Study On Dose-responses Of PAEs And The Removal Of DBP From Water By Modified Chitosan

The phthalic acid esters(PAEs) keep migrating to their surroundings as a result of theirindustrializationand widely use of plastics in recent years. They have become one of the mostuniversal pollutants which would greatly threaten people’s health and other organisms’ growthbecause of the potential toxicity and endocrine-disrupting activity. In the study, thedose-responses of the three PAEs (DMP, DEP and DBP) with bigger solubility toPhotobacterium phosphereum T3were evaluated in order to provide important evidences forresearches on exposure and risk assessment of PAEs.More efforts need to be paid on removal study of PAEs from wastewater since they are lessbiodegradable. The chitosan is a kind of safe and biodegradable nature macromolecule polymerwith a rich source. And the vanillin is a kind of nontoxic chemical which is industrialized inlarge amount. In this study, the industrial chitosan (with degree of deacetylation of79.07%) andvanillin reacted with the guidance of Schiff base reaction theory, through which we got newmaterial vanillin-modified chitosan (CTSV) beads. They were used to adsorb DBP from waterand their performance was evaluated.The results of biology toxicity tests showed the acute toxicity of the three PAEs toPhotobacterium phosphoreum T3was DBP＞DMP＞DEP when methanol was used as aco-solvent under certain conditions. The dose-response of methanol and the three PAEs couldbe separately better non-linear fitted by Logit and Weibull equation (in full concentration range)compared to linear fitting (part of the concentrations). The EC50results calculated by both wayswere similar. During the Weibull non-linear fittings of DMP, DEP and DBP, their correlationcoefficients were0.9749,0.9742and0.9648respectively. Their results were satisfied.The results of preparation and adsorption experiments of CTSV beads indicated that thenew material prepared by microwave radiation technology executed bigger adsorption capacitycompared to raw chitosan and that modified by water bath heating method. The SEM and FTIRanalysis carried out success Schiff base reaction between vanillin and chitosan beads with arough microporous surface. Adsorption isotherm data of DBP from the aqueous solution ontoCTSV beads was better fitted by the Langmuir model with R2=0.9954. It also indicated thatappropriate higher temperature would be benefit from improving the adsorption of DBP fromwater. The experiment of adsorption kinetic models for DBP onto CTSV at constant temperature was implemented. The adsorption process reached in equilibrium in60minutes.The adsorption kinetic for DBP onto CTSV can be well presented by the pseudo-second-orderkinetic model with R2=0.9333. Lastly, the adsorption of simulative DBP wastewater in fixedbeds showed that the adsorption capacity reached1900BV when inlet flow velocity was5BV/h at constant temperature. The whole disposal cycle was30days. All in all, the CTSV beadsare new environmental friendly water treatment materials which was economical, safe, nontoxicand easily prepared.