Adsorption Characteristics Of The Precursors Of N-DBPs In Dringking Water By Activated Carbon

The widely detected dissolved organic nitrogen (DON) composes themajor contents of in micro-polluted waters. More and more attention has beenfocused on these chemicals due to their formation of toxic nitrogenousdisinfection by-products (N-DBPs) with very high carcinogenicity,teratogenicity and mutagenicity during disinfection procees in drinking watertreatment. As adsorbent, pollutants in aqueous solution can achieve goodremoval effect by activated carbon. Therefore, the control of N-DBPsadsorption will ensure the security of water quality by activated carbon.In the experiments, the static and dynamic adsorption characteristics oftryptophan, tyrosine and L-phenylalanine in water by granular activatedcarbon were investigated, and the Yoon-Nelson model was used to describe thebreakthrough curves characteristics of tryptophan on the GAC was studied. Inthe adsorption process, the influence of the adsorption by the single factors(temperature, adsorption time, investment, the amount of carbon and pH), andafter activated carbon from acidic modified, the single factors influence(temperature, adsorption time, cast carbon content and pH) on the adsorptionwere expatiated. Due to the study, experiments of using different activated carbon to testadsorption effects of tryptophan, tyrosine and L-phenylalanine, the highadsorption capacity could be achieves by GAC, and both the Freundlich andLangmuir models were found to fit the adsorption isotherm data well. Thetryptophan and L-phenylalanine`s changing rate were very consistent with theproposed first dynamic models; the tyrosine`s changing rate was veryconsistent with the proposed two dynamic models.The high tryptophan adsorption capacity could be achieved by GAC, andthe breakthrough curves of tryptophan by the GAC fit the Yoon-Nelson modelvery well, and the breakthrough curves of tryptophan in the GAC column wereinfected by flow rates, particle diameter of GAC, influent concentration orquantity of GAC, basing on which the breakthrough dynamic models wereadvanced to simulate the breakthrough dynamic models were advanced tosimulate the breakthrough process accordingly.The study shows that: temperature, the adsorption time, the cast carboncontent and pH have impact on the adsorption; When tryptophan concentrationis10mg/l, the temperature at25℃and pH was kept between6.6-7.3, the castcarbon content from60to100mg, the adsorption time200min, the adsorptionis very well. Addition of activated carbon changed by a modified acid treatment,the activated carbon were processed by0,1,2and5mol/l HNO3respectively,then the single factor experimental were studied, which the temperature, theadsorption time, cast carbon content and pH. The adsorption rate is the similar between the temperature variation; the greater acid concentration, the longerthe time to reach equilibrium adsorption; activated carbon impregnated by acid,the unit activated carbon adsorbed tryptophan`s rate was decreased; and thepH change, the original activated carbon adsorption rate was good in neutralsolution, and after nitrate impregnated activated carbon adsorption propertiesarea was the alkaline solution.