RESUMO
The photocatalytic degradation of salicylic acid was studied by a batch process using ZnO as the catalyst on irradiation with UV light. The effect of process parameters such as pH, catalyst loading and initial concentration of salicylic acid on the extent of degradation was investigated. The degradation of salicylic acid was found to be effective in the neutral pH range. The optimum catalyst loading was observed at 2.0 g/L. The process followed first order kinetics and the apparent rate constant decreased with increase in the initial concentration of salicylic acid. The mechanism for the degradation of salicylic acid could be explained on the basis of Langmuir-Hinshelwood mechanism. The complete mineralization of salicylic acid was observed in the presence of ZnO photocatalyst. The ZnO was found to be quite stable and undergoes photocorrosion only to a negligible extent.
Assuntos
Fotólise , Ácido Salicílico/química , Óxido de Zinco/química , Catálise , Corrosão , Concentração de Íons de Hidrogênio , Cinética , Minerais , Fotólise/efeitos da radiação , Ácido Salicílico/efeitos da radiação , Raios Ultravioleta , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiaçãoRESUMO
The potentiality of commercially available activated carbon has been investigated as an effective adsorbent to remove the dyes from aqueous solutions. The effects of pH of the solution, adsorbent dose, solute concentration and temperature on activated carbon for azo dyes such as acid orange 7 and direct red 31 have been evaluated. The percentage removal of the dyes has been found to be high at neutral pH. The dynamics of adsorption has been studied at different temperatures. The adsorption data follow Langmuir model as well as Freundlich model in the case of acid orange 7 whereas the data for direct red 31 fit into only Langmuir model.
