Muhammad Fajar Arzena Nurhadi, - and Hendrawan, - and Yohanes Susanto Ridwan, - (2025) PREPARASI DAN KARAKTERISASI ELEKTRODA GRAFIT TERMODIFIKASI AuNPS HASIL GREEN-SYNTHESIS SEBAGAI SENSOR LOGAM TIMBAL SECARA ELEKTROKIMIA. S1 thesis, Universitas Pendidikan Indonesia.
Abstract
Timbal (Pb) merupakan logam berat toksik yang berbahaya bagi lingkungan dan kesehatan manusia, sehingga diperlukan metode deteksi yang sensitif, murah, dan ramah lingkungan. Penelitian ini bertujuan untuk menentukan kondisi optimal green-synthesis nanopartikel emas (AuNPs) menggunakan ekstrak kulit buah plum, mengkarakterisasi AuNPs hasil sintesis, dan mengevaluasi kinerja elektroda grafit yang dimodifikasi AuNPs dalam mendeteksi ion Pb(II) dengan teknik Differential Pulse Voltammetry (DPV). Ekstrak kulit buah plum dikarakterisasi menggunakan FTIR yang menunjukkan keberadaan gugus –OH dan C=C sebagai agen pereduksi dan penstabil. Optimasi sintesis AuNPs dilakukan dengan variasi pH, volume ekstrak, dan waktu reaksi. Kondisi optimum diperoleh dengan rasio volume prekursor dibanding volume ekstrak 7:3 dan waktu reaksi 30 menit, serta volume saat aquades saat maserasi adalah 80 mL, ditandai dengan munculnya puncak Surface Plasmon Resonance (SPR) pada 500–550 nm. Spektrum UV-Vis AuNPs memperlihatkan serapan khas pada 534,9 nm, sedangkan FTIR menunjukkan pergeseran pita serapan yang mengindikasikan interaksi antara senyawa fenolik dengan permukaan AuNPs. Hasil analisis TEM menunjukkan ukuran partikel AuNPs berbentuk sferis dengan rentang 3–30 nm dan rata-rata 13 nm. Nilai zeta potensial diperoleh sebesar –2,67 mV dengan konduktivitas 0,222 mS/cm, menunjukkan stabilitas koloid yang relatif rendah namun cukup untuk diaplikasikan dalam modifikasi elektroda. Elektroda grafit pensil (PGE) berhasil dimodifikasi menggunakan metode drop-casting dengan AuNPs hasil sintesis. Analisis SEM-EDX memperlihatkan distribusi AuNPs yang merata di permukaan elektroda serta keberadaan unsur Au. Kinerja sensor diuji menggunakan DPV terhadap larutan standar Pb(II) dengan rentang konsentrasi 25–200 ppb. Hasil pengukuran menunjukkan arus puncak meningkat secara signifikan pada PGE–AuNPs dibandingkan elektroda bare. Kurva kalibrasi menunjukkan hubungan linier antara arus puncak dengan konsentrasi Pb(II) dengan koefisien determinasi (R²) = 0,9294. Limit deteksi (LOD) diperoleh sebesar 18,95 ppb dan sensitivitas elektroda mencapai 1,56 µA/ppb. Secara keseluruhan, penelitian ini berhasil mencapai seluruh tujuan yang ditetapkan. Elektroda grafit termodifikasi AuNPs hasil green-synthesis terbukti memiliki sensitivitas dan kemampuan deteksi yang baik terhadap ion Pb(II), serta berpotensi dikembangkan sebagai sensor elektrokimia yang ekonomis, ramah lingkungan, dan aplikatif untuk pemantauan pencemaran logam berat di perairan. Lead (Pb) is a toxic heavy metal that poses serious threats to the environment and human health; therefore, a sensitive, low-cost, and eco-friendly detection method is required. This study aims to determine the optimal conditions for the green synthesis of gold nanoparticles (AuNPs) using plum peel extract, characterize the synthesized AuNPs, and evaluate the performance of a graphite electrode modified with AuNPs in detecting Pb(II) ions using Differential Pulse Voltammetry (DPV). The plum peel extract was characterized using FTIR, which revealed the presence of –OH and C=C groups acting as reducing and stabilizing agents. The optimization of AuNPs synthesis was carried out by varying pH, extract volume, and reaction time. The optimum condition was achieved at a precursor-to-extract volume ratio of 7:3, with a reaction time of 30 minutes, and using 80 mL of distilled water during maceration. This was indicated by the appearance of a Surface Plasmon Resonance (SPR) peak at 500–550 nm. The UV-Vis spectrum of AuNPs showed a characteristic absorption at 534.9 nm, while FTIR revealed shifts in absorption bands indicating interactions between phenolic compounds and the AuNPs surface. TEM analysis confirmed spherical AuNPs with sizes ranging from 3 to 30 nm and an average of 13 nm. The zeta potential value was –2.67 mV with a conductivity of 0.222 mS/cm, indicating relatively low colloidal stability but sufficient for electrode modification. The pencil graphite electrode (PGE) was successfully modified with the synthesized AuNPs using the drop-casting method. SEM-EDX analysis showed a uniform distribution of AuNPs on the electrode surface and confirmed the presence of Au elements. The sensor performance was tested using DPV for standard Pb(II) solutions in the concentration range of 25–200 ppb. The results demonstrated a significant increase in peak current for PGE–AuNPs compared to the bare electrode. The calibration curve exhibited a linear relationship between peak current and Pb(II) concentration, with a determination coefficient (R²) of 0.9294. The limit of detection (LOD) was determined to be 18.95 ppb, and the electrode sensitivity reached 1.56 µA/ppb. Overall, this study successfully achieved its objectives. The green-synthesized AuNP-modified graphite electrode proved to have good sensitivity and detection capability for Pb(II) ions, and shows potential as an economical, eco-friendly, and practical electrochemical sensor for monitoring heavy metal pollution in aquatic environments.
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| Item Type: | Thesis (S1) |
|---|---|
| Additional Information: | https://scholar.google.com/citations?user=yOmUJVsAAAAJ&hl=id ID SINTA Pembimbing : Hendrawan : 5994163 Yohanes Susanto Ridwan : 6756852 |
| Uncontrolled Keywords: | elektroda pensil grafit, green - synthesis, nanopartikel emas, voltammetri diferensial pulsa (DPV), Timbal (Pb). Differential pulse voltammetry (DPV), gold nanoparticles, green synthesis, Lead (Pb), pencil graphite electrode. |
| Subjects: | L Education > L Education (General) Q Science > QD Chemistry |
| Divisions: | Fakultas Pendidikan Matematika dan Ilmu Pengetahuan Alam > Program Studi Kimia - S1 > Program Studi Kimia (non kependidikan) |
| Depositing User: | Muhammad Fajar Arzena Nurhadi |
| Date Deposited: | 21 Sep 2025 10:11 |
| Last Modified: | 21 Sep 2025 10:11 |
| URI: | http://repository.upi.edu/id/eprint/139248 |
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