Preparation And Properties Of Hydrophobic Materials Based On Bacterial Cellulose

With the frequent occurrence of offshore oil spills and the massive discharge of oily sewage,the environment has been seriously polluted.The treatment and recycling of oily sewage by adopting green adsorption method has been widely concerned.Bacterial Cellulose（BC）has good mechanical properties and adsorption capacity,which has great potential in the field of oil adsorption.However,because BC has a large number of hydrophilic hydroxyl groups（-OH）on the surface,it does not have the selectivity for oil adsorption,and it is easy to be breeding by bacteria and other microorganisms,which affects its practical application.Therefore,it is necessary to develop BC-based modified materials with good hydrophobic and antibacterial properties.This paper,taking the BC as matrix,add the dealkaline lignin（DL）,silane reagents（MTES）and quaternary ammonium salt antimicrobial-methyl acryloyl oxygen ethyl trimethyl ammonium chloride（DMC）,by constant temperature heating mixing method and active site graft copolymerization reaction,successfully achieved hydrophobic and antibacterial modification of BC.The materials were characterized and analyzed by various means of structural property testing and characterization.The adsorption behavior of modified materials in oil-bearing wastewater was studied.Finally,the antimicrobial properties of Gram-positive and Gram-negative bacteria were tested.Specific contents are studied as follows:（1）The hydrophobic modified component DL was added with BC as the matrix by constant temperature heating and stirring method.The hydrophobic material BC-DL with hydrophobic and lipophilic properties was successfully prepared by optimizing the pretreatment process,reaction time,temperature and material ratio.The addition of DL increases the roughness of BC and decreases the proportion of-OH in BC,thus improving the hydrophobicity.The contact Angle test shows that the contact angle（WCA）of pure BC water is about 19.5°,and the modified BC-DL can be increased to 116.8°.The BET results showed that the specific surface area of BC-DL was increased from 33.147 m²/g to 71.090m²/g.The increase of water contact Angle and specific surface area provided the possibility for selective oil absorption of BC-DL.The saturated adsorption capacity（OCA）of peanut oil,diesel oil and vacuum pump waste oil were 31.858 g/g,31.132 g/g and 31.806 g/g,respectively.After 8 cycles,the sizes of OCA were 19.067 g/g,18.355 g/g and 18.820 g/g,respectively.The results showed that BC-DL had good adsorption and recycling properties for the three oils.（2）MTES and DL were combined to hydrophobically modify BC by constant temperature heating and stirring method,and BC-MDL modified material with synergistic hydrophobic performance was successfully prepared.The addition of MTES and DL can better replace the-OH on the BC skeleton with methyl（-CH₃）and related silane derivatives in MTES without damaging the three-dimensional structure of BC.After hydrophobic modification,the WCA of BC-MDL can be significantly increased to 129.8°,and the hydrophobicity of BC-MDL can be significantly improved.BET results showed that the specific surface area of BC-MDL increased from 33.147 m²/g to 53.204 m²/g.The oil absorption test showed that the OCA of BC-MDL for peanut oil,diesel oil and vacuum pump waste oil were 29.934 g/g,29.392 g/g and 31.990 g/g,respectively.After 8 cycles of adsorption and desorption,the values were 19.607 g/g,19.101 g/g and 19.345 g/g,respectively.The results show that BC-MDL has good adsorption and oil holding capacity for the three kinds of oil.（3）Then,the hydrophobic antibacterial material BC-DMC was successfully prepared by grafting copolymerization of the active site and using azo diisobutyrile（AIBN）as initiator.With the addition of DMC,the WCA can reach 117.7°without damaging the three-dimensional structure of BC.The OCA of BC-DMC for peanut oil,diesel oil and vacuum pump waste oil are 30.622 g/g,30.652 g/g and 31.654 g/g,respectively.After 8complete cycles,the OCA values are 20.477 g/g,19.960 g/g and 20.285 g/g,respectively.Through EDS,FTIR and XPS characterization combined with antibacterial experimental results,it was verified that the addition of DMC can introduce negatively charged Cl^-into BC,which can generate electrostatic attraction with the positive charge of bacterial cell membrane and then gather on the membrane surface,destroy the membrane structure and make the cytoplasm leak out,so as to achieve antibacterial effect.The antimicrobial rates were 95.65%and 96.48%,respectively.The results show that the addition of DMC can not only improve the hydrophobicity of BC,but also improve the lack of poor antimicrobial activity of BC as a biomass material,and increase the practical application of the modified material.