Adsorption of phenolic compounds on some hybrid xerogels

Haghbeen, Kamahldin; Legge, Raymond L.

doi:10.1016/j.cej.2008.11.036

Cited by 17 publications

(18 citation statements)

References 35 publications

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“…More specifically K f is interpreted in terms of adsorption capacity of the sorbent and 1/n is considered as an indication of the heterogeneity of the surface and its capacity for the adsorbate. 24 All the systems are observed to follow Freundlich's isotherm (Fig. 5) supporting the fact that the heterogeneous surface of the adsorbents is playing an active role during the adsorption process.…”

Section: Adsorption Studiesmentioning

confidence: 63%

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Potential of PVA templated Silica Xerogels as Adsorbents for Rhodamine 6G

Pirzada¹,

Shah²

2011

Journal of the Korean Chemical Society

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ABSTRACT. PVA/silica hybrid xerogels were synthesized by sonohydrolysis of a mixture of 2-way catalyzed TEOS and water solution of PVA. PVA was successfully removed from the xerogels through calcination and its removal was confirmed through TGA analysis of the calcined gel. Microstructure of the gels was studied through SEM, XRD and FTIR. Nitrogen sorption studies were conducted to find out surface area of different samples. It was found out that the samples having PVA removed through calcinations have higher surface area (411.64 m 2 /g) than the samples (353.544 m 2 /g) synthesized without any PVA. Adsorption properties of these xerogels synthesized by using different ratios of components were studied by taking Rhodamine G6 as a model adsorbate. The experiments were conducted at room temperature (25 o C). UV visible spectroscopy was used to measure the concentration of the dye before and after adsorption. The adsorption data of Rhodamine G6 on PVA modified silica is described by the Freundlich's adsorption model.

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Section: Adsorption Studiesmentioning

confidence: 63%

“…The Freundlich's isothermal model (equation 2) is the most convenient model which has been applied in many cases. [22][23][24] It has the capacity to adopt the heterogeneous surface adsorption data. Mostly, the logarithmic form (equation 3) of the model is used to find out adsorption parameters.…”

Section: Adsorption Studiesmentioning

confidence: 99%

Potential of PVA templated Silica Xerogels as Adsorbents for Rhodamine 6G

Pirzada¹,

Shah²

2011

Journal of the Korean Chemical Society

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“…The Langmuir model is based on monolayer adsorption of the sorbate particles on equal, non-cooperative adsorbing sites. [28] The random polymerization of the silanols in the sol state forms a sieve structure which is initially compliant, but shrinks during drying, and as a result, gives pores of various sizes and accessibility. [39] Therefore it is assumed that a monolayer of the divalent cation is adsorbed on the heterogeneous surface of the classic xerogel.…”

Section: Adsorption Of Divalent Cationsmentioning

confidence: 99%

“…[19][20][21][22][23][24] Due to their chemical, physical, and mechanical properties, various silica-based materials have been prepared and examined for different adsorption applications. [28] The pH where a particle exhibits a zero net electrical surface charge is called PZC. They are prepared with simple reactions and can be shaped or powdered, resulting in a considerable surface area ranging from 200-1500 m 2 /g.…”

Section: Introductionmentioning

confidence: 99%

Cation‐assisted adsorption of chlorophenols by nano‐xerogels

et al. 2015

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With water quality deteriorating globally, identification of novel adsorbents for removal of chloroaromatic compounds for wastewater treatment is of growing interest. Classic xerogels produced by drying sol-gels of tetraalkoxy silanes, such as tetramethoxy orthosilane (TMOS) or tetraethoxy orthosilane (TEOS), carry a negative surface charge in water when the pH is higher than the Point of Zero Charge (PZC). This feature was employed in this study to load divalent metal cations on the surfaces of these materials to facilitate chlorophenol (CP) adsorption. Although classic xerogels do not show a high affinity for the adsorption of chlorophenols such as 2-chlorophenol (2CP) in aqueous media, TEOS xerogels loaded with the cations Ni 2þ , Cd 2þ , and Zn 2þ showed 225, 249, and 306 % increases, respectively, in the adsorption of 2CP compared to the unloaded TEOS xerogel. Adsorption of the divalent cations on the xerogels exhibited the order of Zn 2þ > Cd 2þ > Ni 2þ , with maximum adsorption capacities (Q8) of 15.9 and 13 mg/g for Zn 2þ on TEOS and TMOS xerogels, respectively. Using TEOS xerogels loaded with Zn 2þ (TEOS-Zn), adsorption of 2CP, 2,4-dichlorophenol (DCP), and 2,4,6-trichlorophenol (TCP) in aqueous media was studied. The adsorption was found to be spontaneous and obeyed pseudo-second order kinetics, suggesting a chemisorption mechanism between CP and TEOS-Zn. The equilibrium isothermal adsorption data were most closely fitted with a Langmuir equation resulting in Q8 values of 13.9, 9.17, and 8.5 mg/g for 2CP, DCP, and TCP, respectively.

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“…9(A)], but similar analysis for ChC binding data failed to produce a straight line (R 2 ¼ 0.51). In contrast to Langmuir model, which is based on the assumption of a homogeneous surface containing independent sites for monolayer binding, Freundlich model has the ability to adopt the heterogeneous surface adsorption data [40]. Since both Chit42 and chimeric chitinase were proteins of almost similar sizes, the obvious difference in the linearity might indicate a remarkable difference between the conformational changes of Chit42 and ChC upon binding to the insoluble chitin surface.…”

Section: Chit42mentioning

confidence: 99%