RESEARCH ARTICLE www.ms-journal.de Synthesis of Novel CuO–Gelatin Nanoﬂuids Using Ultrasonic Technique Mathana Gopal Arunachalam,* Padmavathi Paulraj, Irudaya Sahaya Lancy Sreedharan, Krishna Kumar Pandey, Poongodi Jawaharlal, and James C. Nanoﬂuid molecular properties, such as acoustical properties, vary widely in system parameters and are inﬂuenced by liquid cohesive characteristics. Gelatin is a natural polymer made from the partial hydrolysis of collagen, which allows the triple helix to unfold and split, resulting in a polydisperse mixture of proteins in solution. The use of ultrasonic technology to create nanoparticles from biopolymer base ﬂuids is a novel method of nanoﬂuid synthesis. The focus of this research is to measure the ultrasonic velocity and density of synthesized nanoparticles using gelatin as the base ﬂuid at various weight percentages. The study have synthesized the Copper oxide (CuO) nanoﬂuid by transforming an unstable Cu(OH) 2 to CuO as a precursor in aqueous gelatin by ultrasonication process. To characterize the prepared nanoparticles, the XRD and FESEM methods are used. The results of ultrasonic velocity, density, and viscosity measurements are discussed after ultrasonication. Experimental data and a theoretical approach to nanoﬂuids are used to study the stability of nanoﬂuids. The outcomes of ultrasonic spectroscopy and other investigations are very similar. 1. Introduction The conventional working ﬂuid which is used in various heat exchangers such as water, oil, ethylene glycol plays an impor- tant role in many engineering applications for heating and cool- ing processes. To increase the heat transfer eﬃciency several methods can be adopted such as utilization of extended surfaces, M. G. Arunachalam, P. Paulraj, I. S. L. Sreedharan, J. C. PG & Research Department of Physics Scott Christian College Nagercoil, Tamil Nadu 629003, India E-mail: matgop04@gmail.com K. K. Pandey Acoustics Research Laboratory Department of Physics School of Basic Sciences and Research Sharda University Greater Noida, Uttar Pradesh 201310, India P. Jawaharlal Department of Physics Kamaraj College Thoothukudi, Tamil Nadu 628003, India The ORCID identiﬁcation number(s) for the author(s) of this article can be found under https://doi.org/10.1002/masy.202200007 DOI: 10.1002/masy.202200007 applying vibration to the heat transfer sur- faces, and improving the thermal conduc- tivity of the working ﬂuids. The term nanoﬂuid was ﬁrst used by Choi [1] at Argonne National Laboratory in the USA. At present the development takes place in the ﬁeld of nanoscience, the nanoﬂuid are very useful as working ﬂuid due to more heat transfer enhancement. The application of nanoﬂuid has a strong potential for en- hancing the heat transfer in any type of heat exchanger. [2,3] The important requirements considered while preparation of nanoﬂuid is even sus- pension, no chemical changes, and low agglomeration and stable suspension. By using any nanomaterial or oxides with baseﬂuid the nanoﬂuid can prepare by the single-step method or two stepmethod (dispersionmethod). [4–10] 2. Results and Discussions Peaks at 2 values corresponding to the lattice planes of CuO nanoparticles were obtained. CuO nanoparticles with a mon- oclinic structure and a crystalline size of 55.53 nm were pro- duced as conﬁrmed by JCPDS card no. 77–1898. XRD patterns of nanoparticles reveal an excellent crystalline structure among the peaks in their particle size range shown in Figure 1. Images of dry CuO nanoparticles were taken with a FESEM. Highly ag- glomerated particles in the micrometer range are observed under atmospheric conditions, with the bulk of nanoparticles appearing spherical in shape. As a result, the results revealed that the CuO nanoparticles are both spherical in shape shown in Figure 2. [11–13] Ultrasonic velocity of CuO–Gelatin increased as the tempera- ture increased from 308 to 333K. The ultrasonic velocity of CuO– Gelatin increases with weight percentage increases. This results in CuO–Gelatin molecular interactions with a maximum range of 1577 m s −1 , as shown in Figure 3. In Figure 4, the relative den- sity decreases with increase in temperature of all weight percent- ages with uniform behavior. Similarly Auerbach surface tension also shows the same at decreases in parameters at 323 K for all wt% shown in Figure 5. Where the viscosity can also be seen to show the uniform behavior of the CuO–Gelatin while increas- ing the weight percentage, the viscosity also decreases while in- creasing the temperature shows the extensive polymer behavior in Figure 6. Macromol. Symp. 2023, 407, 2200007 © 2023 Wiley-VCH GmbH 2200007 (1 of 4)