Biochar Kulit Singkong Terimpregnasi Mn3O4 untuk Adsorpsi Zat Warna Kristal Violet

Viona Choirun Nisa Bahri, Prof. Dr.rer.nat. Nurul Hidayat Aprilita, M.Si. ; Dr. Agus Kuncaka, DEA

2025 | Skripsi | KIMIA

Telah dilakukan penelitian penggunaan biochar-Mn3O4 sebagai adsorben zat warna kristal violet. Penelitian terdiri dari sintesis biochar kulit singkong, impregnasi biochar dengan Mn3O4, karakterisasi adsorben menggunakan instrumen XRD, FTIR, SEM-EDX, dan SAA, serta studi adsorpsi kristal violet dengan metode batch. Parameter yang mempengaruhi kinerja adsorpsi berupa pH larutan, massa adsorben, waktu kontak, dan konsentrasi awal adsorbat dipelajari untuk mengetahui kondisi optimum adsorpsi. Konsentrasi zat warna kristal violet sebelum dan sesudah adsorpsi diukur dengan spektrofotometer UV-Vis. Selain itu, juga dilakukan perbandingan efektivitas biochar murni dan biochar-Mn3O4 sebagai adsorben zat warna kristal violet. 

Hasil karakterisasi menunjukkan impregnasi Mn3O4 terhadap biochar menyebabkan peningkatan kristalinitas dan kestabilan adsorben. Selain itu, didapatkan penambahan gugus fungsi berupa Mn-O-H dan permukaan karakterisasi menunjukkan impregnasi Mn3O4 terhadap biochar menyebabkan peningkatan kristalinitas dan kestabilan adsorben. Selain itu, didapatkan penambahan gugus fungsi berupa Mn-O-H dan permukaan biochar yang kaya oksigen. Adsorpsi zat warna kristal violet dengan biochar mencapai kondisi optimum pada pH larutan 6, massa adsorben 50 mg, waktu kontak 60 menit, dan konsentrasi awal zat warna 50 ppm. Adsorpsi dengan biochar-Mn3O4 optimum pada pH larutan 8, massa adsorben 50 mg, waktu kontak 120 menit, dan konsentrasi awal zat warna 150 ppm. Proses adsorpsi zat warna kristal violet dengan kedua adsorben tersebut mengikuti kinetika orde dua semu dengan nilai konstanta laju sebesar 3,3 × 10-2 g mg-1 menit-1 dan 1,2 × 10-1 g mg-1 menit-1. Model isoterm yang diikuti adalah Langmuir dengan nilai energi adsorpsi masing-masing 24,12 kJ mol-1 dan 25,01 kJ mol-1, sehingga adsorpsi terjadi secara kimia. Impregnasi Mn3O4 ke dalam biochar memberikan peningkatan kapasitas adsorpsi dari 344,40 mg g-1 menjadi 598,97 mg g-1 pada konsentrasi zat warna violet 1000 ppm.

The use of biochar impregnated with Mn3O4 as an adsorbent for crystal violet dye has been conducted. The study consisted of cassava peel biochar synthesis, biochar impregnation with Mn3O4, adsorbent characterization using XRD, FTIR, SAA, SEM-EDX instruments, and followed by crystal violet adsorption study with batch method. Parameters affecting adsorption performance such as solution pH, mass of adsorbent, interaction time, and initial adsorbate concentration were studied to determine the optimum conditions. The concentration of crystal violet dye before and after adsorption was measured by UV-Vis spectrophotometer. In addition, a comparison of pure biochar and Mn3O4-impregnated biochar in their effectiveness as adsorbents was also conducted.

The characterization results showed that the impregnation of Mn3O4 to biochar caused an increase in crystallinity and stability of the adsorbent. In addition, new functional groups in the form of Mn-O-H and oxygen-rich biochar surface were obtained. Adsorption of crystal dye with biochar reached optimum conditions at pH 6, 50 mg adsorbent mass, 60 minutes contact time, and 50 ppm initial dye concentration. Adsorption with Mn3O4 impregnated biochar was optimum at pH 8, 50 mg adsorbent mass, 120 minutes contact time, and 150 ppm initial dye concentration. The adsorption process of crystal violet dye with both adsorbents followed pseudo second-order kinetics with rate constant values of 3.3 × 10-2 g mg-1 min-1 and. 1.72 × 10-1 g mg-1 min-1. The followed isotherm model was Langmuir with adsorption energy values of 24.12 kJ mol-1 and 25.01 kJ mol-1, respectively, thus proving that adsorption occurred by chemisorption. The impregnation of Mn?O? into biochar increased the adsorption capacity from 344.40 mg/g to 598.97 mg/g at a violet dye concentration of 1000 ppm.

Kata Kunci : adsorpsi, biochar, kristal violet, kulit singkong, trimangan tetraoksida