Preparation And Study Of Hydrophobically Associating Cationic Starch Flocculant

For their efficient flocculation, the grafted starch-modified polymerflocculants were developed rapidly in recent years.Because there is amulti-hydroxyl structure in the starch molecular, the monomer withflocculation effect and variety of function can be introduced in the starchmolecules by free radical reactions, and then the starch can not only showgood flocculation effect, but also can show other effects. In this study, thestarch molecules is treated as the main, the functional monomer such asacrylamide, vinyl acetate is introduced by solution polymerization, andthe product is made cationic by the hydroxymethylation reaction, then anew hydrophobic association cationic starch graft flocculant issynthesized. The introduction of the hydrophobic monomer, not onlygreatly improve the flocculation efficiency, and the oily wastewater canbe emulsion breaking easily by using of the characteristics of thelipophilic of the hydrophobic groups, and the better adsorption andflocculation effect can be made on the larger oil content wastewater, onthe other hand, the hydrophobic group can improve the dewateringcapacity of the flocculant, so that the cake’s strength is increased, and canbe easily flocculation and sedimentation.In this study, the effect of the monomer ratio, initiator concentration,reaction temperature, reaction time and other factors on the flocculationproducts is studied by single factor experiments, then the optimumconditions is determined by orthogonal text: the ratio of the weight of thestarch and monomer is1:2.5, the amount of solvent is92%of the totalsystem, the amount of the initiator is1.25%of the amount of monomer, the reaction time is3hours at60℃, the amount of hydrophobicmonomers is10%of the total monomer amount, the amount of mutualsolvent ethanol is1ml; in the cationic experiment, the optimal conditionsis determined by the single factor method: the mass ratio of acrylamide:formaldehyde and Dimethylamine is1:1:1.5, the reaction temperature is60°C, the time is2h, the grafting rate of the hydrophobically associatingcationic starch flocculant can reach125.91%, the grafting efficiency canreach92.47%, the degree of amination was68.7%, The molecular weightis about384,000, and the structure of the graft copolymer is characterizedby infrared spectroscopy and the existence of a graft copolymer.is provedA test of the flocculation performance of the flocculant products ismade, and the results show that: the amount of the products is small inwastewater treating, and the flocculation efficiency is higher, it adapt to awider range of the pH, and performance better in an alkaline environment,but the temperature and ion concentration have a certain impact on theflocculation performance, high temperatures make the flocculationefficiency dropped significantly; then the flocculant products are used inpulp and paper effluent, oilfield wastewater, electroplating wastewaterand domestic wastewater, and is compared with the flocculant productsgrafting with different hydrophobic monomers, and the result show thatthe removal efficiency of turbidity and SS of the flocculant is superior toother products, so it has a better treatment effect on pulp and papereffluent and electroplating wastewater; while the flocculant productsgrafting with long-chain alkanes does a good job in the oilfieldwastewater. The result of the comparison show that the hydrophobicity ofthe flocculant products grafting with long-chain alkanes is strong, but it ishard to synthesis, and the flocculant products grafting with short alkanehas a better grafting efficiency and suitable for many kinds of waterquality of wastewater flocculation.