Ceramics International xxx (xxxx) xxx Please cite this article as: Neda Sahraeian, Ceramics International, https://doi.org/10.1016/j.ceramint.2020.08.204 Available online 28 August 2020 0272-8842/© 2020 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Hydrothermal synthesis of V 2 O 5 nanospheres as catalyst for hydrogen sulfde removal from sour water Neda Sahraeian a , Feridun Esmaeilzadeh a, b, * , Dariush Mowla a a Department of Oil and Gas and Chemical Engineering, Shiraz University, Shiraz, Iran b Department of Chemical and Petroleum Engineering, School of Chemical and Petroleum Engineering, Enhanced Oil and Gas Recovery Institute, Enhanced Gas Condensate Recovery Research Group, Shiraz University, Shiraz, 7134851154, Iran A R T I C L E INFO Keywords: V 2 O 5 Nanospheres Drying Aggregation Hydrothermal Sour water ABSTRACT Vanadium pentoxide (V 2 O 5 ) nanospheres were synthesized hydrothermally for the frst time with high specifc surface area. The effect of different parameters including pH level, H 2 O 2 /H 2 O volume ratio and reaction tem- perature on the precipitate yield was investigated, and the highest yield was attained at the pH level of 3, H 2 O 2 / H 2 O volume ratio of 0.01 and the reaction temperature of 160 ◦ C. Freeze drying, oven drying and vacuum drying methods along with auxiliary processes were employed to improve the drying process and minimize the ag- gregation of the synthesized nanoparticles (NPs). Two auxiliary processes were used prior to drying in the oven to improve the performance of drying. Firstly, precipitates were immersed in ethanol to get replaced in place of water molecules in a week. The precipitates were then dried at room temperature for a week to evaporate their moisture. In vacuum drying method, only the second auxiliary process was employed. In freeze drying technique, the segregate and uniform nanospheres of V 2 O 5 were produced with an average diameter of 37 nm. Generally, the employed additional treatments cause the drying techniques to enhance and the extent of particles aggre- gation to reduce. Finally, the application of the synthesized NPs as catalyst was investigated for the elimination of H 2 S from sour water with the initial concentration of 1300 ppm. The sour water was provided from Shiraz Oil Refnery Company. Results revealed that the synthesized NPs enable to completely eliminate hydrogen sulfde from sour water with 20% greater conversion at early contact seconds as compared to commercial V 2 O 5 powder. 1. Introduction Nanostructured vanadium pentoxide has received much attention due to its novel physical and chemical properties. Vanadium can exist in different valence states and consequently form various oxides including VO, V 2 O 3 , VO 2 and V 2 O 5 [1]. Among the diverse vanadium oxide compounds, vanadium pentoxide, V 2 O 5 , is thermodynamically most stable [2]. V 2 O 5 nanostructres and V 2 O 5 -based composites have been exploited in a wide variety of applications such as lithium-ion batteries (LIBs) and supercapacitors [3–9], removal of dye from water [10–13], conversion of solar energy via water splitting to hydrogen [10–12,14] and using as a sensor to detect NO X emission [15]. For example, vana- dium pentoxide with their layered structures, high theoretical specifc capacity and high electrochemical potential versus the Li/Li + and tunable number of inserted lithium ions are favorite to be used as a cathode electrode by a variety of authors [3–6]. Supercapacitors are also environment friendly energy storage devices, and heavy metal are not found in their structures. On the other hand, supercapacitors are supe- rior to traditional batteries because of their longer life time and higher power density. Many researchers have reported a high-specifc-capacitance supercapacitor with nanostructured vana- dium oxide electrode [7–9]. Additionally, photocatalysts such as Na 2 Ti 3 O 7 /V 2 O 5 /g-C 3 N 4 [10], Na 2 Ti 3 O 7 nanotube–V 2 O 5 hetero- structures [11], Bi 2 O 3 /V 2 O 5 anchored on graphitic carbon nitride (g-C 3 N 4 ) nanosheets [12] and ZnO-stearic acid/V 2 O 5 -hexadecylamine [13] have been used effciently for the removal of dye from water. Another application of V 2 O 5 as a photocatalyst is to dissociate water into its constituents, hydrogen and oxygen, in the presence of sunlight. This method is a novel and developing technique for the conversion of solar energy to hydrogen, which is a valuable energy source with a high en- ergy value. Recent studies showed an excellent catalytic activity of V 2 O 5 based composites employed in this process [10–12,14]. Furthermore, * Corresponding author. Department of Chemical and Petroleum Engineering, School of Chemical and Petroleum Engineering, Enhanced Oil and Gas Recovery Institute, Enhanced Gas Condensate Recovery Research Group, Shiraz University, Shiraz, 7134851154, Iran. E-mail address: esmaeilzadeh95@gmail.com (F. Esmaeilzadeh). Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint https://doi.org/10.1016/j.ceramint.2020.08.204 Received 11 June 2020; Received in revised form 31 July 2020; Accepted 21 August 2020