Effect Of Different Kinds Of Biochars On The Na~+ Adsorption Capacity Of Salinized Soil

Due to the increasing of soil salientization,the use of biochar for soil improvement has received increasing attention.In order to solve the problem of soil salinization in Northwest China,this study explored the effects of three different kinds of biochar on the adsorption mechanism of sodium ions in salt solutions with different concentrations and different degrees of salinization soils,and confirmed the contribution of biochar to the removal of Na~+in soil,in order to provide scientific basis for the improvement of salinized soil in arid and semi-arid areas.The research results are as follows1.The three kinds of biochar used in this experiment are mesoporous materials,and the nitrogen adsorption isotherms belong to the S-type isotherms,which can carry out multi-layer adsorption.The order of specific surface area,micropore volume,mesoporous volume and total pore volume of the three kinds biochars were:corn cob biochar>wood biochar>rice husk biochar.2.The biochar adsorption kinetics of Na~+datas in salt solutions and salinized soil fit well with both the pseudo-first-order and pseudo-second-order kinetic models.The Na~+adsorption isotherms fit well with both Langmuir and Freundlich adsorption isotherms models.3.The removal rates of Na~+in the solution at addition rates of 3%and 6%are 10.39%and17.88%for corncob biochar respectively,3.86%and 6.28%for wood biochar,respectively,and1.49%and 3.17%for rice husk biochar respectively,indicating that corncob biochar has the best removal efficiencies of Na~+in solution;the main mechanisms leading to the decrease of Na~+in solution are electrostatic attraction,pore filling effect and ion exchange.Similarly,the removal rates of Na in soil are 6.67%and 10.83%for corncob biochar,2.5%and 4.17%for wood biochar,and 0.83%and 2.08%for rice husk biochar,indicating that corncob biochar addition had the best effect on the removal of Na~+from soil.The main mechanisms leading to the decrease of Na in soil are electrostatic attraction,pore filling effect,surface and inner spheroid complexation and ion exchange.4.According to the removal efficiencies of Na~+removal rates of the three different kinds of biochar in this experiment,,It is suggested that corncob biochar should be preferred in the improvement of salinized soil,and biochar is most effective in severe and moderate salinized soils(6%).