Experimental Study On Dynamic Adsorption Of Chromium By Modified Zeolite

Water pollution incidents occurred frequently in recent years,which leads to a serious situation of water resources.Because of its strong refractory,biological toxicity and cumulative and amplification effect,arsenic can cause long-term and serious harm to the ecosystem and human health.Arsenic pollution incidents have been closely watched at home and abroad.Because of its advantages,Permeable reactive barrier,as a kind of in-situ remediation technology,has received extensive attention.There are already many permeable reactive barrier projects in foreign countries,but the technology is still in the laboratory research stage at home.This experimental research based on the national international science and technology cooperation projects.The best modification process of two cationic surfactant(Cetyltrimethylammonium chloride,abb.CTAC and 1-Hexadecy l-3-methylimidazolium chloride monohydrate,abb.HMCM)modified zeolites was studied by static adsorption experiments.The influence of different factors on the dynamic adsorption of chromium ion was explored by using columns filled with modified zeolite.The related parameters of the permeable reactive barrier were determined.Combined with the terrain features,design and construction of permeable reactive barrier was made.Static experiments showed that the adsorption ability of the modified zeolite was greatly improved,and the adsorption capacity was 0.21mg/10 g and 0.25mg/10 g,respectively.The effect on the adsorption properties of modifier dosage,modification time,solid-liquid ratio,different modifier ratio and other factors was explored.Finally,the best process of zeolite modification was obtained.The dynamic adsorption performance of a single modifier modified zeolite packed column was studied.By contrast,after modified by CTAC and HMCM,the life of the column is greatly extended from 1.2 PV to 25 and 40 PV respectively.The influence of different factors on the dynamic adsorption of modified zeolite was discussed.With the increase of particle size and the initial concentration,the saturation velocity of the column is accelerated,and the life span of the column is decreased.Combining the results of static adsorption and dynamic adsorption,zeolite with a particle size of 1～1.5mm modified by CTAC with a small amount of HMCM was determined as filling agent of permeable reactive barrier.Based on the conclusion of the laboratory,combined with the actual terrain,the structure of permeable reactive barrier was designed and improved.A permeable reactive grid project for the treatment of surface runoff was built.The samples of modified zeolite collected on site were tested.Through the dynamic adsorption of the column filled with modified zeolite on site,the lifetime of the modified zeolite packed column was 53 PV,and the performance was excellent.