Modification of bentonite with orange peels extract and its application as mycotoxins ? binder in buffered solutions and simulated gastrointestinal fluids

This study reports the fabrication of orange peels (OP) extract (water:ethanol:acetonitrile) modified organic-inorganic hybrid bentonite (OP-bentonite). The synthesized composite was employed for the adsorptive removal of carcinogenic mycotoxins (aflatoxin B1 (AFB1), fumonisin B1(FB1) and ochratoxin (OTA)). The product was texturally characterized by BET, FTIR, XRD, TGA, SEM, EDX and XPS techniques while quantification of toxins was performed using HPLC/LC-MS. The effect of reaction temperature, pH, adsorbent dosage, coexisting mycotoxins and gastro-intestinal fluids on the adsorption performance of OP-bentonite was systematically investigated. Isothermal data (pH 2.5 and 7.0) for toxins adsorption agreed well with the Langmuir isotherm model revealing maximum adsorption capacity (q(max)) (mg/g) of 166 and 121 for AFB1, 3.87 and 1.78 for FB1 and 1.97 and 3.19 for OTA respectively. The adsorption kinetics followed pseudo-second-order kinetic model while its adsorption capacity surpassed many adsorbents reported for AFB1, FB1 and OTA with orders of magnitude. Therefore, attributed to the advantages of being efficient, green and simplified synthesis, OP-bentonite could be envisaged as a promising adsorbent for the enhanced sequestration of mycotoxins.