from first principles PP-I-1

PP-V-13Mathematical Modelling of Photocatalytic Degradation of Methylene Blueunder Visible IrradiationSannino D., Vaiano V., Sacco O., Ciambelli P.University of Salerno, Department of Industrial Engineering, Via Ponte Don Melillo,84084 Fisciano (SA), Italydsannino@unisa.itMethylene blue (MB) is the most widely employed basic dye, which finds enormousapplications in dyeing and printing industry. Large volumes of coloured wastewater are thusproduced and, for this reason, various treatment methods, based on physical, chemical, andbiological unit operations have being investigated, however the development of a costeffective removal technology still eludes the scientific community [1-2]. In this context,photocatalysis appears as one of the most viable solutions that can be exploitedadvantageously for the complete mineralization of various dye pollutants present in liquidmedia. It is well known that the main photocatalyst used, TiO 2 , absorbs only a little fractionof the solar spectrum emission because of the value of its band-gap energy (3.0-3.3 eV). Thus,the anion-doped TiO 2 has attracted considerable attention due to its reported activity under thevisible light. Among all, the N-doped TiO 2 seems to be the most promising visible absorbingphotocatalyst. In this work, the N-doping TiO 2 , obtained by direct nitration during thehydrolysis of titanium tetraisopropoxide with ammonia aqueous solutions [3], was used toevaluate the photodegradation of MB in aqueous solutions, chosen as model dyecontaminatedwastewater. Photocatalytic tests were carried out in a pyrex photoreactor andirradiated with visible light emitted by WHITE LED surrounding the photoreactor, with atuneable incident light intensity among 8 and 32 mW/cm 2 . The effects of many operatingconditions on MB removal, such as initial MB concentration, the dosage of catalyst amountand light intensity were evaluated by both UV-Vis spectrophotometry and TOC analyses asfunction of time of irradiation. The experimental results were used to develop a mathematicalmodel based on Langmuir-Hinshelwood kinetics [4] that results to well describe thebehaviour of the system in different experimental conditions.References:[1] M. Anpo, Bull. Chem. Soc. Jpn 77 (2004) 1427.[2] G. Cappelletti, S. Ardizzone, C.L. Bianchi,S. Gialanella, A. Naldono, C. Pirola, V. Ragaini,Nanoscale Res. 4 (2009) 97.[3] S. Sato, Chem. Phys. Lett.123 (1986) 126[4] Chun-Hsing Wu and Jia-Ming, Chern Ind. Eng. Chem. Res. 45 (2006) 6450.322