STUDY OF GOLD WIRE COATED POLYPYRROLE AS PHOSPHATE ION SENSOR MATERIALS BY POTENTIOMETRIC

• Main Author: Hikmat
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/32317
• Institution: Institut Teknologi Bandung

Fabrication of Molecular imprinted polymers (MIP) phosphate as phosphate ion sensor materials studied in this research. Phosphorus (commonly found in the form of phosphate) is an essential nutrient for all crops and in modern agriculture. In addition, a cause of eutrophication in phosphate storage dams, sewage treatment plants, rivers, and lakes, is also the cause of the smell of mold during the summer. Phosphate ion release as much as 10 mg L–1 to a body of water can contribute to eutrophication, so it is very important phosphate ion monitoring. Needs precise control of the amount of phosphate added to the plants and water bodies in a fast, selective, accurate and simple way of measuring phosphate can be met by a phosphate selective sensor made of phosphate MIP by using conductive polymer as a phosphate sensor. The problems that emerged in this study is how MIP phosphate synthesis, characterization and testing. The study begins by making reference electrode. Reference electrode was made by coating the Ag wire with AgCl. Electrolyzed Ag wire in 3 M KCl solution with a potential of 2 volts for 15 minutes. Ag wire which has been coated AgCl later incorporated into the electrode body, and then filled by 3 M KCl solution. Reference electrodes were characterized before use. The characterization results show that made reference electrode has slightly shifted compared to the peak oxidation commercial reference electrode. However, the shift is relatively small, so that the characteristics of electrodes made references treated the same as commercial references electrodes. It can be concluded that electrodes made references can be used in this study. MIP-making process using a potentiostat of E-DAQ type e-corder 401 with cyclic voltammetry method. Working conditions when making MIP is set parameters at 2 mA current, potential range between -0,9 to 1,0 V, scan rate 100 mV / s and cycle 10 times. MIP selectivity phosphate test performed using the potentiometric method. Preparation of electropolymerize MIP solution done by mixing 0,05 M pyrrole, 0,05 M diphenyl phosphate, 0,05 M ethylene glycol dimethacrylate (EGDMA), and 0,5 M NaClO4 in 25 mL of distilled water. Optimization result of fabrication MIP obtained in working condition 50 mA current, potential range between -0,8 to 0,6 V, scan rate 100 mV/s, and cycle 10 times. Results of electropolymerization is a black coating that sticks to the gold wire. Pyrrole electropolimerize results are consistent with the reference voltammogram electropolimerization of pyrrole. MIP phosphate then characterized using infrared spectrophotometer. Results characterization using infrared spectrophotometer can not be used as a reference to determine whether the material is synthesized polypyrrole or not. This is because the resulting peaks was wide. In addition, the resulting pattern spectra are not in accordance with polypyrrole spectra. So that the characterization is done by visual observation. Visual observation of the synthesized electrode is black solid phase, and attached to a gold wire is used. Results Scanning Electron Microscope (SEM) showed that the morphology of the synthesized polypyrrole uniform, regular, and has cavities. MIP electrode was then tested using anion selectivity PO4 3-, HPO4 2-, and H2PO4- with variations in the concentration of 10–1 M to 10–7 M and bullies ion Cl-, NO3-, and SO4 2–. Test results and the selectivity coefficient calculation shows that MIP electrode can be made to respond phosphate anion with the presence of anion bullies.