Synthesis And Applied Research Of The Rapeseed Meals-based Composite Oil-absorbents

With the rapid development of petroleum industry,the environmental pollution caused by oily wastewater is becoming increasingly serious.Up to now,the most economic and effective method to solve this problem is the utilization of oil absorption materials.Rapeseed meals(RSMs)are the by-products of rapeseeds after oil expression.Owing to the unique advantages such as partial lipophilicity,environmental richness,cheapness and biodegradability,RSMs can be utilized as oil-absorbents to prevent oil pollutant.However,the massive hydroxyl within cellulose in RSMs will affect their hydrophobicity and oil absorption capacity.In order to expand the application fields of RSMs,in this paper,two novel RSMs-based composite oil-absorbents were prepared by graft copolymerization or mussel-inspired hydrophobic modification,and their physical and chemical properties were analysed by various characterization and testing methods.The main research contents are listed as follows:(1)The RSMs-g-P(MMA-co-BA)composite high oil absorption resins were successfully synthesized through free radical graft copolymerization from waste RSMs,methyl methacrylate(MMA)and butyl acrylate(BA)with benzoyl peroxide(BPO)as initiator and N,N?-methylenebisacrylamide(MBA)as crosslinker under nitrogen atmosphere.The synthetic mechanism and swelling process were thoroughly analysed.Moreover,FT-IR,FE-SEM and contact angle measurements were employed to characterize the structure,surface morphology and wettability of the products.The results indicated that the graft copolymerization reaction was successfully carried out,and the prepared oil-absorbents exhibited distinctive 3D network structures and good hydrophobic and oleophilic properties.(2)The effects of reaction conditions on oil absorbency of the RSMs-g-P(MMA-co-BA)were investigated by single factor experiment to determine the optimal region.Then on this basis,three parameters,including monomer ratio,initiator and crosslinker,were selected as independent variables to evaluate the effects on oil absorbency,which were designed and optimized by BBD response surface method.Also,the interactions between each factor were discussed.The relevant results indicated that under the optimized reaction condition: m(MMA):m(BA)=3:5,?(BPO)=0.72%,?(MBA)=0.04%,?(RSMs)=3.2%,70 oC and 1 h,the maximum oil absorbency of the RSMs-g-P(MMA-co-BA)for chloroform was 41.67 g·g-1.More importantly,the addition of RSMs powder for the preparation of the RSMs-g-P(MMA-co-BA)could not only reduce the production costs to some extent,but also could improve the composites' mechanical stability and oil absorbency.(3)The swelling kinetics,absorption thermodynamics,reusability as well as the oil/water separation performance of the composite high oil absorption resins were all investigated in detail in this part.The specific conclusions are as follows: The swelling kinetics of the RSMs-g-P(MMA-co-BA)was found to follow the pseudo-second-order kinetic model,and there was a negative correlation between the absorption rate and the polarity of the organic solvents.The thermodynamics analysis demonstrated that the gasoline absorption was mainly dominated by physisorption,and was a spontaneous,entropy gained and endothermic process within the studied temperature range.In terms of reusability,the change of oil absorbency after eight repeated cycles of swelling/deswelling was marginal.Furthermore,the RSMs-g-P(MMA-co-BA)had outstanding buoyancy and excellent selectivity for oil and water,which could selectively remove diesel from water rapidly.(4)RSMs-based hydrophobic particles(ODA-PDA/FA-RSMs)were successfully fabricated by a novel mussel-inspired strategy in a low concentration of dopamine(DA).Specifically,the polydopamine and folic acid(PDA/FA)particles could be loaded on RSMs surface through the structure directing role of FA,self-polymerization of DA and adhesive effect of PDA.After subsequent octadecylamine(ODA)chemical manipulation with PDA layer,the as-prepared ODA-PDA/FA-RSMs exhibited better hydrophobicity and oil absorption capacity than raw RSMs,and higher oil absorbency could be achieved for the oil with bigger density.Moreover,FT-IR,FE-SEM and contact angle measurements revealed the excellent hydrophobic property was determined by both the surface roughness and hydrophobic functional groups.The experimental results of reusability indicated that the oil absorbency had little decrease after eight repeated cycles of absorption and desorption,and could be used for several times in practical application.Two novel RSMs-based composite oil-absorbents prepared in this paper had plenty of advantages including high hydrophobicity and lipophilicity,excellent reusability,outstanding selectivity for oil and water,great buoyancy,and could rapidly remove oils from water,which could not only realize the utilization of waste RSMs resources,but also achieve the goal of treating oily wastewater and improving environment.The proposed technology had certain theoretical value and application prospect for large-scale treatment and purification of oily wastewater in actual production,and might also provide a reference for the fabrication of other natural biological resources based composite oil-absorbents.