Study On The Preparation Of Nano Polyaluminium Chloride And Its Application In Petrochemical Wastewater Disposal

The purpose of this article is developing a kind of nano polyaluminium chloride (nano-PAC) which applying in petrochemical wastewater disposal. Then the technologies of preparation and purification, the factors influencing the preparation and purification, and the characteristics and the structures of nano-PAC are discussed. And the coagulation efficiency of the nano polyaluminium in petrochemical wastewater disposal chloride is studied.According to the experiments, it is found that the samples prepared by slow injection method are better than the samples prepared by instantaneous injection method. When the basicity is 2.5, the reaction temperature is about 70℃, and the concentrations of NaOH and AlCl₃ are both 2mol/L, the samples with high Al₁₃ contents are obtained. The advantages and disadvantages are found in the separation and purification operations with ethanol/acetone precipitation method and SO₄^2-/Ba²⁺ method, and the effective way for purification should be choosed on the basis of the property of samples. The optimum purification conditions with SO₄^2-/Ba²⁺ method are as follows: in the SO₄^2- precipitation test, the reaction time with Na₂SO₄ is 48h, optimum SO₄^2-/Al³⁺ ratio is 1:1, and the concentration of PAC is 0.01mol/L. The effect of separation and purification will be good in Ba²⁺ permutation test, when the Ba²⁺/SO₄^2- ratio is 1:1 and the ultrasonic time is 1.5h. And it is authenticated that Al₁₃ is the predominance form in the purifying samples with the investigation of SEM and XRD.The petrochemical wastewater quality of oil separation pool in Shenghua refinery has been analysed and was studied by nano-PAC flocculent. According to the coagulation-flocculation jar test, it is proved that Al₁₃ is the best coagulation form in polyaluminium chloride, and the contents can reflect the coagulation efficiency of products. The optimum conditions of coagulation process are: the pH value of wastewater is about 9, the doses of flocculent are 20 mg/L, the operation temperature is between 20～30℃, the mixture speed is 225～250r/min and the mixture time is 70～90s in the fast mixture process. Comparing with other general inorganic flocculent in the removal effect of turbidity, COD and petroleum oil, nano-PAC has the advantage over the others in petrochemical disposal.