DOI: 10.21776/ub.jpacr.2020.009.03.524 J. Pure App. Chem. Res., 2020, 9 (3), 171-176 22 October 2020 X The journal homepage www.jpacr.ub.ac.id p-ISSN : 2302 – 4690 | e-ISSN : 2541 – 0733 This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (http://creativecommons.org/licenses/by-nc/4.0/) The Effect of Rhodamine B on the Properties of Fluorescent Nanoparticles Derived from Geothermal Silica Yovilianda Maulitiva Untoro, 1 Diaz Ayu Widyasari, 2 Edi Supriadi, 1 S.N Aisyiyah Jenie 1* 1 Research Centre for Chemistry, Indonesian Institute of Sciences, Kawasan Puspiptek, Building 452, Serpong, Tangerang Selatan, Banten 15314 Indonesia 2 Department of Chemistry, Faculty of Science and Technology, Universitas Islam Negeri Syarif Hidayatullah Jakarta, Jl. Ir.H.Juanda No.96 Cempaka Putih, Ciputat, Kota Tangerang Selatan,Banten 14512 Indonesia * Corresponding email: siti045@lipi.go.id Received 18 December 2019; Accepted 22 October 2020 ABSTRACT Rhodamine B can be used as a fluorophore to produce fluorescent silica nanoparticles derived from geothermal sludge. The purpose of this research is to synthesize fluorescent silica nanoparticles (FSNP) modified with rhodamine B and cetyl trimethyl ammonium bromide (CTAB) using sol-gel method. Geothermal waste was used as a precursor and added with NaOH at 90 0 C to generate sodium silicate. Rhodamine B, as the fluorescent dye were added with concentration variations ranging from 0.156 mg/g to 10 mg/g.CTAB was used as template and HCl 2N was applied as gelling catalyst with aging time of 18 hours. Characterization of FSNP was measured using spectrofluorometer to identify the fluorescent intensity, fourier transform infrared (FT-IR) to determine the functional group of FSNP, Brauner-Emmett-Teller (BET) adsorption to calculate the specific area of the particles, X- ray diffraction (XRD) to analyze the crystallographic phases, and transmission electron microscopy (TEM) to analyze the surface morphology of the FSNP. FT-IR and fluorescent intensity results showed that FSNP with 2.5 mg/g of rhodamine B had the optimum characteristics. The FSNP was in amorphous phase with uniform pore distribution. BET analysis showed that the specific surface of the FSNP was 190.22 m 2 /g. Keywords: fluorescent silica nanoparticles, rhodamine B, cetyl trimethyl ammonium bromide, sol-gel, geothermal. INTRODUCTION Geothermal sludge is a waste material generated from geothermal power plants which has been reported to reduce the productivity hence should be removed. The geothermal waste contains high amount of amorphous silica which is potential to be modified into silica nanoparticles. Using the geothermal silica to generate silica-based nanomaterial provides a way to solve the waste problem. Silica is a non-toxic and functionable material with the general formula of SiO2 consisting silicon and oxygen [1]. Conventionally, silica was synthesized from either silicate solution or silane reagents [2]. There are some methods to synthesize silica nanoparticles one of which is the sol-gel method due to its simplicity, low temperature requirement and low cost [3]. Fluorescent silica nanoparticle can be modified by the incorporation of organic molecules such as fluorescent dyes within the silica matrix through sol-gel process. When fluorescent dyes are assembled within the silica pores, the fluorescence properties of such dye changes [4].