The prime objective of the present experimental work is to evaluate the impact of ultrasonication time and surfactants on the optical characteristics (transmittance and absorbance) and stability of CuO/water, CNTs/water, and Fe₃O₄/water nanofluids to be used in spectrum selective applications. Two-step method with various ultrasonication times (30 min, 60 min, and 90 min) was employed to prepare nanofluids (having volume fractions of 0.004 % and 0.0004 %). Furthermore, various surfactants (anionic, cationic, and polymer) were added to the base fluid. The study results revealed that surfactants have a significant effect on the stability of nanofluids over ultrasonication time. The nanofluids prepared using sodium dodecylbenzene sulfonate (SDBS) have the highest zeta potential values than other surfactants used in the experimentation. The increase in transmittance of nanofluid was more prominent for lower concentration (0.0004 %) after one week of preparation. The concentration of nanoparticles, ultrasonication time, temperature, and surfactants influenced the optical characteristics of nanofluids. The most stabled CNTs nanofluid with 0.004 % concentration and 90 min of ultrasonication obtained an average of 67.6 % and 74.6 % higher absorbance than stabled CuO and Fe₃O₄ nanofluids, respectively. The irradiance transmitted through nanofluid was strongly dependent on the concentration and type of nanoparticles.

本实验工作的主要目的是评估超声处理时间和表面活性剂对 CuO/水、CNT/水和 Fe ₃ O _{4的光学特性（透射率和吸光度）和稳定性的影响。}/水纳米流体用于光谱选择性应用。采用具有不同超声时间（30 分钟、60 分钟和 90 分钟）的两步法制备纳米流体（体积分数分别为 0.004% 和 0.0004%）。此外，将各种表面活性剂（阴离子、阳离子和聚合物）添加到基液中。研究结果表明，表面活性剂对纳米流体在超声处理时间内的稳定性有显着影响。与实验中使用的其他表面活性剂相比，使用十二烷基苯磺酸钠 (SDBS) 制备的纳米流体具有最高的 zeta 电位值。制备一周后，较低浓度（0.0004%）的纳米流体透射率的增加更为显着。纳米粒子的浓度、超声时间、温度、和表面活性剂影响纳米流体的光学特性。最稳定的 0.004% 浓度的 CNTs 纳米流体和 90 分钟的超声处理比稳定的 CuO 和 Fe 获得平均高 67.6% 和 74.6% 的吸光度₃ O ₄纳米流体，分别。通过纳米流体传输的辐照度很大程度上取决于纳米粒子的浓度和类型。