, SEM and EDAX analysis. The experimental data was fitted to various isotherms and thermodynamic parameters. The mechanism of phosphate removal by M@CSBent composites was governed by ion-exchange, electrostatic attraction and inner sphere complexation. This study reveals a feasibility of biocomposites for phosphate uptake from polluted water sample at field situation.