Adsorption of Au(III), Cu(II) and Ni(II) on Magnetite Coated with Mercapto Groups Modified Rice Hull Ash Silica

Abstract

Adsorption of Au(III) in multi-metal systems Au/Cu/Ni on mercapto modified silica coated on magnetite (Fe 3 O 4 /SiO 2 -SH) has been studied. Fe 3 O 4 /SiO 2 -SH was synthesized via sol-gel process by using magnetite obtained through co-precipitation of Fe 2+ /Fe 3+ salt mixture with NH 4 OH as the precipitating solution, sodium silicate solution extracted from rice hull ash and 3-mercaptopropyltrimethoxysilane (MPTMS) as the mercapto group source. Fe 3 O 4 /SiO 2 -SH was characterized with Fourier transform infrared (FTIR) spectrophotometer, X-ray diffraction (XRD) and ion chromatography for sulfur analysis. Optimization of Au(III) adsorption in a batch system was carried out as function of pH, contact time and ion concentration. Adsorption kinetics was evaluated with pseudo-first order and pseudo-second order models based on the data of contact time variation, while the adsorption isotherm was studied based on Langmuir and Freundlich models. The adsorbed metal ions Au(III), Cu(II) and Ni(II) quantitatively were calculated based on the difference of metal concentrations before and after adsorption analyzed with flame atomic absorbance spectrophotometer (FAAS). Results of characterization showed that Fe 3 O 4 /SiO 2 -SH has been successfully synthesized. Adsorption of Au(III) on Fe 3 O 4 /SiO 2 -SH slightly decreased with increasing the pH in a range of 2.0-6.0 and fits to pseudo-second order model with the rate constant of 1.37x10 -3 g mg -1 min -1 . Fe 3 O 4 /SiO 2 -SH shows a linear plot of Langmuir isotherm model with adsorption the capacity for Au(III) of 125 mg/g. Adsorption on multimetal systems shows that capacity of Au(III) on Fe 3 O 4 /SiO 2 -SH is higher than that of Cu(II) and Ni(II), and high selectivity for Au(III) toward Cu(II) and Ni(II) ions.

Coating of 2-Aminobenzimidiazole and 1-(o-Tolyl)biguanide Functionalized Silicas on Iron Sand Magnetic Material for Sorption of [AuCl₄]^–

“…From k2 value, also known that MM@SiO2/AB has a greater adsorption rate than MM@SiO2/TB, as a result from inversely proportional to k2 value. This result supported the kinetics models reported by previous researchers revealing that Au(III) adsorption on adsorbent follows pseudo-second-order with k2 value in the order of 10 -2 g/mg min [3,16].…”

Adsorben Magnetit Terlapis Dimerkaptosilika untuk Adsorpsi Anion Logam [AuCl4]- dan [Cr2O7]-

“…Nuryono, et al (2010) telah melaporkan bahwa silika dari sekam padi berhasil disintesis dan memodifikasi gugus Si-OH dengan 3-mercapto propil trietoksisilana sebagai sumber mercapto membentuk Hibrida Merkapto Silika (HMS) yang melapisi magnetit. Hasil penelitian menunjukkan adsorben magnetik yang dilapisi silika-mercapto efektif dan selektif untuk Au(III), Cu(II) dan Ni(II) [13] . Fadhilah, et al (2019) telah mensintesis silika dari abu sekam padi dan memodifikasi gugus Si-OH dengan menambahkan 2,3-dimerkapto-1-propanol membentuk dimerkaptosilika (DMS) [14] .…”

Preparation of L-Arginine-Modified Silica-Coated Magnetite Nanoparticles for Au(III) Adsorption

“…In all spectra, the peak at 796.55 cm 33 . This suggests that silica has been coated on the magnetite surface 34 . From Fig 2(b-d) 32 , from GPTMS and L-arginine.…”

“…Silica coating may stabilize magnetite from an acidic medium 34,39,40 . In this work, the magnetite nanoparticles were coated with silica and added a modifier of L-arginine.…”