Zeolites and related mesoporous materials for multi-talented environmental solutions

Perego, Carlo; Bagatin, Roberto; Tagliabue, Marco; Vignola, Rodolfo

doi:10.1016/j.micromeso.2012.04.048

Cited by 111 publications

(54 citation statements)

References 124 publications

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“…With fouling/performance design, fundamental understandings of the diffusion mechanisms coupled with heat and mass transfer has unlocked the critical science needed to select optimal operating conditions, membrane materials and module designs that ultimately give better flux performance for the same operational conditions [52,53,127]. Fouling of membranes has explored scaling issues for the classic applications in brine concentration [72,128], and the more novel application in dairy processing [129]. While this research progresses to uncover further fundamental improvements, the focus here is on the novel process configurations that address the performance limitations defined in Section 2.1.…”

Section: State Of the Art MD Research And Systemsmentioning

confidence: 99%

Advances in Membrane Distillation for Water Desalination and Purification Applications

Camacho

Dumée

Zhang

et al. 2013

Water

642

342

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Membrane distillation is a process that utilizes differences in vapor pressure to permeate water through a macro-porous membrane and reject other non-volatile constituents present in the influent water. This review considers the fundamental heat and mass transfer processes in membrane distillation, recent advances in membrane technology, module configurations, and the applications and economics of membrane distillation, and identifies areas that may lead to technological improvements in membrane distillation as well as the application characteristics required for commercial deployment. Keywordsa function of temperature, vapor pressure, and of the gas molecular mass K 0 membrane characteristic defined by Equation (9) Kn Knudsen number K(T) a function of temperature and molecular weight of the gas l mean free path of the molecules l m distance between parallel spacer fibres (m) LEP Limit Entry Pressure (kPa) M molecular mass (g/mol) M w molecular weights of water (g/mol) M a molecular weights of air (g/mol) n number of CNTs per unit cross section in bucky-paper P pressure in the air gap (kPa) half time to reach the maximum intensity-laser flash technique (s) t proportion of conductive heat (balance due to evaporative heat) loss through the membrane T mean temperature in the pores (K)

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Section: State Of the Art MD Research And Systemsmentioning

confidence: 99%

Advances in Membrane Distillation for Water Desalination and Purification Applications

Camacho

Dumée

Zhang

et al. 2013

Water

642

342

View full text Add to dashboard Cite

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“…The main advantages are related to their high surface area and porous structure, high specific capacity and organic pollutants selectivity. Additionally, fast kinetics, mechanical, biological and chemical stability make them promising and efficient adsorbents [4,[6][7][8][26][27][28]. Furthermore, their high thermal stability guarantees the possibility of regeneration through thermal treatments in order to reintroduce them in new adsorption processes [5,[29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Insights into Adsorption of Chlorobenzene in High Silica MFI and FAU Zeolites Gained from Chromatographic and Diffractometric Techniques

et al. 2018

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Abstract:In this work, the capability of two commercial high silica zeolites (HSZs), namely ZSM-5 and Y, for the removal of chlorobenzene (CB) from water was investigated by combining chromatographic and diffractometric techniques. The adsorption isotherms and kinetics of CB on ZSM-5 and Y zeolites were determined from batch tests. The adsorption kinetics were very fast; the time to reach equilibrium was less than 10 min. The equilibrium data of CB on the two HSZs showed dissimilarities that are particularly evident in the adsorption data concerning the low concentration range, where Y zeolite is characterized by low adsorption. On the contrary, at higher solution concentrations the adsorption capacity of Y is higher than that of ZSM-5. The crystalline structures of Y and ZSM-5 saturated with CB were investigated by X-ray diffraction (XRD) techniques. Rietveld refinement analyses of XRD data allowed for quantitative probing of the structural modifications of both zeolites after CB adsorption and provided insight into the preferred zeolite adsorption sites in both microporous materials. The refined framework-extraframework bond distances confirm that interactions between the selected organic contaminant and hydrophobic zeolites are mediated via co-adsorbed H 2 O. The occurrence of H 2 O-CB-framework oxygen oligomers explains variations in both the unit cell parameters and the shape of the channels, clearly confirming that water plays a very relevant role in controlling the diffusion and adsorption processes in hydrophobic zeolites.

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“…addition of oxides of lanthanides, aluminium or zirconium) has been cited as a possible way to improve natural zeolite removal efficiency. Two mechanisms have been inferred for fluoride sorption: hydroxide/fluoride exchange (due to steric and electrostatic similarities between these anions) [61] and fluoride occlusion [79]. …”

mentioning

confidence: 99%

Natural Zeolites in Water Treatment – How Effective is Their Use

Margeta¹,

Logar²,

Šiljeg³

et al. 2013

Water Treatment

171

150

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Additional information is available at the end of the chapter http://dx.doi.org/10.5772/50738 IntroductionNatural zeolites are environmentally and economically acceptable hydrated aluminosilicate materials with exceptional ion-exchange and sorption properties. Their effectiveness in different technological processes depends on their physical-chemical properties that are tightly connected to their geological deposits. The unique treedimensional porous structure gives natural zeolites various application possibilities. Because of the excess of the negative charge on the surface of zeolite, which results from isomorphic replacement of silicon by aluminum in the primary structural units, natural zeolites belong to the group of cationic exchangers. Numerous studies so far have confirmed their excellent performance on the removal of metal cations from wastewaters. However, zeolites can be chemically modified by inorganic salts or organic surfactants, which are adsorbed on the surface and lead to the generation of positively charged oxihydroxides or surfactant micelles, and which enables the zeolite to bind also anions, like arsenates or chromates, in stable or less stable complexes. Natural zeolites have advantages over other cation exchange materials such as commonly used organic resins, because they are cheap, they exhibit excellent selectivity for different cations at low temperatures, which is accompanied with a release of non-toxic exchangeable cations (K + , Na + , Ca 2+ and Mg 2+ ) to the environment, they are compact in size and they allow simple and cheap maintenance in the full-scale applications. The efficiency of water treatment by using natural and modified zeolites depends on the type and quantity of the used zeolite, the size distribution of zeolite particles, the initial concentration of contaminants (cation/anion), pH value of solution, ionic strength of solution, temperature, pressure, contact time of system zeolite/solution and the presence of other organic compounds and anions. For water treatment with natural zeolites, standard procedures are used, usually a procedure in column or batch process. Ion exchange and adsorption properties of natural zeolites in comparison with other chemical and biological processes have the advantage of Water Treatment 82removing impurities also at relatively low concentrations and allows conservation of water chemistry, if the treatment is carried out in the column process [1]. Subject of further academic and industrial research should be to improve the chemical and physical stability of modified zeolites and to explore their catalytic properties, which would allow their use in catalytic degradation of organic pollutants. More careful consideration of their superb metal removal properties and awareness of possible regeneration or further use of contaminant/metal-loaded forms can considerably increase their environmental application possibilities, with a focus the reduction of high concentrations of cations and anions in drinking water and wastewater, for surface, und...

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Zeolites and related mesoporous materials for multi-talented environmental solutions

Cited by 111 publications

References 124 publications

Advances in Membrane Distillation for Water Desalination and Purification Applications

Advances in Membrane Distillation for Water Desalination and Purification Applications

Insights into Adsorption of Chlorobenzene in High Silica MFI and FAU Zeolites Gained from Chromatographic and Diffractometric Techniques

Natural Zeolites in Water Treatment – How Effective is Their Use

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