Study On The Preparation Of Compound Conditioning Agent And Its Stabilization Effect On Heavy Metal Cadmium In Soil

The treatment and restoration of heavy metal contaminated soil is a very important task.Reduce the toxicity of heavy metal pollution in the soil by adding certain materials to the soil.It is one of the important ways to control and repair heavy metal contaminated soil.Application of compound conditioner as a soil heavy metal repair technology,Not only can it play a role in controlling soil pollution,And can guarantee the quality of land output products.This study uses cement slag and red brick slag and potassium feldspar in urban construction rubbish as raw materials.a method for preparing a composite conditioning agent,In situ stabilization effect,Research work on the stability of soil cadmium under planting conditions,etc.The research results are as follows:Based on the ratio of red brick slag: cement slag: potassium feldspar to 1:1:2,Calcined at 400°C,500°C,600°C,700°C,800°C,900°C and 1000°C,respectively,And the calcined material was subjected to in-situ passivation simulation experiment.The optimum calcination modification temperature for the preparation of the composite conditioning agent can be judged by the heavy metal speciation analysis to be 900°C.After determining the modification temperature to 900°C,We will add three kinds of addition ratio(0.5%,1% and 2%)and three different proportions of cement slag: potassium feldspar(1:2),red brick slag: potassium feldspar(1:2)and red brick slag: cement slag:potassium feldspar(1:1:2)for in situ passivation screening test of simulated cadmium contaminated soil.Through the test results,you can get:(1)In the passivation experiment of single-component materials,Potassium feldspar has the best passivation effect,And the passivation ability of the three components is in order: potassium feldspar > cement slag >red brick slag.(2)In the rescreening experiment of the compounding agent,Cement slag:Potassium feldspar(1:2)has the best passivation effect on effective cadmium,and the stability efficiency reaches 41.2%.(3)The order of passivation ability is: Cement slag:Potassium feldspar(1:2)> Red brick slag: Potassium feldspar(1:2)> Cement slag> Red brick slag: Cement slag: Potassium feldspar(1:1 :2)>K-feldspar>Red brick slag.(4)Cement slag:Potassium feldspar(1:2)was added to the passivation experiment with optimized conditions to indicate:0.5% cement residue: the percentage conversion of potassium feldspar toexchangeable cadmium is 19.31%;1% cement residue: potassium feldspar conversion percentage of exchangeable cadmium is 21.5%;2% cement residue: potassium feldspar conversion percentage of exchangeable cadmium is 18.32%.From this,cement slag with a soil addition ratio of 1% can be obtained: potassium feldspar(1:2)has the best treatment effect.The application of compound conditioning agent significantly reduced the accumulation of cadmium in various parts of Chinese cabbage,And the accumulation of cadmium in the upper part of Chinese cabbage decreased with the increase of the amount of compounding agent,The accumulation of cadmium in the aboveground and underground parts decreased by37.5% and 42.7%,respectively.As the amount of compounding agent increases,The accumulation of cadmium in the aboveground parts of Chinese cabbage was significantly reduced,and the accumulation of heavy metals in the roots of Chinese cabbage was also gradually reduced.The available cadmium in the soil is still reduced to some extent after one season of Chinese cabbage cultivation.The application of compound conditioning agent satisfies the demand for potassium in Chinese cabbage,and reduces the absorption of heavy metals in the soil of various parts of Chinese cabbage.The application of compound conditioner improves the yield of Chinese cabbage,At the same time,the absorption and accumulation of heavy metals in Chinese cabbage were inhibited.