Screening And Studying The Characterization Of Composite Biomaterials For Efficient Removal Of Aflatoxin Pollution From Bulk Grain

Aflatoxin is the number one threat to food security,with aflatoxin B1(AFB1)being the most dangerous.The objective of this paper is to investigate a biological method to isolate and recover an adsorbent capable of industrial-scale removal of aflatoxin from grain.Four magnetic adsorbents were prepared: magnetic activated carbon(CSH),magnetic pine biochar(CFS),magnetic straw biochar(CJB)and magnetic bentonite(CPA),and the best adsorbent for AFB1 adsorption,CSH,was screened using specific surface area analysis,vibrating sample magnetometer and Fourier infrared spectroscopy.Bacillus subtilis WTX1 as the strain material immobilized to form a composite bacterial carrier(FCSH)for the adsorption and degradation of AFB1-contaminated maize by Aspergillus flavus.The following research conclusions were drawn:(1)In this study,magnetic activated carbon(CSH),magnetic pine biochar(CFS),magnetic straw biochar(CJB)and magnetic bentonite(CPA)were prepared from activated carbon(SH),pine biochar(FS),straw biochar(JB)and bentonite(PA);The overall adsorption performance of the four magnetic adsorbents was found to be CSH > CFS > CPA > CJB.(2)The single-factor conditions were optimized by immobilization method using CSH and laboratory-owned Bacillus subtilis WTX1,which can degrade AFB1,to prepare the composite bacterium FCSH,and it was found that when 4.0 g of FCSH was weighed into 20.0g of corn kernels with different concentration gradients,the immobilization time was 16 h,the rotation speed was 160 r/min,the temperature was 35℃,and the p H was 8.0.The removal rate was up to 97.45% at AFB1 concentration of 200 ng/m L.(3)FTIR analysis revealed that the Fe-O peak of FCSH did not decrease but increased before and after adsorption,and the basic structure remained unchanged compared with CSH in terms of carbon structure,and the peaks of other polarity-rich sites weakened after the adsorption of AFB1 by FCSH,which proved that FCSH had adsorption effect on AFB1 and the adsorption effect was better than that of CSH alone.SEM scanning electron microscopy Observation of the microscopic surface of FCSH revealed that both microorganisms and magnetic adsorbent had a removal effect on AFB1.(4)The recovery of magnetic activated carbon CSH was found to decrease from 86.75%to 37.43% after five repetitive recycling experiments.The adsorption decreased from 91.43%to 19.56%.It is presumed that the recovery times of magnetic activated carbon CSH in the composite bacterial agent FCSH should be less than four times,and after three times it is recommended to add magnetic adsorbent to use again.