RESUMO
Fluorosis disease can be prevented by the defluoridated water. Hence, the present work focused on the fabrication of hybrid materials using graphene oxide (GO) and Ce-based metal organic frameworks namely cerium fumarate (Ce-Fu) which gives GO/Ce-Fu for defluoridation of water. Further, the powdered GO/Ce-Fu was dispersed with alginate (Alg) and chitosan (CS) biopolymeric matrixes to give GO/Ce-Fu/Alg-CS biopolymeric hybrid beads for defluoridation investigations. The developed GO/Ce-Fu and GO/Ce-Fu/Alg-CS beads have defluoridation capacities (DCs) of 4.410 and 4.753 mg/g within 30 min. The fabricated GO/Ce-Fu and GO/Ce-Fu/Alg-CS beads were analyzed by XRD, FTIR, TGA, BET, SEM and EDAX studies. The performance of fluoride adsorption influencing parameters such as dosage, contact time, solution pH, interfering anions and temperature studies were optimized with batch scale. Thermodynamic, adsorption isotherms and kinetic studies were carried out using hybrid materials to find the nature and order of fluoride adsorption. The fluoride adsorption mechanism of GO/Ce-Fu and GO/Ce-Fu/Alg-CS beads was investigated. The performance of recyclability of the hybrid materials was examined. In addition, the field studies of hybrid materials were also explored to identify their field suitability nature.
Assuntos
Alginatos , Quitosana , Fluoretos , Grafite , Quitosana/química , Grafite/química , Alginatos/química , Fluoretos/química , Adsorção , Estruturas Metalorgânicas/química , Cinética , Biopolímeros/química , Concentração de Íons de Hidrogênio , Metais Terras Raras/química , Termodinâmica , Purificação da Água/métodos , TemperaturaRESUMO
Hexavalent chromium is an emerging environmental pollutant that leads to various effects on living organisms. The developed clay material, hydrocalumite (HC) possesses promising chromium adsorption capacity but because of its powder form it cannot be used in column studies. Hence, it is aimed to prepared HC in an usable hybrid bio-composite form by dispersing HC in biopolymeric matrixes like chitosan (CS) and cellulose (Cel) as HCCS and HCCel bio-composites for Cr(VI) removal from water. For quick separation after adsorption, the magnetic particles sprayed HCCS (Fe3O4@HCCS) and HCCel (Fe3O4@HCCel) bio-composites were prepared which possess high adsorption capacity. Different instrumental techniques like FTIR, SEM, and EDAX studies were used to examine the synthesized magnetic bio-composites in order to determine their physicochemical properties. The promising adsorbents namely Fe3O4@HCCS and Fe3O4@HCCel bio-composites were examined for Cr(VI) removal in batch mode. The maximum chromium adsorption capacity of Fe3O4@HCCS and Fe3O4@HCCel bio-composites were found at 43.4 mg/L and 31.8 mg/L, respectively within 45 min. The Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherms were used to reinterpret the equilibrium data of the synthetic magnetic bio-composites. According to the thermodynamic findings, chromium adsorption onto magnetic bio-composites is an endothermic and spontaneous reaction. The NaOH solution makes it simple to regenerate the chromium adsorbed magnetic bio-composites, which can be successfully employed upto four times. The synthesized Fe3O4@HCCS and Fe3O4@HCCel bio-composites act as efficient adsorbents for chromium removal.
Assuntos
Poluentes Químicos da Água , Purificação da Água , Purificação da Água/métodos , Concentração de Íons de Hidrogênio , Cinética , Cromo/química , Adsorção , Fenômenos Magnéticos , Poluentes Químicos da Água/análiseRESUMO
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.
