Abstract:

This study used water hyacinth as the raw material and CaCl₂ as the modifier to prepare calcium-modified water hyacinth-based biochar (CWHBC) by one-step pyrolysis. Based on characterization techniques, the surface morphology, specific surface area, pore size distribution, and main functional group composition of CWHBC were analyzed, and its adsorption efficiency and mechanism for removing diuron from water were explored. The results showed that compared with unmodified biochar (WHBC), CWHBC had a larger specific surface area, a more abundant pore structure, more oxygen-containing functional groups, and stronger hydrophilicity. These changes in physicochemical properties enhanced the adsorption ability of biochar. The adsorption of diuron by CWHBC conformed to the pseudo-second-order adsorption kinetic model and the Langmuir adsorption isotherm model, indicating that the adsorption was mainly a monolayer chemical adsorption. The main adsorption mechanisms were hydrogen bonding, π-π interactions, and surface complexation. The results of single-factor experiment showed that CWHBC had good adsorption performance under various conditions, and the adsorption capacity after five cycles of adsorption/desorption with 0.2mol/L HCl was still as high as 94.62% of the initial adsorption capacity. Therefore, the CWHBC prepared by one-step pyrolysis could effectively remove diuron from water and had good environmental adaptability and repeatability. This study provided a low-cost and efficient adsorbent that could effectively achieve the resource utilization of water hyacinth and had good engineering application prospects and potential.

Key words: biochar, calcium modification, adsorbents, diuron, adsorption, kinetics, mechanism

摘要：

以水葫芦为原料、CaCl₂为改性剂，通过一步热解法制备了钙改性水葫芦基生物炭（CWHBC），基于表征技术分析了其表面形貌、比表面积、孔径分布、官能团组成等物化性能，并探究了其吸附去除水中敌草隆的效能与机理。结果表明，CWHBC比未改性生物炭（WHBC）具有更大的比表面积、更丰富的孔隙结构、更多的含氧官能团、更强的亲水性，这些物化性能的改变增强了生物炭的吸附能力。CWHBC对水中敌草隆的吸附符合准二级吸附动力学模型和Langmuir吸附等温线模型，表明该吸附以单层化学吸附为主，主要吸附机理为氢键作用、π-π作用和表面络合。单因素试验结果表明，CWHBC在各种条件下均具有良好的吸附性能，采用0.2mol/L HCl对其进行5次吸附/解吸循环后的吸附容量仍高达初次吸附容量的94.62%。因此，使用一步热解法制备的CWHBC可有效去除水中敌草隆，且具有较好的环境适应能力和重复使用性能。该研究提供了一种低成本、高效的吸附材料，能有效实现水葫芦的资源化利用，具有良好的工程应用前景与潜力。

关键词: 生物炭, 钙改性, 吸附剂, 敌草隆, 吸附, 动力学, 机理