Preparation Of ZnO/SiO2 Composite From Battery Waste And Rice Husk Ash For Decolorization Of Methylene Blue Eko Prabowo Hadisantoso 1 , Popy Listiani 2 , Soni Setiadji 3 {ekoph@uinsgd.ac.id 1 , popylistiani27@gmail.com 2 , s.setiadji@uinsgd.ac.id 3 } Department of Chemistry, Faculty of Science and Technology, UIN Sunan Gunung Djati Bandung Jl. A.H. Nasution No. 105 Bandung, West Java, Indonesia 1 Abstract. The composite of ZnO/SiO2 has been synthesized from battery waste as a source of ZnO and rice husk ash as a source of SiO2. The composite was used to decolorize of methylene blue by the photocatalytic method under visible light. The ZnO/SiO2 composites were synthesized by the sol-gel method. The Zinc metal from the waste battery is separated, cleaned, and reacted with acid which then produces a solution of Zn 2+ . While rice husk ash was reacted with a strong base to produce Na2SiO3 solution. Then the two solutions are mixed with the mole ratios of ZnO:SiO2 are 1:4, 1:1, 4:1, 8:1 and 16:1. Composite characterization was carried out using XRD for all composites and SEM for composites with the best photocatalytic performance. The photocatalytic performance of composites was tested against methylene blue solution. The best performance of composites can decolorize methylene blue as much as 96.91% by using composite 4:1 as much as 150 mg with the exposure time of visible light for 180 minutes and using methylene blue 20 ppm as much as 25 mL. Keywords: ZnO/SiO2 composites, methylene blue, photocatalysts, battery waste, rice husk ash. 1 Introduction ZnO is one semiconductor that the application is extensive [1] [2] [3] [4]. One of them is as a photocatalyst for handling organic dye [5]. Photocatalytic treatment is preferred because it has high efficiency [6], economical [7], and environmentally friendly [8]. Photocatalyst performance is influenced by particle size distribution [9], morphology [10], crystalline phase [11], porosity [3], and accessibility of active sites [12]. To increase the porosity of the material, it can be done by combining ZnO with another material that is not photocatalyst and has high porosity [13]. So it is expected that accessibility to active sites can be improved. In this study, the synthesis of ZnO/SiO2 composites was derived from waste batteries and rice husk ash. SiO2 is chosen as a matrix because the amorphous state has a high porosity [14]. Besides that, the source of silica is quite easy to find from nature. ZnO is obtained from the treatment of Zn-C primary battery waste [15]. This battery is a type of disposable battery that usually after using it, Indonesian people disposed it into the environment without further handling. The metal mass of Zn found in battery size AA (R6) is around 20%. ZnO synthesis from battery waste was carried out using the precipitation method, this method was chosen because it produced ZnO with high purity [16]. ICONISTECH 2019, July 11-12, Bandung, Indonesia Copyright © 2021 EAI DOI 10.4108/eai.11-7-2019.2297521