Preparation Of High-performance Ceramic Membrane Using Dredged Sediment As Raw Material

The heavy metal pollution has become one of the most serious concern for the river sediments all over the world.Although some technologies have been developed for the remediation of contaminated sediment,most of them need relatively high cost,complicated processes,and ineffective the remediation results.Therefore,dredging the sediment out for the beneficial utilization have been received widespread attention,including for highway subgrade filling,architectural ceramsite,landscaping,filling materials,compost fermentation and other utilization method.However,the above utilization process cannot effectively prevent the further release of the original heavy metals in the sediment.Through sintering processes,heavy metals can be incorporated into the stable aluminosilicate crystal structures,achieving effective stabilization.The river sediment system is mainly composed of aluminum-and silicon-compounds,and therefore,heavy metals might be well immobilized after the sintering process.Moreover,as the aluminum-and silicon-compounds are major ceramic materials,the sintered samples may be potentially used as ceramic products.Among many ceramic products,ceramic membranes are widely used due to their superior performance during the wastewater treatment processes.However,the preparation of ceramic membranes is usually based on pure chemicals at an extremely high temperature(around 1500 oC),which limits the wide application of the ceramic membranes.Therefore,this study proposed a strategy for a high-value utilization of the dredged sediments through the preparation of ceramic membrane based on the sintering technology,with simultaneous heavy metal stabilization.The sediment collected from Maozhou River in Shenzhen was used as the raw materials for the preparation of the ceramic membrane,which may reduce the cost of the ceramic membranes while solving environmental problems.The support layer of the membrane was fabricated by the dry pressing method,while the double-layer was prepared by the spin coating method with coating liquid of different concentrations.The obtained ceramic membrane was characterized by X-ray fluorescence spectrometry(XRF),scanning electron microscopy(SEM)and X-ray diffractometer(XRD).The optimum condition was obtained for thepreparation of the ceramic membrane.Compared with the membrane production from pure chemicals,the sediment ceramic membrane can be prepared at a much lower temperature(900 oC),with the pore diameter as 70 nm,the porosity as 39.86%.The optimal pore-forming agent was also confirmed for ceramic membranes,together with the determination of the flux,stability,safety,corrosion resistance.The experimental results show a better filtration performance by using the ceramic membrane prepared from the dredged sediment with much lower cost.Through this study,the dredged sediment can be potentially used as raw materials for ceramic membrane,which not only stabilized the heavy metals by incorporating them in mineral structures,but also effectively reduced the cost of the ceramic membrane through the adoption of solid waste and significant reduction in sintering temperature.