Preparation Of Chitosan/Organic Acid And Adsorption Properties On Cr(?)

Cr(?)is one of the most dangerous heavy metals in the water,if Cr(?)accumulate in the body continuously,it will increase the risk of cancer in humans,and damage the human life and health seriously,so it is the time to remove Cr(?).Adsorption technology is the one of the most effective removal of Cr(?)technologies,it has the characteristics of no secondary pollution and simple production,but some adsorbate is expensive.In many adsorbents,chitosan is a natural polymer material,whuch can be obtained directly from nature,and it is cheap,however,the biggest drawback of chitosan adsorption is that the recovery rate is not very high.To solve the above problems,this paper studied the removal of Cr(?)by the composite material of chitosan and organic acid.Chitosan and organic acids are widespread in nature,both of which have the ability of chelating with metal ion.Chitosan / organic acid composite is a compound which obtained by connect the functional groups of chitosan and the functional groups of organic acid.This paper discussed the chitosan/organic acid composite ratio(2:1,2:2,2:3,2:4,2:6),compound dosage(2,4,8 and 12g/L),pH(2,3,4,6),temperature(296,306,316 and 326K)and initial concentration of Cr(?)(500,1000,1200,2000M)effect on chitosan / organic acid composite adsorption Cr(?).It was found that the optimal ratio of chitosan / organic acid composite was 2:2,2:3,the best pH value was 4,the best adsorption concentration was about 20mg/g.With the increase of temperature,the efficiency chitosan / organic acid complexes on removal of Cr(?)was increased,the adsorption was endothermic reaction,Freundlich isotherm model was more accurate adsorption isotherm than Langemuir isotherm equation,the kinetic of organic acid / chitosan composite on chromium adsorption accorded with the second kinetic equation.The effect of different functional groups on the adsorption of Cr(?)was also discussed.With the increase of the number of carbon atoms,the coordination of organic acid and chromium increased,the stability of the complex was reduced and the ability of chromium removal was decreased;The more the number of hydroxyl groups,the more obvious the effect of chromium removal,but steric hindrance will weaken the effect of hydroxyl group;The more the number of carboxyl groups,the more obvious the effect of chromium removal,but steric hindrance will weaken the effect of carboxyl group;The presence of steric hindrance greatly affected the adsorption of Cr(?).