Assuntos
Cério , Quitosana , Poluentes Químicos da Água , Fluoretos , Adsorção , Biopolímeros , Termodinâmica , Concentração de Íons de Hidrogênio , CinéticaRESUMO
The template preparation of hydroxyapatit (HAp) layered lanthanum-benzene tricarboxylic acid based metal organic frameworks (La-BTC MOFs) abbreviated as HAp-La-BTC-MOFs has been investigated here for defluoridation of water. The nucleation and growth of La-based MOFs was carried out in the prepared HAp hard template using layer-by-layer (LBL) technique. The coulomb and chelation contacts on HAp surface between Ca2+ ions and COO- organic ligands of La-BTC MOFs play vital roles in the preparation process. The batch experiments were employed to assess the defluoridation capacity (DC) of HAp-La based MOFs. The physicochemical properties of HAp-La based MOFs were investigated by various instrumentation techniques. To identify the nature, order and feasibility of HAp-La based MOFs towards defluoridation was examined by adsorption kinetics, isotherms and thermodynamics studies. The mechanism of defluoridation using HAp-La based MOFs were explained in detail. The field and reusability investigations of HAp-La-BTC MOFs also explored to find the potential applicability.
Assuntos
Durapatita , Estruturas Metalorgânicas , Adsorção , Durapatita/química , Lantânio/química , Estruturas Metalorgânicas/química , Termodinâmica , Água/químicaRESUMO
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.
Assuntos
Quitosana , Estruturas Metalorgânicas , Poluentes Químicos da Água , Adsorção , Alumínio , Fluoretos , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica , ÁguaRESUMO
The promising adsorbent like graphene oxide (GO), chitosan (CS) and amine functionalized graphene oxide (AGO) decorated chitosan (CS) namely AGO@CS composite beads was efficiently prepared for defluoridation studies. The prepared AGO@CS composite beads possess enriched defluoridation capacity (DC) of 4650 mgF- kg-1. Batch method was used to optimize the maximum DC of AGO@CS composite beads. The physicochemical properties of AGO@CS composite beads were explored by numerous instrumental techniques viz., FTIR, Raman, XPS, SEM and TGA investigation. The experimental values of AGO@CS composite beads for fluoride removal at various temperature conditions were assessed with adsorption isotherms, kinetic and thermodynamic studies. The possible defluoridation mechanism of AGO@CS beads was mostly proposed that electrostatic attraction. The reusability and field investigation results of AGO@CS beads shows they are regenerable and applicable at field circumstances.
Assuntos
Aminas/química , Quitosana/síntese química , Fluoretos/isolamento & purificação , Grafite/síntese química , Microesferas , Poluentes Químicos da Água/isolamento & purificação , Água/química , Adsorção , Quitosana/química , Grafite/química , Concentração de Íons de Hidrogênio , Íons , Cinética , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Temperatura , Termogravimetria , Fatores de TempoRESUMO
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.
Assuntos
Quitosana/química , Grafite/química , Microesferas , Nutrientes , Triazinas/química , Poluentes Químicos da Água , Purificação da Água/instrumentação , Adsorção , Técnicas de Química Analítica , Relação Dose-Resposta a Droga , Composição de Medicamentos , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Nitritos , Fosfatos , Porosidade , Termodinâmica , Águas Residuárias/análise , Purificação da Água/economiaRESUMO
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 1034â¯mgF-/kg than the individual components viz., TCP and chitosan which has got DC of 490 and 52â¯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.
Assuntos
Fosfatos de Cálcio/química , Quitosana/química , Fluoretos/química , Fluoretos/isolamento & purificação , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica , Purificação da ÁguaRESUMO
Recently, nanomaterials based adsorbents play a prominent role in the removal of toxic ions from aqueous solution. Hence in the present study, nano-graphene oxide (n-GO) fabricated hydrotalcite (n-GO@HT) composite was prepared by hydrothermal method for chromium removal. To improve the mechanical strength and chromium removal capacity, GO@HT composite was reinforced with chitosan (CS) to form hybrid composite namely n-GO@HTCS biocomposite. The synthesized biocomposite was characterized using various instrumental techniques like FTIR, SEM, TEM and EDAX with mapping analysis. To get the maximum chromium retention, the various sorption experiments like agitation time, dosage, pH, competing ions and temperature were optimized. The sorption capacity (SC) of n-GO@HTCS biocomposite was found to be 42.64â¯mg/g within 50â¯min. The obtained equilibrium data was explained with Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms wherein the chromium sorption process was best fitted with Langmuir isotherm. The thermodynamic results prove that the chromium sorption of n-GO@HTCS biocomposite was endothermic and spontaneous. The chromium sorbed n-GO@HTCS biocomposite could be easily regenerated with 0.1â¯M NaOH. The synthesized n-GO@HTCS biocomposite was also utilized in the field conditions.
