Eastern-European Journal of Enterprise Technologies ISSN 1729-3774 3/6 ( 123 ) 2023 32 VALORIZATION OF CASHEW NUT PROCESSING BY-PRODUCT: DEVELOPMENT OF A CARDOL/STARCH BIOPOLYMER COMPOSITE WITH ELECTROCHEMICAL PROPERTIES AND TECHNOLOGICAL POTENTIAL Alvaro Angel Arrieta Corresponding author Doctor in Advanced Chemistry, Professor Department of Biology and Chemistry* E-mail: alvaro.arrieta@unisucre.edu.co Jorge Alberto Ducuara Biologist, Master's student in Environmental Sciences* Enrique Miguel Combatt Doctor en Ciencia de Suelos, Profesor Department of Agricultural Engineering and Rural Development Universidad de Cordoba avе., 6, 77-305, Montería, Colombia, PC 230002 *Research Group in Development and Innovation in Advanced Materials University of Sucre ave., 28, No. 5-267, Red Door neighborhood-Sincelejo, Colombia, PC 700001 The problem of food agro-industry res- idues represents a growing concern in our society, therefore its use as a raw material to obtain biopolymers of technological interest is an attractive alternative. The objective of this work was to assess the viability of utilizing cardol, derived from cashew nut shell liquid, in the production of a biopolymer composite by combining it with cassava starch. The bio- polymer composite was prepared by thermo- chemical method using different cardol con- centrations and varying the synthesis pH. The results allowed us to demonstrate the forma- tion of cardol/starch biopolymeric films. The infrared spectra showed possible interactions by hydrogen bonds between the cardol and the glucose units of the starch. The impedance behavior showed a similar conduction mecha- nism in all cases, allowing the establishment of a single equivalent circuit. The electrochemical parameters showed that the presence of car- dol and the lower pH increased the values of the electrical resistance and the double layer capacitance in the biopolymers. In addition, the values of the CPE/Rre system, related to the electractivity, were not affected by the pH, but by the presence of cardol. The biodegrad- ability tests showed a complete decomposi- tion of the biopolymer composite films in three stages in a period of 17 to 19 days. It could be concluded that it is possible to use the cardol extracted from the cashew nut shell liquid to elaborate a biopolymer composite with elec- trochemical properties when combined with cassava starch. The electrical properties of the biopolymer can be modulated by varying the synthesis pH and the amount of cardol used. The composite cardol/starch biopolymer could be used as a biopolymeric solid electrolyte in the manufacture of batteries, capacitors, etc. Keywords: cardol, cassava, biopolymer, electrochemistry, composite, waste, cashew, nut, shell, starch UDC 330 DOI: 10.15587/1729-4061.2023.282208 How to Cite: Arrieta, A. A., Ducuara, J. A., Combatt, E. M. (2023). Valorization of cashew nut processing by-product: development of a cardol/starch biopolymer composite with electrochemical properties and technological potential. Eastern-European Journal of Enterprise Technologies, 3 (6 (123)), 32–41. doi: https://doi.org/10.15587/1729-4061.2023.282208 Received date 12.04.2023 Accepted date 22.06.2023 Published date 30.06.2023 1. Introduction Carrying out research on the use of residues from the food agribusiness to produce new biopolymers is of the utmost importance. These investigations allow the develop- ment of innovative technologies that promote the efficient use of resources, the reduction of waste and the generation of sustainable materials. In addition, by turning waste into value-added products, the circular economy is fostered and the transition towards a greener and more environmentally friendly industry is promoted. Materials made from biological resources with renew- able, biodegradable and low-cost properties have attracted the attention of research centers and industry, allowing new alternatives to replace non-renewable products to be explored. In addition, the sources of raw material for the new bio-based materials are concentrated in agro-industrial products, waste or by-products, thus reducing post-harvest residues and generating added value in production [1–4]. Among the agro-industrial waste is the shell of the cashew nut, which is a by-product of obtaining the almond. Annu- ally its world production of this fruit exceeds 4.1 million tons [5]. This residue is rich in an oil called cashew nut shell liquid (CNSL), it presents a reddish-brown color due to car- bonization and chemical changes, CNSL constitutes about 20–25 % of the weight of the cashew [5, 6]. The main components of CNSL are long chain substi- tuted phenolic compounds at the meta position. These com- pounds can be used as a basis for the production of polymeric substances widely used in industry. CNSL has an attractive Copyright © 2023, Authors. This is an open access article under the Creative Commons CC BY license