Magnetic material Mg/Al-NO3 hydrotalcite-magnetite (HT-M) has been successfully prepared by co-precipitation method as an adsorbent for removal [AuCl4]– in aqueous solution. Mg/Al-NO3 HT-M was synthesized by co-precipitation with modifications hydrothermal treatment at 120 °C for 3 hours. The presence of functional groups in the adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy and the X-ray diffraction (XRD) were used to verify the crystallinity. The morphology of the samples was observed by the Scanning electron microscopy (SEM), the specific surface area and pore volume of Mg/Al-NO3 HT-M have been evaluated according to Brunauer-Emmett-Teller (BET) and Vibrating sample magnetometer (VSM) for magnetization. Batch experiments were conducted to study the adsorption efficiency of [AuCl4]– by getting the optimum pH, optimum contact time and the optimum concentration. The adsorption kinetic and isotherm of [AuCl4]– from the aqueous solution containing Mg/Al-NO3 HT-M also were studied. The characterization result indicated that magnetite was successfully loaded on Mg/Al-NO3 HT. This produce the magnetic property of the adsorbent (13.48 emu g-1), which facilitate the separation of the adsorbent from aqueous solution. The results of adsorption experiment demonstrated that a maximum [AuCl4]– adsorption is achieved at pH 3 and contact time of 60 min. Lagergren’s pseudo-first order, Ho’s pseudo-second order and Santosa’s first order models were used to analyze the sorption kinetics while isotherm data were analyzed following the isotherm models of Langmuir and Freundlich. The kinetic data were described better by the pseudo-second order kinetic equation, confirming that the velocity control mechanism of adsorption is chemical adsorption. Data of equilibrium experiments were fitted well to Langmuir isotherm model with adsorption capacity 31.3 mg g-1.
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