Study On Preparation And Surface Modification Of Submicron Barium Sulfate

Barium sulfate is widely used in many fields as an environmentally friendly functional material with the advantages of non-toxic,tasteless,chemically stable,acid and alkali resistance.Domestic is actively engaged in the improvement of barium sulfate production process,aimed at obtaining high-quality barium sulfate products,get a small particle size,regular morphology of barium sulfate products.Current industrial products,some problems still exist in such aspects as quality and yield:Because of the high surface energy of the ultrafine particles,the agglomeration of the adjacent particles is easy to occur in the preparation and application.Besides,the surface of Ba SO₄ particles are shown as strong polarity,which caused the poor affinity with organic polymer.Thus the application of barium sulfate is limited greetly.Therefore,preventing the agglomeration between Ba SO₄ particles,changing its hydrophilic property are still the main challenges in the production process of Ba SO₄ products.The optimum preparation conditions were shown as below: The addition of EDTA was 6%,the addition of reactant was 0.5mol / L,the preparation temperature was 45 ?,the drip rate of Mg SO₄ was 50 d / min,the stirring rate was 200 r / min,aging time was 6h,and the p H value was 8.Ba SO₄ particles with good dispersibility were prepared in such conditions with 1.0 wt% polyethylene glycol 400 as dispersant.The D50 of Ba SO₄ products was 0.56?m,and the particle size were ranging from 0.5 to 1?m.The mechanism of the dispersion of and the mechanism of the additive on the microstructure and particle size distribution of the product were discussed.And after the end of the reaction,the filtrate was treated for the preparation of magnesium oxychloride cement,both to solve the filtrate pollution,and to achieve its economic value.The hydrophobic barium sulphate was prepared by surface modification method using palmitic acid and sodium dodecyl sulfonate and its complex modifier as modifier.When the amount of palmitic acid was 1.5wt% and the reaction temperature was 60 ?,the activation degree of the product reached 99.90%.Using sodium stearate alternative 30% palmitic acid sodium,the product activation degree is 99.89%,and the heat resistance of their products a single modifier modified products is also improved.Using sodium dodecyl sulfate barium sulfate products for the surface modification,addition amount of 1.0 wt %,reaction temperature 80 ?,reaction time,80 min,stirring speed 500 r/min,product activation degree is 99.33%.Sodium dodecyl sulfate/sodium stearate composite best replacement ratio of 10%,product activation degree was 99.78%,the modified product of heat-resisting temperature are increased single modifier modified 20 ?.The effect of surface modification mechanism and compound modifier was discussed.In this paper,palmitic acid and sodium dodecyl sulfonate and its complex modifier were used as modifiers.The barium sulphate was modified by in situ modification to make it hydrophobic.When the amount of palmitic acid added 1.0wt%,the product activation rate can reach 99.80%,with sodium stearate instead of 30% sodium palmitate,the product activation rate of 99.81%,and the product heat resistance increased by 20 ?.The addition of sodium dodecyl sulphate to in situ modification of barium sulphate product,the amount of SDS was 1.5wt%,the activation degree of the product reached 99.52% and the particle size D50 was 0.59?m.When the content of palmitic acid sodium 1.0 wt %,product activation degree reached 99.80%,using sodium stearate alternative 30% palmitic acid sodium,sodium product activation degree was 99.81%,the product improves the heat resistance of 20 ?.The mechanism of in situ modification was discussed.