Preparation of magnetic mesoporous silica from rice husk for aflatoxin B1 removal: Optimum process and adsorption mechanism

Abstract

The liquid foodstuffs such as edible oil products remain a problem of excessive aflatoxin B1 (AFB1) content. This paper focused on the preparation of magnetic mesoporous silica (MMS) from rice husk ash for the removal of AFB1 in oil system. The MMS preparation process, adsorption conditions, structural characteristics, and adsorption mechanism were investigated. The optimum conditions for MMS preparation were pH 11.0 and 80˚C for 24 h. The characterization results showed that magnetic particles were successfully embedded in the MMS and had high responsiveness to a magnetic field, which was advantageous for recyclability. The MMS had ordered uniform channels with a specific surface area of 730.98 m 2 /g and pore diameter of 2.43 nm. The optimum adsorption conditions were 2 h at 20˚C. For AFB1 with an initial concentration of 0.2 μg/mL, the MMS adsorption capacity was 171.98 μg/g and the adsorption rate was 94.59%. The MMS adsorption isotherm fitted the Langmuir model well under the assumption of monolayer AFB1 adsorption with uniformly distributed adsorption sites on the MMS surface. The maximum amount of AFB1 adsorbed according to the Langmuir isotherm was 1118.69 μg/g. A quasi-second-order kinetic model gave a better fit to the process of AFB1 adsorption on MMS. The values of ΔH (−19.17 kJ/ mol) and ΔG (−34.09, −34.61, and −35.15 kJ/mol at 283, 293, and 303 K, respectively) were negative, indicating that AFB1 adsorption on MMS was a spontaneous exothermic process. The results indicated that MMS was a promising material for AFB1 removal in oil system, and this study will serve as a guide for practical MMS applications.

Improving adsorption performance of l-ascorbic acid from aqueous solution using magnetic rice husk as an adsorbent: experimental and RSM modeling

“…If its value is less than 8 kJ/mol, it shows in adsorption that the mechanism of the adsorption process is physical 65 . In the D–R model, it is obvious that the physical adsorption mechanism (E > 8) is the dominant mechanism for adsorption 68 .…”

Synthesis of Rice Husk-Based MCM-41 for Removal of Aflatoxin B1 from Peanut Oil

“…The nitrogen adsorption-desorption isotherm of MCM-41 was shown in Figure 1b. MCM-41 exhibited a type-IV isotherm of the IUPAC (International Union of Pure and Applied Chemistry) [35]. The adsorption-desorption isotherm showed a similar hysteresis loop in the pre-capillary condensation range (P/P0 = 0.2-0.4).…”

“…It can be hypothesized that MCM-41 could be an excellent adsorbent for complex organic compounds such as AFB 1 . However, the application of rice husk-based MCM-41 on the removal of AFB 1 from peanut oil has been rarely attempted [35].…”

Effect of the Structure of Highly Porous Silica Extracted from Sugarcane Bagasse Fly Ash on Aflatoxin B1 Adsorption

“…Additionally, the observed adsorption behavior of BPS-5 could be ascribed to the characteristic bimodal mesoporous sizes and volumes (Table 1), which helped enhance the diffusion of the AFB1 molecules from the surface into the pores (pore diffusion). 37 Compared with the previously reported results, the ability of our highly porous silica, especially BPS-5 (0.607 mg/g), in adsorbing AFB1 was higher than those of magnetic mesoporous silica (0.165 mg/g), 38 magnetic graphene oxide (2.36 × 10 −6 mg/g), 36 natural montmorillonite (0.166 mg/g), 13 rice husk-based mesoporous silica (0.189 mg/g), 13 and commercial activated carbon (0.200 mg/g). 13 The adsorption rates of all of the highly porous silica during in vitro intestinal digestion were nevertheless lower than that of bentonite.…”