Adsorption Behavior And Mechanism Of Functionalized Biochar On Marine Oil

The rapid development of shipping industry inevitably destroys the Marine environment,especially the frequent occurrence of Marine oil pollution accidents leads to the increasingly severe Marine ecological environment.In the face of large-scale oil pollution after an accident,physical adsorption is still the preferred treatment method because of its advantages of high efficiency,easy recovery and low cost.Biochar and mineral soil,as two inorganic materials with high adsorption performance,have been widely used in the field of pollution treatment.The carbon soil composite material obtained by combining the two materials is a hotspot in the field of marine pollution treatment and has high research value.As a kind of agricultural by-product with high yield and easy availability,corn straw biochar has become a common material in the field of adsorption because of its low price and strong adsorption ability.In this paper,the functional carbon soil composite material was prepared by the composite of corn stalk biochar and mineral soil material,and its adsorption capacity was investigated.The selected carbon soil composites were modified to investigate the adsorption performance and process of the modified composites for oil pollution.Finally,a response surface model was constructed to optimize the preparation conditions of the modified composite.The main research contents and results are as follows:(1)Biochar-diatomite composite(BDCM),biochar-bentonite composite(BBCM)and biochar-kaolin composite(BKCM)were prepared by mixing modified corn stalk carbon with mineral soil in phosphoric acid and ferric chloride solutions in different proportions.The results of SEM,FTIR,BET and XRD showed that the specific surface area and other adsorption parameters of carbon-soil composites were better than those of biochar and modified biochar,and the content of hydrophilic functional groups such as hydroxyl was lower.The results of adsorption experiments show that the adsorption and oil retention properties of the three carbonaceous composites are better than those of biochar.Among the three carbon soil composites,BKCM has the best properties,with adsorption capacity and oil retention reaching 35.78 g/g and71.31%,respectively.The adsorption mechanism of BDCM,BBCM and BKCM on oil stains was found to be chemisorption on monolayer.(2)Furthermore,BKCM was modified by γ-methylacryloxy propyl trimethoxysilane(KH570)and dodecyltrimethyl ammonium bromide(DTAB)to prepare KH570 modified biochar-kaolin composite(KBKCM)and DTAB modified biochar-kaolin composite(DBKCM).By SEM,FTIR,BET and XRD,the structural parameters and functional group composition of KBKCM and DBKCM were optimized.Through single factor experiment,KBKCM and DBKCM have better adsorption and oil retention performance than BKCM,while DBKCM has better adsorption performance,reaching 38.21 g/g.The adsorption processes of the two modified adsorption materials are all chemical adsorption in the monolayer of the material,and the adsorption process is easy to occur and irreversible.(3)The key preparation conditions of DBKCM were optimized by single factor experiment and response surface model.Based on the single factor experimental results,a three-level and three-factor response surface model was designed.The correlation coefficient of the model was close to 1,and the signal-to-noise ratio and variation coefficient were low,indicating that the model was reliable and could well predict the amount of oil pollution adsorbed by DBKCM.The optimal modification conditions predicted by the model are reaction temperature 62.50℃,modification concentration 1.85%,modification time 2.5 h,and the predicted oil absorption is44.94 g/g.The experimental results show that the oil absorption is 45.26 g/g,and the prediction accuracy of the model is up to 99.29%,which proves that the prediction accuracy of the response surface model is accurate.In summary,functional carbon soil composites have the advantages of wide raw material sources,low cost and strong oil adsorption capacity,and have a good application potential in oil/water mixture adsorption.In today’s increasingly serious Marine oil pollution situation,the research and development of green and environmentally friendly functional carbon soil composite materials can provide a new idea for the treatment of Marine oil pollution,and provide technical support for the development of green shipping.