Rapid Treatment Of Oil-containing Micro-polluted Water By Magnetic Enhanced Coagulation Based On Ultraviolet Spectrum Analysis

Enhanced coagulation technology has been widely used to treat surface micro-polluted water.In the study,magnetic enhanced coagulation as a typical enhanced coagulation method was applied to treat low concentration oily-micro-polluted surface water caused by oil products pipeline leakage emergency aimed to establish an efficient ex-situ technology for treating oil products pollution.The oily contaminant removal characteristics and the enhancing mechanism of magnetic seeds were investigated,and in-situ method based on UV-Vis spectrum for coagulation reaction process monitoring and analyzing was established.The study was supported by the joint technology research project of SINOPEC and Tianjin Polytechnic University named "Development of Key Materials and Complete Technology for Emergency Treatment of Oil Leakage Incident".Firstly,oil removal rate and flocs sedimentation velocity of traditional coagulation and magnetic enhanced coagulation were compared by oily contaminants concentration kinetics below reactor liquid level during sedimentation process.The results showed the magnetic coagulation achieve above 95%oil removal rate within 1 min gravity sedimentation at the optimum dosage of PAC50mg/L+ Fe3O450mg/L+PAM10mg/L,which significantly increased the efficiency of traditional coagulation and confirmed its ability for oily-micro-polluted water efficiently treatment.The magnetic seeds were recycled and reusing for several times to investigate their remained enhanced ability,and it showed that magnetic seeds could be reused for 6-7 times after simply wash procedure by water,which technology was really cost-effective.This part of study laid the foundation for technology parameters and equipment designment of magnetic coagulation ex-situ efficient treatment for oily-micro-polluted water.Secondly,the enhanced mechanism of magnetic seeds strengthen flocs adsorbing oily contaminants was studied by coagulation materials' Zeta potential and adsorption kinetics.On the on hand,magnetic seeds enlarged the PAC+Fe3O4 flocs' positive charge property so as to strengthen the charge neutralization of negatively charged oily contaminants.On the other hand,PAC pre-hydrolysis products coated on Fe3O4 surface formed cluster structure to increased the adsorption sites hence strengthen the PAC+Fe3O4 flocs' adsorption ability.The main mechanism of PAC and PAC+Fe3O4 flocs for oily containments adsorption were then concluded as charge neutralization With hydrogen bonding and charge neutralization with chemical bonding,respectively.At last,an in-situ monitor and analysis method based on UV-Vis spectrum was established to record the real-time data of spectroscopic features in coagulation reactor supernatant liquid,which was used to further investigate the rapid and efficient merits of magnetic coagulation for removing oily contaminants.The results of flocs breakage and re-growth procedure indicated that PAC+Fe3O4 flocs has better re-growth property and oily contaminants attachment intensity than PAC flocs and PAC+Fe3O4+PAM flocs.Absorbance peak value of live data sharply raised as the magnetic seeds reusing time increased,which indicated that residual impurity contaminants attached on Fe3O4 surface after wash such as hydrolysis products,colloidal solids and oily contaminants accumulated bit by bit,hence resulted in the coagulation enhanced property of magnetic seeds decrease.