pH-dependent absorbance of a centrifuged rhodamine B-TiO sub(2) suspension, and a practical filtration method with minimized dye loss in a dye decoloration test

• Published in: Reaction kinetics, mechanisms and catalysis Vol. 111; no. 1; pp. 361 - 370
• Main Authors: Park, Se-Keun, Shin, Hyunho
• Format: Journal Article
• Language: English
• Published: 01.02.2014
• Subjects: Absorbance; Centrifuging; Decoloring; Dyes; Feasibility; Filtration; Rhodamine; Titanium dioxide
• ISSN: 1878-5190; 1878-5204
• DOI: 10.1007/s11144-013-0632-8

Although the centrifugation of a rhodamine B (RhB)-TiO sub(2) suspension cannot separate TiO sub(2) particles completely, the UV/Vis absorbance of the residual TiO sub(2) in the centrifuged suspension, under neutral and basic conditions, is not fully revealed under the presence of RhB molecules. Therefore, in a dye decoloration test, the centrifuged suspension can be used for estimating the concentration of RhB molecules based on the RhB absorbance peak in a Vis light regime. From acidic suspensions, however, the elimination of TiO sub(2) is so difficult that the centrifuged suspension results in a significant shift of the baseline of the RhB absorbance peak. An additional use of a microfilter removes not only the residual TiO sub(2), but also a part of the dye. A practical recipe for the successful microfiltration of TiO sub(2) powder with a minimal loss of dye from the acidic suspension has been proposed and its feasibility has been validated.