Study On The Adsorption Performance Of Modified Coal Slurry For Arsenic Mercury Wastewater And SO₂

In this paper,Pinglu coal slime in Shanxi province was selected as the subject of study,which was treated by impregnation of iron salts and preparation with the method of activated carbon.The effect of modified coal slime on the adsorption properties of mercury,arsenic in wastewater and sulfur dioxide in gas was investigated,providing theoretical and experimental support for the subsequent resource utilization of coal-based solid waste.In this project,for the adsorption of mercury and arsenic slime in wastewater,the main method is to use Fe Cl₃,Fe SO₄ and H₂O₂ reagents to impregnate the slime,and the modified slime is used to adsorb Hg²⁺,As³⁺and As⁵⁺in the wastewater,and the search for optimal adsorption conditions was focused on exploring the factors affecting adsorption in terms of reagent concentration,adsorption time,adsorbent dosage,p H value,ect.The experimental results show that the unit adsorption capacity of Hg²⁺decreased due to the decrease of the S content in the treated samples of Fe Cl₃,while the adsorption capacity of arsenic-containing wastewater increases.Samples treated with Fe SO₄ showed good adsorption of mercury and arsenic-containing wastewater.The adsorption capacity of mercury-containing and arsenic-containing wastewater increases with the increase of p H value.The adsorption peak value of mercury-containing wastewater reaches the maximum when p H value is 11,and that of arsenic-containing wastewater reaches the maximum when p H value is 4.However,when the p H value continues to rise,the adsorption capacity decreases due to the effect of reaching the upper limit of the precipitation of Hg and As and the occurrence of arsenic in the form of water.The samples before and after adsorption were analyzed by scanning electron microscopy（SEM）and X-ray photoelectron spectroscopy（XPS）to determine the changes in the surface characteristics of the modified samples and the changes in the occurrence form and content of the elements before and after adsorption,and to determine the adsorption mechanism of the modified slime on the elements Hg and As,Hg is mainly responsible for the production of Hg S and Hg O compounds,As mainly occurs oxidation,iron complex co-precipitation and other reactions.The coal slime was treated by simulating activated carbon preparation,and was used to adsorb sulfur dioxide,so as to explore its adsorption effect.After pretreatment with KNO3,the mud was impregnated,carbonized and activated with KOH.Optimal adsorption conditions were determined by exploring the ratio of alkali to carbon,activation time and activation temperature.The results show that the optimum adsorption conditions are as follows:alkali-carbon ratio 4:1,activation temperature 850℃and activation time 80 min at optimal adsorption conditions,the adsorption capacity of sulfur dioxide is 199.1 mg/g.