Study On The Synthesis And Application Of Sulfonic Acid-Based Scale Inhibitors

Inorganic scaling is a common phenomenon in the pulping and papermaking process. It often causes a great amount of problems such as lowering the operating efficiency of the paper machine, raising production costs and decreasing the quality of paper. Pulping and papermaking raw materials, such as water, wood, fillers and the wet end chemicals are all origions of the scaling materials. Whether and how scaling is produced are highly related to scaling control methods used in water treatment. Adding scale inhibitors to the white water system is one of the most cost-effective and widely-used ways. Meanwhile, introducing sulfonic acid groups to polymeric scale inhibitors has been interested in recent years.In this thesis, a water-soluble terpolymer AA/IA/AMPS was prepared by solution polymerizing acrylic acid (AA), itaconic acid (IA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in aqueous phase under different conditions, where ammonium persulfate was used as initiator, isoproply alcohol was used as chain-transfer agent. The influence of polymerization conditions such as monomer mass ratio, initiator amount, reaciton temperature, reaciton time on the performance of the scale inhibitors'the calcium carbonate scale inhibiting effect, calcium ions chelating effect, and inorganic particles dispersing effect, were studied. And scanning electron microscopy was used to briefly explore the mechanism of scale inhibitors on the generation of calcium carbonate scales. The optimum conditions for the synthesis reactions were determined first by single factor experiments and then by orthogonal experiments, and the results were as follows:(1) From the aspect of the calcium carbonate scale inhibiting performance, the optimum conditions for the synthesis of the AA/IA/AMPS sacle inhibitors were found to be: m(AA):m(IA):m(AMPS)=2:6:2, initiator dosage of 8% to the total monomer mass, reaciton temperature of 90?, reaction time of 4 h.(2) From the aspect of calcium ion chelating performance, the optimum conditions for the synthesis were found to be:m(AA):m(IA):m(AMPS)=2:6:2, initiator dosage of 10% to the total monomer mass, reaciton temperature of 95?, reaction time of 4 h.(3) From the aspect of inorganic particles dispersing performance, the optimum conditions for the synthesis were found to be:m(AA):m(IA):m(AMPS)=2:6:2, initiator dosage of 8% to the total monomer mass, reaciton temperature of 90?, reaction time of 3 h.However, considering that the influence of changing the inititor dosage from 10%to 8% and reaciton temperature from 95? to 90? on the chelating properties was small, and;as well, the influence of changing reaction time from 3h to 4h on the scale inhibitors' dispersion properties was not large, the optimal synthesis conditions for the scale inhibitors were comprehensively determined to be:AA/IA/AMPS mass ratio of 2:6:2, initiator dosage of 8%, reaction temperature of 90?, and reaction time of 4h.Comparison on the infrared spectra of the self-made scale inhibitors and the commercial ones showed that their functional groups were basically the same. However, as the contents of the functional groups were different, the overall performance of the self-made scale inhibitors are significantly better than the commercial ones. The application results suggest that the preparation of the self-made scale inhibitors was successful.By observing the photos of scanning electron microscope, it was found that the morphology of the calcium carbonate crystals and aggregates occurred significant change under the influence of the scale inhibitors. And for different scale inhibitors, their effects on the calcium carbonate crystals were not the same.For our best self-made scale inhibitor, it was found to have the ability to induce a shift from a stable calcite to unstable vaterite and aragonite. At the same time, the influence of the self-made scale inhibitor on crystalline form was significantly different at different dosages. Under a certain amount of scale inhibitor, the optimal inhibiting effects could be achieved, but the effects would be reduced when it was overdosed.