The Study Of Fulvic Acid Purity And Applied Base

There are many active function groups in fulvic acid (abbreviated as FA) structure, FA can combine with many metal ions and organic pollutants, and pure FA have good medical value, so it is significance to study the purity method and adsorption mechanism.In the thesis, we studied the purify process of fulvic acid which was bought in the market, and the influences of resin type, ion exchange time and resin quantity on FA purity. Secondly, we investigated the effect of pH value, time and temperature on adsorption of Cr⁶⁺, Fe³⁺ and Cu²⁺ and TNT by FA respectively, and discussed the adsorption thermodynamics and mechanism. At last, we studied the competition adsorption of Cr⁶⁺, Fe³⁺ and Cu²⁺ on FA and the effects of Cr⁶⁺, Fe³⁺ and Cu²⁺ on adsorption of TNT by FA when these metal ions existed in solution. The results were showed as follow:FA purity can reach 99% after dealed with 001*7 and D751 resin.Adsorption of metal ions by FA was influenced by pH, and the adsorption amounts and rates enhanced with the increase of time. The adsorption amounts of FA to metal ions varied in the order of Cu²⁺>Fe³⁺>Cr⁶⁺, the adsorption promoted by entropy followed Freundlich equation, and adsorption amounts of Cr⁶⁺, Fe³⁺ or Cu²⁺ increased with the increase of temperature. Adsorption ability of FA to Cu²⁺ is stronger than that to Cr⁶⁺and Fe³⁺ in complex system. The primary adsorption mechanism is ion-exchange, companied by other different physical and chemical adsorption.The adsorption of TNT by FA was also effected by pH, the maximum adsorption rate of 95% can be reached when pH=7.5. Adsorption progressed slowly due to adsorption equilibrium was not up to till 24h. Adsorption of TNT by FA that promoted by entropy followed Freundlich equation, and it is advantaged to the adsorption when temperature was elevated. The FA interacted with TNT through H-bonding mainly, as well as ion bonding, covalent bonding, charge transfer, electronic giving-acceptance and van der Waals force also contributed to adsorption of TNT by FA. FA can complex Cr⁶⁺, Fe³⁺ or Cu²⁺ to weak ligands when these metals in the solution, and TNT can complex these weak ligangs through exchange its function group with these weak ligangs, leading to the amount of adsorption of TNT by FA increased.