Isotermis dan termodinamika adsorpsi methylene blue menggunakan batang Jagung termodifikasi asam sitrat

INDONESIA:

Batang jagung memiliki potensi sebagai biosorben dalam penurunan kadar zat warna dalam limbah. Penelitian ini bertujuan untuk mengetahui tipe isotermis adsorpsi dan termodinamika adsorpsi batang jagung terhadap methylene blue. Selain itu dilakukan karakterisasi morfologi dan gugus fungsi menggunakan Scanning Electron Microscopy (SEM) dan Fourier Transform Infrared Spectroscopy (FTIR) pada biosorben batang jagung.

Tahapan penelitian ini meliputi: (1) Optimasi analisis methylene blue menggunakan spektrofotometer UV-Vis. (2) Preparasi sampel meliputi demineralisasi dan modifikasi batang jagung (3) Penentuan isotermis adsorpsi dengan variasi konsentrasi methylene blue 50, 100, 150, 200, 250, 300, 350, dan 450 mg/L (4) Penentuan termodinamika adsorpsi dengan variasi suhu 30, 40, 50 dan 60 °C, (5) Karakterisasi batang jagung menggunakan FTIR dan SEM.

Hasil penelitian menunjukkan bahwa isotermis pada penelitian ini mengikuti tipe isotermis adsorpsi Langmuir dengan (R²) 0,9911 dan kapasitas adsorpsi sebesar 40,3226 mg/g. Hasil termodinamika adsorpsi menunjukkan bahwa adsorpsi methyelene blue berlangsung secara spontan dengan nilai (ΔG°) adalah -0,8880 kJ/mol, proses eksotermis dengan nilai (ΔH°) adalah -8,912 kJ/mol dan terjadi penurunan ketidakteraturan antara permukaan adsorben dengan adsorbat selama proses adsorpsi dengan nilai (ΔS°) -0,0265 kJ/mol.K. Karakterisasi morfologi permukaan batang jagung menggunakan SEM menunjukkan batang jagung tanpa modifikasi memiliki struktur serpihan yang tak beraturan. Dan setelah modifikasi batang jagung berbentuk serat, sedangkan setelah adsorpsi methylene blue seratnya lebih terdispersi. Hasil analisis spektra IR menunjukkan bahwa setelah proses modifikasi, muncul puncak baru pada bilangan gelombang 1736 cm-¹ menunjukkan vibrasi C=O yang menandai adanya gugus ester.

ENGLISH:

Corn stalks has the potential as a biosorbents in decreasing levels of dyes in waste. This research aims to determine the type of isothermic and thermodynamic adsorption of corn stalks on methylene blue. Furthermore, the morphological and functional groups were characterized using the Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) on the biosorbent corn stalks.

The stages of this research are: (1) Optimization of methylene blue analysis using UV-Vis spectrophotometer, (2) Sample preparation includes demineralization and modification of corn stalks, (3) Determination of isothermic adsorption with variatons in concentration of Methylene Blue of 50, 100, 150, 200, 250, 300, 350, and 450 mg/L, (4) Determination of thermodynamic adsorption with temperature variations of 30, 40, 50, and 60 °C, (5) Characterization of corn stalks using FTIR and SEM.

The results showed that the isotherms in this research followed the Langmuir isothermic adsorption type with (R²) 0,9911 and the adsorption capacity was 40,3226 mg/g. The thermodynamic adsorption showed that methylene blue spontaneously with the value (ΔG°) was -0,8880 kJ/mol, the exothermic process with the value (ΔH°) was -8,912 kJ/mol and there was a decrease in irregularity between the surface adsorbent with adsorbate during the adsorption process with the value (ΔS°) -0,0265 kJ/mol.K. The morphological characterization of the surface corn stalks using SEM showed that unmodified corn stalks has an irregular flake structure. And after modification the corn stalks were thought in the form of fiber, while after adsorption of methylene blue the fiber is more dispered. The result of the IR spectra analysis showed that after the modification process, a new peak appeared at the wave number 1736 cm-¹ indicating a C=O vibration that indicated the presence of an ester group.