Assuntos
Hidróxido de Alumínio/química , Quitosana/química , Cromo/química , Cromo/isolamento & purificação , Grafite/química , Hidróxido de Magnésio/química , Nanocompostos/química , Óxidos/química , Adsorção , Concentração de Íons de Hidrogênio , Resíduos Industriais/análise , Temperatura , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da ÁguaRESUMO
A magnetic adsorbent namely magnetic iron oxide encrusted hydrocalumite-chitosan (Fe3O4@HCCS) composite was prepared by the fabrication of magnetic iron oxide (Fe3O4) particles on hydrocalumite-chitosan (HCCS) composite for fluoride sorption studies in batch mode. The prepared magnetic Fe3O4@HCCS composite possesses an enhanced defluoridation capacity (DC) of 6.8mg/g compared to hydrocalumite (HC) which possesses the DC of 2.4mg/g. The various physico-chemical parameters such as contact time, pH, co-existing anions, initial fluoride concentration and temperature were optimized for the maximum fluoride removal. The structural changes of the sorbent, before and after fluoride sorption were studied using FTIR and SEM with EDAX techniques. The equilibrium data was well modeled by Freundlich and Langmuir isotherms. The thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of fluoride sorption. The field performance and efficiency of Fe3O4@HCCS composite was examined with the waste-water sample collected from a fluoride endemic area of Dindigul district, Tamilnadu, India using standard protocols.
Assuntos
Óxido de Alumínio/química , Cloreto de Cálcio/química , Quitosana/química , Fluoretos/isolamento & purificação , Nanopartículas de Magnetita/química , Nanocompostos/química , Temperatura , Purificação da Água/métodos , Adsorção , Técnicas de Química Sintética , Fluoretos/química , Concentração de Íons de Hidrogênio , Cinética , Nanotecnologia , Termodinâmica , Águas Residuárias/químicaRESUMO
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 34.91â¯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.
Assuntos
Aegle/química , Quitosana , Lantânio , Nitratos , Óxidos , Fosfatos , Adsorção , Quitosana/química , Concentração de Íons de Hidrogênio , Íons , Lantânio/química , Nanocompostos/química , Nanocompostos/ultraestrutura , Nitratos/química , Óxidos/química , Fosfatos/química , Análise Espectral , Temperatura , TermodinâmicaRESUMO
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¯0.071â¯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¯0.059â¯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.
RESUMO
The present study was focused on Cr(VI) removal using eco-friendly materials like cellulose (Cel), hydrotalcite (HT), hydroxyapatite (HAp) and their composite forms. The cellulose/hydrotalcite (CelHT) and cellulose/hydroxyapatite (CelHAp) composites were synthesized by dispersing HT and HAp individually in cellulose polymeric matrix. To enhance the Cr(VI) sorption capacity (SC) and easy separation, cellulose supported magnetic composites namely iron-oxide coated cellulose/hydrotalcite (Fe3O4@CelHT) and cellulose/hydroxyapatite (Fe3O4@CelHAp) were synthesized by in situ fabrication method. The different adsorption influencing parameters like contact time, pH, co-ions, dosage, initial Cr(VI) concentration and temperature were optimized for maximum Cr(VI) sorption. The structure and morphology of cellulose supported magnetic composites were analyzed using FTIR, BET and SEM with EDAX analysis. The obtained equilibrium value was interpreted with Freundlich and Langmuir isotherms. The suitable Cr(VI) uptake mechanism for cellulose supported magnetic composites was demonstrated. The values of thermodynamic parameters helps in the prediction of nature of Cr(VI) sorption process. The suitability of these magnetic cellulose supported composites was tested at field conditions by collecting chromium contaminated water.
RESUMO
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.
