Effect of particle size on mineral element content and binding of harmful element of wheat bran

To study the binding ability of wheat bran to harmful elements, the ability of adsorption for wheat bran with different particle sizes ( < 0.074、0.074 ~ 0.125、0.125 ~ 0.425 mm) to harmful elements ( aluminum, arsenic, lead) was tested. In the meantime, minerals ( potassium, calcium, magnesium, iron, zinc, copper) contents and harmful elements ( aluminum, lead, arsenic, cadmium, chromium) contained by different-size brans were evaluated respectively in the study.The result showed that the particle size of wheat bran had a significant influence on the amounts of minerals and harmful elements ( p < 0.05) .All the detected contents of minerals were the lowest from 0.074 mm size bran, and the contents of macro element potassium, calcium and magnesium were 7.222, 0.812 and 2.008 g·kg^-1respectively, and the contents of trace element iron, zinc and copper were170, 82.3 and 11.9 mg·kg^-1respectively. However, the contents of harmful elements aluminum, lead, and chromium were the highest that were 13.7, 0.1169, and 0.3150 mg·kg^-1, respectively in these brans.0.125 mm to 0.425 mm size bran contained a lot of macro elements ( The contents of potassium and magnesium were 15.867 and 5.984 g·kg^-1, respectively) , and the detection contents of harmful elements were the lowest, and lead content was only 0.0449 mg·kg^-1. Under the condition of different p H and different particle sizes, the change was consistent for bran adsorption aluminum and arsenic ability. The adsorption capacity increased firstly and then decreased with the decrease of particle size at p H = 2.The adsorption capacity of bran at p H = 7 remarkable increased with the decrease of particle size ( p < 0.05) .And the adsorption capacity under p H = 7 was much smaller than that at p H = 2.The ability of bran for adsorbing lead was greater at p H = 7 than that at p H = 2. And the capacity significantly increased with the decrease of particle size at p H = 7 ( p < 0.05) . Whereas, that binding capacity to lead increased first then decreased with the decrease of particle size at p H = 2.In conclusion, particle size of wheat bran hadremarkable influences on its mineral element content and capacity of binding harmful element.