跳至主要内容

The Behavior of Zeta Potential of Silica Suspensions

Zeta potential, also known as electrokinetic potential, is one of the most relevant parameters controlling the rheological behavior of ceramic suspensions. It is the potential difference across phase boundaries between solids and liquids. Its measurement is frequently used in coagulation (aggregation) and dispersion processes in several applications, such as colloidal processing of ceramic pastes and slurries, water purification, paints and cosmetics.

In this paper, the authors discussed the behavior of zeta potential versus pH, in the vicinity and away from the isoelectric point (IEP), presented by suspensions of several silica raw materials of different crystal structures and specific surface area. The chosen silica powdered raw materials for this study were two crystalline polymorphs of silica (α-quartz and α-cristobalite), as well as vitreous silica. And it was observed that for pH values below the isoelectric point (IEP), the positive value of zeta potential of water suspensions of α-quartz and α-cristobalite, experienced a sudden steep increase with the increase in specific surface area of the powders. For pH values above the IEP, the zeta potential values of crystalline forms of silica (α-quartz and α-cristobalite) got gradually more negative with the increase in pH. Conversely in the case of vitreous silica, for pH values above 6, there was a steep change towards more negative values of zeta potential than those presented by quartz and cristobalite.

In conclusion, through this work, it was possible to identify different behaviors of the zeta potential versus pH for silica samples, crystalline or vitreous, which was found remarkably different from pH values below and above the IEP. And understanding how the zeta potential varies with crystalline and vitreous character and its dependence on powder surface area of silica raw materials would help to predict and control the rheological behavior of the silica slips. In this manner, the stabilization and destabilization of these ceramic materials under colloidal processing can be considerably facilitated.

Article by José Antonio Alves Júnior and João Baptista Baldo, from Universidade Federal de São Carlos, São Carlos, Brazil.

Full access: http://mrw.so/vja34
Image by Geoff Whiteway, from Flickr-cc.


评论

发表评论

此博客中的热门博文

Electron Spin and Proton Spin in the Hydrogen and Hydrogen-Like Atomic Systems

Read full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=52202#.VIj7tMnQrzE Author(s) Stanisław Olszewski * Affiliation(s) Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland . ABSTRACT The mechanical angular momentum and magnetic moment of the electron and proton spin have been calculated semiclassically with the aid of the uncertainty principle for energy and time. The spin effects of both kinds of the elementary particles can be expressed in terms of similar formulae. The quantization of the spin motion has been done on the basis of the old quantum theory. It gives a quantum number n = 1/2 as the index of the spin state acceptable for both the electron and proton
发表评论
阅读全文

Remarks on the Complexity of Signed k-Domination on Graphs

Read  full  paper  at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=53574#.VMnXsCzQrzE Author(s)    Chuan-Min Lee 1 , Cheng-Chien Lo 1 , Rui-Xin Ye 2 , Xun Xu 2 , Xiao-Han Shi 2 , Jia-Ying Li 2 Affiliation(s) 1 Department of Computer and Communication Engineering, Ming Chuan University, The First American University in Asia, Taoyuan, Taiwan, Chinese Taipei . 2 Department of Electronic Information Engineering, Fuzhou University, Fuzhou, China . ABSTRACT This paper is motivated by the concept of the signed k-domination problem and dedicated to the complexity of the problem on graphs. For any fixed nonnegative integer k, we show that the signed k-domination problem is NP-complete for doubly chordal graphs. For strongly chordal graphs and distance-hereditary graphs, we show that the signed k-domination problem can be solved in polynomial time. We also show that the problem is linear-time solvable for trees, interval graphs, and chordal comparability graphs
发表评论
阅读全文

Dietary Fiber Content of Waterleaf (Talinum triangulare (Jacq.) Willd) Cultivated with Organic and Conventional Fertilization in Different SeasonsDietary Fiber Content of Waterleaf (Talinum triangulare (Jacq.) Willd) Cultivated with Organic and Conventional Fertilization in Different Seasons

Read  full  paper  at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=53985#.VN21HizQrzE Author(s)  Nuri Andarwulan 1,2 , Didah Nur Faridah 1,2 , Yolanda Sylvia Prabekti 1 , Harum Fadhilatunnur 1 , Leo Mualim 3 , Sandra Arifin Aziz 3 , Luis Cisneros-Zevallos 4   Affiliation(s) 1 Department of Food Science and Technology, Bogor Agricultural University, Bogor, Indonesia . 2 Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, Bogor Agricultural University, Bogor, Indonesia . 3 Department of Agronomy and Horticulture, Bogor Agricultural University, Bogor, Indonesia . 4 Department of Horticultural Sciences, Texas A&M University, College Station, USA . ABSTRACT Waterleaf ( Talinum triangulare (Jacq.) Willd has long been eaten in Indonesia as vegetable and the main parts consumed are leaves and young shoots. Waterleaf is sticky presumably due to its pectin content which is associated to dietary fiber. The dietary fiber which
发表评论
阅读全文