In the framework of the circular economy, spent coffee grounds were converted into powdered activated carbon by means of pyrolysis, using potassium hydroxide as the activating agent. Its adsorption capacity on a panel of phenolic compounds was compared with those of two commercial powdered activated carbons, after preliminary studies on organic dyes with different ionic properties, to assess the affinity between adsorbates and adsorbents. Pseudo-first-order and pseudo-second-order kinetic models were carried out, together with Freundlich and Langmuir isotherms. They were useful to calculate the breakthrough at 5%, 10%, and 50% of adsorption and the partition coefficients for the comparison of performance between different sorbent systems in a less biased manner (e.g., reducing bias associated with operational settings like sorbate concentration and sorbents dosage). The results showed that the removal efficiency for SCGs-AC was comparable with that of the commercial activated carbons with the highest partition coefficients for methylene blue (12,455 mg/g/μM, adsorption capacity = 179 mg/g) and 3-chlorophenol (81.53 mg/g/μM, adsorption capacity = 3765 mg/g). The lower efficiency in bromothymol blue and bisphenol-A adsorption was due to its different morphology and surface properties.

中文翻译：

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废咖啡渣中的活性炭：用于水净化的商业碳的良好竞争对手

在循环经济的框架内，用氢氧化钾作为活化剂，通过热解将废咖啡渣转化为粉末状活性炭。在对具有不同离子性质的有机染料进行初步研究之后，将其在一组酚类化合物上的吸附能力与两种市售粉末状活性炭的吸附能力进行了比较，以评估吸附剂与吸附剂之间的亲和力。进行了伪一级和伪二级动力学模型，以及Freundlich和Langmuir等温线。它们可用于计算5％，10％和50％吸附时的穿透率以及分配系数，用于比较偏差较小的不同吸附剂系统之间的性能（例如，减少与操作设置（如山梨酸盐浓度和吸附剂剂量）相关的偏差。结果表明，SCGs-AC的去除效率与市售活性炭相当，亚甲基蓝（12,455 mg / g /μM，吸附容量= 179 mg / g）和3-氯苯酚（81.53）的分配系数最高。 mg / g /μM，吸附容量= 3765 mg / g）。溴百里酚蓝和双酚A的吸附效率较低是由于其形态和表面性质不同。