SINTESIS Mg/Al-NO3 HIDROTALSIT-MAGNETIT DAN APLIKASINYA SEBAGAI ADSORBEN [AuCl4]-

TRIASTUTI SULISTYANINGSIH, Prof. Drs. Sri Juari Santosa, M.Eng., Ph.D.; Drs. Dwi Siswanta, M.Eng., Ph.D.; Prof. Dr. Bambang Rusdiarso, DEA.

2016 | Disertasi | S3 Kimia

Sintesis komposit Mg/Al-NO3 hidrotalsit-magnetit telah berhasil dilakukan. Komposit yang diperoleh diaplikasikan sebagai adsorben ion [AuCl4] negatif dalam larutan. Sintesis dilakukan dengan metode ko-presipitasi, secara mekanik dan ultrasonik dengan perlakuan hidrotermal dan kalsinasi. Perlakuan hidrotermal dilakukan pada suhu 120 derajat C selama 5 jam. Kalsinasi dilakukan pada suhu 450 derajat C selama 3 jam. Karakterisasi adsorben dilakukan dengan menggunakan Fourier transform infrared (FTIR) spektroskopi, X-ray diffraction (XRD), Scanning mikroskop elektron (SEM), model Brunauer Emmett-Teller (BET), Vibrating sample magnetometer (VSM) dan Transmission electron microscope (TEM). Teknik batch digunakan dalam proses adsorpsi dan desorpsi untuk mempelajari pH, waktu kontak dan konsentrasi optimum. Kinetika, isoterm dan selektivitas adsorpsi juga dikaji. Hasil karakterisasi menunjukkan bahwa perlakuan hidrotermal meningkatkan kristalinitas komposit dan kalsinasi merusak sebagian struktur komposit. Sifat kemagnetan dimiliki oleh komposit dikarenakan partikel-partikel magnetit menempel pada hidrotalsit sehingga memudahkan proses pemisahan adsorben dari larutan. Hasil kajian adsorpsi diperoleh pH optimum 3. Kinetika adsorpsi untuk semua adsorben terhadap ion [AuCl4]- mengikuti kinetika adsorpsi pseudo-order dua. Isoterm adsorpsi untuk Mg/Al-NO3 hidrotalsit-magnetit mengikuti model isoterm Langmuir sedangkan untuk produk kalsinasi Mg/Al-NO3 hidrotalsit-magnetit mengikuti model isoterm Freundlich. Interaksi antara ion [AuCl4]- dengan Mg/Al-NO3 hidrotalsit-magnetit terjadi secara kimia melalui pembentukan jembatan hidrogen, sedangkan interaksi dengan produk kalsinasi Mg/Al-NO3 hidrotalsit-magnetit melalui rekontruksi lapisan hidrotalsit. Desorpsi ion [AuCl4]- pada adsorben dengan perlakuan hidrotermal lebih cepat dan mencapai optimum menggunakan larutan pendesorpsi NaOH 0,5 M. Hasil kajian selektivitas menunjukkan bahwa Mg/Al-NO3 hidrotalsit-magnetit dapat mengikat anion tetrakloroaurat(III) dan kation seperti Ni2+, Pb2+ dan Cu2+.

Synthesis of Mg/Al-NO3 hydrotalcite-magnetite composite has been successfully done. The composite obtained is applied to the adsorbent [AuCl4]- in aqueous solution. Synthesis is done by mechanic and ultrasonic co-precipitation method with hydrothermal treatment and calcining modification. Hydrothermal treatment was carried out at 120 C degree for 5 hours and calcination was carried out at a temperature of 450 C degree for 3 hours. The adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD, Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) model, Vibrating sample magnetometer (VSM) and Transmission electron microscope (TEM). The batch technique was conducted on adsorption and desorption process for investigation the optimum pH, contact time, and concentration. Kinetic, isotherm and selectivity of adsorption were also studied. Characterization result shows that hydrothermal treatment enhances composite crystallinity and calcination destroy part of the composite structure. Magnetic properties owned by the composite due to magnetic particles attached to the hydrotalcite thus facilitating the process of separating the adsorbent from aqueous solution. The results of adsorption experiment demonstrated that a maximum [AuCl4]- adsorption is achieved at pH 3. The kinetic data for all adsorbent to [AuCl4]- were described better by the pseudo-second order kinetic equation. The adsorption isotherm Mg/Al-NO3 hydrotalcite-magnetite for [AuCl4]- followed the Langmuir isotherm model and Mg/Al-NO3 hydrotalcite-magnetite calcined followed the Freundlich model. The interaction between [AuCl4]- with Mg/Al-NO3 hydrotalcite-magnetite occurs chemically through the formation of hydrogen bridge while interacting with calcination product Mg/Al-NO3 hydrotalcite-magnetite through the layer reconstruction of hydrotalcite. Desorption [AuCl4]- on the adsorbent with hydrothermal treatment more quickly and achieve optimum using NaOH 0.5 M solution. The results of selectivity study show that the Mg/Al-NO3 hydrotalcite-magnetite can bind anions [AuCl4]- and cations such as Ni2+, Pb2+ and Cu2+.

Kata Kunci : Mg/Al-NO3 hydrotalcite-magnetite, ultrasonic, adsorption, desorption, [AuCl4]-