Study On The Propane Gas Hydrate Method For Wastewater From Acid Pickling Electrolysis Seperation Process

In the steel industry,hydrochloric acid?HCl?has been widely used as a effective surface cleaning agent,so resulting in a large number of annual hydrochloric acid pickling electroplating waste was discharged,the main component is a high concentration of Fe²⁺and free acid.The main features of the waste water are high acidity and concentration,if not properly handled,not only endanger the ecological environment and human health,but also cause a lot of waste of resources.The hydrochloric acid pickling wastewater has become the main environmental problems of the steel industry.Taking the wastewater treatment of an electroplating factory in Baoding,Hebei as the background.To achieve rational utilization of electroplating wastewater,developing a new separation technology to concentrate Fe Cl₂in the ternary system H₂O-Fe Cl₂-C₃H₈has practical significance to recycling of electroplating wastewater.The following research work has been investigated in this work:1. At 272.15 K,274.15 K and 276.15 K temperature,solid-liquid phase composition and equilibrium pressure of clathrate compounds have been measured in the ternary system H₂O-Fe Cl₂-C₃H₈.The results show that the equilibrium pressure of C₃H₈hydrate increases with the increase of Fe Cl₂content and decreases with the increase of temperature.The content of Fe Cl₂in the equilibrium liquid phase is higher than that in the feed liquid,and the concentration ratio is greater than 1,which has the effect of concentrating the Fe Cl₂solution.This proves that it is feasible to concentrate the Fe Cl₂solution by the gas hydrate formation method.The equilibrium pressure of gas hydrate in the ternary system H₂O-Fe Cl₂-C₃H₈was calculated by the Chen-Guo thermodynamic model.The calculated values closed to the experiment values.The model parameters were determined.2. The change of reaction rate in the formation of C₃H₈hydrate in H₂O-Fe Cl₂-C₃H₈ternary system was investigated. The effects of temperature and concentration in solution on the formation rate were investigated.The results showed that the reaction rate was promoted by the low temperature,and the reaction rate was inhibited by the presence of Fe Cl₂.3. The effect of sodium dodecyl sulfat?SDS?on the formation of hydrate in H₂O-Fe Cl₂-C₃H₈ternary system was investigated.The kinetic model of hydrate formation in H₂O-Fe Cl₂-C₃H₈ternary system under SDS addition conditions was established.The mechanism of promoting the formation of C₃H₈hydrate by SDS was analyzed.The results showed that SDS can shorten the induction time of C₃H₈hydrate formation and increase the formation rate.The best dosage is 0.3 g/L.The established kinetic model can well predict the formation of H₂O-Fe Cl₂-C₃H₈ternary system hydrates.4. The influence of SDS as an additive H₂O-Fe Cl₂-C₃H₈ternary system hydrate formation was investigated.The temperature and pressure factors of SDS were optimized.The optimal temperature was 274.15 K and the optimal pressure was 0.4 MPa.H₂O-Fe Cl₂-C₃H₈ternary system equilibration experiments were carried out under optimized conditions.The results show that the addition of SDS at the appropriate concentration can promote the hydrate reaction rate.