Science Journal of Chemistry 2023; 11(2): 45-50 http://www.sciencepublishinggroup.com/j/sjc doi: 10.11648/j.sjc.20231102.11 ISSN: 2330-0981 (Print); ISSN: 2330-099X (Online) Kinetics and Thermodynamic Study of the Acetylation of Cucumeropsis mannii Seed Shell Amalachukwu Ifeyinwa Obi * , Vincent Ismael Egbulefu Ajiwe, Ozioma Juliana Anekwe, Emeka Christian Ezeudu, Cecilia Nkemjika Aduaka Department of Pure and Industrial Chemistry, Nnamdi Azikiwe University, Awka, Nigeria Email address: * Corresponding author To cite this article: Amalachukwu Ifeyinwa Obi, Vincent Ismael Egbulefu Ajiwe, Ozioma Juliana Anekwe, Emeka Christian Ezeudu, Cecilia Nkemjika Aduaka. Kinetics and Thermodynamic Study of the Acetylation of Cucumeropsis mannii Seed Shell. Science Journal of Chemistry. Vol. 11, No. 2, 2023, pp. 45-50. doi: 10.11648/j.sjc.20231102.11 Received: March 3, 2023; Accepted: March 21, 2023; Published: March 31, 2023 Abstract: The use of lignocellulosic materials for oil sorption from aqueous medium has directed attention to acetylation as a means of increasing the hydrophobicity of these materials. In this paper, acetylation of Cucumeropsis mannii seed shell, a readily available agricultural waste, was studied. Effects of different acetylation conditions on the extent of acetylation of the seed shell was investigated. The kinetics of the acetylation process was studied using pseudo first order, pseudo second order, and intraparticle diffusion models. The thermodynamics of the acetylation process was also studied. FTIR analysis provided evidence of successful acetylation of the seed shell. The extent of acetylation increased with increase in acetylation duration, temperature and catalyst concentration. Pseudo second order kinetics best described the acetylation process, with minimum extent of acetylation and rate constant values of 0.317 and -0.0148 min -1 , respectively. Thermodynamic studies revealed that the acetylation process was endothermic in nature. The critical extent of acetylation, heat capacity at constant pressure, and change in entropy values were 1.002, 0.162 kJ.mol -1 .K -1 , and 0.020 kJ.mol -1 .K -1 , respectively. The acetylation process was spontaneous at temperatures of 328 K ‒ 348 K, but non-spontaneous at lower temperatures (308 K and 318 K). The critical temperature of acetylation was 419 K, which shows that acetylation of CMSS can easily take place at mild conditions. Keywords: Acetylation, Cucumeropsis mannii Seed Shell, Kinetics, Thermodynamics 1. Introduction Lignocellulosic materials are substances made up of lignin, cellulose and hemicellulose. Agricultural wastes belong to this class of materials, and due to their low cost, renewability and biodegradability, they are usually employed for numerous purposes which include paper manufacture, biofuel production, cement preparation, and as sorbents for removal of organic and inorganic pollutants from aqueous medium. Most of these agricultural wastes are hydrophilic in nature due to the abundance of hydroxyl groups in their cell wall [1]. This hydrophilic nature affects their oil sorption performance in aqueous medium. In order to address this, hydrophobic modifications are usually performed on these materials. One of the most popular modification methods is acetylation, which converts the hydrophilic properties of these lignocellulosic materials to hydrophobic ones by raising their acetyl contents and lowering their hydroxyl contents [2]. Previous studies have been carried out on the acetylation of various agricultural materials such as corn cob [3], Delonix regia pods [4], sugarcane bagasse and groundnut husk [5], Pinus taeda wood [6], oil palm empty fruit bunch fiber [2, 1], wheat straw [7], coconut coir [8], pride of Barbados and cocoa pods [1], Ensete ventricosum plant fibre [9], and Borassus aethopum coir [10]. Cucumeropsis mannii, commonly called white-seed melon, is a species of melon native to tropical West-Africa [11]. It is a tendril climber or crawling annual crop with a fibrous and shallow root system that is used primarily as a subsidiary crop inter-planted with early maize and yam in the savanna belts of Nigeria [12]. It is often grown for its seeds which are high in protein and oil content [13]. The seed shell is not edible and is usually discarded, thereby constituting environmental pollution. This study investigates the suitable conditions for the