Morphological, chemical surface and electrical characterizations of lignosulfonate-modified membranes

Torras, Carles; Zhang, X.; García-Valls, Ricard; Benavente, J.

doi:10.1016/j.memsci.2007.03.030

Cited by 22 publications

(8 citation statements)

References 34 publications

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“…As expected, the IL-solution only presents a relaxation at high frequencies ( f max ≈ 3 × 10 6 Hz) since only free or "solution" charges are involved; however, the membrane/IL-solution system exhibits different behaviours depending on the time period which is associated to the exchange kinetic: (a) at the beginning of the exchange process the main effect observed corresponds to the increase in of membrane characteristic parameters (electrical resistance and capacitance) due to the replace of the small and high conductive proton (H + ) by the wider and heavy DTA + -cation and two relaxation processes, one associated to the membrane ( f max ≈ 10 4 Hz) and another to the electrolyte solution placed between the electrodes and the membrane surfaces ( f max ≈ 2-3 × 10 6 Hz) can be observed; (b) after some hours of membrane immersion in the IL-solution (around 10 h) a structured profile seems to be developed at the membrane interface and then three different relaxation processes with maximum frequencies around 200 Hz (interface), 10 4 Hz (membrane), and 2-3 × 10 6 Hz (electrolyte solution) are obtained. These latter curves are similar to those obtained with composite membranes (as those used for reverse osmosis or nanofiltration processes) in contact with common electrolytes solutions (NaCl or KCl) and are associated to the typical double layer (dense-active layer/porous-support) structure of that kind of membranes [36,37]. The fitting of the impedance data obtained for each time allows the estimation of the electrical resistance and capacitance associated to both bulk membrane and interface and its dependence with membrane immersion time in the ILsolution is shown in Figure 10.…”

Section: Monitoring Il-cation Inclusion Electrical Effectssupporting

confidence: 72%

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Romero

Yuso

Arango

et al. 2012

International Journal of Electrochemistry

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Bulk and surface changes in two proton-exchange membranes (Nafion-112 and Nafion-117) as a result of the incorporation of the IL-cation n-dodecyltriethylammonium (or DTA + ) by a proton/cation exchange mechanism after immersion in a DTA + aqueous solution were analysed by impedance spectroscopy (IS), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), and contact angle measurements performed with dry samples of the original Nafion and Nafion-DTA + -modified membranes. Only slight differences were obtained in the incorporation degree and surface chemical nature depending on the membrane thickness, and DTA + incorporation modified both the hydrophobic character of the original Nafion membranes and their thermal stability. Electrical characterization of the dry Nafion-112 membrane was performed by impedance spectroscopy while different HCl solutions were used for membrane potential measurements. A study of time evolution of the impedance curves measured in the system "IL aqueous solution/Nafion-112 membrane/IL aqueous solution" was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA + hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

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Section: Monitoring Il-cation Inclusion Electrical Effectssupporting

confidence: 72%

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Romero

Yuso

Arango

et al. 2012

International Journal of Electrochemistry

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“…4. Low irradiation dose increases membrane porosity (around 20%, according to IFME analysis of the membrane surface [33,34]), in agreement with that reported in the literature for UV-treated ultrafiltration membranes, which is attributed to the cleaning of the membrane surface (in concordance with the XPS results previously obtained) or pore enlargement caused by severe chain scission [8,35], but the increase of radiation dose could also affect membrane surface roughness as a result of the heating effect associated with radiation.…”

Section: Resultssupporting

confidence: 90%

Electrokinetic and surface chemical characterizations of an irradiated microfiltration polysulfone membrane: Comparison of two irradiation doses

Lara

Benavente

2007

Journal of Colloid and Interface Science

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“…(Li et al 2011;Torras et al 2007), and the type of chemical bonds of carbon in pure cellulose can be categorized into two groups: C2 and C3 carbon (Johansson et al 1999). So, the LS content can be evaluated by C1, C4 and C5 carbon if the test sample contains only LS and cellulose.…”

Section: Formation Of Cpam/ls Multilayers On Cellulose Fibermentioning

confidence: 99%

Surface modification of cellulose fibers with layer-by-layer self-assembly of lignosulfonate and polyelectrolyte: effects on fibers wetting properties and paper strength

Peng

et al. 2012

Cellulose

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To convert the hydrophilic cellulose fiber into hydrophobic, multilayers composed of cationic polyacrylamide (CPAM) and lignosulfonate (LS) were constructed on cellulose fiber surface using layer-bylayer (LBL) self-assembly technique. The presence of CPAM/LS multilayers were validated by zeta potential, X-ray photoelectron spectroscopy and atomic force microscopy (AFM). It was found that potential of fiber surface inversed after deposition of each layer, the contents of characteristic elements (i.e. S and N) of CPAM/LS multilayers increased with increasing bilayer number, furthermore, the calculated surface LS content increased linearly as a function of bilayers. AFM phase images indicated that the cellulose microfibrils on fiber surface were gradually covered by LS granules, resulting in an increase in fiber surface roughness as self-assembly proceeded. The wetting properties of modified cellulose fibers were detected by dynamic contact angle measurement. The results showed that the initial water contact angle gradually increased and the attenuation rate of the contact angle gradually decreased with the number of bilayers, suggesting that the controllable hydrophobicity of cellulose fiber can be achieved depending on the number of bilayers. It also showed that the polyelectrolyte presented in the outermost layer significantly influenced the wetting properties of cellulose fibers, and a higher hydrophobicity was observed when LS was in the outermost layer. Moreover, tensile strength test was performed on the handsheet prepared from LBL modified fibers to evaluate the effect of CPAM/ LS multilayers on strength property of cellulose fiber networks. The tensile index of handsheet prepared from fibers modified with a (CPAM/LS) 5 multilayer increased by 12.4% compared with that of handsheet prepared from original fibers. The print density of handsheet increased with the number of bilayers, suggesting that printability of the handsheet was improved by constructing CPAM/LS multilayers on cellulose fiber surface. This strategy will have a positive impact and potential application value in printing process control of cellulose fiber-based products.

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Morphological, chemical surface and electrical characterizations of lignosulfonate-modified membranes

Cited by 22 publications

References 34 publications

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

Electrokinetic and surface chemical characterizations of an irradiated microfiltration polysulfone membrane: Comparison of two irradiation doses

Surface modification of cellulose fibers with layer-by-layer self-assembly of lignosulfonate and polyelectrolyte: effects on fibers wetting properties and paper strength

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