腐殖酸对生物炭吸附水环境中雌激素的影响

以玉米秸秆为原料,通过500℃限氧裂解制备生物炭(记为500BC),并采用批量吸附实验对比500BC及腐殖酸负载后生物炭(记为500BC-HA)对于水环境中两种雌激素(双酚A(BPA)和17α-乙炔雌二醇(EE2))的吸附性能及作用机制。结果表明,腐殖酸分子可阻塞部分500BC孔隙,使500BC的孔径、孔容及比表面积下降,负载腐殖酸后,500BC的比表面积由8.43m2/g减小至4.40m2/g,孔径从26.1nm减小至3.2nm,孔容由0.018cm3/g下降至0.001cm3/g;与500BC相比,500BC-HA对BPA、EE2的吸附能力均明显降低,一方面是因为腐殖酸分子占据了500BC表面的吸附点位并堵塞部分孔隙,使其吸附能力降低,另一方面腐殖酸负载后引入更多的含氧官能团,使500BC表面疏水性降低,与雌激素间的疏水作用减弱。腐殖酸负载质量浓度为0~10mg/L时,增加负载质量浓度对500BC吸附性能影响明显,当负载质量浓度大于10mg/L时,腐殖酸在500BC表面达到饱和,继续增加负载浓度对500BC的吸附性能不再产生影响。

Effect of humic acid on estrogens adsorption by biochar in aquatic environment

In this paper,corn straw was oxygen-limited pyrolyzed at 500 ℃ to produce biochar (500BC). The batch adsorption approach was conducted to compare the adsorption process and mechanism of 500BC and humic acid loaded biochar (500BC-HA) to two estrogens (bisphenol A (BPA) and17 alpha-ethinyl estradiol (EE2)) in aquatic environment. The results indicated that humic acid molecules could block part of the pores and result in the decrease of pore diameter,pore volume and specific surface area of 500BC. After humic acid loading,the specific surface area of 500BC decreased from 8.43 m2/g to 4.40 m2/g ,the pore diameter decreased from26.1 nm to 3.2 nm,and the pore volume decreased from 0.018 cm 3/g to 0.001 cm 3/g . Compared with 500BC,the adsorption ability of the biochar was significantly decreased. It was because the humic acid occupied the adsorption sites on the surface of biochar and blocked some pores,resulting in the decrease of BPA and EE2 adsorption ability. On the other hand,the loaded humic acid could introduce oxygen-containing functional groups,thus the hydrophobicity of the biochar was reduced,and the hydrophobic interaction between the biochar and the estrogens was weakened. When the humic acid loading concentration was 0-10 mg/L ,the adsorption ability of estrogen was significantly affected by the humic acid loading concentration. When the humic acid loading concentration was greater than10 mg/L ,the humic acid adsorption reached saturation,the further effect of increasing humic acid loading concentration on adsorption capacity was negligible.