Study On The Natural Macromolecular Flocculant Of Aloe

The natural macromolecular plant aloe vera L.with abundant source and cheap price was selected in this dissertation,and its flocculating performance was studied.Aloe gel,aloe polysaccharide and aloe powder were prepared,and the techniques of extraction of polysaccharides from aloe were studied.The contents of polysaccharide extracted by technique of alcoholic sedimentation at room temperature is 12.27%,highest ratio in this experiment.The flocculants prepared above were studied,and flocculation tests were carried on to kaolin simulated water sample prepared in the laboratory,with the method of stirring in beakers.The results indicate that aloe gel has the best flocculation effect to the sample prepared,and the removal ratio of turbidity is 99.08%,the optimum dosage of aloe gel is 0.75mg/L.The influence of different factors on flocculation effect of aloe gel were studied.Aloe gel has an extensive applicable pH range,the removal ratio of turbidity reach up to 92%when the pH of water sample is between 3 and 11,and the flocculation effect of aloe to high turbidity sample is better than to low turbidity sample.Compared with Fe₂(SO₄)₃,PFS and PAM,the results indicate that aloe has a good flocculation effect,with characteristics of low dosage,high sedimentation velocity of flocs, thick floes.Compounded with Fe₂(SO₄)₃,PFS and PAM separately,the results indicate that aloe compounded with Fe₂(SO₄)₃ has the best effect,the removal ratio of turbidity is 99.12%, the optimum dosage of aloe is 1.68mg/L,and that of Fe₂(SO₄)₃ is 20mg/L.Practical application of aloe was studied preliminarily,and the waste water of the YouYi River in Nanjing University of Science and Technology was treated.The results indicate that aloe has a good effect to the turbidity removal,and COD is also decreased.The removal ratio of turbidity is 93.44%and the removal ratio of COD is 64.34%,when aloe is compounded with Fe₂(SO₄)₃ and the dosage of aloe gel is 4 mg/L,the dosage of Fe₂(SO₄)₃ is 15mg/L.The stabilization of aloe gel was studied preliminarily.The results show that aloe gel can be preserved for 18 days when treated by potassium sorbate,citric acid,and adsorpted by active carbon,under the condition of refrigerated storage.The removal ratio of turbidity still keeps above 90%after stabilizing treatment and storaged for 14 days,which indicates that aloe keeps a good flocculation activity.