Electronic Theses and Dissertation

Pencemaran air akibat zat pewarna sintetis seperti metilen biru menjadi permasalahan lingkungan yang serius karena sifatnya yang sulit terurai secara alami, beracun, dan berdampak negatif pada organisme perairan. Salah satu upaya yang dapat dilakukan adalah memanfaatkan material alami seperti patahan terumbu karang sebagai sumber kalsium oksida (CaO) yang kemudian dimodifikasi dengan penambahan perak oksida (Ag₂O) untuk meningkatkan sifat adsorptif dan fotokatalitik. Penelitian ini bertujuan untuk mengetahui karakteristik komposit CaO–Ag₂O yang disintesis serta kemampuan komposit tersebut dalam proses adsorpsi dan fotodegradasi metilen biru pada berbagai variasi konsentrasi. Komposit disintesis melalui metode kalsinasi pada suhu tinggi dilanjutkan dengan proses impregnasi larutan AgNO₃, kemudian dikarakterisasi
menggunakan Fourier Transform Infrared (FTIR) untuk analisis gugus fungsi, Scanning Electron Microscopy (SEM) untuk morfologi permukaan, dan X-Ray Fluorescence (XRF) untuk komposisi unsur. Pengujian adsorpsi dilakukan pada variasi konsentrasi metilen biru 5–25 mg/L, sedangkan fotodegradasi dilakukan di bawah paparan sinar matahari selama 2 jam. Hasil menunjukkan bahwa komposit CaO–Ag₂O berhasil terbentuk dengan indikasi adanya pita serapan ikatan Ag–O, morfologi permukaan yang lebih halus, dan distribusi partikel Ag₂O yang merata. Kandungan Ag₂O meningkat menjadi 1,15% sesuai hasil XRF. Komposit ini mampu mengadsorpsi metilen biru dengan efisiensi mendekati 100% pada konsentrasi rendah hingga sedang, serta mampu mendegradasi metilen biru hingga 100% dalam waktu reaksi singkat. Sebagai kesimpulan, komposit CaO-Ag2O berpotensi menjadi solusi teknologi pengolahan air limbah pewarna yang lebih ramah lingkungan dan berkelanjutan.

Kata Kunci: Metilen biru, karakterisasi, fotodegradasi, komposit, patahan terumbu karang

Water pollution caused by synthetic dyes such as methylene blue is a serious environmental problem due to its nature, which is difficult to break down naturally, toxic, and has a negative impact on aquatic organisms. One approach that can be taken is to utilize natural materials such as coral fractures as a source of calcium oxide (CaO), which is then modified by adding silver oxide (Ag₂O) to enhance its adsorbent and photocatalytic properties. This study aims to determine the characteristics of the synthesized CaO-Ag₂O composite and its ability in the adsorption and photodegradation of methylene blue at various concentration variations. The composite was synthesized through a high-temperature calcination method followed by impregnation with AgNO₃ solution, then characterized using Fourier Transform Infrared (FTIR) for functional group analysis, Scanning Electron Microscopy (SEM) for surface morphology, and X-Ray Fluorescence (XRF) for elemental composition. Adsorption testing was conducted at methylene blue concentrations ranging from 5 to 25 mg/L, while photodegradation was performed under sunlight exposure for 2 hours. The results showed that the CaO–Ag₂O composite was successfully formed, indicated by the presence of Ag–O bond absorption bands, smoother surface morphology, and uniform Ag₂O particle distribution. The Ag₂O content increased to 1.15% according to XRF results. This composite was able to adsorb methylene blue with an efficiency approaching 100% at low to moderate concentrations and was able to degrade methylene blue by 100% in a short reaction time. In conclusion, the CaO-Ag₂O composite has the potential to become a more environmentally friendly and sustainable technological solution for wastewater treatment involving dyes. Keywords: Methylene blue, characterization, photodegradation, composite, coral fracture