Preparation,Surface Modification And Oil/water Separation Properties Of Sepiolite Porous Ceramics

With the continuous development of industries,water pollution due to oil spilling and oily industied wastewater has became a worldwide problem.Traditional oil/water separation patterns including centrifugation way,gravitational method,bio-oxidation process and chemical method,suffered from folliwing disadvantage the separation efficiency or effect is not good because of their low wettability.To address these issues,this study used sepiolite porous ceramics as the raw materials for the modification,high-efficient water/oil separation porous ceramics by in-situ catalytic cracking methods.In this thesis,sepiolite porous ceramics were prepared by foam-gelcasting technique.The effects of sintering temperature and solid contents on the mechanical properties,thermal insulation and air permeability were examined.And then carbon nanotubes were prepared by catalytic-pyrolysis using waste plastic as staring materials.The carbon nanotubes modified superhydrophobic/superlipophilic sepiolite porous ceramics were used for separation domestic wastewater and industrial organic contaminated liquids.The effects of catalyst types,catalyst dosage,pyrolysis temperature and heating rate on oil/water separation of the carbon nanotubes modified sepiolite porous ceramics were investigated.This study can alleviate the problem of water pollution and solved"white pollution"of plastic.The results indicated that:1)Porous sepiolite ceramics were prepared via foam-gelcasting technique using sepiolite powders as the main raw materials,Isobam-104 as the dispersing and gelling agent,triethanolamine lauryl sulfate as the foaming agent,and sodium carboxymethyl cellulose as the foam stabilizing agent.After 2h firing at 1473 K,the as-prepared porous sepiolite ceramics possessed high porosity of 73.24%,high flexural and compressive strength of 1.67 MPa and 2.34 MP,high permeability of 1.1×10^-10 m²and a low thermal conductivity of 0.202 W·m^-1·K^-1.2)Byusingnickelascatalysts,carbonnanotubesmodified superhydrophobic/superlipophilic sepiolite porous ceramics were in-situ synthesized via catalytic pyrolysis of polyethylene.The carbon nanotubes synthesized at 823K using0.5mol·L^-11 Ni catalysts were 20 nm in diameter and hundreds of micrometers in length.The contact angle of modified porous ceramics to water was about 140o.In the environment of high temperature,low temperature,acid and alkali condition,and sea water,the as-prepared porous ceramics showed a stable superhydrophobic property,high separation efficiency and durability.Separated oil can be recycled without loss.3)A continuous separation device was builded.The separation rates for different viscosity oils including diesel,paraffin oil,vegetable oil and vacuum pump oil were respectively 200 kg·s^-1·m^-2,185 kg·s^-1·m^-2,165 kg·s^-1·m^-22 and 120 kg·s^-1·m^-2.The oil separation efficiency was higher than 95%.The separation rate at low temperature?273k?of device was increased 120¹40 times for high viscosity vacuum pump oil and 6⁷ times for low viscosity paraffin oil via an electric field for heating.4)High porosity carbon nanotubes modified sepiolite porous ceramics were prepared by an one-step freeze-drying process.The carbon nanotubes modified porous ceramics with superhydrophobic/superlipophilic properties could be prepared under the condition of solid content of 15 wt%,sintering temperature of 823 K,and nickel nanoparticle as catalysts.The maximum adsorption capacity of the modified porous ceramics for diesel oil,paraffin oil,vegetable oil and vacuum pump oil were respectively 15.7,20.8,23 and 25 times of their own mass.The continuous separation efficiency of the as-prepared modified porous ceramics is up to 250 kg·s^-1·m^-2 which did not decrease clearly within 5 h continuous using.