Nano-silica modified stainless steel mesh for oil-water separation
Silica sol,prepared by sol-gel method using ethyl orthosilicate as raw material,reacted with stainless steel mesh(SSM)pre-deposited with polydopamine(PDA)through stepwise deposition and in-situ growth to obtain superhydrophilic-underwater superoleophobic stainless steel mesh(SSM-PDA-SiO2),which was further characterized by FTIR,XRD,TG,SEM,and contact angle tester.The effect of reaction time on the hydrophilic-oleophobic properties of SSM-PDA-SiO2 was investigated.The oil-water separation performance was evaluated by self-gravity driving,while its cyclic separation and mechanical stability were further explored.The results showed that PDA acted as a"bridge"to deposit nano-SiO2 onto the surface of SSM.SSM-PDA-SiO2-8 prepared with reaction time of 8 h exhibited the best hydrophilic and lipophobic properties,with water droplets spreading completely on its surface within 60 ms,the underwater oil contact angle to dichloromethane and other 5 organic solvents between 156.4°～160.9°,and the rolling angle to dichloromethane 4.0°,demonstrating its super-hydrophilic-underwater super-oleophobic properties.The modified stainless-steel mesh achieved an initial separation flux of 40165 L/(m2·h)with a separation efficiency of 99.3%,and still maintained a flux of 17728 L/(m2·h)and a separation efficiency of>98%even after 50 separation cycles,indicating its good recyclability.Moreover,the modified stainless steel mesh with 35 cycles of sandpaper abrasion retained a separation efficiency of over 98%,showing its good mechanical stability.Hydrophilic groups such as hydroxyl and amino groups of PDA improved the superhydrophilic and underwater superlipophobic properties of SSM-PDA-SiO2,while nano-SiO2 increased its surface roughness.
万方数据
维普
