Structure investigation of As(III)- and As(V)-species bound to Fe-modified clinoptilolite tuffs

Šiljeg, Mario; Stefanović, Štefica Cerjan; Mazaj, Matjaž; Tušar, Nataša Novak; Arčon, Iztok; Kovač, Janez; Margeta, Karmen; Kaučič, Venceslav; Logar, Nataša Zabukovec

doi:10.1016/j.micromeso.2008.09.009

Cited by 40 publications

(32 citation statements)

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“…Chemical modification with inorganic salts (NaCl, CaCl2, BaCl2, NH4Cl, FeCl3) or a cationic surfactant (hexsadecyltri-methylammonium (HDTMA) -bromide) give to improve zeolite properties and increase its efficiency in water treatment [19,[31][32][33][34][35][36][37][38]. For successful modification high-concentration solutions of inorganic salts on the surface of zeolite is significant as shown in Figure 6.…”

Section: Modification With Solution Of Inorganic Saltsmentioning

confidence: 99%

Natural Zeolites in Water Treatment – How Effective is Their Use

Margeta¹,

Logar²,

Šiljeg³

et al. 2013

Water Treatment

168

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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Section: Modification With Solution Of Inorganic Saltsmentioning

confidence: 99%

Natural Zeolites in Water Treatment – How Effective is Their Use

Margeta¹,

Logar²,

Šiljeg³

et al. 2013

Water Treatment

168

150

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“…Suggested sorbents have included, for example, activated carbon [13], fly ash [14], limestone 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 efficiency in water treatment [47][48][49]. In the present study, a similar approach was applied for 21 geopolymer modification.…”

mentioning

confidence: 99%

“…In the present study, a similar approach was applied for 21 geopolymer modification. In the case of anion removal, the modification has been reported to for 22 example create an oxi-hydroxide adsorption layer on the surface and change the surface charge (from 23 negative to positive) [49,50]. These changes allow to form stable complexes with anions in solution.…”

mentioning

confidence: 99%

Sulphate removal over barium-modified blast-furnace-slag geopolymer

Runtti

Luukkonen

Niskanen

et al. 2016

Journal of Hazardous Materials

122

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16Blast-furnace slag and metakaolin were geopolymerised, modified with barium or treated with a 17 combination of these methods in order to obtain an efficient SO 4 2-sorbent for mine water treatment. 18Of prepared materials, barium-modified blast-furnace slag geopolymer (Ba-BFS-GP) exhibited the 19 highest SO 4 2-maximum sorption capacity (up to 119 mg g -1 ) and it compared also favourably to 20 materials reported in the literature. Therefore, Ba-BFS-GP was selected for further studies and the 21 factors affecting to the sorption efficiency were assessed. Several isotherms were applied to describe

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“…Incorporating our results from the XRD, SEM, and FT-IR analyses and the related literature, 22,26,45 it can be proposed that Fe 3+ ions inside the zeolites can be in different forms as follows: iron atoms could substitute in the framework, they can be at ion-exchange positions in the form of oxygen-bridged binuclear iron species, they can be in the pores as small clusters of iron species, and they can exist on the external surface as large agglomerates of iron oxides.…”

Section: The Possible Degradation Mechanism Of Ar17 By a Heterogeneoumentioning

confidence: 99%