The Preparation Of Coal Based Sorbents And Study On Cr⁶⁺ Adsorption

This disquisition prepared the sorbent by coal through chemistry oxidation and machine chemistry with the use of the lignite, to research the molding of the coal powder and the sorption of the molding sorbent which adsorb Cr6+ from solution.The coal powder together with FeCl3 can increase the adsorption capability through the grind with ball. When the weight ratio of FeCl3 and coal is one to ten, the sorbent of the coal powder is better after 20min ball grind, washing with acid, washing with water and drying. Through the research for chemistry character of the surface, the reaction of the machine chemistry occurred in the process of the ball grind, and the function group of the acid is adding. The research indicated that the proportion of the surface minish but the capability of the aperture increased after oxidation comparing with the former of the reaction.After the oxidation within measure by HNO3, the adsorption capability of the coal powder is increased. The reaction last 12 hours under the condition that the concentration is 3M, the temperature is 60℃and the ratio of the HNO3 and coal is ten to one. The. mix solution is filtrated with pump after washing with acid and washing with water to the pH7.0. The receiving sorbent with the coal group after drying is best for the adsorption capability. The proportion of the surface and the capability of the aperture are increased after oxidation comparing with the former of the reaction. The middling capability of the aperture is increased accounting for the total capability of the aperture 79.3%, which is propitious to adsorbing Cr6+. The function group of the acid is adding through the research for chemistry character of the surface.Using the test to the molding condition, the research indicated, when the ratio of the aperture reagent, coal and the felt reagent is 25 to 100 to 15, the latter disposal temperature is 220 and the latter disposal time is 90min, the adsorption capability of the molding sorbent received is best. The proportion of the surface and the capability of the aperture are increased comparing with the original coal.The conditions experimental about Cr6+ adsorption on molding absorbent shows that:when pH=2, and the temperature of 20℃for adsorption, adsorption effect is best. In the best adsorption conditions, Cr6+ removal rate about molding adsorbent processing by mechanochemical method can reach 99.7%, better than molding adsorbent processing by chemical oxidation. Cr6+ removal rate about molding adsorbent processing by chemical oxidation is 62.3%. According at the adsorption thermodynamics, the research indicated that the molding sorbent accord with the adsorption isothermal equation of Freundlich or Langmuir for Cr6+. Through the research about the molding sorbent to Cr6+, the adsorption accord with the second degree adsorption dynamics model.