Preparation Of Hydrophobic/oleophilic Materials Based On Paper And Study Of The Water/Oil Separation Characteristics

Plant fiber was a kind of perfect substrate to prepare functional composite materials.Super-hydrophobic materials made with plant fiber have the advantages of reproducible,degradable and without secondary pollution.Filter paper is with abundant pores which formed by thousands of micro fibers.The hydrophobic filter papers have ability to separate water and oil.They can be used to remove the water dispensed or emulsified in fuel oil.Commercial filter papers were dipped in different solution to get hydrophobic.Different sized TiO₂ helped to enhance the hydrophobicity of paper.The paper with 330nm/112nm TiO₂on had highest water contact angle of 151.8°.The water contact angle enhanced with the increased paper roughness and the trend was obvious when the roughness was below 7?m.It showed that the coarse structure of the obtained hydrophobic papers was relatively stable because the water contact angle only decreased several degrees after dipping in acid or alkali for 5 h.In addition,these papers were effective in water/oil.The water content in diesel could decrease from 10⁵ ppm to 700 ppm by filtrating through the paper based materials.The water/oil separation ability of paper materials was affected not only the water contact angle,but also the porosity?air permeability and average pore diameter?.The lower air permeability and smaller pore of hydrophobic paper would resist more water so that the less water passed through the hydrophobic paper.And the pore diameter may affect more on the water/oil separation ability.The carnauba wax and nano HDTMS/TiO₂ sufficiently mixed in ethanol and became a composite coating to soak original papers.The treated papers then modified by HDTMS and dried at 100?.The SEM images indicated that there was micro structure formed by carnauba wax flakes and nano hydrophobic TiO₂ beads.This kind of micro structure was benefit for the water repellency of papers.The water contact angle could reach to 149°if the composite coating quality on paper was 6.4%.These as-prepared paper based materials performed better in water/oil separation.The water content in diesel decreased to 100 ppm finally.The bee wax and carnauba wax were mixed and emulsified with chitosan in hot water and then coat filter paper with this mixed wax emulsion.The water contact angle of coated paper dried at room temperature?25??was around 140°.The coated papers,which were dried at 60?,had extra wrinkle structure on the wax particles so that the hydrophobicity was more strong.If the dry temperature was up to 75?,the wax beads on paper would disappear along with an obvious decline in water contact angle.The greasy wax made the filter paper very oleophilic to separate water and diesel.The 25?dried papers had small pores,low air permeability and they could resist 90.97%water in diesel.The 75?dried papers only resist 73.94%water in diesel because their pore diameter was bigger,air permeability was higher.The water content was 4190 ppm after separation and filtration by 75?dried papers.Make papers with several kinds of fibers and coat they with mixed wax emulsion?bee wax:carnauba wax=7:3?.As mentioned above,the 60?dried papers had high hydrophobicity and the strength properties improved at the same time.Before coating operation,the bursting strength of papers contained cotton stalk or fiberglass was better,the air permeability of papers contained linters or fiberglass was better.After coating operation,the stiffness and bursting strength of all the papers increased obviously,the air permeability of papers contained linters or fiberglass was still higher.The WCA of papers contained linters and cotton stalk was up to 150°and their slide angles were less than 10°.Adding mixed wax emulsion into pulp,the obtained dried filter papers had WCA over 140°and their air permeability was higher compared to the emulsion coated filter papers.The separation ability of lab-made papers coated with mixed-wax emulsion was determined.The filtration/separation results showed that the air permeability and the average pore diameter both had important effect on the ability or the efficiency of the filer paper.To the obtained paper,the separation ability and the separation efficiency always was a pair of contradictions,and they could not be improved at the same time.The relationship of water content in fuel after separation?Y?and the filtration efficiency?X?meet the equation:Y=0.0007X2+3.2411X+290.63.When the average pore size was 4.44?m and the air permeability was about 3760 ml/min,the hydrophobic paper based materials would separate water/diesel mixture efficiently.