SINTESIS Fe3O4-Ni-Zn LHS (MAGNETITE-NICKEL-ZINK LAYERED HYDROXIDE SALTS) DAN APLIKASINYA SEBAGAI ADSORBEN ION [AuCl4]- DALAM LARUTAN BERAIR

LIA KURNIA, Prof. Drs. Sri Juari Santosa, M.Eng., Ph.D

2019 | Tesis | MAGISTER KIMIA

Telah dilakukan sintesis Magnetite-Nickel-Zinc Layered Hydroxide Salts (Fe3O4-Ni-Zn LHS) yang bertujuan untuk memperoleh adsorben berupa material berlapis yang bersifat magnetit dan aplikasinya sebagai adsorben ion [AuCl4]- dalam larutan. Material Ni-Zn-LHS dan magnetit disintesis secara terpisah dengan metode kopresipitasi, kemudian kedua material dikombinasikan dengan metode yang sama. Larutan Zn2+ dan Ni2+ (rasio molar 1:2) dicampurkan, kemudian ditambahkan larutan NaOH (0,75 M) sebanyak 32 mL untuk membentuk Ni-Zn LHS. Magnetit disintesis dengan larutan NH4OH (1 M) yang ditambahkan ke dalam campuran larutan Fe2+ dan Fe3+ (rasio molar 1:2) sampai pH 11,5. Pada sintesis Fe3O4-Ni-Zn LHS dilakukan dengan metode kopresipitasi dimana padatan magnetit hasil sintesis yang terdispersi dimasukkan ke dalam campuran larutan Zn2+ dan Ni2+, kemudian campuran tersebut dititrasi dengan NaOH sebanyak 32 mL. Ketiga material hasil sintesis dikarakterisasi menggunakan FTIR, XRD, VSM, SEM-EDX, dan TEM. Aplikasi Fe3O4-Ni-Zn LHS sebagai adsorben ion [AuCl4]- dipelajari dengan mengkaji pengaruh pH, kinetika dan isoterm adsorpsi. Hasil penelitian menunjukkan bahwa magnetit yang terdistribusi pada struktur LHS dapat menjadikan Fe3O4-Ni-Zn LHS sebagai adsorben yang tidak hanya memiliki kemampuan adsorpsi, tetapi juga memiliki sifat kemagnetan sehingga proses pemisahan kembali mudah dilakukan dengan medan magnet eksternal. Hasil VSM menunjukkan nilai kemagnetan Fe3O4-Ni-Zn LHS sebesar 12,021 emu/g. Adsorpsi optimum ion [AuCl4]- oleh Fe3O4-Ni-Zn LHS tercapai pada pH 4 dan mengikuti kinetika pseudo orde dua Ho dengan nilai konstanta laju adsorpsi (k) sebesar 1,7542 x 10-3 g/mg.menit. Adsorpsi paling sesuai dengan model isoterm adsorpsi Freundlich yang menunjukkan kapasitas adsorpsi 9,055 mg/g. Nilai ini lebih kecil dari kapasitas adsorpsi Ni-Zn LHS yang memiliki nilai 13,921 mg/g.

The synthesis of Magnetite-Nickel-Zinc Layered Hydroxide Salts (Fe3O4-Ni-Zn LHS) has been carried out to obtain adsorbents in the form of layered magnetic material and its application as [AuCl4]- ions adsorbent in solution. Ni-Zn-LHS and magnetite material were synthesized separately by the coprecipitation method, then both materials were combined by the same method. Solutions of Zn2+ and Ni2+ (1:2 molar ratio) were mixed to form Ni-Zn LHS, then 32 mL of NaOH solution (0.75 M) was added. Magnetite was synthesized in which the solution of NH4OH (1 M) was added into the mixture of Fe2+ and Fe3+ solution (1:2 molar ratio) until it reached pH 11.5. The synthesis of Fe3O4-Ni-Zn LHS was carried out by coprecipitation method in which the dispersed magnetite solid was added to the mixture of Zn2+ and Ni2+ solutions, then the mixture was titrated with 32 mL of NaOH. The three synthesized materials were characterized by FTIR, XRD, VSM, SEM-EDX, and TEM. The application of Fe3O4-Ni-Zn LHS as adsorbent of [AuCl4]- ions was studied by examining the effect of pH, adsorption kinetics, and isotherm. The result showed that distributed magnetite in the LHS structure could form Fe3O4-Ni-Zn LHS as an adsorbent that not only had adsorption capability, but also had magnetic properties so that the separation process was easily carried out with an external magnetic field. The VSM characterization showed that the magnetic property value of the Fe3O4-Ni-Zn LHS was 12.021 emu/g. The adsorption results showed that the adsorption of [AuCl4]- ions by Fe3O4-Ni-Zn LHS optimally at pH 4 and followed the pseudo second-order kinetics of Ho with an adsorption rate constant (k) of 1.7542 x 10-3 g/mg. The adsorption was most suitable for the Freundlich adsorption isotherm model indicating the adsorption capacity of 9.055 mg/g. This value was smaller than Ni-Zn LHS adsorption capacity which possessed a value of 13.921 mg/g.

Kata Kunci : Nickel, Zinc, Magnetite, LHS, [AuCl4]-, Adsorption