Removal of textile azo-dyes from industrial wastewater is a concerning problem in the modern societies. Adsorption of organic dyes is an alternative for removing these pollutants, but efficient and low-cost adsorbents are required. In this work, a natural (crude) bentonite was used as adsorbent to remove a model cationic (basic) textile dye (basic red 46). Some parameters such as initial dye concentration, time, pH, and temperature were studied in semi-batch experiments to obtain the best conditions for adsorption of basic red 46 (BR-46) with minimal quantity of adsorbent (10 mg in 100 mL of solution). An experimental adsorption capacity (q_m) of 594 mg g⁻¹ was determined directly from the adsorption curve for 60 mg L⁻¹, pH=7 and 25 °C. The thermodynamic parameters ΔG°, ΔH° and ΔS° were also estimated. Several adsorption isotherms (Langmuir, Freundlich, and Temkin) and kinetic models (pseudo-first order, pseudo-second order, and intra-particle diffusion) were applied to the experimental data; thus, the best settings were obtained by Langmuir isotherm and pseudo-second order kinetic model. The comparison of results obtained for this natural bentonite with respect to some materials published in the literature reveals the excellent performance of this material for adsorption of BR-46, allowing a fast and higher removal (94% ± 4, at 10 min), under mild conditions (neutral pH, 25 °C and atmospheric pressure).

在现代社会中，从工业废水中去除纺织品偶氮染料是一个令人关注的问题。吸附有机染料是去除这些污染物的替代方法，但是需要高效且低成本的吸附剂。在这项工作中，天然（粗）膨润土被用作吸附剂，以去除模型性的阳离子（碱性）纺织染料（碱性红46）。在半分批实验中研究了一些参数，例如初始染料浓度，时间，pH和温度，以最少的吸附剂（在100 mL溶液中10 mg）获得了碱性红46（BR-46）吸附的最佳条件。 ）。直接从60 mg L ^-1的吸附曲线确定了594 mg g ^-1的实验吸附容量（q _m），pH = 7和25°C。还估算了热力学参数ΔG°，ΔH°和ΔS°。实验数据采用了几种吸附等温线（Langmuir，Freundlich和Temkin）和动力学模型（伪一阶，伪第二阶和粒子内扩散）。因此，通过Langmuir等温线和拟二阶动力学模型可以获得最佳设置。将该天然膨润土与文献中公开的某些材料进行的结果比较表明，该材料具有优异的吸附BR-46的性能，可在10分钟内快速，更高地去除（94％±4，在10分钟内）。温和的条件（中性pH，25°C和大气压）。