Research On The Synthesis, Properties And Application Of Serial P(DMC-AM)

P（DMC-AM）,the copolymer of methacryloyloxyethyl trimethyl ammonium chloride（DMC）and acrylamide（AM）,is a kind of cationic polyacrylamide with positive charge that is widely used in oil exploration,papermaking,wastewater treatment,textile printing and dyeing,etc,because of its advantages of good water solubility,easy to control intrinsic viscosity,high efficiency and non-toxic.In this dissertation,P（DMC-AM）with serial cationicities and high intrinsic viscosity were synthesized.Then,the thermal stability and solution properties were studied systematically.Finally,it was used to flocculate and dewater sludge from different sources.The obtained research progresses in this dissertation are showed as following.（1）Synthesis of P（DMC-AM）with serial cationicities and high intrinsic viscosityTo study on the synthesis technology of P（DMC-AM）with serial cationicities and high intrinsic viscosity,the P（DMC-AM）with cationicities 10%～90%were synthesized by using the intrinsic viscosity（[η]）and monomer conversion rate（Conv.）as quantitative criterion via the initiating system of oxygen acid salt-sulphite and aqueous solution polymerization with one stage addition of the monomers and stepwise increasing temperature.The effects of the monomer concentration,initiator dosage,additives dosage and reaction temperatures which around the optimal synthesis conditions on[η]and Conv.of P（DMC-AM）were investigated;The relationships between the cationicities of copolymers and their optimum process factors,[η]and Conv.were discussed;The structures of both monomers and P（DMC-AM）with serial intrinsic viscosities and cationicities were characterized and analyzed by FTIR and ¹H NMR.The results showed that under the optimum synthesis conditions,the[η]of P（DMC-AM）with cationicity of 10%～90%were 18.14～14.15 d L/g,and the Conv.were 98.65%～90.11%,respectively.With the increase of process factor values,the[η]first increased and then decreased,the Conv.first increased and then stabilized or decreased.The optimum process conditions were affected by the cationicity and the reactivity of monomers in the polymerization system.The spectra of FTIR and ¹H NMR confirmed the components of the copolymerization happened between two kinds of monomers.In addition,it was observed that,with the increase of the polymer cationicity,the relative area of the absorption peaks concerning the cationic unit from DMC monomer were increased.The research work finished above could be the foundation for improving the synthesis technology of the high[η]of P（DMC-AM）with serial cationicities and further researches on polymerization mechanism,the relationship among the structures and properties of P（DMC-AM）and its industrial application.（2）Study on the thermal decomposition process and mechanism of P（DMC-AM）The thermal thermodynamics and kinetics in thermal decomposition processes of P（DMC-AM）samples with10%～90%cationicities and 5.80～15.51 d L/g were investigated by TG and DSC.The thermal decomposition mechanism of P（DMC-AM）was meanwhile studied by calculating bond orders and analyzing the evolved gas during thermal decomposition process by using TG-FTIR and TG-MS.Under the thermal thermodynamics study,TG-DSC curves showed that the thermal process had two stages.The change of thermodynamic parameters declared that it was mainly broken the side chains at first decomposition stage,broken the main chains and the groups connected to main chains at second decomposition stage.Under the kinetics study,the activation energies E at different conversion rates were obtained by the Flynn–Wall-Ozawa（FWO）method and Kissinger–Akahira–Sunose（KAS）method.The changes of E values showed that the reaction process at 50%cationicity existed at each cationicity,but the proportion of the reaction process different.Reaction order n and pre-exponential factor A were obtained by the Coast-Redfern method.The results showed that the two decomposition processes were characterized all as first-order reactions.Under the thermal decomposition mechanism,the bond orders of the representative unit were calculated by quantum chemistry,and the decomposition fragments of 50%cationic P（DMC-AM）were obtained by the escape gas analysis method,leading to a mechanism of thermal decomposition of 50%cationic P（DMC-AM）molecules in the first and second stages.The above research results not only filled in the thermodynamics and kinetics research defects existed because of using the single sample with mono cationicity and intrinsic viscosity,until now,but also formed a new hypothesis of P（DMC-AM）thermal decomposition mechanism model.（3）Study on the salt solution viscosity property of P（DMC-AM）and its mechanismThe salt solution viscosity behaviors of P（DMC-AM）resulting from the various cationicity and intrinsic viscosity and their mechanism were studied.The effects of ionic radius,cationic valence and anion valence of a selected salt on the apparent viscosity（η_a）of P（DMC-AM）samples in salt solution with increasing concentration were discussed.The results showed that,on the one hand,for any selected P（DMC-AM）sample used in various salt solutions,the itsη_afirst decreased sharply to a lowest value and then either remained stable with the increase of the monovalent salt concentrations such as Li Cl,Na Cl and KCl,respectively,or turned to increase with the increase of the multivalent salt concentrations such as Mg Cl₂,Al Cl₃,Na₂SO₄and Na₃PO₄,respectively;Meanwhile,the larger the cationic radius of salt,the higher the cationic valence or anion valence in the solution,the greater the effect was on the above change tendency ofη_a;The effect of multivalent anions on theη_a was greater than that of multivalent cations.On the other hand,for various P（DMC-AM）samples used in a selected salt solution,theη_a of the solutions increased with the cationicity or intrinsic viscosity increasing of the polymer samples.Furthermore,depending on theη_a changing rules of P（DMC-AM）sampples in multivalent salt solutions,an action mechanism model between ions of multivalent salts and P（DMC-AM）molecules was proposed.Therefore,all above progresses have improved the more deeply understanding of the viscosity properties of P（DMC-AM）in various salt solutions and provided theoretical support for the practical application.（4）Study on the flocculation and dehydration performance of P（DMC-AM）and its action mechanismTo study the flocculation and dehydration performance of P（DMC-AM）,sludge from different sources such as the poly-aluminum chloride production process and the alcohol production process using were conditioned by using P（DMC-AM）with serial cationicities and[η]as flocculants and using commercial polyacrylamide samples with serial cationicities as comparison agents.The results showed that for flocculating the sludge mainly containing inorganic substances from poly-aluminum chloride production process,the flocculation and dehydration efficiency of P（DMC-AM）samples was lower the optimum samples selected from the commercial products in comparison.However,for flocculating the aerobic sludge mainly containing organisms such as cellulose,amylose and humus,the best flocculation and dehydration efficiency was from the polymer with 10%～50%cationicity,especially 50%cationicity of P（DMC-AM）sample,resulting that the cake moisture content was 75.23%,the filtrate transmittance and CODcr were 96.8%and 350 mg/L,respectively,beneficial for sequent treatments and discharge.It was found in the research that P（DMC-AM）had a unique dehydration effect on the above aerobic sludge,due to the effect of extra methyl on its main backbone chain,presumably,when in comparison of its molecule structure with that of popular cationic polyacrylamide in commercially.These results could provide theoretical guidance for selecting the most suitable flocculants to match sludge properties in their practical flocculation and dehydration application.