双酚A和邻苯二甲酸二正丁酯在纸类上的吸附特性研究

采用序批式实验,考察了报纸对双酚A(BPA)和邻苯二甲酸二正丁酯(DnBP)的吸附能力,用Freundlich、Langmuir、Dubinin-Radushkevich(D-R)、Flory-Huggins(F-H)、BET、Temkin 6种吸附等温线模型对实验数据进行了拟合.并选择了回归系数(R2)、均方根差(RMSE)和卡方检验(X2检验)3种非线性回归方法评价了模型拟合度.结果表明,Freundlich和Temkin吸附等温线模型能很好地描述BPA和DnBP在纸类表面的吸附,BPA和DnBP的R2均大于0.95(P<0.01),RMSE和X2分别小于0.05和0.02;吸附能力与吸附质的疏水性呈正相关.由D-R和F-H吸附等温线模型拟合结果可知,BPA和DnBP的吸附平均自由能分别为1.484和1.609 kJ/mol;Gibbs自由能分别为-6.559和-7.021 kJ/mol.说明BPA和DnBP在纸类上的吸附为自发的物理吸附.BPA和DnBP在纸类上的Freundlich吸附常数k分别为0.147和0.502 mg(1-n)·L"·g-1,均高于文献报道的底泥等的吸附常数,说明生活垃圾填埋场中纸类会阻碍BPA和DnBP的迁移和生物可利用性.

Isothermal Studies on Liquid-Phase Adsorption of Bisphenol A and Dibutyl Phthalate by Paper

Adsorption behavior of bisphenol A (BPA) and dibutyl phthalate (DnBP) from aqueous solution onto newsprint was investigated through batch adsorption experiments. Adsorption isothermal data was interpreted by the Freundlich, Langmuir, Dubinin-Radushkevich (D-R), Flory-Huggins (F-H), BET and Temkin equations. In order to determine the best fit isotherm, three error analysis methods were used to evaluate the data: correlation coefficient (R2), residual root mean square error (RMSE) and chi-square test (chi2 test). The results show that the Freundlich and Temkin equations provide the best models for BPA and DnBP biosorption with high R2 (R2 > 0.95, p < 0.01) and low values of RMSE and chi2 (RMSE < 0.05, chi2 < 0.02). The adsorption capacity increases with the hydrophobicity of adsorbate. The mean free energy of adsorption process is calculated by D-R isotherm as 1.484 and 1.609 kJ/mol while the Gibbs free energy calculated by F-H isotherm is -6.559 and -7.021 kJ/mol for BPA and DnBP, respectively. From D-R and F-H models, it is inferred that biosorption of BPA and DnBP by newsprint might be physical adsorption and a spontaneous process. As a comparison, it is indicated these Kf values in Freundlich equation (0.147 and 0.502 mg(1-n) x L(n) x g(-1) for BPA and DnBP, respectively), considered as a measure of the adsorption capacity, are higher than those obtained in the adsorption of same adsorbate by natural organic adsorbents, such as sediment. This suggests the presence of paper will retard BPA and DnBP transport and bioavalability in landfills.