Investigation Of Alkali/Surfactant/Polymer Flooding Produced Water Removed By In-situ Generated Metallic Hydroxides

In this paper,freshly in-situ generated metallic hydroxides?IGMHs?was prepared by adding the leaching solution of white mud?LSWM?to alkaline oily wastewater,which have large adsorptive surface area,small particle sizes and positive surface charge can be used as treatment agent to removal emulsified oil?EOs?from oily wastewater.The chemical component of the white mud was measured by X-ray fluorescence spectrometry?XRF?.The morphology of the IGMHs before and after adsorption was determined by transmission electron microscopy?TEM?.The IGMHs before and after adsorption emulsified oil were characterized by X-ray diffraction?XRD?and Fourier-transform infrared spectroscopy?FT-IR?.The influence of LSWM dosage,initial pH,contact time,and reaction temperature on oil removal efficiency was investigated.The thermodynamics was used to explain the removal mechanism of EOs onto IGMHs.The experimental results revealed that:?1?The XRF result indicated that the main component of WM was CaO and MgO.The freshly in-situ generated hydroxides was obtained by adding LSWM into alkaline solution,which formed by Ca?OH?₂ and Mg?OH?₂ nanosheets.?2?The EOs in oily wastewater can be effectively and rapidly removed by IGMHs.The IGMHs-EOs precipitates can be regenerated by adding HCl,indicating potential application for reuse the brine and petroleum.?3?Adding leaching solution of white mud into alkali/surfactant/polymer?ASP?flooding wastewater,the oil removal efficiency up to 99.2%under the condition that the LSWM dosage was 4.0 g/L,the initial pH was 12.0,the contact time was 6 min,and the temperature was 0?.?4?During the co-adsorption/precipitation process,hydrogen bonding and electrostatic attraction were the main adsorption mechanisms.Moreover,cohesion between MOH+/M?OH?2 particles and adhesion between MOH+/M?OH?2 particles and oil droplets also strongly influenced the co-precipitation/adsorption process.The IGMHs and EOs assembled to IGMHs-EOs complexes under the effect of hydrogen bonding,electrostatic attraction,adhesion and cohesion.?5?The thermodynamic parameters was utilized to describe the type of adsorption and interaction of EOs with IGMHs.An increase in the ?G0 values with increasing temperature indicated a decrease in the spontaneity and feasibility of the co-precipitation/adsorption process at higher temperatures.The negative value of?H0 suggested that the adsorption of the emulsified oil onto IGMHs might represent an exothermic process.