Preparation of TiO 2-Bamboo Leaves Ash Composite as Photocatalyst for Dye Photodegradation

Textile waste containing dye can generate environmental problems especially for human. Therefore some techniques are developed to overcome the impact of toxic contaminant from dyes residue, one of these is the photocatalysis technique. The photocatalysis mechanism TiO2 is a popular photocatalyst and in order to improve its activity the composite formation with a some solid support are attempted. The development of TiO2 composite with a sustainable support source; bamboo leaves was conducted. The composite was prepared by dispersing titanium isopropoxide into bamboo leaves ash (BLA) followed by calcination process. Hysicochemical characterization of the photocatalyst was performed by using XRD, gas sorption analyzer and SEM-EDX analysis. By the characterization it is found that BLA contains silica in highest percentage and furthermore TiO2 in the mixed anatase and rutile phases were formed the composite.


Introduction
Bamboo is a kind of plants widely grown in Indonesia and also one of the fastest growth plants.Until now, its utilization is very wide especially in building and architecture mainly related to its stem, but for leaves the utilization is very limited or sometime it let to be rubish.In other side, photocatalytic treatment of dye waste is one of interesting and popular mechanism in environmental issue.Photocatalytic treatment is more usefull compared to adsorption process and usually it utilize titanium dioxide (TiO2) as main photocatalyst (Andriantsiferana et al., 2013).For economy and effectivity reasons, the some modifications of TiO2 are attempted, one of this is immobilizing TiO2 into a stable solid support such as MCM-41, zeolite, kaolinite or silica (Choi et al., 2010;Gao et al., 2012).The immobilization into silica is considerable for preparing low cost photocatalyst since silica can be derived from such plants waste or called as biogenic silica material.
Considering that bamboo leaves are plant waste, in this work, the preparation of TiO2 immobilized silica was prepared by biogenic silica from bamboo laves (TiO2-Bamboo leaves ash/ Ti-BLA) in that the bamboo levaes were used without any treatment (Kowa et al., 2014).The study focused on the preparation, characterization and photocatalytic activity of Ti-BLA and the photocatalytic study in dye degradation.Methylene blue (MB) as chosen as dye model for the study refer to some studies reported.

Materials
Bamboo leaves were obtained from a village plantation in Klaten, Central of Java, Indonesia.Some chemicals in analytical grade consist of MB, titanium isopropoxide, isopropanol were purchased from Merck, Germany.

Method
Bamboo leaves ash (BLA) was prepared by calcination using furnace in optimal temperature of 700 0 C for 2 hours.The aim of calcination is to remove organic content in the leaves and raw silica material was obtained.Ti-BLA was prepared by mixing titania precursor obtained by diluting titanium into isopropanol.The mixture was stirred overnight after the addition of acetic acid.The gel obtained was dried and then calcined at 400 o C for 2h.
Photocatalytic activity of Ti-BLA was tested into MB dye degradation by mixing the powder of Ti-BLA and MB solution in photocatalytic reactor.The schematic representation of the reactor is presented in Figure 1.

Figure 1. Schematic representation of photocatalytic reactor
The reaction variable was the use of UV light in the photodegradation reaction.The sampling was conducted in certain time and the absorbance of the solution was analyzed using UV-Vis spectrophotometer HITACHI U-2010.

Photocatalytic activity
Photodegradation was done using methylene blue with the concentration of 10 - 3 M. Kinetic of MB degradation by varied treatment: with UV illumination and without UV illumination is presented in Figure 5.The kinetic of MB degradation shows that the utilization of UV in the photodegradation give rapid MB degradation compared with the reaction without UV.When the photocatalyst was irradiated by UV-light, then it would produce an electron excitation and producing the hole which is then strongly produce radical *OH for further oxidation of MB (Figure 6).
From the kinetic data it is also concluded that the presence of TiO2 gives contribution strongly to the MB oxidation.

Conclusion
Bamboo leaves ash showed the effectiveness as TiO2 support as indicated by the increasing surface parameter data and photocatalytic activity in MB degradation.

Figure 2 .
Figure 2. XRD pattern of materials

Figure 5 .
Figure 5. Kinetic of MB degradation over varied treatment

Table 1 .
Surface parameter data of Ti-BLA compared with BLA