Abstract

Soft chemical treatments of dried stalks of the spotted golden thistle yielded novel sorbents; both the stiff nature and mass of the raw material were preserved. For minimal environment impact, the solution concentrations of the tested reagents were optimized at ambient temperature. The sorbents obtained were tested for the removal of methylene blue. The approach used kinetics and equilibrium studies. NaOH (0.1 mol L⁻¹) treatment was efficient and afforded two new materials with seriously improved sorption features: the equilibrium time was reduced from 17–19 h to 10–12 h whilst, maximal sorption capacity increases from 65 to 100 and 112 mg g⁻¹ i.e., enhancements of 54 and 72%. The Avrami model followed by the pseudo second-order model, best fitted the kinetic data. The isotherms were of Hmx type and were satisfactorily fitted to the Redlich-Peterson model. The Langmuir, Tóth, and Sips models were suitable to describe the H type isotherms relating to limited data ranges. Microanalysis, scanning electron microscopy (SEM), SEM coupled to energy dispersive X-ray, and attenuated total reflectance infrared spectroscopy showed an increase of the lignocellulosic content and the strengthening of the interactions between the dye and the sorbent. However, zeta potential measurements showed that the charge of the surface became almost inexistent after the pretreatment.

摘要

对斑点金蓟的干茎进行软化学处理，产生了新型吸附剂；原材料的坚硬性质和质量都得到了保留。为了最小化环境影响，测试试剂的溶液浓度在环境温度下进行了优化。测试获得的吸附剂去除亚甲基蓝。该方法使用动力学和平衡研究。NaOH (0.1 mol L ^-1 ) 处理是有效的，并提供了两种具有显着改善吸附特性的新材料：平衡时间从 17-19 小时减少到 10-12 小时，同时最大吸附容量从 65 增加到 100 和 112 毫克g ^-1即，增强 54% 和 72%。Avrami 模型，其次是伪二阶模型，最适合动力学数据。等温线是 Hmx 型的，并且符合 Redlich-Peterson 模型。Langmuir、Tóth 和 Sips 模型适用于描述与有限数据范围相关的 H 型等温线。微量分析、扫描电子显微镜 (SEM)、与能量色散 X 射线耦合的 SEM 和衰减全反射红外光谱显示木质纤维素含量增加，染料与吸附剂之间的相互作用增强。然而，zeta 电位测量表明，预处理后表面的电荷几乎不存在。