Study On High Efficiency Separation Of Oil Coated Water Emulsion With Anhydrous Sodium Sulfate Micron Particles

The oil contamination by water will lead to the deterioration of oil quality,which may damage the related equipment.In the viewpoint of reducing the oil pollution,reusing the energy and saving the resources,it is uegent to develop one technology that can efficiently separate the oil and water phase.One of the oil-water separation method is to use the adsorbent with superhydrophilic oor superhydrophilic surface to realize the separation of oil and water.However,most of the reported absorbents are only limited to separate the layered oil/water mixture.Their efficiency in separating the emulsified oil-water mixture,especially the surfactant-stabilized emulsion,is unsatisfactory.This work reported a facile approach to prepare microscale sodium sulfate anhydrite（Na₂SO₄）by pouring the sodium sulfate-saturated aqueous solution into anhydrous ethanol,which can efficiently separatethe water fromthe surfactant-stabilized water-in-oil emulsion.A comparative study on the separation efficiency of the commercial Na₂SO₄,activated clay powder,activated carbon powder and other inorganic particles separation effect found that in the same experimental conditions,our Na₂SO₄ powder performs best.Furthermore,it can be recycled without any drop in the separation eficiency,though part of Na₂SO₄ will be lost during the separation-collection process.In the end,the mechanism involved in the surfactant-stabilized water-in-oil emulsion separation by Na₂SO₄ was explored in terms of the dispersibility of the sample in the oil and the crystal lattice fixed water molecules.The main conclusions of this paper are as follows:1.the leading two factors determing the performance of sodium sulphate powder are the concentration of sodium sulfate in the precursor solution and the volume ratio of anhydrous ethanol to sodium sulfate solution.When the concentration of sodiumsulfate solution is 0.453g/ml and the volume ratio of anhydrous ethanol to sodium sulfate solution is 6:1,the prepared Na₂SO₄ powder has a lower crystallinity and a maximum specific surface area,as well as the best oil/water separation efficiency.2.The orthogonal experiment finds that that the oil water separation efficiency of Na₂SO₄ can be improved effectively by increasing the stirring speed,the amount of the sample and the reaction time.The reaction time shows the greatest effect,followed by the dosage of Na₂SO₄ and the stirring speed.The optimum conditions of oil and water separation are as follows:the stirring speed is 1500r/min,the amount of the sample is 0.02g/ml,and the reaction time is 30min.3.The Na₂SO₄,the commercial Na₂SO₄,the active white clay powder and the activated carbon powder were used to separate the oil and water of the oil water emulsion,and can reduce the water content from 10000 ppm in the original emulsion to 136.2 ppm,1337.1 ppm,3597.3 ppm and 438.6ppm respectively,indicating that our Na₂SO₄ has the best oil and water separation effect.4.To reduce the pollution of the waste to the environment and the efficient utilization of the resources after the separation of oil and water.The Na₂SO₄ has been recycled for 5 times.The separation efficiency has not been reduced by every cycle.However,because of the partial dissolution of sodium sulfate powder,there will be a certain amount of sodium sulfate powder lost.5.The as-syntheized Na₂SO₄ is also efficient in separating for the actual waste oil emulsified with water.Under the best experimental conditions,it can reduce water content from 3921.4ppm to 185.9ppm,and successfully achieve oil-water separation in emulsion.6.Compared with the commercial Na₂SO₄,the sa-synthezied Na₂SO₄ has a better dispersion in oil phase,and a better affinity with water.7.sodium sulfate powder is used for oil-water separation of oil-water emulsion.It can form competitive adsorption with surfactant on the droplet surface,leading to a increased the surface tension of the emulsion,a reduced stability of the droplets,and ultimately a better demulsification effect.8.Na₂SO₄ can be converted to sodium sulfate hydrate when adsorb the water into their lattice,so that it can firmly fix the water molecules in the oil and facilitatesolid-liquid separation.