Efektivitas Karbon Dot Terdoping Single dan Multi Heteroatom pada Deteksi Ion Besi(III) di Lingkungan Perairan

Naufal Aqila Harits Faiza, Prof. Suherman, S.Si., M.Sc., Ph.D.; Dr. Deni Pranowo, S.Si., M.Si.

2026 | Skripsi | KIMIA

Penelitian ini bertujuan untuk mensintesis karbon dot terdoping single- dan multi- heteroatom (doped-CDs) sebagai sensor deteksi ion Fe³⁺ di lingkungan perairan. Doped-CDs disintesis dengan metode one-pot microwave-assisted synthesis menggunakan asam sitrat sebagai sumber karbon dengan dopan heteroatom N, F, S, dan kombinasi multi-heteroatomnya. Optimasi kondisi sintesis dilakukan dengan variasi daya (100-800 W), waktu (10-420 detik), dan massa dopan (0%-100% massa asam sitrat). Kajian fotostabilitas doped-CDs menguji ketahanan sifat optiknya terhadap pengaruh pH, paparan sinar UV, dan waktu penyimpanan. Uji selektivitas dan sensitivitas terhadap ion Fe³⁺ dilakukan dengan memvariasikan konsentrasi ion tersebut untuk mengevaluasi efek quenching yang dimunculkan. Karakterisasi CDs dilakukan menggunakan spektrofluorometer, spektrofotometer UV-Vis, ATR, dan LR-TEM untuk memastikan pembentukan carbon core dan keberhasilan pasivasi heteroatomnya.

Doped-CDs (N-CDs, N,S-CDs, dan N,S,F-CDs) berhasil disintesis dengan kondisi optimum yang berbeda dan menghasilkan partikel quasi-spherical berukuran 1,6–5,6 nm, dengan N-CDs menunjukkan intensitas fluoresens tertinggi. Hasil karakterisasi mengonfirmasi keberhasilan dopan N, S, dan F dalam memodulasi sifat optik, termasuk peningkatan intensitas oleh N dan F serta red-shift oleh F. Seluruh doped-CDs menunjukkan fotostabilitas baik pada pH 4–9 dan peningkatan intensitas fluoresens lebih dari 20% selama 50 hari penyimpanan, namun mengalami photobleaching setelah paparan UV berkepanjangan. Ketiganya menunjukkan selektivitas tinggi terhadap Fe³? dengan rentang linearitas dan sensitivitas yang bervariasi; N-CDs cenderung mengalami quenching berbasis Inner Filter Effect (IFE), sedangkan N,S-CDs dan N,S,F-CDs menunjukkan indikasi Static Electron Transfer (SET). Seluruh doped-CDs berhasil diaplikasikan pada sampel riil air dengan presisi tinggi (RSD < 5>

This study aims to synthesize single- and multi-heteroatom-doped carbon dots (doped-CDs) as Fe³⁺ ion detection sensors in aquatic environments. Doped-CDs were synthesized using a one-pot microwave-assisted synthesis method with citric acid as the carbon source and N, F, S, and combinations of its multi-heteroatoms as dopants. Synthesis conditions were optimized by varying the power (100-800 W), time (10-420 seconds), and dopant mass (0%-100% citric acid mass). The photostability of doped-CDs was examined by testing the resistance of their optical properties to the effects of pH, UV exposure, and storage time. Selectivity and sensitivity tests for Fe³⁺ ions were performed by varying the concentration of these ions to evaluate the quenching effect produced. CDs were characterized using a spectrofluorometer, UV-Vis spectrophotometer, ATR, and LR-TEM to confirm the formation of the carbon core and the success of heteroatom passivation.

Doped-CDs (N-CDs, N,S-CDs, and N,S,F-CDs) were successfully synthesized under different optimal conditions and produced quasi-spherical particles measuring 1.6–5.6 nm, with N-CDs exhibiting the highest fluorescence intensity. Characterization results confirmed the success of N, S, and F dopants in modulating optical properties, including intensity enhancement by N and F and red-shift by F. All doped-CDs exhibited good photostability at pH 4–9 and more than 20% increase in fluorescence intensity during 50 days of storage, but underwent photobleaching after prolonged UV exposure. All three exhibited high selectivity toward Fe³ with varying linearity ranges and sensitivities; N-CDs tended to undergo Inner Filter Effect (IFE) based quenching, while N,S-CDs and N,S,F-CDs showed indications of Static Electron Transfer (SET) mechanisms. All doped-CDs were successfully applied to real water samples with high precision (RSD < 5>

Kata Kunci : dopan heteroatom, Fe3+, IFE, karbon dot, microwave, SET