THE POTENTIAL OF ACTIVATED BIOCHAR DERIVED BY COCONUT SHELLS (COCOS MUCIFERA L.), MAGNETITE AND DIMETHYLGLYOXIMATE AS MODIFIER FOR CARBON PASTE ELECTRODES IN THE VOLTAMMETRIC DETERMINATION OF NI(II)

• Main Author: Wirhamna
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/79207
• Institution: Institut Teknologi Bandung

Ni(II) is one of the heavy metal ions that present in domestic water. Due to the potential toxicity that can contaminate the environment, it is important to determine the lowest concentrations of Ni(II) as a preventive measure againts pollution. The research aims to develop a simple method using voltammetry for analyzing the concentration of Ni(II) ions, employing a modified carbon paste electrode (CPE). Activated biochar (AB) serves as alternative modifier due to its microporous that acting as active sites and enhancing the sensitivity of the carbon paste electrode (CPE). Activated biochar is derived from environmentally friendly biomass precursor, coconut shell. The preparation of activated biochar involves carbonization at a temperature of 400 ? followed by activation process using nitric acid (HNO3). Magnetite (Mag) is employed as a modifier to enhance the conductivity and sensitivity of the carbon paste electrode (CPE). The preparaton of magnetite is carried out through the co-precipitation method. Dimethylglioximate (DMG) acts as a selectively complexing agent for Ni(II) and is used as modifier to improve the selectivity of the CPE. The sinthesized activated biochar and magnetite were subsequently characterized using Fourier Transform Infra Red Spectroscopy (FTIR), Scanning Electron Microscopy – Energy Dispersive X-Ray (SEM-EDX) and X-Ray Diffraction (XRD). The optimized measurement conditions yielded CPE- DMG/BA/Mag with optimum percentage composition of DMG; BA; Mag being 10; 7.5; 1 % using Square Wave Voltammetry (SWV). The measurement conditions of Ni(II) ions were set at 0,1 mM in Ammonium Buffer Solution at pH 9 as electrolyte conditions, within potential range of -1300 to -700 mV with scan rate of 100 mV/s. The validation results of CPE indicate the stability of CPE-DMG/BA/Mag over 45 repetitions and 10 electrodes replicateds with consecutive %CV values of 4.31 and 3.71 %, respectively that both below the %CV Horwitz criterion of 4.33%. The scan rate analysis indicates that the electron transfer process is controlled by the adsorption process. The linier range analysis indicates that the CPE-DMG/BA/Mag measurement achieves a detection limit up to 1.2745 nM in linier range at 2 – 20 nM Ni(II). The working electrode CPE-DMG/BA/Mag also demonstrates selectivity and stability in measurement of Ni(II) ions, even in presence of interfering ions up to 100 times Ni(II) concentrations. The measurements of Ni(II) using CPE-DMG/BA/Mag with voltammetric methods have also been validated againts the standar method of Atomic Absorption Spectroscopy (AAS). The analysis of real samples was conducted in citarum River : Babakan Siliwangi, revealing a measured concentration of Ni(II) using CPE-DMG/BA/Mag at 13.223 nM. The measured concentration of Ni(II) in real samples is lower that the river quality standard that set by Republik Indonesia Government Regulation Number 22 of 2021, which has a minimum requirement of 0.05 mg/L. Therefore, it can be concluded that there is no contamination of Ni(II) ions in the river water.