Study On Preparation Of Compound Biolfocculant CBF-1and Its Flocculation Properties

In recent years, for the high production cost and flocculation capacity limitations ofbioflocculants, researchers have proposed a variety of new solutions. Currently, researchershave done much work on preparation of compound bioflocculant （CBF）, which is complex,cheap and efficient. In this paper, for biopolymeric flocculant （CG-A） and bioflocculant（MBF8） have good solubility and chemical, electrical phase-capacitive, and thecomplementary nature of molecular weight, chemical groups, we use CG-A and MBF8toprepare a new type compound bioflocculant （CBF-1）, which is of low-cost and highflocculation efficiency. The paper are focused mainly on the following points:The results showed that the optimum weight ratio of CG-A: MBF8was4:6. CBF-1waspale yellow solution with0.013%of undissolved substance. The pH value, relative viscosity（effective constituent0.5%,30℃） and isoionic point （effective constituent0.1%） of suchsolution were6.1,1.72and pH=1.5, respectively. The main specific functional groups werehydroxyl group, carboxyl group, amino group, amide group and phosphate group. With thePAC dosage of3mg/L and the CBF-1dosage range from1.0to8.0mg/L, the optimum pHvalue was6.0-10.0and the optimum ionic strength was0.5-5.0mM for the Jar tests. For thekaolin suspension with turbidity of100NTU, the removal rate of turbidity could achieve92%and the residual aluminum was less than75μg/L under a reaction pH of8.0and ionicstrength of3.0mM. For the kaolin suspension with turbidity of6to300NTU, the removalefficiency of turbidity was range from61to98%.When PAC and CBF-1complex were used to flocculate molybdenum ore washingwastewater, the residual turbidity reduced to5.12NTU with the optimum condition of pH7.75, the PAC dosage was2.0mg/L and the CBF-1dosage of1.5mg/L. For starchwastewater, PAC+CBF-1complex flocculate could reduce the residual turbidity to3.02NTU with the optimum condition of pH9.0, the PAC dosage of10.0mg/L and the CBF-1dosage was1.0mg/L. It indicated that CBF-1had a broad prospect for application inpractice. The flocculation characteristics of PAC+CBF-1, PAC+CBF-1（solube） and PAC+MBF8were determined by Jar test, microscope and iPDA instrument respectively. The resultsshowed that the PAC+CBF-1complex flocculation flocs were more rough and loose and theflocculation intensity was higher, but its recover ability was weak.Using PAC+CBF-1complex to flocculate kaolin suspension include three processes:hydroxyl polymer of PAC could lead kaolin colloidal particle to be destabilization cohesion;-OH,-CONH₂,-NH₂in the dissolved species of the CBF-1could adsorb kaolin colloidalparticles with the hydrogen bonds, while-PO₄^3-and-COO–could adhesion PAC through thevan der Waals forces, leading to the formation of flocs. The undissolved substance of CBF-1could adsorption flocs through bridging with its huge specific surface area, and ultimatelyform a larger particle size, good settling properties flocs.