窄孔径含磷棉秆生物质炭的制备及对四环素的吸附机制

以棉秆为生物质原料，磷酸为改性剂，一步碳化制备了兼具高比表面积(1 916 m²·g^-1)和孔体积(1.398 2 mL·g^-1)的窄孔径含磷棉秆生物质炭(CSP),并研究了其对四环素(TC)的吸附行为.结果表明，磷酸改性制备的窄孔径含磷棉秆生物质炭对TC吸附量高达669mg·g^-1,是未改性棉秆炭的43.6倍；红外光谱(FTIR)、 X射线(XPS)和等温吸附研究表明，CSP对TC的高吸附量是表面络合、氢键、孔隙填充和π-π色散等多种吸附力共同作用的结果，其中磷酸改性赋予的高活性磷酸酯类基团(P—O—C)与TC分子间的化学络合作用强且贡献度高，是吸附量显著提升的最关键因素.静态等温吸附与热力学研究结果进一步证实TC在含磷棉秆炭吸附过程中化学吸附起主要作用，吸附过程属于自发的吸热过程.研究结果可为利用棉秆资源定向制备高效吸附TC的高活性磷掺杂生物质炭提供了一种潜在的简便高效途径.

Preparation of Narrow Pore Diameter Phosphorus Containing Cotton Stalk Carbon and Its Adsorption Mechanism for Tetracycline

Using cotton stalk as biomass raw material and phosphoric acid as a modifier, narrow pore distribution phosphorus-containing cotton stalk biochar (CSP) with a high surface area (1916 m²·g^-1) and pore volume (1.3982 mL·g^-1) was prepared through one-step carbonization, and the adsorption characteristics and mechanisms for tetracycline (TC) were investigated. The results showed that the TC adsorption capacity of CSP was up to 669 mg·g^-1, which was 43.6 times that of unmodified cotton stalk carbon. FTIR, XPS, and isothermal adsorption studies showed that the high adsorption capacity of CSP for TC resulted from the joint action of complexation, hydrogen bonding, pore filling, and π-π dispersion forces, and the highly active phosphate ester group (P-O-C) endowed by phosphoric acid modification greatly enhanced the chemical interaction with TC molecules, which was the key factor for the significant increase in adsorption capacity. Isotherm and thermodynamic study further confirmed that chemical adsorption played a major role in the adsorption process, the adsorption process was spontaneous and endothermic, and the material had good regeneration performance. This study provides theoretical guidance for the preparation of modified biomass carbon with high adsorption performance to remove tetracycline antibiotic pollution.