壳聚糖和FeS改性生物炭吸附四环素:吸附机制与位能分布

Study on the adsorption of tetracycline by chitosan and FeS modified biochar: Adsorption mechanism and site energy distribution

实验以市政污泥为生物质炭原料,并以硫化亚铁和壳聚糖对其改性,制得一种新型环保的吸附材料(SB-FeS).以四环素(TC)为目标污染物,通过批次实验、大量表征分析、数学模型分析对SB-FeS吸附TC的机制进行了详述.实验结果表明, SB-FeS对TC的最大吸附量为183.01 mg·g^-1;SB-FeS对TC的吸附为物理吸附和化学吸附共同作用. SB-FeS对TC的吸附机制主要为静电吸引、孔隙填充、螯合、离子交换、硅酸盐键结合和氢键结合.此外,位点能量分布的研究表明,TC会优先占据高能吸附位点,随后逐渐占据低能位点;且溶液温度升高, SB-FeS表面会愈发不均匀.实验证明SB-FeS对TC吸附是有效的,并且对于吸附机理的探讨可以为后续研究提供帮助.

In this study, the municipal sludge was used as the raw material, a new type of environmentally friendly adsorbents(SB-FeS) was obtained by ferrous sulfide and chitosan modification. Tetracycline(TC) was selected as target pollutant, and the mechanism of SB-FeS adsorption of TC was described in detail through batch experiments, together with characterization and mathematical model analysis. The experimental results show that the maximum adsorption of TC by SB-FeS is 183.01 mg·g^-1, which is a combination of physical and chemical adsorption. The adsorption mechanism of SB-FeS on TC consists of mainly electrostatic attraction, pore filling, chelating, ion exchange, silicate bonding and hydrogen bonding. In addition, the site energy distribution shows that TC will preferentially occupy high-energy adsorption sites and then gradually occupy low-energy sites. The temperature of the solution will increase, and the surface of SB-FeS will become more and more uneven. The experiments proved that the adsorption of SB-FeS to TC was effective, and could provide help for subsequent research.