Performance and retention mechanisms of corn silk to atmospheric heavy metal lead

Atmospheric heavy metals are seriously harmful, and porous materials have unique advantages in the control of air pollutants. However, the direct use of plant porous materials to purify atmospheric heavy metals are rare. So agricultural waste corn silk with porous structures was selected to analyze the retention capability and mechanism to the atmospheric lead. The results show that the corn silk can effectively retain atmospheric lead in natural growing state or fixed experimental conditions. The analysis of a total of 765 corn silk samples from 17 different regions in Shandong province, China, shows that atmospheric lead is the main source of lead in the corn silk, and corn silk can be used for biological monitoring of atmospheric lead to some extent. Based on the analysis with different techniques including scanning electron microscope (SEM), energy spectrum dispersive X-ray spectrometer (EDS), Fourier infrared spectrometer (FTIR) and Zeta potential, the effective retention of lead by corn silk is due to a variety of mechanisms, including physical adsorption, electrostatic adsorption, complexation, chelation and ion exchange. So agricultural waste corn silk has great potential in the application of biosorption or preparation of porous materials in purification of atmospheric heavy metals. Novelty statement (1) Atmospheric lead is the main source of lead in the corn silk based on the analysis of a total of 765 corn silk samples from 17 different regions in Shandong province, China. (2) The pore diameter in the corn silk is 1.62-3.51 mu m, suitable for lead retention, and the functional groups -OH, -COOH and -O- of the corn silk play a vital role in the lead retention process. (3) The potential value of agricultural waste corn silk was firstly revealed in the purification of atmospheric heavy metals.