Addition of ionic liquids (ILs) into the fluids containing nanoparticles is often used to minimize particle aggregation and improve dispersion behavior of nanofluids. However, they also affect the physical characteristics of liquids, such as thermophysical properties and viscosity. The aim of this work was to investigate the role of 1-butyl 3-methylimidazolium bromide [C₄mim][Br] and 1-butyl 3-methylimidazolium chloride [C₄mim][Cl] on the dispersion stability, volumetric characterizations and viscosity of polyethylene glycol 200 (PEG 200) nanofluids containing ZnO nanoparticles. Particle size distribution of these nanofluids has been studied by UV–Vis spectroscopy and dynamic light scattering (DLS). The obtained results show that the nanofluids with PEG 200 + [C₄mim][Cl] have lower stability than PEG 200 + [C₄mim][Br]. Additionally, in order to understand molecular interactions between components of studied nanofluids (ZnO, PEG 200 and ILs) the density (d), speed of sound (u) and viscosity (\(\eta\)) of these nanofluids were measured at 293.15, 298.15, 308.15 and 308.15 K. The excess molar volume (\(V_{m}^{E}\)), apparent molar volume (\(V_{\phi }\)) and isentropic compressibility (\(\kappa_{s}\)) have been calculated using density and speed of sound data. These properties can help us to discuss about the stability and volumetric characterizations of the nanofluids. Also, theoretical analyses of \(V_{m}^{E}\), \(\kappa_{s}\) and \(\eta\) were performed using some existing models (Ott et al., Redlich–Kister, Eyring-mNRF and Eyring-NRTL) and the obtained results were compared with experimental data.

通常将离子液体（ILs）添加到包含纳米颗粒的流体中，以最大程度地减少颗粒聚集并改善纳米流体的分散性能。但是，它们也会影响液体的物理特性，例如热物理性质和粘度。这项工作的目的是研究1-丁基3-甲基咪唑鎓溴化物[C ₄ mim] [Br]和1-丁基3-甲基咪唑鎓氯化物[C ₄ mim] [Cl]对分散稳定性，体积表征和含有ZnO纳米颗粒的聚乙二醇200（PEG 200）纳米流体的粘度。这些纳米流体的粒径分布已通过紫外可见光谱和动态光散射（DLS）进行了研究。所得结果表明，具有PEG 200 + [C ₄mim] [Cl]的稳定性低于PEG 200 + [C ₄ mim] [Br]。另外，为了了解所研究的纳米流体（ZnO，PEG 200和ILs）的组分之间的分子相互作用，在293.15处测量了这些纳米流体的密度（d），声速（u）和粘度（\（\ eta \））。 ，298.15、308.15和308.15K。多余的摩尔体积（\（V_ {m} ^ {E} \）），表观摩尔体积（\（V _ {\ phi} \））和等熵压缩率（\（\ kappa_ { s} \））已使用声音数据的密度和速度进行了计算。这些性质可以帮助我们讨论纳米流体的稳定性和体积特征。另外，理论分析\（V_ {m} ^ {E} \），\（\ kappa_ {s} \）和\（\ eta \）是使用某些现有模型（Ott等人，Redlich–Kister，Eyring-mNRF和Eyring）执行的-NRTL），并将所得结果与实验数据进行比较。