Study On The Adsorption Characteristics Of Endocrine Disruptors Phthalic Acid Dibutyl On Different Substrates

Environmental endocrine disruptors(EEDs), known as environmental hormones,are widely present in the environment and the chemicals can disturb the human or animal’s endocrine system and cause reproductive, developmental and behavioral disorder. Phthalic acid esters(PAEs), the important group of environment hormones,are mainly used as a plasticizer. Recently, with the development of plastic industry and the extensive use of plastics products,lots of PAEs has polluted the environment,which has also become one of the most common pollutants in the world. Three different substrates(sand,gravel and aluminum sludge) were selected to absorb the typical endocrine disrupting chemicals dibutyl phthalate(DBP), and adsorption kinetics,thermodynamic characteristics,adsorption isotherm characteristics as well as the factors affecting the adsorption behavior of DBP were studied in this paper. The results were as follows:Adsorption kinetics experiments showed that : Pseudo-first order kinetic model,Pseudo-second order kinetic model,Elovich equation,and Double constant equation could describe the DBP adsorption kinetic process of these three substrates accurately. Compared with this four models,for the gravel and sand,Pseudo-second order kinetic model was the most accurate model,the correlation coefficient R2 reached 0.99;for aluminum sludge,Double constant equation was the best and Pseudo-second order kinetic model was second,the correlation coefficient R2 reached 0.97. By the Pseudo-second order kinetic model under the same conditions,the maximum adsorption rate on three matrixes of DBP were sand,gravel,aluminum sludge.Adsorption thermodynamics experiments showed that:in the adsorption process of DBP of the three different substrates(sand,gravel and aluminum sludge),The positive value of ?H and the negative value of ?G indicated that the adsorption of DBP onto substrates are endothermic and spontaneity.Adsorption isotherm experiments showed that: Langmuir, Freundlich, Temkin and Dubinin-Radushkevich equation were used to describe the DBP adsorption isotherm process. In the four equations, Langmuir isotherm equation was found to fit the adsorption process best,the correlation coefficient R2 reached 0.99.Factors affecting the adsorption experiments showed that:In the pH range studied(5.0, 7.0, 8.0, 9.0), the capacity and removal of the gravel and sand didn’t change specifically,while aluminum sludge adsorption DBP process had slight impact,whose equilibrium adsorption capacity and removal rate value decreased slightly with the increase of pH. With the increase of the ionic strength of NaCl,the capacity and removal rate of the three substrates of DBP adsorption raised slightly. As the DBP initial concentration of the solution in adsorption system increases, a developing trend of the adsorption volume of the three substrates on DBP was found and the removal rate decreased accordingly, but when the initial concentration increased to a certain value, the adsorption capacity didn’t change; take initial concentration, pH, the type of substrate, ionic strength as the test factor to design a orthogonal test of L9(34),The results showed that range value of this four factors was in the order: initial concentration ? the type of substrate ? ionic strength ? pH, indicating that the initial concentration is the most important factor.