Electronic Theses and Dissertation

Metilen Biru merupakan salah satu zat warna dengan struktur senyawa kimia aromatik heterosiklik dan bersifat kationik. Metilen biru bersifat toksik yang dapat menyebabkan iritasi, muntah, mual, diare, pusing dan meningkatnya detak jantung. Penurunan kadar zat warna metilen biru dalam lingkungan dapat melalui proses adsorpsi menggunakan adsorben cangkang tiram, Fe3O4, dan asam humat. Adsorben cangkang tiram, Fe3O4, dan asam humat memiliki kemampuan adsorpsi zat warna dikarenakan memiliki gugus hidroksil dan gugus karboksil serta bersifat magnetik yang mudah dikumpulkan dalam air. Adsorben cangkang tiram, Fe3O4, dan asam humat terbuat dari hasil sintesis material mikro-nano magnetik cangkang tiram, Fe3O4, dan asam humat. Karakteristik adsorben cangkang tiram, Fe3O4, dan asam humat menggunakan SEM, XRD, dan FTIR. Hasil uji SEM menunjukkan banyak pori-pori yang terbentuk dengan luas permukaan terbesar 5,412 µm. Hasil uji XRD menunjukkan bahwa adsorben cangkang tiram, Fe3O4, dan asam humat hanya menunjukkan 3 puncak dan memiliki struktur intermediate antara struktur kristal dan amorf yang disebut turbostratik atau struktur lapisan kisi acak. Selain itu, uji FTIR menunjukkan adanya gugus-gugus fungsi yang terdapat dalam adsorben cangkang tiram, Fe3O4, dan asam humat yang berperan aktif dalam proses penyerapan zat warna metilen biru seperti gugus karboksil dan gugus hiroksil. Hasil uji FTIR adsorben cangkang tiram, Fe3O4, dan asam humat dengan metilen biru menunjukkan serapan daerah yang mengadsorpsi metilen biru muncul pada puncak bilangan gelombang 1170,79 cm-1 yang berasal dari gugus C-N aromatik metilen biru. Adsorben cangkang tiram, Fe3O4, dan asam humat yang dihasilkan mampu menyerap metilen biru dalam larutan berair pada kondisi optimum yang terjadi pada pH 5 dengan waktu kontak 90 menit dengan persentase penyerapan 71,42%. Kinetika adsorpsi reaksi yang dianalisis menunjukkan bahwa adsorpsi metilen biru yang terjadi sesuai dengan kinetika pseudo orde dua dengan nilai R2 yaitu 0,9949, dan konstanta laju reaksi 0,0621 g.mg-1.menit-1.

Kata kunci: cangkang tiram, SEM, XRD, FTIR, Fe3O4, asam humat, adsorpsi, metilen biru

Methylene Blue is a dye with a heterocyclic aromatic chemical compound structure and is cationic. Methylene blue is toxic which can cause irritation, vomiting, nausea, diarrhea, dizziness and increased heart rate. Reducing the levels of methylene blue dye in the environment can be through an adsorption process using oyster shell adsorbents, Fe3O4, and humic acid. Oyster shell adsorbents, Fe3O4, and humic acid have the ability to adsorb dyes because they have hydroxyl and carboxyl groups as well as magnetic properties which are easy to collect in water. Oyster shell adsorbent, Fe3O4, and humic acid is made from the synthesis of oyster shell, Fe3O4, and humic acid micro-nanomagnetic materials. Characteristics of oyster shell, Fe3O4, and humic acid adsorbents using SEM, XRD, and FTIR. SEM test results showed that many pores were formed with the largest surface area of ​​5.412 µm. The XRD test results showed that the oyster shell, Fe3O4, and humic acid adsorbents only showed 3 peaks and had an intermediate structure between crystalline and amorphous structures called turbostratic or random lattice layer structures. In addition, the FTIR test showed the presence of functional groups contained in the oyster shell adsorbent, Fe3O4, and humic acid which play an active role in the absorption process of methylene blue dye such as carboxyl groups and hydroxyl groups. The FTIR test results for the adsorbent of oyster shell, Fe3O4, and humic acid with methylene blue showed that the absorption of the methylene blue adsorbing area appeared at the peak of wave number 1170.79 cm-1 originating from the aromatic C-N group of methylene blue. The oyster shell adsorbent Fe3O4 and humic acid produced were able to adsorb methylene blue in aqueous solutions at optimum conditions which occurred at pH 5 with a contact time of 90 minutes with an absorption percentage of 71.42%. The adsorption kinetics of the analyzed reactions showed that the adsorption of methylene blue was in accordance with pseudo second order kinetics with an R2 value of 0.9949, and a reaction rate constant of 0.0621 g.mg-1.minute-1. Keywords: oyster shell, SEM, XRD, FTIR, Fe3O4, humic acid, adsorption, methylene blue