The pre-treatment of waste cooking oil (WCO) by removing free fatty acids (FFAs) is pivotal for biodiesel production. This study develops a low-cost, efficient adsorbent derived from water hyacinth (Eichhornia crassipes), activated with 5 M NaOH, termed WHA-H, for this purpose. Characterization through FT-IR and SEM analyses revealed that NaOH activation significantly enhanced the surface roughness and functional group availability on WHA-H, leading to improved adsorption capabilities. Nitrogen adsorption–desorption isotherms of WHA-H confirmed a complex pore structure with Type II and Type IV isotherms combination, indicating the presence of both meso- and macroporosity. Kinetic studies conformed to the pseudo-second-order model, suggesting chemisorption as the primary FFA adsorption mechanism, while isotherm data were best described by the Langmuir model, indicating monolayer coverage on a homogeneous surface. WHA-H exhibited a maximum FFA adsorption capacity (q_m) of 1666.67 mg g⁻¹. Thermodynamic parameters indicated that the adsorption process is spontaneous and exothermic, with desorption studies establishing diethyl ether as an effective solvent for WHA-H regeneration. Our study not only demonstrates WHA-H’s potential as a sustainable adsorbent for improving WCO quality but also offers an eco-friendly approach to managing the invasive water hyacinth.

通过去除游离脂肪酸 (FFA) 对废弃食用油 (WCO) 进行预处理对于生物柴油生产至关重要。为此，本研究开发了一种源自水葫芦（ Eichhornia crassipes ）的低成本、高效吸附剂，并用 5 M NaOH 活化，称为 WHA-H。通过 FT-IR 和 SEM 分析表征表明，NaOH 活化显着提高了 WHA-H 的表面粗糙度和官能团可用性，从而提高了吸附能力。 WHA-H 的氮气吸附-解吸等温线证实了具有 II 型和 IV 型等温线组合的复杂孔隙结构，表明同时存在介孔和大孔。动力学研究符合伪二级模型，表明化学吸附是主要的 FFA 吸附机制，而等温线数据最好由 Langmuir 模型描述，表明均匀表面上的单层覆盖。 WHA-H表现出最大FFA吸附容量(q _m )为1666.67 mg g ^-1。热力学参数表明吸附过程是自发且放热的，解吸研究确定二乙醚是 WHA-H 再生的有效溶剂。我们的研究不仅证明了 WHA-H 作为提高 WCO 质量的可持续吸附剂的潜力，而且还提供了一种管理入侵水葫芦的环保方法。