The Study On The Sorption Of Nitrobenzene On Sediments In Weihe Basin

Nitrobenzene is considered as "priority pollutants" in international society. By the characteristics of hard-degradation and high toxicity, once the river is polluted, nitrobenzene will do harm to the health of people and animals. Wei River has the characteristics of population concentration, developed industry and agriculture, but serious pollution of water quality. Movement and absorption of nitrobenzene in unsaturated zone, provide major theoretical support for further study of behavior characteristics of nitrobenzene in river. Therefore, it has important theoretical meaning and actual meaning to study adsorption characteristic and the factors of nitrobenzene in river sediments.According to indoor batch experiments about river sediments in middle and lower reaches of Wei River, the author drew the conclusion as follows by studying adsorption characteristic and the factors of nitrobenzene in river sediments:1.Non-equilibrium adsorption isotherm shows that:(1)Among Wei River typical sediments, adsorption of nitrobenzene in medium sand, silty sand, silty soil, silty clay are all consistent with quasi-second dynamic equation. Adsorption of nitrobenzene in aquifer is in connection with organic content. (2) Isothermal adsorption of nitrobenzene can reach balance state in three hours in medium sand, dissolved organic matter content is 0.39%-0.58%; silty sand, silty soil, silty clay, in which dissolved organic matter content is 0.65%-2.55%, equilibration time is 0.5 hour.2.Equilibrium adsorption isotherm shows that:(1)Adsorption isotherm can be described by Freundlich Equilibrium adsorption isotherm mode. (2) The finer particle size of river sediments is,the larger partition ratio kfis. When the target pollutants move to lower reach, blocking ability of nitrobenzene in lower reach sediments is higher then middle reach. (3) Block coefficient Rd can be used for quantitative description of migration of nitrobenzene in river sediment, block coefficient has a linear correlation with migration. According to the difference of soil lithology, the order of block coefficient is:silty clay (Rd=2.04)>silty soil (Rd=1.84)>silty sand(Rd=1.31)>medium sand(Rd=1.20)3.Adsorption influence factors show that:(1)The adsorption of nitrobenzene in river sediments mainly due to organic water transmission distribution coefficient, so organic matter content has a significant linear correlation with adsorption capacity of nitrobenzene.(2) If particle size of sandy medium>0.1mm,adsorption capacity and POM are positive linear correlation; or particle size of sandy medium<0.1mm,adsorption capacity and clay content and specific surface area are positive linear correlation. (3)Adsorption ability of river sediments towards nitrobenzene in acidic environment is more significant then alkaline condition.