Preparation Of Green Porous Materials Based On Immobilized Microorganism And Its Degradation Performance

The sustainable development of human society can't be separated from fossil energy.In the process of exploitation,transportation and application,oil will inevitably leak.When oil enters the environment,it can exist in the environment for a long time because of its lasting stability,which brings serious pollution problems to the environment.Therefore,it has become an urgent problem to find an efficient and green technology for degrading petroleum hydrocarbon(PHs)pollutants.In recent years,the treatment of oily wastewater by immobilized microorganism technology is favored by researchers because of its green and no secondary pollution,but there are some insurmountable problems such as low efficiency and long time-consuming.As a research hotspot at present,superwetting material has the performance of selective adsorption and separation of oil and water,and is one of the best materials for treating oily wastewater.However,its application is limited by the disadvantages of high cost and secondary pollution.Therefore,this paper adopts the strategy of combining biomass-based immobilized microorganism technology with super-infiltration material to prepare a green porous material which can selectively adsorb oil in oily wastewater and biodegrade after adsorption,and studies the dual-infiltration characteristics of the material and the performance and mechanism of degrading oily wastewater.The main contents of this paper are:(1)First,we demonstrated a new strategy of selective adsorption of oil pollution by ultra-light hydrophobic/lipophilic microorganism-loaded biomass porous foam(BTS-MSFT4@MTMS),and then green degradation of adsorbate under mild conditions to effectively eliminate oil pollution.The porous structure of biomass porous foam(MSFT)can provide a large amount of space for immobilization of Bacillus thuringiensis(BTS),while simple surface modification of foam loaded with BTS strain(BTS-MSFT4)with methyl trimethoxysilane(MTMS)can change its wettability from hydrophilicity to lipophilicity,which makes it possible to selectively adsorb hydrophobic petroleum pollutants in water for biodegradation.The results show that the prepared BTS-MSFT4@MTMS has both excellent selective adsorption performance and high degradation performance for the 3%n-hexadecane petroleum hydrocarbon simulated oil solution.Under the conditions of 37°C,120 r min^-1 and p H=7,the degradation rate is as high as 86.65%within 8 days,while the degradation rate of BTS-MSFT4 and free BTS strains is only 81.62%under the same conditions.In addition,the results of environmental tolerance study showed that BTS-MSFT4@MTMS showed strong tolerance at different p H,temperature and initial concentration.(2)Next,we demonstrated a new type of hydrophobic/lipophilic sponge material based on nano cellulose(B10NCS-DTMS),which is used to efficiently remove petroleum hydrocarbon pollutants in water.Compared with the materials previously studied,this microporous/super-wetting structure can support more microorganisms and provide space and nutrition for the growth and reproduction of microorganisms.The mixed microorganisms have excellent synergistic degradation effect,which greatly improves the degradation potential.We used high-stability modified long-chain silane solution to modify the surface of microorganism-loaded materials,which showed excellent selective adsorption performance.As expected,using 5%petroleum hexadecane solution as simulated oily wastewater,B10NCS-DTMS not only has excellent selective absorption(up to 99%),but also has a degradation rate of 95.85%within 96 h.In addition,B10NCS-DTMS showed strong tolerance at different p H,temperature and initial concentration.(3)Finally,in order to solve the shortcomings of the above materials,such as weak surface hydrophobicity and low practical application value of simulated oil,etc.In this study,the mixed solution of ethyl orthosilicate/dodecyl trimethyl silane in ethanol and epoxy resin was loaded on stainless steel mesh by simple impregnation method,and a super hydrophobic/super lipophilic mesh was obtained.Using kapok fiber as raw material,a gel solution was prepared by a simple crosslinking method,and then the cellulose gel solution was poured into a superhydrophobic/superhydrophilic stainless steel mesh mold.After freeze-drying,the mixed microorganisms were loaded into the aerogel material with ultra-light,superhydrophilic and high porosity,and a new type of superhydrophobic/superhydrophilic composite microbial aerogel material(100@M-aerogel and 200@M-aerogel)was obtained for adsorption degradation.The results show that this composite material has high selective adsorption performance for oil substances,which can be completely adsorbed within 10s and quickly transferred to the internal microbial aerogel.Within 204 hours,the degradation rate of diesel oil by composite materials is as high as 95%,and it also has a certain degradation effect on emulsified oil(O/W).In a word,compared with the related research at home and abroad,the series of green porous materials studied in this paper have high biological activity,more excellent selective adsorption performance,efficient degradation of oily wastewater and self-floating.This kind of material is cheap,green and has no secondary pollution when degraded,which opens up a new way for efficiently removing petroleum hydrocarbon pollutants in water.