The Preparation And Characterization Of Sodium Polyacrylate Using Inverse Emulsion

Settlement and separation of red mud was a key link in alumina production. Thecapacity of equipment, product quality and enterprise benefit was contracted closelywith the separating efficiency. The settling separation efficiency could be obviouslyimproved after flocculant added.The preparation and modification of hydroxamated acrylamide polymer werestuied and the experiment was divided into two parts. One part was about usingsodium polyacrylate, dimethyl sulfate and hydroxylamine hydrochloride as rawmaterials, Span80-OP10as composite emulsifier, sodium polyacrylate was oximationmodified by inverse emulsion modified method using liquid paraffin as continuousphase and water as dispersed phase. The study was focused on the viscosity andstability of the polymer-modified products. Many factors were investigated, such asdifferent of oil phase, the volume ratio of oil to water, type and dosage of emulsifier,temperature, degree of esterification and so on. The optimal reactive conditions wereas follows: the volume ratio of oil to water was1:1, the content of emulsifier was5%of quality of the oil phase, the content of sodium polyacrylate was25%quality of theoil phase, the molar ratio of sodium polyacrylate to dimethyl sulfate was1:1, themalar ratio of hydroxy lamine hydrochloride to the ester groups in the esterifiedproducts was2:1, the temperature of esterification was50℃, the temperature ofhydroxamation was35℃, the reaction time was2h of esterification and2h ofoximation reaction. With these optimal reactive conditions, the polymer was obtainedand the viscosity was42mPa.s while the polymer concentration was0.2g/L. Anotherpart was about hydroxamated acrylamide polymer which synthesized through inverseemulsion polymerization. The experiment was about using sodium acrylate andmethylacrylate as monomers, Span80-OP10as compound emulsifier, V-50as initiator,hydroxamic acid was synthesized by inverse emulsion polymerization using liquidparaffin as continuous phase and water as dispersed phase. Many factors wereinvestigated，such as temperature, stirring speed, pH, concentration of monomers,dosage of initiator and so on. The optimal reactive conditions were as follows: themonomer concentration was25%, the volume ratio of oil to water was1:1, the contentof emulsifier was5%quality of the oil phase, mass ratio of Span80to OP10was2:1, mass ratio of sodium acrylate to methylacrylate was1:1, the ratio of initiator was0.08%, inlet time of N2was30min, polymerization time was3h, polymerizationtemperature was35℃, oximation time was2h, oximation temperature was35℃, thetime of heat preservation for2h. With these optimal reactive conditions, the polymerwas obtained and the viscosity was45mPa.s when the concentration of the polymerwas0.2g/L.The products obtained by the two methods were demulsified by ethanol and thenwere dried under60℃for6h. The infrared spectroscopy result showed that theoximation modification was successfull.The products obtained from the two methods were used to flocculate thehome-made red mud. The result showed that the modified product was obviouslybetter than the non-modified ones. And the effect of flocculation by the two methodswas similar: the viscosity was45mPa.s when the concentration of the polymer was0.2g/L. Under the optimum conditions, the transmittance of the upper clean liquidwas up to86%, the water content for press cake was decreasing to63.75%.