UV-H₂O₂ Preparation Of Cationic Polyacrylamide （CPAM） And Its Application In Sludge Condition

In recent years,due to the increasing speed of urbanization in China,the large amount of urban sewage discharge is a serious problem to be faced in accelerating urbanization.In addition,a large amount of sewage discharge at the same time also generated a large amount of water content of nearly 95%of the sludge,so in the process of solving this problem,the relevant research and sludge dehydration can not be ignored.Cationic polyacrylamide（CPAM）,a product of the interaction between acrylamide（AM）and acryloxyethyl trimethylammonium chloride（DAC）,was prepared by low temperature UV-H₂O₂assisted polymerization and applied to municipal sludge flocculation.By means of infrared spectroscopy（FTIR）analysis,differential scanning calorimetry（DSC）,electron microscopy（SEM）and nuclear magnetic resonance（¹H NMR）,the microscopic morphology,conformation characteristics and thermodynamic properties of the product PAD were detected.Then,the prepared polymer was applicated in buildings drain mud and water flocculation,discuss the product dosing quantity,p H value and molecular weight of the product and the cationic degree on the municipal sludge flocculation effect,the turbidity removal rate,the morphological characteristics and Zeta potential,and further explore in the flocculation mechanism in the process of flocculation.The conclusions are as follows:（1）FTIR and ¹H NMR verified the successful synthesis of PAD through UV-H₂O₂initiated copolymerization.The TG/DSC results and SEM revealed that PAD had inferior thermal stabilities.And an uneven and porous surface area with a D_f value of1.634.（2）The appropriate synthesis conditions included 35 wt%total monomer concentration,25 mol%DAC concentration,0.06 wt%H₂O₂,p H 4.5 and illumination for 25min.Under these conditions,PAD with 6.89×10⁶ Da of molecular weight and99.7%of conversion had been obtained.（3）The results of sludge dewatering experiments indicated that,when the p H was7.0 and the dosage was at 40 mg/L,the addition of PAD-3（molecular weight:6.89×10⁶Da,cationic degree:40%）showed more excellent dewatering performance,with the70.6%of FCMC and 2.8×10¹² m·kg^-1 of SRF were acquired.（4）The tests on characteristic of sludge floc manifested that sludge floc size and floc fractal dimension of PAD-3 were larger than that of PAM、PAD-1 and PAD-2,with those were 436.802μm and 1.59,respectively under the optimal flocculation condition.（5）The mechanism involved in sludge dewatering contained charge neutralization,patching and bridging,corresponding formed large and dense flocs which steadily remained sufficient hydrophobic pores and gaps and hence were convenient for sludge dewatering.