| The mobility of cadmium in farmland soil may lead to the accumulation of cadmium in crops,which may pose a threat to human health.Therefore,it is of great practical significance to control the migration of cadmium in farmland soil.In this study,corn cob biochar with high efficiency,environmental protection and low price was selected to load Bacillus subtilis（BC@B）,as an amendment to stabilization and remediation of cadmium in farmland soil.The efficiency and persistence of amendment to cadmium migration in solution and soil were evaluated by soil incubation experiment and pot experiment.Using SEM、FTIR、XRD、XPS ect to reveal the mechanism of cadmium migration in soil amended by corncob biochar loaded Bacillus subtilis.The main results are as follows:（1）With the temperature of corncob biochar loaded Bacillus subtilis and corncob biochar（BC）rising（300℃,350℃,400℃,450℃,500℃,550℃）,the pores of biochar become dense and structure was more obvious,the content of founctional groups decreased gradually.In addition,corncob biochar loaded Bacillus subtilis contains more functional groups than corncob biochar.（2）Compared with corncob biochar loaded Bacillus subtilis and corncob biochar at other pyrolysis temperatures,corncob biochar loaded Bacillus subtilis and corncob biochar at 400℃pyrolysis temperatures pyrolysis has the highest adsorption capacity of cadmium ion in solution,and the adsorption rates were 81.21%and 5.70%respectively.This was due to surface structure of 400℃corncob biochar loaded Bacillus subtilis contains a large number of oxygen-containing functional groups（COOH、OH、Si-O-Si et al）,minerals and metal oxides,Bacillus subtilis in corncob biochar loaded Bacillus subtilis plays a major role in the adsorption of cadmium ions.（3）Soil stabilizated by 0.25%of 400℃corncob biochar loaded Bacillus subtilis and 400℃corncob biochar for 56 days,the content of Ca Cl2 extracted cadmium in decreased by 56.37%and 26.08%respectively.Compared with 7-14 days,incubation after 56 days,the stabilization effect of 400℃corncob biochar on cadmium was improved.A similar trend was also shown in Tessier five-step sequential extraction procedure experiment.The low stabilization efficiency of BC at 400℃may be due to the promotion of cadmium migration in soil by dissolved organic carbon in the structure.400℃corncob biochar loaded Bacillus subtilis has the positive combined effects of biological adsorption,electrostatic adsorption,extracellular material polymerization and o-functional group complexation,so it has significant and durability stabilization effect in cadmium standard solution adsorption experiment and soil stabilization experiment.In summary,corn cob biochar in corncob biochar loaded Bacillus subtilis can be a safe habitat to provide necessary nutrients for bacteria,and Bacillus subtilis has strong immobilization effect.The combination of Bacillus subtilis and corncob biochar can overcome the disadvantages of poor stabilization effect of corncob biochar alone and short life cycle of Bacillus subtilis,to control the migration of cadmium further and achieve the purpose of synergy. |
PDF Full Text Request