Optimasi Kadar Dopan Fe3+ Pada g-C3N4 dan Uji Aktivitas Fotokatalitiknya terhadap Degradasi Metilen Biru

Divari, Dennise Atlan Aulia (2026) Optimasi Kadar Dopan Fe3+ Pada g-C3N4 dan Uji Aktivitas Fotokatalitiknya terhadap Degradasi Metilen Biru. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5004221112_Undergraduate_Thesis.pdf - Accepted Version Restricted to Repository staff only Download (5MB)

Abstract

Pencemaran lingkungan akibat limbah zat warna industri tekstil menjadi permasalahan serius yang memerlukan solusi penanganan efektif, salah satunya melalui pendekatan fotokatalisis menggunakan graphitic carbon nitride (g-C3N4), namun laju rekombinasi pasangan elektron-lubang yang tinggi menjadi kendala utama yang membatasi efisiensi fotokatalitiknya. Penelitian ini bertujuan untuk meningkatkan aktivitas fotokatalitik g-C3N4 melalui doping logam besi (Fe) dengan variasi konsentrasi sebagai fotokatalis untuk degradasi zat warna metilen biru. Sintesis g-C3N4 terdoping Fe dilakukan dengan metode polikondensasi termal satu tahap menggunakan melamin sebagai prekursor karbon nitrida dan Fe(NO3)3·9H2O sebagai sumber dopan Fe. Variasi konsentrasi Fe sebesar 1, 2, 4, dan 6%. Proses kalsinasi dilakukan pada suhu 550°C selama 4 jam. Karakterisasi material dilakukan menggunakan XRD, FTIR, UV-Vis DRS, dan EIS. Hasil XRD menunjukkan struktur g-C3N4 tetap terjaga pada seluruh sampel, dengan kristalinitas terbaik (FWHM 1,05°; ukuran kristalit 8,1 nm) diperoleh pada g-C3N4 terdoping Fe 2%, sedangkan g-C3N4 terdoping Fe 6% menunjukkan kerusakan struktur akibat kelebihan dopan. Analisis FTIR mengonfirmasi kehadiran pita khas g-C3N4, termasuk pita diagnostik 808 cm-1 untuk moda vibrasi cincin heptazin, tanpa pergeseran signifikan pada seluruh sampel dan tanpa munculnya pita serapan baru yang mengindikasikan pembentukan fase oksida terpisah. Analisis UV-Vis DRS menunjukkan penurunan energi celah pita dari 2,87 eV (g-C3N4 murni) menjadi 2,65 eV pada g-C3N4 terdoping Fe 2%. Uji aktivitas fotokatalitik terhadap degradasi MB (30 ppm, 0,03 g katalis, 150 menit) menunjukkan sampel g-C3N4 terdoping Fe 2% memiliki performa terbaik dengan efisiensi degradasi 61,39% (k = 0,00617 menit-1), melampaui g-C3N4 murni (37,98%) maupun variasi dopan lain. Performa optimal ini berkaitan dengan resistansi transfer muatan (Rct) terendah (87,62 Ω) dari analisis EIS, bukan oleh lebar celah pita maupun kapasitas adsorpsi. Optimasi kondisi reaksi pada sampel g-C3N4 terdoping Fe 2% menghasilkan efisiensi degradasi tertinggi sebesar 85,1% (k = 0,01304 menit-1) pada dosis katalis 50 mg, pH 3, dan konsentrasi MB 10 ppm. Uji scavenger mengidentifikasi hole (h+) sebagai spesies reaktif paling dominan, diikuti oleh elektron (e−) dan radikal superoksida (•O2−), sedangkan radikal hidroksil (•OH) berperan minor yang konsisten dengan posisi EVB material yang tidak cukup positif untuk mengoksidasi air secara langsung menjadi •OH. Hasil penelitian menunjukkan bahwa doping Fe optimum pada kadar 2% efektif meningkatkan aktivitas fotokatalitik g-C3N4 melalui peningkatan efisiensi pemisahan muatan.
======================================================================================================================================
Environmental pollution caused by dye waste from the textile industry has become a serious problem requiring effective treatment solutions, one of which is the photocatalytic approach using graphitic carbon nitride (g-C3N4); however, the high electron-hole recombination rate remains the main obstacle limiting its photocatalytic efficiency. This study aims to enhance the photocatalytic activity of g-C3N4 through iron (Fe3+) metal doping at various concentrations as a photocatalyst for the degradation of methylene blue dye. Fe-g-C3N4 was synthesized via one-step thermal polycondensation using melamine as the carbon nitride precursor and Fe(NO3)3·9H2O as the Fe3+ dopant source. Fe3+ concentrations varied at 1, 2, 4, and 6%, calcined at 550°C for 4 hours. Material characterization was performed using XRD, FTIR, UV-Vis DRS, and EIS. XRD results showed that the g-C3N4 structure was preserved across all samples, with the best crystallinity (FWHM 1.05°; crystallite size 8.1 nm) obtained for 2% Fe-doped g-C3N4 while 6% Fe-doped g-C3N4 exhibited structural degradation due to excess dopant. FTIR analysis confirmed the presence of characteristic g-C3N4 bands, including the diagnostic band at 808 cm-1 corresponding to the heptazine ring vibration mode, with no significant shift obseerved across all samples and no emergence of new absorption bands indicating the formation of a separate oxide phase. UV-Vis DRS analysis revealed a decrease in bandgap energy from 2.87 eV (pristine g-C3N4) to 2.65 eV for 2% Fe-doped g-C3N4. Photocatalytic activity tests for MB degradation (30 ppm, 0.03 g catalyst, 150 minutes) showed that 2% Fe-doped g-C3N4 exhibited the best performance, with a degradation efficiency of 61.39% (k = 0.00617 min⁻¹), surpassing pristine g-C3N4 (37.98%) and the other doping variations. This optimal performance was associated with the lowest charge transfer resistance (Rct = 87.62 Ω) from EIS analysis, rather than bandgap width or adsorption capacity. Reaction condition optimization for 2% Fe-doped g-C3N4 yielded the highest degradation efficiency of 85.1% (k = 0.01304 min-1 ) at a catalyst dose of 50 mg, pH 3, and an MB concentration of 10 ppm. Scavenger tests identified photogenerated holes (h+ ) as the most dominant reactive species, followed by electrons (e- ) and superoxide radicals (•O2- ), while hydroxyl radicals (•OH) played only a minor role that consistent with the material's EVB position, which was not sufficiently positive to directly oxidize water into •OH. These findings demonstrate that optimum Fe doping at 2% effectively enhances the photocatalytic activity of g-C3N4 through improved charge separation efficiency.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	grafit karbon nitrida (g-C3N4), doping besi (Fe), fotokatalisis, degradasi metilen biru, graphitic carbon nitride (g-C3N4), iron (Fe) doping, photocatalysis, methylene blue degradation.
Subjects:	Q Science > QD Chemistry > QD501 Catalysis. Catalysts. Q Science > QD Chemistry > QD716 Photocatalysis.
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Chemistry > 47201-(S1) Undergraduate Thesis
Depositing User:	Dennise Atlan Aulia Divari
Date Deposited:	05 Aug 2026 04:14
Last Modified:	05 Aug 2026 04:14
URI:	http://repository.its.ac.id/id/eprint/144037

Actions (login required)

View Item