A study of process variables for the photocatalytic degradation of rhodamine B

Abstract

-The photoactivated degradation reaction of rhodamine B (RB) was studied using P-25 TiO 2 (Degussa) as catalyst. Three process variables -temperature, initial pH, and catalyst concentration -were evaluated. Temperature had a slight effect on reaction rate; however, the combined effect of pH and catalyst concentration was greater. pH affected the catalyst particle's adsorption of RB, altering the reaction rate. The concentration of the catalyst was significant only up to 0,65 g L -1 . The effect of temperature was studied at optimum pH and 50ºC was found to be the optimum operational temperature. The effect of the presence of a surfactant (sodium dodecylsulfate, SDS) and ionic contaminants (Cl -and SO 4 --) in the reaction system was also studied. The surfactant improved the catalyst's adsorption of RB by more than 80%, increasing the degradation reaction rate as well. The ionic contaminants reduced the reaction rate.

Parameters affecting the photocatalytic degradation of dyes using TiO2: a review

“…The effect of temperature on the reaction was also studied by Soares et al (2007). The optimum range of operational temperatures was found to be in the range 40-50°C.…”

Dye aggregation and influence of pre-micelles on heterogeneous catalysis: A photophysical approach

“…The use of oppositely charged surfactant and dye introduces the advantage of sensitization of TiO 2 from direct interaction of semiconductor and dimers of rhodamine B with the adequate energy transfer from excited dye to titanium dioxide, for instance, allowing the photocatalysis and, consequently, an efficient photodegradation of rhodamine B [15][16][17][18][19], reducing the bandgap from 3.2 eV to intermediate level from which the irradiation in the visible region promotes the excitation of electrons from excited dye to the conduction band of TiO 2 with the electron-hole pair generation.…”

Síntese, caracterização e atividade fotocatalítica de catalisadores nanoestruturados de TiO2 dopados com metais

“…O valor de k foi calculado assumindo-se que a reação seja de pseudoprimeira ordem, com base em estudos anteriores. 25 Foram realizados ensaios preliminares para se estabelecer as concentrações de catalisador e substrato que maximizam o percentual de degradação quando a reação ocorre no aparato experimental empregado no presente trabalho.…”