Assuntos
Quitosana/química , Metais/química , Fosfatos/química , Adsorção , Concentração de Íons de Hidrogênio , Água/químicaRESUMO
The present study was performed to examine the probability of magnetic iron oxide fabricated hydrotalcite/chitosan (Fe3O4@HTCS) composite for the removal of excess fluoride content from drinking water. The developed Fe3O4@HTCS composite not only demonstrate the good separation ability but also display an extreme enhanced defluoridation capacity (DC) when compared to other base components and composite. The DCs of Fe3O4@HTCS composite, Fe3O4@HT composite, Fe3O4, HT and CS was found to be 5032, 3041, 1050, 1030 and 52mgF-/kg respectively. The structure and morphology of the prepared adsorbent and fluoride sorbed adsorbent was analysed using FTIR, SEM and EDAX with mapping techniques. The dependence of DC on various parameters like initial fluoride concentration, pH, contact time, interfering anions and temperature was studied by batch method. From isotherm modeling, the equilibrium data is well described by Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Thermodynamic parameters confirm the spontaneity and endothermic nature of the fluoride adsorption. The performance of Fe3O4@HTCS composite to field water sample designates its adaptable nature at field conditions.
Assuntos
Hidróxido de Alumínio/química , Quitosana/química , Água Potável/química , Óxido Ferroso-Férrico/química , Fluoretos/química , Fluoretos/isolamento & purificação , Hidróxido de Magnésio/química , Purificação da Água/métodos , Adsorção , Cinética , TermodinâmicaRESUMO
Biocomposites were synthesized by dispersing bentonite (Bent) clay in a biopolymer namely alginate (Alg) and cross-linked with bi (Ca(2+)), tri (Ce(3+)) and tetravalent (Zr(4+)) metal ions viz., Ca@AlgBent, Ce@AlgBent and Zr@AlgBent composites respectively. The synthesized biocomposites were characterized by various instrumental techniques like FTIR, SEM and EDAX. Cr(VI) sorption capacities (SCs) of the biocomposites Ca@AlgBent, Ce@AlgBent and Zr@AlgBent were examined by batch process. Various adsorption influencing factors viz., contact time, dosage of the sorbent, pH of the medium, temperature, presence of common co-ions and initial Cr(VI) concentration were studied. Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherm models were adopted to examine the adsorption equilibrium. Kinetics of the sorption process was carried out by pseudo-first-order and pseudo-second-order models. The nature of the sorption process was explained using thermodynamic parameters like ΔS°, ΔG° and ΔH° and a possible mechanism for the sorption of Cr(VI) onto the biocomposites was given. The application of the biocomposites at field conditions was also examined by testing it with industrial water. The regeneration studies were carried to know about the reusability of the biocomposites.
Assuntos
Alginatos/química , Bentonita/química , Cromo/química , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Adsorção , Técnicas de Química Sintética , Cromo/isolamento & purificação , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Cinética , TermodinâmicaRESUMO
Biopolymers are widely used for the removal of chromium from aqueous medium but it possesses limitations like poor sorption capacity and low stability. To overcome the limitations of biopolymers and to improve their properties, the present study was designed in such a way to develop a novel sorbent with enhanced chromium sorption capacity and better stability by synthesizing metal ion cross-linked binary biocomposites using biopolymers like alginate and gelatin cross-linked with Ca2+, Ce3+ and Zr4+ ions namely Ca@AlgGel, Ce@AlgGel and Zr@AlgGel composites. The functional groups, agglomeration, surface area, surface morphology, elemental analysis and thermal stability of the composites were investigated by FTIR, TEM, BET, SEM with EDAX and TGA analysis. The chromium removal studies of the biocomposites were carried out in batch mode. The sorption process was optimized by varying the influencing aspects like contact time, dosage, presence of common ions, pH, initial chromium concentration and temperature. The maximum sorption capacity of Ca@AlgGel, Ce@AlgGel and Zr@AlgGel composites were found to be 19.40, 24.50 and 25.40 mg/g, respectively. The sorption data was fitted by using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Thermodynamic parameters indicate the nature of chromium sorption. The suitability of the composite materials was also tested under the field conditions.
