Functionalization of ZnO Particles with Tetraethyl Orthosilicate (TEOS) and Application as Heavy Metal Adsorbent Cu²⁺

Department of Chemistry, Faculty of Mathematics and Natural Sciences, State University of Malang, Malang, Indonesia

^* Corresponding author: adilah.aliyatulmuna.fmipa@um.ac.id

Abstract

The increase in Indonesia’s population is directly proportional to industrial growth which also has an impact on the industrial waste produced. One type of waste that is mostly generated from the industrial sector is Cu²⁺ heavy metal waste. Research that has been developed to overcome this problem is the use of adsorbents such as TiO₂, SiO₂, Al₂O₃, and zinc oxide (ZnO). The presence of silanol groups aims to control particle size homogeneity and increase the ability of ZnO particles as heavy metal adsorbents. The research was carried out by synthesizing ZnO particles and then functionalizing them with the addition of by adding tetraethyl orthosilicate (TEOS) as a coating on the surface of ZnO particles through the coprecipitation method. The synthesized PZnO and S-ZnO particles were tested with Atomic Absorption Spectrophotometer (AAS) to determine the absorption ability of S-ZnO and P-ZnO particles. The test results showed that the adsorption capacity of P-ZnO was 202.11 mg/g and S-ZnO was 202.54 mg/g with an adsorbent mass of 16 mg. The adsorption isotherm model of P-ZnO and S-ZnO particles followed Temkin’s model with an adsorption heat on P-ZnO particles of 1.35 x 10^-3 kJ/mol and S-ZnO particles of 7.67 x 10^-3 kJ/mol, and a physical interaction between adsorbent and adsorbate. P-ZnO particles had a ΔG value of -14.00 kJ/mol and ΔS of 0.09 kJ/mol.K while S-ZnO particles had a ΔG value of -13.401 kJ/mol and ΔS of 0.07 kJ/mol K which indicated that adsorption occurred spontaneously. The ΔH value of P-ZnO was 12.34 kJ/mol and S-ZnO was 7.21 kJ/mol which indicated that the reaction occurred endothermically.