Kinetic Studies on Fluoride Removal by Calcined Layered Double Hydroxides

Lv, Liang; He, Jing; Wei, and Min; Duan, Xue

doi:10.1021/ie050363d

Cited by 86 publications

(52 citation statements)

References 33 publications

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“…By example, Barboza et al [5] and [12] reported values of the Biot in the range of 30 ~ 50 for the adsorption of CA into synthetic resin Amberlit IRA 400. Other authors have related Bi 100 with external mass transfer resistance as a limiting step [17,18]. In this present work, the calculated Biot values were very low (< 1.0) for all the adsorbents.…”

Section: Model Parameters and Mass Transfer Resistancescontrasting

confidence: 40%

“…It is known that increasing the amount of solids in the reactor increased the productivity of the process since there was a decrease in equilibrium time, mainly due to the contact surface of the adsorbent [18]. However, this confirmation is important, since there are cases where the increase in the amount of solids causes a decrease in the adsorption capacity [19].…”

Section: Applicability Of Nax Zeolite To Recovery Clavulanic Acidmentioning

confidence: 99%

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Evaluation of kinetic and mass transfer parameters for adsorption of clavulanic acid into natural and synthetic zeolites

Forte

Mazutti

Filho

et al. 2011

Biotechnol Bioproc E

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This work investigates the adsorption of clavulanic acid using natural six cationic forms (Na + , Ca +2 , Ba +2 , Sr 2+ , K + , and Mg 2+ ) of the X and NZ zeolites in a stirred tank reactor since the separation is an important step of the biomolecule production. A mathematical model was proposed taking into account the transport of CA molecules from the liquid phase to the surface of the adsorbent and after diffusion into the particles. The estimated kinetic and mass transfer parameters were used to evaluate adsorption rates and mass transfer resistances involved in the separation of clavulanic acid from the broth. It has been shown that mass-transfer phenomena were a limiting step in the clavulanic acid adsorption process and that the adsorption rate should be considered to evaluate the system. Amongst the materials, the synthetic zeolite NaX was selected as the most appropriate material to separate clavulanic acid because this material presented the highest values for the observed reaction rate, compensating for the external mass transfer resistance. Modeling and simulation of clavulanic acid purification using the zeolite NaX showed a satisfactory fitting of experimental data. The model was used to simulate the process and it was evaluated for its technical and economical viability by comparisons considering the influence of the solid:liquid ratio on the adsorption equilibrium time and on the hydrolysed mass of biomolecule.

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Section: Model Parameters and Mass Transfer Resistancescontrasting

confidence: 40%

Section: Applicability Of Nax Zeolite To Recovery Clavulanic Acidmentioning

confidence: 99%

Evaluation of kinetic and mass transfer parameters for adsorption of clavulanic acid into natural and synthetic zeolites

Forte

Mazutti

Filho

et al. 2011

Biotechnol Bioproc E

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“…Layered double hydroxides (LDHs) are widely used for catalysis and sorption and are sinks for the mineralization of insidious anions such as chromates [2,3], selenates [4], fluorides [5], radioactive anions [6], and various organic pollutants [7]. LDHs exhibit anion exchange properties, which make them candidate materials for the immobilization of arsenate in the interlayer region of the LDHs.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of arsenate-intercalated layered double hydroxides (LDHs): Prospects for arsenic mineralization

Prasanna

Kamath

2009

Journal of Colloid and Interface Science

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The arsenate-intercalated layered double hydroxide (LDH) of Mg and Al is synthesized by coprecipitation. The higher thermodynamic stability and the consequent lower solubility of the unitary arsenates preclude the formation of arsenate-intercalated LDHs of other metals directly from solution. However other M/AlAsO 4 (M = Co, Ni, Zn) LDHs could be prepared by anion exchange, showing that arsenate intercalation proceeds topotactically. The intercalation of various species of As(V) into the interlayer of LDHs and the subsequent arsenate carrying capacity are dependent upon the pH of the solution. Upon thermal decomposition, the intercalated arsenate ion undergoes reductive deintercalation to give a mixture of As(III) and As(V) oxides. The product oxides revert back to the LDH upon soaking in water on account of the compositional and morphological metastability of the former. This is in contrast with the phosphateintercalated LDHs, in which the reversibility is suppressed, consequent to the formation of stable metal phosphates.

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“…They have recently received increasing attention, owing to their versatility and usefulness in a wide range of technological applications such as adsorbents, 8 functional materials, 9 twodimensional solid-state nanoreactors, 10 bioactive nanocomposites, 11 and so on. LDHs can be represented by the general formula [M 2+ 1-x M 3+…”

Section: Introductionmentioning

confidence: 99%

Controllable Nanocage Structure Derived from Cyclodextrin-Intercalated Layered Double Hydroxides and Its Inclusion Properties for Dodecylbenzene

et al. 2008

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A novel nanocage structure derived from carboxymethyl--cyclodextrins (CMCDs) intercalated in layered double hydroxides (LDHs), whose gates can be controlled by the process of swelling/drying the CMCD-LDH, has been prepared. Furthermore, the extent of opening of this nanocage structure can be controlled by swelling in different solvents. Dodecylbenzene (DDB) as the guest molecule has been incorporated into the nanocage structure through two different routes: intercalation of CMCD in the LDH followed by inclusion of DDB (intercalation-inclusion method) and inclusion of DDB in CMCD followed by intercalation of the host-guest complex into the LDH (inclusion-intercalation method). For the convenience of using this nanocage as an absorbent and storage vessel for neutral guest, films of the resulting composite materials (CMCD-LDH) were fabricated by the method of solvent evaporation on glass substrates. The structures, chemical compositions, morphologies, and physicochemical properties of the materials were fully studied. Moreover, the effects of the combined confinement of both the LDH layers and the cyclodextrin cavity on the encaged guest were investigated. Compared with the confinement effect produced by cyclodextrin only, this double-confinement imposes stronger restrictions on the mobility of the guest molecule, which leads to a blue shift of the fluorescence spectrum and increases the decay time of the guest. Therefore, this structured nanocage might have potential applications as adsorbents, synergistic agents, and storage vessels for neutral molecules.

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Kinetic Studies on Fluoride Removal by Calcined Layered Double Hydroxides

Cited by 86 publications

References 33 publications

Evaluation of kinetic and mass transfer parameters for adsorption of clavulanic acid into natural and synthetic zeolites

Evaluation of kinetic and mass transfer parameters for adsorption of clavulanic acid into natural and synthetic zeolites

Synthesis and characterization of arsenate-intercalated layered double hydroxides (LDHs): Prospects for arsenic mineralization

Controllable Nanocage Structure Derived from Cyclodextrin-Intercalated Layered Double Hydroxides and Its Inclusion Properties for Dodecylbenzene

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