The magnetic nanoparticles prepared through the co‐precipitation method were surface modified using Spirulina platensis. The mesoporous and superparamagnetic nature of the adsorbent was confirmed by Brunauer‐Emmett‐Teller (BET) and vibrating sample magnetometer (VSM) analyses, respectively. Further, an increased specific surface area of 75.3 m²/g was reported in the BET studies. Parameters such as pH, contact time, concentration, and temperature were studied to optimize the operating conditions influencing adsorption. Thermodynamic studies justified the spontaneity and endothermic nature of adsorption. The adsorbent exhibited a better performance at 1.5 pH and 120 minutes of contact time. The monolayer adsorption capacity of the material was found to be 29.23 mg/g from the evaluation of Langmuir adsorption isotherm. The second‐ order kinetic studies suggest the predominance of chemisorption. Further, the X‐ray photoelectron spectroscopy (XPS) studies confirmed that the adsorption mechanism is electrostatic attraction accompanied by reduction. Notably, a regeneration efficiency of 75.26% was achieved with NaOH as the desorbing agent.

中文翻译：

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螺旋藻覆盖的介孔磁性纳米粒子用于铬的吸附去除

通过共沉淀法制备的磁性纳米粒子使用螺旋藻进行了表面改性。吸附剂的介孔和超顺磁性质分别通过Brunauer-Emmett-Teller（BET）和振动样品磁力计（VSM）分析得到证实。此外，比表面积增加了75.3 m ²/ g在BET研究中报告。研究了诸如pH，接触时间，浓度和温度等参数，以优化影响吸附的操作条件。热力学研究证明了吸附的自发性和吸热性。吸附剂在1.5 pH和120分钟的接触时间下表现出更好的性能。通过对Langmuir的吸附等温线进行评估，发现该材料的单层吸附容量为29.23 mg / g。二级动力学研究表明化学吸附占主导地位。此外，X射线光电子能谱（XPS）研究证实，吸附机理是伴随着还原的静电吸引。值得注意的是，使用NaOH作为解吸剂，再生效率达到了75.26％。