Study On Zr_xSi_1-xO₂/Al₂O₃ Dynamic Membrane For Cleaning Seawater Containing Oil

Oily seawater is difficult to purify for its compositional complexity and existence of various organic contaminants which is hard to degrade.Conventional methods for treating seawater containing oil can not satisfy the requirements of water quality standard.Membrane technology has been widely used in the advanced treatment of seawater containing oil due to its high efficiency.However,there are many problems such as vulnerable to be contaminated,poor selectivity,high-cost and dramatic loss of membrane permeation flux when treating seawater containing oil.These defects seriously hamper the widespread application of membrane technology.Therefore,it is an urgent task to look for a highly efficient and economical method of deeply cleaning oily seawater.In this paper,small scale Zr_xSi_1-xO₂/Al₂O₃?S-ZSA?particles were prepared through cohydrolysis,silanization treatment and phosphorylation treatment,followed by coating of Al₂O₃.The preparation conditions were optimized by the results of treating seawater containing oil.Then the S-ZSA particles were characterized by SEM?EDX?FT-IR and XRD.Moreover,size-regulated Zr_xSi_1-xO₂/Al₂O₃?L-ZSA?particles were also prepared by changing aging time and the optimum aging time was studied.Then the L-ZSA particles were characterized by SEM.The results show that Zr elements have been doped into the lattice of SiO2 and ?-Al₂O₃ has been coated on the surface of ZrxSi1-x O2.Alternatively,S-ZSA particles have a spherical structure with the diameter of about 500 nm.While L-ZSA particles have a better spherical structure with the diameter of about 3⁵?m.Self-assembled dynamic membranes were prepared by using Zr_xSi_1-xO₂/Al₂O₃particles?S-ZSA particles or L-ZSA particles?and diatomite as coating materials and stainless steel wire as support.The preparation conditions were optimized and the membranes were characterized by SEM.Furthermore,we compared S-ZSA self-assembled dynamic membrane with L-ZSA self-assembled dynamic membrane by the results of treating seawater containing oil.The results show that it is compact on the surface of membrane and loose inside the membrane with many channels in it;After treated by S-ZSA and L-ZSA self-assembled dynamic membrane once on the area of 15.2cm2,the 600 ml of seawater containing oil could satisfy the requirementsof water quality standard,and the number of treating times could be adjusted according to different requirements for its flexibility;The results of L-ZSA self-assembled dynamic membrane are not as good as S-ZSA self-assembled dynamic membrane when treating seawater containing oil,but its permeation flux is satisfactory and the apparatus runs stably.In this paper,effect of physical cleaning and calcination on recycle of self-assembled dynamic membranes were also studied,and the cleaning conditions were optimized.The results show that the two methods are both effective while the way of physical cleaning is better.The results of treating seawater containing oil were compared among self-assembled dynamic membranes,organic-inorganic composite membranes and photocatalytic membranes.The results show that the self-assembled dynamic membranes have a better ability than photocatalytic membranes and have better results than ultrafiltration membranes when adjusting number of treating times.Moreover,self-assembled dynamic membranes have some advantages such as highly efficient,easy to prepare,low-cost and will be desirable for application in cleaning oily seawater.