Study On The Removal Characteristics And Mechanism Of Hydrophobic Organic Pollutants From Water By Rhamnolipid Modified Corn Stalk

Hydrophobic organic pollutants pollution in the environment was more and more serious with the rapidly social and economic development.Hydrophobic organic pollutants pose a serious threat to human health because of their strong toxicity,difficult to be degraded and bioaccumulation,and hydrophobic organic pollutants pollution in water has been paid more and more attention by governments and scholars all over the world.It is one of the hotspots in the field of environmental remediation and agriculture to absorb the hydrophobic organic pollutants by using cheap or environmentally friendly materials in the light of the current situation of resource utilization in China.The development of environmentally friendly,low cost and good adsorbent is the key to improve the adsorption effect.The development of environmentally friendly,low cost and high efficient adsorbent is the focus of the development of adsorbent.In this paper,we studied the removal of hydrophobic organic pollutants from corn stalk modified by biosurfactant rhamnolipid.We chose phenanthrene and di-n-butyl phthalate to discuss the adsorption characteristics and possible mechanism of modified adsorbent.The main findings are as follows:(1)Corn stalk as raw material was used to prepare a kind of biomaterial(rhamnolipid modified corn stalk,RL-CS)with environment-friendly,low-cost and good adsorption performance.The best pretreatment reagent is HCl with a mass fraction of 2%.The adsorption performance of RL-CS to phenanthrene was significantly higher than that of raw material,and the saturated adsorption capacity of straw to phenanthrene increased from 1.675 mg/g to 7.846 mg/g,the saturated adsorption capacity of straw to di-n-butyl phthalate increased from 4.746 mg/g to 24.89 mg/g.(2)RL-CS was characterized.Results showed that RL-CS surface had rougher surface,larger surface area,lower polarity,higher crystallinity,more oxygen content,and more oxygen-containing groups than raw corn stalk.Modified straw improved its affinity to hydrophobic organic pollutants and could provide more adsorption sites on the surface of the material,so that promoted its adsorption of hydrophobic organic pollutants.(3)The adsorption kinetics of RL-CS on phenanthrene and di-n-butyl phthalate showed that the adsorption process was in accordance with the pseudo-second-order kinetics model.The adsorption of phenanthrene on RL-CS was controlled by membrane diffusion and particle diffusion.Membrane diffusion was the main limiting rate of the adsorption process of di-n-butyl phthalate.The adsorption isotherm of phenanthrene was non-linear,indicating that the adsorption process may be the π-π electrons between the polycyclic aromatic hydrocarbon molecules and the aromatic nuclei of the corn stalk,and the adsorption process of phenanthrene is spontaneous and exothermic,which belonged to the physical adsorption.The sorption of phenanthrene by RL-CS was controlled by surface adsorption and partition.The adsorption isotherm of RL-CS on di-n-butyl phthalate is linear,indicating that the adsorption process is mainly determined by the partition.