Biological Effect And Inactivation Of Biochar To Arsenic In Soil

Modified cotton stalks and corn cobs biochar are prepared that based on cotton stalks and corn cobs as material and added different quality FeCl₃·6H₂O ?with iron mass?, then their performance is tested by scanning electron microscopy?SEM?, Fourier transform infrared spectroscopy?FTIR? and X-ray diffraction analyzer?XRD?. Investigating the effect of biochar on arsenic mobility and morphology in soil and the laws of arsenic in plants migration by arsenic content of soil and plants is determined by atomic fluorescence spectrometer. The main research results are as follows:?1? The specific surface area and C, H, N, O content have significantly occurred, —CH₂—, C=C and —COOH have decreased, C60 has decreased, and ash content increases with the increase of Fe mass fraction. Alkaline biochar will form Fe?OH?3 precipitate after the addition of Fe by Scanning electron microscopy and surface area analyzer which made it's porous becomes less. The characterization of cotton stalks and corn cobs biochar before and after show that:all indicators of modified cotton stalks biochar are better than modified corn cobs biochar, so subsequent trials in the paper selected cotton stalks before and after modification biochar.?2? Adding 1-8% before and after modification biochar in the soil column, the content of leachate arsenic is less than 5 ?g/L compared with the control that shows that the biochar of bioburden iron can effectively prevent arsenic migrate to groundwater. Adding biochar can inhibit migration of arsenic in the soil column, the inhibition of modified biochar is more significant compared with the unmodified biochar. These results indicate that biochar and modified biochar can make the content of effective arsenic in the soil decreased, namely promote the effective arsenic transition to steady state. The content of effective arsenic in surface soil is 0.23% and residual arsenic is 55.6% when modified biochar dosage is 8%.?3? Biochar ?10-40 g/kg? and modified biochar ?10 g/kg? can promote the growth of cabbage, the biomass of cabbage is the maximum when their amount are 20 and lOg/kg, respectively, the biomass of cabbage when the amount is 10 g/kg is higher than the control and the same amount of unmodified biochar treatment. The arsenic in soil after the end of test exists mainly residual arsenic, and the content water arsenic and exchange arsenic of modified biochar are lower than biochar treatment when exogenous arsenic mass fraction is 10 and 20 mg/kg and adding different proportions of biochar and modified biochar. The arsenic in soil exists mainly aluminum arsenic, residues arsenic followed when concentrations of arsenic is 40 and 80 mg/kg. The mass fraction of arsenic in edible parts and root of each treatment cabbage varies after adding 10-40 g/kg biochar, it significantly reduced after adding the same amount of modified biochar, which means modified biochar can significantly reduce the content of arsenic in cabbage, and made the effective arsenic in soil to transform stable.