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

对斑点金蓟干茎进行软化学处理后产生了新型吸附剂。原材料的坚硬性质和质量得以保留。为了将对环境的影响降到最低，在环境温度下优化了测试试剂的溶液浓度。测试获得的吸附剂对亚甲基蓝的去除。该方法使用动力学和平衡研究。NaOH（0.1 mol L ^-1）处理有效，并提供了两种新材料，其吸附特性得到了显着改善：平衡时间从17–19 h减少至10–12 h，同时最大吸附量从65 mg增加至100和112 mg g ^-1即提高了54％和72％。其次是伪二阶模型的Avrami模型最适合动力学数据。等温线是Hmx型的，可以很好地拟合到Redlich-Peterson模型。Langmuir，Tóth和Sips模型适合描述与有限数据范围有关的H型等温线。显微分析，扫描电子显微镜（SEM），耦合至能量色散X射线的SEM和衰减的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，ζ电势测量表明在预处理之后表面的电荷几乎不存在。