Adsorption for environmental applications is normally studied in gas and liquid phases. For the first time in the literature, Ni(II) was adsorbed from a subcritical water stream in a fixed column using activated carbon as an adsorbent. Several breakthrough curves were constructed at different conditions of pressure (from 5 to 25 MPa) and temperature (from 100 to 200 °C), so that, the effects of these variables on the adsorption operation were evaluated using an experimental design. The results were also compared with an adsorption in normal conditions. The fixed bed performance was largely improved when subcritical conditions were used, mainly at 25 MPa and 200 °C. The values of stoichiometric adsorption capacity (Q_eq), breakthrough time (t_r) and length of mass transfer zone (MTZ) were, respectively, 1.54 mg g^–1, 5 min and 28.31 cm for the operation in normal conditions. Under subcritical conditions, Q_eq was 6.30 mg g^–1, t_r was 166 min and the MTZ decreased around 10 cm. These results show that a fixed bed column containing activated carbon has better performance when adsorption take place using subcritical water instead of water under ambient conditions.

通常在气相和液相中研究用于环境应用的吸附。在文献中，首次使用活性炭作为吸附剂从亚临界水流中在固定塔中吸附了Ni（II）。在压力（5到25 MPa）和温度（100到200°C）的不同条件下绘制了几条突破曲线，因此，使用实验设计评估了这些变量对吸附操作的影响。还将结果与正常条件下的吸附进行了比较。当使用亚临界条件时，主要是在25 MPa和200°C的条件下，固定床性能得到了极大的改善。化学计量吸附容量（Q _eq），穿透时间（t _r）的值）和传质区（长度为MTZ）分别为1.54毫克克^-1，5分钟和28.31厘米对于在正常条件下的操作。在亚临界条件下，Q _eq为6.30 mg g ^-1，t _r为166 min，MTZ下降约10 cm。这些结果表明，当使用亚临界水而不是环境条件下的水进行吸附时，包含活性炭的固定床色谱柱具有更好的性能。