The evaluation of mixed Al,Co pillared catalyst in degradation of tartrazine dye in presence of peroxymonosulfate

Abstract

In this work smectite pillared with mixture of aluminium and cobalt poly(hydroxo metal) cations (Al,Co-PILC) was synthesized and tested as catalyst in degradation of food dye tartrazine by peroxymonosulfate. The Al,Co-PILC was obtained using a common procedure consisting of the following steps: grinding, sieving, Na exchange, intercalation, drying and calcination. Co2+ to (Al3++Co2+) molar ratios in the pillaring solution was 10%. Catalytic tests were carried out in a semibatch reactor under stirring and constant temperature maintained by circulation of thermostatic fluid using Julabo MC 4 heating circulator. Initial dye concentration was 50 ppm in the presence of excess of peroxymonosulfate. Decolorization of tartrazine solution was monitored using UV-Vis spectrophotometry at max= 426 nm. The influence of the mass of the catalyst and reaction temperature was investigated. Catalyst mass and temperature increase were beneficial for dye degradation rate. The catalytic process at 30 ºC reached 97% for 120 min and besides decolorization included further degradation of products of tartrazine oxidation. At 50 ºC complete decolorization occurred for only 30 min. This work showed that application of smectite pillared with mixture of aluminium and cobalt poly(hydroxo metal) cations as peroxymonosulfate activators for degradation of water pollutants is very promising.