Assuntos
Alginatos/química , Alginatos/síntese química , Cromo/química , Cromo/isolamento & purificação , Poluentes Ambientais/química , Poluentes Ambientais/isolamento & purificação , Gelatina/química , Adsorção , Técnicas de Química Sintética , Ácido Glucurônico/síntese química , Ácido Glucurônico/química , Ácidos Hexurônicos/síntese química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Temperatura , TermodinâmicaRESUMO
Adsorption is a significant reaction occurs between adsorbent/water interface for controlling the pollutants in the aqueous environment. In this regard, an eco-magnetic biosorbent was prepared by uniform deposition of magnetic Fe3O4 particles on the surface of nano-hydroxyapatite (n-HAp)/chitosan (CS) nanocomposite namely Fe3O4@n-HApCS composite as versatile sorbent for fluoride sorption. The resulting Fe3O4@n-HApCS nanocomposite was characterized by FTIR and SEM with EDAX techniques. The defluoridation capacity (DC) was found to depend on the contact time, pH, co-existing anions, initial fluoride concentration and temperature. The sorption isotherm was investigated by Freundlich, Langmuir and Temkin isotherm models using the batch method. The thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of fluoride sorption. The results of this research work designated that Fe3O4@n-HApCS composite having the excellent defluoridation capacity than the individual components and interesting to note that the easy magnetic separation of Fe3O4@n-HApCS composite from aqueous medium.
Assuntos
Quitosana/química , Durapatita/química , Fluoretos/química , Fluoretos/isolamento & purificação , Nanopartículas de Magnetita/química , Nanocompostos/química , Adsorção , Técnicas de Química Sintética , Cinética , Termodinâmica , Água/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
In this research study, a new magnetic biosorbent was developed by the fabrication of magnetic Fe3O4 particles on nano-hydroxyapatite(n-HAp)/alginate (Alg) composite (Fe3O4@n-HApAlg composite) for defluoridation in batch mode. The synthesized Fe3O4@n-HApAlg biocomposite possess an enhanced defluoridation capacity (DC) of 4050 mgF(-)/kg when compare to n-HApAlg composite, Fe3O4@n-HAp composite, n-HAp and Fe3O4 which possesses the DCs of 3870, 2469, 1296 and 1050 mgF(-)/kg respectively. The structural changes of the sorbent, before and after fluoride sorption were studied using FTIR, XRD and SEM with EDAX techniques. There are various physico-chemical parameters such as contact time, pH, co-existing anions, initial fluoride concentration and temperature were optimized for maximum fluoride removal. The equilibrium data was well modeled by Freundlich, Langmuir, Dubinin-Radushkevich (D-R) and Temkin isotherms. The present system follows Dubinin-Radushkevich isotherm model. The thermodynamic parameters reveals that the feasibility, spontaneity and endothermic nature of fluoride sorption. The performance and efficiency of the adsorbent material was examined with water samples collected from fluoride endemic areas namely Reddiyarchatram and Ammapatti in Dindigul District of Tamil Nadu using standard protocols.
Assuntos
Alginatos/química , Fracionamento Químico/métodos , Durapatita/química , Fluoretos/química , Nanopartículas de Magnetita/química , Nanocompostos/química , Adsorção , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica , Água/químicaRESUMO
This article enlightens the synthesis of carboxylated alginic acid (CAA) and metal ions coordinated CAA (M-CAA) for defluoridation studies in batch mode. The oxidation of alginic acid (AA) with KMnO4 gives CAA and the metal coordination was enabled in CAA by using high valence metal ions viz., La(3+) (La-CAA) and Zr(4+) (Zr-CAA). The synthesized materials Zr-CAA, La-CAA and CAA possess the defluoridation capacities (DCs) of 4064, 3137 and 880 mgF(-)/kg respectively. An enhanced DC was observed for metal-coordinated CAA (M-CAA) than CAA. The defluoridation experiments were carried with numerous influencing parameters like contact time, pH and competitor anions for optimization. The characterization of materials was carried out using FTIR, EDAX and SEM analysis. The sorption data was fitted with various isotherms and kinetic models. The values of thermodynamic parameters indicate the nature of fluoride removal is spontaneous and endothermic. At field conditions, M-CAA reduce the fluoride concentration below the tolerance limit.