SYNTHESIS OF TA-Ni-Zn-LHS (TANNIC ACID-NICKEL-ZINC-LAYERED HYDROXIDE SALTS) AND ITS APPLICATIONS FOR REDUCTIVE-ADSORPTION OF [AuCl4]- IONS IN AQUEOUS MEDIUM

ASLAN IRUNSAH, Prof. Dr. Sri Juari Santosa, M.Eng.; Dr. Dwi Siswanta, M.Eng.

2021 | Tesis | MAGISTER KIMIA

Sintesis Ni-Zn-LHS (Nikel-Zinc Layered Hydroxide Salts) terimobilisasi asam tanat dan aplikasinya untuk adsorpsi-reduksi [AuCl4]- telah dilakukan. Ni-Zn-LHS disintesis menggunakan metode kopresipitasi dengan mencampurkan Ni(NO3)2.6H2O dan Zn(NO3)2.4H2O dengan perbandingan molar 2:1. Larutan campuran tersebut ditambah dengan NaOH dan selanjutnya diaduk. Proses imobilisasi asam tanat pada Ni-Zn-LHS dilakukan pada kondisi optimum. Instrument FTIR dan XRD digunakan untuk menguji keberhasilan proses imobilisasi asam tanat pada Ni-Zn-LHS dan aplikasi TA-Ni-Zn-LHS untuk adsorpsi-reduksi [AuCl4]-. Hasil penelitian menunjukkan bahwa TA-Ni-Zn-LHS dapat dimanfaatkan sebagai adsorben sekaligus dapat mereduksi Au(III) menjadi Au(0). Spektra FTIR TA-Ni-Zn-LHS menunjukkan adanya puncak serapan yang karakteristik pada bilangan gelombang 1512 cm-1 yang merupakan vibrasi gugus C=C dari asam tanat yang terimobilisasi pada Ni-Zn-LHS. Proses adsorpsi ion [AuCl4]- oleh TA-Ni-Zn-LHS optimum pada pH 3,0 dan cenderung mengikuti kinetika pseudo orde dua Ho dengan nilai konstanta laju adsorpsi (k) sebesar 0,32 g mg-1 min-1. Proses adsorpsi ion [AuCl4]- mengikuti model isotherm Freundlich dengan kapasitas adsorpsi sebesar 3,29 mg g-1. Hasil karakterisasi XRD material TA-Ni-Zn-LHS setelah proses adsorpsi menunjukkan adanya puncak karakteristik logam Au pada 2 theta: 38,27derajat and 44,48 derajat.

The synthesis of tannic acid-immobilized Ni-Zn-LHS (Nickel-Zinc Layered Hydroxide Salts) and its application for the reductive-adsorption of [AuCl4]- have been carried out. The Ni-Zn-LHS was synthesized using the coprecipitation method by dissolving Ni(NO3)2.6H2O and Zn(NO3)2.4H2O with a molar ratio of 2:1.The immobilization of tannic acid onto Ni-Zn-LHS was carried out under optimum conditions. The FTIR and XRD instruments were used to examine the success of tannic acid immobilization on Ni-Zn-LHS and the application of TA-Ni-Zn-LHS for the reductive-adsorption of [AuCl4]-. The results showed that TA-Ni-Zn-LHS could be used to adsorb and subsequently reduce Au(III) to Au(0). The FTIR spectra of TA-Ni-Zn-LHS showed a characteristic absorption peak at wavenumber1512 cm-1 which was attributed to a vibration of the C=C group of tannic acid immobilized on Ni-Zn-LHS. The adsorption process of [AuCl4]- ions by TA-Ni-Zn-LHS was optimum at pH 3.0 and tended to follow the Ho pseudo-second-order kinetic model with a constant value of adsorption rate (k) of 0.32 g mg-1 min-1. The adsorption process of the [AuCl4]- ions followed the Freundlich isotherm model with an adsorption capacity of 3.29 mg g-1. The XRD characterization results of TA-Ni-Zn-LHS-Au material showed characteristic peaks of Au metal at 2 theta: 38.27 degree and 44.48 degree.

Kata Kunci : Ni-Zn LHS, tannic acid, immobilization, reductive-adsorption, [AuCl4]-