Photocatalytic degradation of an azo-dye on TiO₂/activated carbon composite material

Abstract

A sequential adsorption/photocatalytic regeneration process to remove tartrazine, an azo-dye in aqueous solution, has been investigated. The aim ofthis work was to compare the effectiveness of an adsorbent/photocatalyst composite-TiO2 deposited onto activated carbon (AC) - and a simple mixture of powders of TiO2 and AC in same proportion. The composite was an innovative material as the photocatalyst, TiO2, was deposited on the porous surface ofa microporous-AC using metal-organic chemical vapour deposition in fluidized bed. The sequential process was composed of two-batch step cycles: every cycle alternated a step of adsorption and a step of photocatalytic oxidation under ultra-violet (365 nm), at 25 degreeC and atmospheric pressure. Both steps, adsorption and photocatalytic oxidation, have been investigated during four cycles. For both materials, the cumulated amounts adsorbed during four cycles corresponded to nearly twice the maximum adsorption capacities qmax proving the photocatalytic oxidation to regenerate the adsorbent. Concerning photocatalytic oxidation, the degree of mineralization was higher with the TiO2/AC composite: for each cycle, the value of the total organic carbon removal was 25% higher than that obtained with the mixture powder. These better photocatalytic performances involved better regeneration than higher adsorbed amounts for cycles 2, 3 and 4. Better performances with this promising material - TiO2 deposited onto AC - compared with TiO2 powder could be explained by the vicinity of photocatalytic and AC adsorption sites.

Photodegradation of 1-Butyl-3-methylimidazolium Chloride [Bmim]Cl via Synergistic Effect of Adsorption–Photodegradation of Fe-TiO2/AC

“…Figure 8, the total degradation of [bmim]Cl increased until the optimum [photocatalyst] was achieved. Insufficient amount of photocatalyst supplied to the system will cause a blockage of the active site by [bmim]Cl, causing poor efficiency of the system [46]. As the dosage increased, the active sites available for the photodegradation process also increased, leading to a higher degradation rate.…”

Effect of Zn Content on the physicochemical Characteristics and Photoactivity of ZnO supported Activated Carbon

“…Not only by its great specific surface area and low cost, but AC also give synergistic effect on photocatalysis via the strong adsorption properties which is also the controlling factor in photocatalysis 10,11 . From previous research, it is found that the combination of some photocatalyst with AC give synergistic effects 2,12 . There are several methods developed and reported by previous researches.…”

“…Several techniques were developed including adsorption, oxidation and photooxidation method. Among some methods applicable for industrial scale, in recent years photocatalytic degradation of pollutant in aquatic system became the advance technique since it can reduce the cost the treatment due to its reusability [1][2][3] . The main factor in the system is highly active photocatalyst and one of the potential photocatalyts can be elected, ZnO materials have attracted much attention due to their excellent optical properties and facile synthesis methods.…”

One Step Carbonization/Activation Process for Carbonaceous Material Preparation from Pecan Shells for Tartrazine Removal and Regeneration after Saturation

“…This could indicate that a higher temperature and steam activation would enhance the adsorption capacity. The adsorption capacities of tartrazine over a variety of adsorbents (Klett et al 2014;Banerjee and Chattopadhyaya 2013;Wawrzkiewicz and Hubicki 2009;Mittal et al 2007;Dotto et al 2012;Ansari et al 2011;Monser and Adhoum 2009;Andriantsiferana et al 2014) are compared and reported in Table 6. …”