β Jurnal Kimia Sains dan Aplikasi 23 ( 9 )( 2020): 333 - 337 333 Jurnal Kimia Sains dan Aplikasi 23 ( 9 ) ( 2020): 333 - 337 »«14** -•»•? j - QJurnal Kimia H3Sains dan Aplikasi ISSN: 1410- 8917 Jurnal Kimia - Sains & Aplikasi e - ISSN: 2597- 9914 Jurnal Kimia Sains dan Aplikasi Journal of Scientific and Applied Chemistry Journal homepage: http: // ejournal .undip.ac.id / index.php / ksa Characterization and Application of Chitosan as a Natural Coagulant in Reducing Remazol Red Dyestuff Concentration and COD Value of Batik Liquid Waste H ) Check for updates a ,2,* Rifana Adilla Safitria > 1 , Maya Rahmayanti a Department of Chemistry, Faculty of Science and Technology, Universitas Islam Negeri Sunan Kalijaga , Yogyakarta , Indonesia * Corresponding author: ( 1 ) rifanaadillasafitri @gmail. com; ( 2 ,*) maya. rahmayanti@uin-suka. ac.id https: / /doi . 0rg/10.14710/ jksa. 23.9.333- 337 Article Info Abstract Article history: Received : 18 th July 2020 Revised: 11 th September 2020 Accepted: 20 th September 2020 Online: 30 th September 2020 Research on chitosan application as a natural coagulant in reducing the concentration of remazol red dye from batik liquid waste has been carried out. This study aims to study the effect of the acidity of batik wastewater on the coagulant ability to reduce the remazol red dye concentration and the COD value of batik liquid waste. In this study, chitosan compounds before and after coagulation were characterized using Fourier Transform Infrared ( FTIR) Spectroscopy. The pH range used in the coagulation process was pH 2- 6. Post - coagulation chitosan FTIR spectra showed a shift in the wave number in the 3400 cm 1 area , which indicated an interaction between the - OH group of chitosan and the dye remazol red. Remazol red dye was maximally coagulated by chitosan at pH 2. The percentage reduction in the dye concentration reached 100%, and the decrease in COD value at that pH was 71.69 %. Keywords: coagulation ; chitosan ; remazol red 1 . Introduction The development of the batik industry has had some positive and negative impacts. The negative impacts include the emergence of environmental problems due to batik liquid waste containing synthetic dye residue. The use of synthetic dyes such as remazol , naphthol , and indigosol produces synthetic dye waste that is non- biodegradable , carcinogenic, and can cause liver , kidney, anemia , and other cell disorders [ 1 ] . The treatment of dye waste before disposal needs to be done to avoid the risk of these hazards. Several researchers have reported using the adsorption method to reduce the dye contained in batik wastewater [ 2, 3 , 4 , 5 , 6 , 7 ]. Based on this research, the use of the adsorption method could not reduce the dye concentration in batik waste optimally. In this study, the remazol red concentration in batik wastewater was reduced using the chitosan coagulation method. Remazol red dye is one type of dye that is often used by the batik industry in Yogyakarta. Remazol red dye is widely used because it has a reasonably strong color resistance. However , its photodegradation process in nature is prolonged [8], so it is necessary to find an appropriate and straightforward method to reduce the concentration of remazol red dye in batik liquid waste. Coagulation is treating waste by adding a coagulant to the waste by stirring rapidly so that a homogeneous waste dispersion is obtained. Coagulation occurs due to the ions originating from the coagulant , which have a charge opposite the colloidal particles ' charge. The addition of a coagulant causes instability of the colloid particles and binds the colloid particles to form a floe. Coagulants can neutralize the charge of colloidal particles and bind these colloidal particles to form floe [ 9 ] . The use of coagulants from synthetic chemicals can cause new problems in the environment due to synthetic byproducts. Therefore, it is necessary to look for alternative coagulants from natural materials that tend to be environmentally friendly and effective in reducing the dye content in batik wastewater. Chitosan is poly- 2- amino- 2- deoxy- - 1 , 4 -D- glucopyranose with the molecular formula C6H11NO6 obtained from the chitin distillation process. Chitin comes from the skin, head , and tail of shrimp, which can be obtained from waste of vanamei shrimp, crab waste , and silage from tiger prawn heads [ 10] . Chitosan has a