Synthesis And Flocculation Performance Of Hyperbranched Polyacrylamide

In the situation of the lack of water resources in the world,the emission of oil containing waste-water has become one of the problems in water pollution.Therefore,the development of an efficient water treatment agent is an effective way to resolve the problem.The study found that adding a certain amount of flocculant to the water can destroy the stability of the emulsified oil,making the fine particles and suspended particles collide with each other to form flocs,and achieve the effect of solid liquid liquid separation by flocculation and sedimentation.Hyper-branched poly-acrylamide has a three dimensional structure and a large number of unique molecules containing terminal can be modified by chemical modification,which has special function of polymer internal hole.The hole can be wrapped a large number of adsorption of guest molecules,reach the aim of water purification.It has certain application prospect and the development value in the field of water treatment.Hyper-branched amphoteric poly-acrylamide was synthesized with free radical polymerization and in-situ polymerization through core-first method using pentaerythritol?PETL?as branched agent,cerium ammonium nitrate?CAN?as initiator,acrylamide as the main chain,and the acryl oxide ethyl three methacrylate ammonium cationic monomer was added to increase its positive charge density.Water solubility improved by 2-acrylamide-2-methylpropane sulfonate anion monomer.The flocculation property and mechanism of the polymer were studied.The main contents of this thesis are as follows:?1?Hyper-branched amphoteric poly-acrylamide was synthesized with free radical polymerization and in-situ polymerization through core-first method using acrylamide?AM?,acryloxyethyl trimethyl ammonium chloride?DAC?,tetraethoxysilane as the raw materials,pentaerythritol?PETL?as branched agent,cerium ammonium nitrate?CAN?as initiator.The structure was characterized by FTIR,¹H-NMR and elemental analysis.The surface morphology was observed and analyzed by environmental scanning electron microscope.The results showed that the expected product has been successfully synthesized and its micro-morphology was coral-like.On the basis of single factor,the optimal process parameters of the hyper-branched amphoteric poly-acrylamide intrinsic viscosity are as follows:reaction time was 3.5 h,reaction temperature was 50?,initiator mass fraction was 0.004%,ethyl orthosilicate mass fraction was 1.0%,monomer mass fraction 20%,the intrinsic viscosity of PAD was 307.67 mL/g.?2?Hyper-branched amphoteric poly-acrylamide was synthesized with free radical polymerization and in-situ polymerization through core-first method using acrylamide?AM?,acryloxyethyl trimethyl ammonium chloride?DAC?,2-acrylamido-2-methylpropane sulfonic acid?AMPS?,tetraethoxysilane as the raw materials,pentaerythritol?PETL?as branched agent,cerium ammonium nitrate?CAN?as initiator.The structure was characterized by FTIR,¹H-NMR The surface morphology was observed and analyzed by environmental scanning electron microscope.The results showed that the expected product has been successfully synthesized and its microscopic morphology was spherical-like.On the basis of single factor,the optimal process parameters of the hyper-branched amphoteric poly-acrylamide intrinsic viscosity are as follows:the dosage of initiator is 0.04%,the monomer mass fraction was 20%,the reaction temperature was 65?,the reaction time was 3.5 h,and the amount of tetraethyl orthosilicate was 2.5%,the intrinsic viscosity of PAD was 421.07 mL/g.?3?The flocculation performance of PAD and PADS in simulated waste-water of diatomite earth was studied by the supernatant transmittance and flocculation settling time.The results showed that PAD and PADS have good flocculation performance in simulated waste-water of diatomite with a mass fraction of 3%.When the PAD dosage was 8 mg,the transmissivity reached98.49%.When the PADS dosage was 5 mg,the transmissivity reached 98.7%.It indicating that the PADS dosage was less than dosage of the PAD and the flocculation performance of PADS was better.?4?The flocculation mechanism of PAD and PADS in simulated diatomite waste-water with mass fraction of 3%was studied by means of Zeta potential,particle size analysis,fractal dimension and micro structure before and after flocculation.The results showed that the best Zeta potential values of PAD were0.27 mV and PADS were-0.38 mV,and the average particle size of PAD was572?m and the average particle size of PADS was 631?m.After flocculation,the floc clusters were dense and the volume of particles was large,indicating that PAD and PADS had good electrical neutralization and adsorption bridging.?5?The flocculation performance of PAD and PADS to oily waste-water was studied by removal rate and COD removal rate.At the same time,it was applied to the waste-water with different salinity and shear stress to study its salt tolerance and shear resistance.The results showed that the oil removal rate of both PAD and PADS is above 85%,and the removal rate of COD is above75%,it has good oil removal performance.When the salt concentration was 0.20g/L and the shear rate was 50 s^-1,the apparent viscosity was in an ascending state,indicating that both PAD and PADS had good salt tolerance and shear resistance.