# Immobilized TiO\({}_{2}\)-Polyethylene Glycol: Effects of Aeration and pH of Methylene Blue Dye
## 1 Introduction  
Dye pollutants or effluents have attracted wide attention due to their toxicity and resistance for removal-feature. It has been a challenging task to decompose these effluents (e.g., methylene blue (MB) dye) [1,2]. Some of the major works conducted on MB dye were in aqueous solutions using photocatalysis method, and some of these photocatalytic studies were also employed in immobilization systems [3, 4, 5, 6]. In aqueous systems such as slurry or suspension method, photocatalysts require an expensive photocatalyst recovery process which limits its application due to high scale-up cost and because it is not environmentally friendly [7,8]. Even though there are several commercial photocatalysts available, the TiO\({}_{2}\) photocatalyst is always an option used in photocatalysis such as in wastewater remediation due to its high performance, low equipment cost, and low toxicity [9,10]. Alternatively, immobilization of TiO\({}_{2}\) has been explored, and displayed better catalytic compared to TiO\({}_{2}\) suspension [11]. Moreover, a comprehensive review of TiO\({}_{2}\) films was conducted by [PERSON] et al. (2016), in which various types of coating methods (e.g., doctor-blade, chemical vapour deposition, hydrothermal, electrophoretic deposition, sputter deposition, spray pyrolysis, and flame aerosol coating methods) are thoroughly explained [12]. In an earlier study by [PERSON] et al. [13], immobilized TiO\({}_{2}\) was used for the photodegradation of MB dye. This study revealed that more MB dye wasremoved in a shorter amount of time through immobilized TiO\({}_{2}\)-polymer. Studies have shown that the incorporation of polymer such as polyethylene glycol (PEG) in photocatalysis is highly beneficial for the enhancement of the catalytic activity of the immobilized sample. PEG is a polymeric material that can be employed to boost the functionalization of TiO\({}_{2}\) surface which acted as a matrix agent or as a structure directing agent [14; 15; 16]. [PERSON] et al. [17] claimed that immobilized TiO\({}_{2}\) with PEG exhibited higher catalytic activity and achieved higher surface density compared to other immobilized sample without the addition of PEG. The addition of PEG was proven to create a remarkable porosity in immobilized TiO\({}_{2}\) sample [18]. It has been realized that the size of pores increased with increased molecular weight of PEG [19]. This factor indirectly promotes an excellent performance of immobilized photocatalyst sample. In another study by [PERSON] et al. [20], the addition of high molecular weight PEG (i.e., PEG 6000) presented a major increase in specific surface area, well-defined particle size, and enhanced photo-generated charge separation rate between conduction band (CB) and valence band (VB) during oxidation process. Meanwhile, studies have shown that adhesive tapes (e.g., scotch tape, double sided adhesive tape (DSAT), and hatch tape) were previously used to measure the adhesiveness of TiO\({}_{2}\) films onto substrate [21; 22]. However, the functionalization of adhesive tapes (i.e., DSAT) as a support binder has not been studied extensively. Besides, improving the adherence of TiO\({}_{2}\) film with flat supports such as glass plates is crucial to obtain an optimal photocatalytic effect. This is because film adhesion is one of the biggest challenges in polymer-immobilized photocatalyst [23]. Based on our previous works [24; 25], DSAT was not only proven to strengthen the adhesion of TiO\({}_{2}\) film to glass plate, but also improved the reusability of immobilized photocatalyst for up to 30 cycles. The immobilized TiO\({}_{2}\)-DSAT successfully demonstrated an outstanding photocatalytic activity on the decolorization of Reactive Red 4 (RR4) and methylene blue dye. During the 30 cycles, the photocatalyst sample maintained a high photodegradation rate, indicating good stability of immobilized TiO\({}_{2}\)-DSAT. Therefore, in this study, efforts have been made to immobilize TiO\({}_{2}\) photocatalyst with pore matrix PEG 6000 and DSAT as a thin layer binder.