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.

Defluoridation using hydroxyapatite implanted lanthanum organic framework-based bio-hybrid beads

The present study reports on biopolymer based material namely HAp–La-BTC MOFs@Alg–CS hybrid beads were developed and it was potentially employed for fluoride removal.

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.