Advisor(s)

Albert Sacco Jr.

Contributor(s)

Fabrizio Lombardi, Elizabeth J. Podlaha-Murphy

Date of Award

2009

Date Accepted

11-2009

Degree Grantor

Northeastern University

Degree Level

M.S.

Degree Name

Master of Science

Department or Academic Unit

College of Engineering. Department of Chemical Engineering.

Keywords

chemical engineering, nanotechnology, colloidal anatase, Engelhard Titanosilicate, ETS-10, Nano anatase, Titanium Dioxide, zeolite

Subject Categories

Textile fabrics, Titanium dioxide crystals

Disciplines

Mechanics of Materials | Polymer and Organic Materials

Abstract

Functionalized textiles present a vast and growing niche in the global textile market at US $400 billion [1, 2]. Engelhard Titanium Silicate 10 (ETS-10), a photocatalytic zeo-type material if coated on textiles, is expected to impart useful properties similar to TiO2, such as stain-resistant, odor repellant, bactericidal and enhanced UV protection [3, 4]. Typically, small ETS-10 crystals of size ~300-800 nm are synthesized using solid titania (e.g., anatase or P25) sources [5, 6, 7]. However, smaller ETS-10 crystals are required for a uniform surface coating with highly effective surface area. The dissolution of titania particles (i.e., their size) is hypothesized to be important in small ETS-10 crystal formation [5, 6, 7]. Nano anatase was synthesized by modification of two methods: direct precipitation [7] and sol-gel synthesis [3]. Analysis by XRD confirmed that both methods produced nano anatase of crystallite size ~4-5 nm. However, FE-SEM analysis showed that product from direct precipitation, existed as intergrown spheroidal particles with size ~1.0 μm. These particles dispersed poorly in deionized water. Therefore, the best nano anatase samples were from sol-gel synthesis in two forms, dry powder and colloidal anatase.

ETS-10 synthesis was investigated using two methods adopted from literature [6, 7]. The method of Yoon and co-workers [7], with nano anatase in a molar composition of 5.5TEOS: TiO2: 8.4NaOH: 1.43KF: 350H2O:2.2H2SO2 produced unknown phase(s) with some ETS-10 and quartz. Using colloidal anatase with molar composition 5.5TEOS:1.0TiO2:8.4NaOH:1.43KF:400H2O:2.2H2SO2 also produced unknown phase(s). The method of Anderson and co-workers [6] with nano anatase powder in a molar composition of 5.5SiO2: TiO2: 5.2Na2O: 0.5K2O: 113H2O produced quartz with ETS-10 impurity. When colloidal anatase was used, with molar composition TiO2:5.5SiO2:5.2Na2O:0.5K2O:332H2O, unreacted anatase and quartz were formed. It was hypothesized that the very low reaction mixture pH of ~4.1 was responsible for the absence of ETS-10. Therefore, pH of this mixture was modified between ~6.55-12.75.At low pH of ~6.55 unreacted anatase was present, while, pH higher than ~11.24 formed ETS-4 crystals. At an &Idquo;optimum” pH of ~11.24 nearly phase-pure ETS-10 crystals were formed. However, these ETS-10 crystals were not small but ~10-20 μm. This is the first time, that colloidal anatase has been utilized for ETS-10 synthesis.

Document Type

Master's Thesis

Rights Holder

Shihara Shafeque


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