ADSORPSI ION Cr(VI) MENGGUNAKAN ADSORBEN AMPAS KOPI TERMODIFIKASI SETILTRIMETILAMONIUM BROMIDA (CTAB) DAN Fe?O?

DEWI WULAN SARI, Prof. Dr. Endang Tri Wahyuni, M.S. ; Suherman, S.Si., M.Sc., Ph.D

2024 | Skripsi | KIMIA

Adsorpsi ion Cr(VI) menggunakan adsorben ampas kopi termodifikasi setiltrimetilamonium bromida (CTAB) dan Fe?O? telah dilakukan. Adsorben disintesis dari ampas kopi yang dikeringkan. Ampas kopi dimodifikasi Fe?O? melalui metode kopresipitasi dengan pencampuran (FeCl??4H?O) dan (FeCl??6H?O), kemudian ditambahkan larutan NH?OH hingga pH 11. AK/Fe?O? dimodifikasi dengan variasi konsentrasi CTAB menghasilkan AK/Fe?O?-CTAB. Karakterisasi adsorben AK/Fe?O?-CTAB dilakukan dengan instrumen FTIR, XRD, dan SEM. Kemampuan adsorpsi AK/Fe?O?-CTAB diuji melalui adsorpsi ion Cr(VI) dengan mempelajari pengaruh konsentrasi CTAB dalam adsorben AK/Fe?O?-CTAB, pH larutan ion Cr(VI), waktu adsorpsi, dan konsentrasi awal ion Cr(VI) terhadap efektivitas adsorpsi ion Cr(VI). Konsentrasi ion Cr(VI) yang teradsorpsi ditentukan dengan instrumen UV-Vis. Hasil penelitian menunjukkan bahwa adsorben AK/Fe?O?-CTAB telah berhasil disintesis yang terdeteksi melalui spektra FTIR, XRD, dan SEM. Adsorben AK/Fe?O?-CTAB dengan konsentrasi CTAB 0,5 mmol memiliki aktivitas adsorpsi paling besar. Adsorpsi Cr(VI) oleh adsorben AK/Fe?O?-CTAB berlangsung efektif pada pH 3, waktu kontak 60 menit, dan konsentrasi awal Cr(VI) sebesar 5 mg L?¹. Adsorpsi Cr(VI) oleh adsorben AK/Fe?O?-CTAB mengikuti orde dua semu dengan nilai R² 0,9996 dan konstanta laju adsorpsi sebesar 3,303×10-1 g mg?¹ menit?¹. Adsorpsi berjalan mengikuti model isoterm Freundlich dengan nilai R² 0,9961 dan konstanta Freundlich sebesar 1,757 L mg?¹.

Adsorption of Cr(VI) ions using cetyltrimethylammonium bromide (CTAB) and Fe?O? coffee ground adsorbent has been conducted. The adsorbent was synthesized from dried coffee grounds. The coffee grounds were modified with Fe?O? through a coprecipitation method by mixing (FeCl??4H?O) and (FeCl??6H?O), followed by the addition of an NH?OH solution until the pH reached 11. The AK/Fe?O? was then modified with varying concentrations of CTAB, resulting in AK/Fe?O?-CTAB. The AK/Fe?O?-CTAB adsorbent was characterized using FTIR, XRD, and SEM instruments. The adsorption capacity of AK/Fe?O?-CTAB was tested for Cr(VI) ion adsorption by studying the effects of CTAB concentration in the AK/Fe?O?-CTAB adsorbent, the pH of the Cr(VI) ion solution, adsorption time, and initial Cr(VI) ion concentration on the effectiveness of Cr(VI) ion adsorption. The concentration of adsorbed Cr(VI) ions was determined using a UV-Vis instrument. The results of the study show that the AK/Fe?O?-CTAB adsorbent was successfully synthesized, as detected through FTIR, XRD, and SEM spectra. The AK/Fe?O?-CTAB adsorbent with 0.5 mmol CTAB concentration exhibited the highest adsorption activity. The adsorption of Cr(VI) by AK/Fe?O?-CTAB was most effective at pH 3, with a contact time of 60 minutes, and an initial Cr(VI) concentration of 5 mg L?¹. The adsorption of Cr(VI) by AK/Fe?O?-CTAB followed pseudo-second-order kinetics with an R² value of 0.9996 and an adsorption rate constant of 3.303×10?¹ g mg?¹ min?¹. The adsorption follows the Freundlich isotherm model with an R² value of 0.9961 and a Freundlich constant of 1.757 L mg?¹.

Kata Kunci : adsorpsi, ampas kopi, Cr(VI), CTAB, Fe?O?