To Recycle Zinc (Zn) from Used Zinc-Carbon Battery as Biogas Desulfurizer Tjokorda Gde Tirta Nindhia, I Wayan Surata, I Ketut Adi Atmika, Dewa Ngakan Ketut Putra Negara, and I Wayan Putra Adnyana Department of Mechanical Engineering, Engineering faculty, Udayana University, Jimbaran, Bali, Indonesia, 80361 E-mail: nindhia@yahoo.com Abstract—Biogas should be purified before further application as a fuel for engine. Hidrogen Sulfide (H 2 S) is one the gas impurities that rising problem for the engine since will caused acidity to lubricant and corrosive to metal part of the engine. In this research, zinc obtained from used battery is utilized as desulfurizer. Two methods are introduced in this article for processing zinc as desulfurizer. First by immersing in the salt water to produce zinc oxide (ZnO) and secondly by galvanic coupling with iron in order to obtain ion Zn 2+ . It is found that both processing techniques having optimum result in reducing H 2 S impurity in the biogas. Index Terms—zing, used battery, recycle, desulfurizer, hidrogen sulfide, biogas I. INTRODUCTION In developed country such as Japan [1] and Switzerland [2], the battery waste is well managed. The Japanese government takes care of establishing a system to transport and treat them. Similarly in Switzerland there is an action to treatment of the unrecoverable waste in an environmentally safe manner. Zinc is in a limited amount on the earth. The world resource of zinc is in the range 20-40 year [3]. Therefore recycle of the zinc should be promoted The zinc-carbon battery consist of zinc case as a container and negative terminal, carbon road as positive terminal and mixture of MnO 2 , graphite powder and ammonium chloride as electrolyte as can be seen in Fig. 1. After used or spent, the used battery still contains zinc case that possible to be recycled again. In order to use biogas as fuel of the engine, the removal of hydrogen sulfide (H 2 S) is particularly crucial because it can cause corrosion to metal parts of the engine [4]. Several techniques of H 2 S removal from biogas are available in several publications. In situ removal of H 2 S from biogas during anaerobic digestion process [5] for example, this technique using FeCl 3 dosing which is quite problem for local farmer in developing country to obtain it. The next generation of desulfurizer was introduced by Tippayawong and Thanompongchart [6] which involved Manuscript received December 12, 2013; revised February 13, 2014. column reactor. This technique using external energy for circulating aqueous solution countercurrent flow so that not appropriate for small portable or mobile type of biogas system because consume quite large space. By using just activate carbon (AC) as demonstrated by Mescia et al. [7] resulting in low selectivity of activated carbon towards the adsorption of only sulfur species. Finally it was informed recently [8] that ZnO is powerful for desulfurization of biogas. Figure 1. Section view of zinc-carbon battery It is the purpose of this research to utilize zinc from used zinc-carbon battery as desulfurizer. The process will be developed for this purpose in order problem of waste battery could be overcome simultaneous with elimination of H 2 S impurities in the biogas. The technique involved galvanic coupling between zinc and iron that can release ion Zn 2+ which is reactive to H 2 S. Galvanic coupling is a potential difference that usually exists between two dissimilar metals when they are immersed in conductive solution. This potential difference produce electron flow between them and metal ion will be released from one of the coupling [9]. The metal ion is hoped will react with H 2 S so that process of desulfurization to occur. II. EXPERIMENTAL The zinc case from the used battery was taken out and cut to become small pieces as depicted in Fig. 2 and iron International Journal of Materials Science and Engineering Vol. 2, No. 1 June 2014 ©2014 Engineering and Technology Publishing 39 doi: 10.12720/ijmse.2.1.39-42