| Aromatic compounds are important intermediates for synthesis of fine chemicals. However,during their production,enormous wastewater which contains poisonous organic compounds with high concentration and poor biodegradability was generated. Up to the present,it is still a serious environmental problem and a great challenge to effectively treat the high concentration organic wastewater.In recent years,there has been much progress for treating high-concentration organic industrial wastewaters with polymer adsorbents in China.The synthesis and the use of novel adsorbents become an active research subject in environmental protection.Using different crosslinking reagents,two types of novel hypercrosslinked polymeric adsorbents which modified by amino and hydroxyl groups were prepared through Friedel-Crafts reaction of low crosslinked St-DVB copolymers with different chemical modifications. Thermodynamic and kinetic analyses of these two novel adsorbents were investigated in single adsorbate aqueous and nonaqueous solution.According to the adsorption experiment,LY-3 was selected to study the selective adsorption capability of phenol from mixture solution of phenol and aniline.These results will provide some theoretic gists to explore new functional adsorbent polymers.The main conclusions were presented as follows:Both in aqueous solution and in nonaqueous solution,the adsorption capacity of phenol onto amino-modifying adsorbents is bigger than that of aniline.However,in aqueous solution,the adsorption capacity of phenol onto hydroxyl-modifying adsorbents is lower than that of aniline.The adsorption enthalpies of△H for adsorption of phenol(aniline) onto the four adsorbents are all negative and their absolute values are lower than 42 kJ/mol,which indicate that the adsorption is exothermic process and the physical adsorption is dominant in the adsorption process. The Gibbs free energy change of△G of the adsorption is also less than zero which demonstrates that the adsorption is a spontaneous process.The negative values of adsorption entropy change△S are in agreement with the fact that the mobility of adsorbates on adsorbent surface is more restricted compared to the situation in solution.In aqueous and nonaqueous solution,the adsorptions of phenol(aniline) onto adsorbents which modified by three types of amino groups were studied with the same equilibrium concentration.The sequence of adsorption capacity is LY-1＞LY-2＞LY-3.The value of△H,△G and AH for adsorption of phenol(aniline) onto adsorbents decreases with the increasing of the amido group content of these three types of resin.However,as it for hexane solution,the sequence of adsorption capacity is LY-3＞LY-2＞LY-1 and the value of△H,△G and△H for adsorption of phenol (aniline) onto adsorbents increases with the increasing of the amido group content.In ethanol solution,the adsorption capacity of phenol(aniline) onto resins nearly equals to zero.Dynamic analyses of the adsorption process of phenol(aniline) on these four types of resins were investigated.Kinetic data shows that adsorption of phenol (aniline) on resins fitted well to Lagergren and Kannan-Sundaram model,and thus it can be described as a first order rate adsorption equation.The high rate constants of adsorption equations of phenol(aniline) on resins demonstrate that adsorbents possess a quick adsorption property.Adsorptions of phenol(aniline) on these four types of resins were impulsed by grain diffusion and film diffusion.The experiment of selective adsorbing phenol onto LY-3 was investigated in mixture solution which containing phenol and aniline.The result shows that the adsorption capacities of phenol and aniline onto LY-3 increase with the increasing of equilibrium concentration.The values of K_F and n of Freundlich equation for adsorbing phenol are bigger than those for adsorbing aniline,which means that adsorption capacity of phenol on LY-3 is a prior adsorption. |
