不同土壤环境因素对微塑料吸附四环素的影响

为探究不同土壤环境因素对于微塑料吸附抗生素的影响,选用三种常见的微塑料:聚乙烯(PE)、聚苯乙烯(PS)和聚酰胺(PA),以四环素(TC)代表抗生素,通过批平衡试验来研究微塑料对TC的吸附行为和机理。研究发现,3种微塑料对TC的等温吸附方程均可用Langmuir方程进行拟合,其吸附能力为PEPSPA,最大吸附量分别为0.154、0.086、0.075 mg·g~(-1)。在中性条件下PE对TC的吸附量达到最大,pH对PA吸附TC影响较小,而PS在酸性条件下对TC的吸附量最大,且随着pH增加吸附量逐渐降低。不同浓度的Ca~(2+)和Mg~(2+)会影响微塑料对TC的吸附,且随着浓度的增加,吸附量逐渐降低。富里酸的存在抑制了TC在PE上的吸附,但低浓度的富里酸(1 mg·L~(-1))会促进PA和PS吸附TC。结果表明,不同微塑料对TC的吸附存在显著差异,且不同土壤环境因素明显影响了微塑料对TC的吸附行为,该结果为进一步研究和评估微塑料在土壤环境中的吸附行为奠定了基础。

Effects of different soil environmental factors on tetracycline adsorption of microplastics

To investigate the effect of different soil environmental factors on the adsorption of antibiotics on microplastics, this study used three microplastics, i. e., polyethylene(PE), polystyrene(PS), and polyamide(PA), with tetracycline(TC) as the target antibiotic, in a batch equilibrium experiment to study the mechanism of TC adsorption on microplastics and the influence of different soil environmental factors on its adsorption behavior. The results showed that the TC adsorption capacities of the microplastics were in the order PE > PS > PA, and these microplastics were suitable for fitting using Langmuir''s equation. The maximum adsorption capacities were 0.154, 0.086, and 0.075 mg·g^-1, respectively. The TC adsorption capacity for PE reached the maximum value under neutral pH conditions; for PS, it was the largest under acidic conditions, and it decreased with an increase in pH; and for PA, pH had little effect on TC adsorption capacity. Different concentrations of Ca²⁺ and Mg²⁺ hinder the absorption of TC by microplastics, and the cation concentration was inversely proportional to the adsorption capacity. The presence of fulvic acid inhibited the adsorption of TC on PE; however, the presence of low concentration fulvic acid(<1 mg·L^-1) promoted the adsorption of TC on PA and PS. In conclusion, the experiments showed that the adsorption of TC on different microplastics was significantly different; furthermore, different soil environmental factors considerably affected the adsorption behavior of TC on microplastics, which lays the foundation for further investigation of the adsorption behavior of microplastics in soil.