Sifat adsorpsi kitosan tercetak ionik nikel dan kadmium

HANAFI, Prof. Dr. Narsito

2010 | Tesis | S2 Ilmu Kimia

Sintesis KTI-Ni dan KTI-Cd diawali dengan membuat kompleks kitosan menggunakan ion logam Ni(II) dan Cd(II) 3000 mg/L dalam larutan asam asetat, kemudian dikait silang dengan glutaraldehid dan terakhir mendesorpsi ion logam prekursor dengan EDTA. Selanjutnya padatan hasil sintesis diidentifikasi gugus fungsionalnya dengan metode FTIR dan kristalinitasnya dengan metode XRD. Proses adsorpsi ion logam Ni(II) dan Cd(II) dilakukan dengan metode batch adsorption sebagai fungsi pH, waktu kontak dan variasi konsentrasi ion logam Ni(II) dan Cd(II), juga dipelajari selektivitas adsorpsi dari adsorben dalam campuran ion logam Ni(II) dan Cd(II). Jumlah ion logam Ni(II) dan Cd(II) yang teradsorpsi dihitung menggunakan metode AAS. Hasil penelitian menunjukkan bahwa konstanta laju adsorpsi ion logam Ni(II) pada KTI-Ni sebesar k1= 10-3 menit-1 dan KTS sebesar k1= 10-4 menit-1. Adapun konstanta laju adsorpsi ion logam Cd(II) pada KTI-Cd maupun KTS sebesar k1= 10-3 menit-1. Pada hasil kajian kapasitas adsorpsi ion logam Ni(II) berdasarkan model isoterm adsorpsi Langmuir pada KTI-Ni sebesar 8,4 x 10-4 mol/g dan KTS sebesar 4 x 10-4 mol/g, sedangkan kapasitas adsorpsi ion logam Ni(II) berdasarkan model isoterm adsorpsi Freundlich pada KTI-Ni sebesar 4,4 x 10-5 mol/g dan KTS sebesar 3,1 x 10-5 mol/g. Adapun kapasitas adsorpsi ion logam Cd(II) berdasarkan model isoterm adsorpsi Langmuir pada KTI-Cd sebesar 7,7 x 10-4 mol/g dan KTS sebesar 3,2 x 10-4 mol/g, sedangkan kapasitas adsorpsi ion logam Cd(II) berdasarkan model isoterm adsorpsi Freundlich pada KTI-Cd sebesar 2,03 x 10-5 mol/g dan KTS sebesar 1,26 x 10-5 mol/g. Hasil kajian selektivitas relatif diperoleh bahwa KTI-Ni sangat selektif terhadap ion logam Ni(II) dengan koefisien selektivitas (aNi/Cd= 1,88), demikian pula KTI-Cd, sangat selektif terhadap ion logam Cd(II) dengan koefisien selektivitas (aCd/Ni = 1,83). Selanjutnya hasil kajian stabilitas menunjukkan bahwa KTS, KTI-Ni dan KTI-Cd pada pH 1-3 memiliki stabilitas masing–masing 87,7-95,8%, 91,0-97,3% dan 89,8-96,8% yang relatif jauh lebih besar dibanding kitosan bahan baku (0,8-6,8%).

The synthesis of IIC-Cd and IIC-Ni was started by complexing chitosan with 3000 mg/L Cd (II) and Ni(II) metal ions in acetic acid solution, followed by crosslinking with glutaraldehyde and finished by desorbing the metal ion precursor using EDTA. The functional groups of the as synthesized solid material was then characterized by using FTIR, and XRD were used to characterize its crystalinity. The Cd(II) and Ni(II) adsorption process was conducted by using batch adsorption method as a function of pH, contact time and variety of Cd(II) and Ni(II) ion concentrations. Moreover, the adsorption selectivity of adsorbent with respect to the mixture of Cd(II) and Ni(II) ions was also studied. The amount of adsorbed Cd(II) and Ni(II) ions was calculated using AAS method. The result showed that the adsorption rate constant of Ni(II) ions on IIC-Ni was 10-3 min-1 and on crosslinking-chitosan (CC) was 10-4 min-1. Meanwhile, the adsorption rate constant of Cd(II) ion on IIC-Ni and CC was 10-3 min-1. The adsorption capacity of Ni(II) ion based on La ngmuir adsorption isotherm model on IIC-Ni was 8.4 x 10-4 mol/g and on CC was 4 x 10-4 mol/g, while the adsorption capacity of Ni(II) ion based on Freundlich adsorption isotherm model on IIC-Ni was 4.4 x 10-5 mol/g and on CC was 3.1x10-5 mol/g. The adsorption capacity of Cd(II) ion based on Langmuir adsorption isotherm model on IIC-Cd was 7.7 x 10-4 mol/g and on CC was 3.2 x 10-4 mol/g, while the adsorption capacity of Cd(II) ion based on Freundlich adsorption isotherm model on IIC-Cd was 2.03 x10-5 mol/g and on CC was 1.26 x 10-5 mol/g. The relative selectivity analysis indicated that IIC-Ni was very selective with respect to Ni(II) ion with selectivity coefficient (aNi/Cd =1.88), and IIC-Cd was also very selective with respect to Cd(II) ion with selectivity coefficient (aCd/Ni)=1.83. The stability studies indicated that IIC-Cd, IIC-Ni and CC on pH 1-3 is stability have 87.7-95.8%, 91.0-97.3% and 89.8-96.8% respective ly were much more stable than chitosan materials (0.8-6.8%)

Kata Kunci : Kitosan, Glutaraldehid, KTS, KTI-Ni, KTI-Cd, Adsorpsi