The synthesis and application of the SiO2@Fe3O4@MBT nanocomposite as a new magnetic sorbent for the adsorption of arsenate from aqueous solutions: Modeling, optimization, and adsorption studies

摘要

This study was conducted for the purpose of showing that the mercaptobenzothiazole (MBT)-functionalized SiO2@Fe3O4 nanocomposite can be applied as a new adsorbent for the adsorption of As (V) ions from aqueous solutions. SiO2@Fe3O4@MBT synthesized via a two-stage process was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), the transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET). The SEM showed good adsorbing capacity for SiO2@Fe3O4@ MBT due to the average core size 40 nm with a vast surface. The appearance of bands attributed to the C-H stretch of methylenes of the alkyl chain in FTIR analysis showed SiO2@Fe3O4 was successfully modified by MBT. The XRD spectrum clearly demonstrates the occurrence of two phases of iron oxide/hydroxide and silica oxide, and also the spinal structure of SiO2@Fe3O4@ MBT reveals the presence of SiO2, by revealing the specific peaks at 2 theta = 26.62, 39.44, 42.41, 54.83.The TEM micrograph of SiO2@Fe3O4@ MBT showed the Fe3O4 nanopartide anchored on SiO2 and formed a large amount of Fe3O4 with different size. Surface area of SiO2@Fe3O4@ MBT was investigated and determined 5835 m(2)/g. Response surface methodology (RSM) was employed to model the effects of the operating parameters, such as pH (2-8), adsorbent dosage (10-100 mg L-1), initial As (V) concentration (1-10 mg L-1), and contact time (2-180 min) using the R software. Based on the results obtained from the analysis of variance (ANOVA), the reduced full second-order model demonstrated satisfactory adjustment with the experimental data. The Solver "Add-ins" were applied using the effective parameters to optimize important operating variables. The optimum operating points were established at the initial As (V) concentration of 10 mg L-1, the adsorbent dosage of 82.7 mg L-1, the time of 169.1 min, and the pH of 5.07, corresponding to the maximum predicted As (V) removal percentage of 93.89%