AIM: With the increased bacterial resistance and the resulting problems in recent years, it seems necessary to find new biocompatible compounds to confront this problem. This research was conducted to optimise the synthesis of cobalt oxide nanoparticles with the highest antibacterial activity. METHODS: In the present study, 9 experiments were designed using the Taguchi method. The effect of three factors of cobalt nitrate, KOH and the stirring time in the synthesis of cobalt oxide nanoparticles with the highest antibacterial activity was investigated. The bactericidal effect of synthesised nanoparticles was evaluated using the colony-forming unit (CFU) and disk diffusion methods. The characteristics of nanoparticles were studied using the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and the scanning electron microscopy (SEM). RESULTS: The results indicated that all three evaluated factors were effective on the antibacterial properties of the synthesised nanoparticles. The best antibacterial activity of cobalt oxide nanoparticles was observed in experiment 9 (cobalt nitrate 0.6 M, KOH 2M and stirring time 60 min). The study of nanoparticles synthesised by FTIR, XRD, and SEM confirmed the formation of cobalt oxide nanoparticles with size (24 nm) and a proper structure (spinel structure). CONCLUSION: Due to the optimal antibacterial properties of the synthesised cobalt oxide nanoparticles, they can be used in the fabrication of dental and medical equipment with antibacterial properties.

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Activated charcoal bio adsorbent is a method that can be developed because the raw material is easy to obtain and does not require large costs such as processing sago. The stages of making activated carbon include the stages of dehydration, carbonization, and extraction of silica using 4% NaOH solution (1:10). The activation stage successively used 250 mL of 1M NaCl, 1M MgCl2, 1M CaCO3, 1M K2Cr2O7 and the addition of 100 mL of 1M HNO3, 3% H2O2, 1M H3PO4 and 4NH2SO4 respectively. The activation process uses a water bath at 700°C for 3 hours. In the conventional carbonization stage in a vacuum used drum for 1x24 hours. Physicochemical analysis of activated carbon products, namely moisture content, ash content, pH, Activated Carbon Adsorption Test against Iod Test and methylene blue. FT-IR analysis showed a wide band of 3442.94 cm‒1 to 3415.93 cm‒1 which showed the free O-H strain vibrations of the OH group in the cellulose molecule. 1178.51 cm‒1, –1039.53 cm‒1, -1024.20 cm‒1, C-C and C-O-C glycosidic ether band. SEM data describes the differences in the surface morphological structure of each sample and is supported by XRD data.

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Zeolites are compounds which have many applications in chemistry and industry; therefore, studies of synthesis of zeolites are of great importance. In this work, kinetic and thermodynamic study of hydrothermal crystallization for zeolite synthesis process performed at different time intervals (17, 20, 23 and 26 h) and various temperatures (70, 90, 110 and 125 0 C). By time intervals we got out the rate of the zeolite synthesis reaction in this research was first order. The synthesized zeolites were similar in their crystallinity according to the Zeolites synthesis at different of the time intervals. The thermodynamic parameters indicated that the change in Gibbs free energy was negative value. The degrees of crystallinity of the synthesized zeolites decreased with increasing the hydrothermal crystallization temperature. Moreover, the change of hydrothermal crystallization time and temperature caused synthesis of different types of zeolites. The synthesized zeolite samples characterized by Infra-Red (IR), X-ray diffraction (XRD), X-ray Fluorescence (XRF) and scanning electron microscopy (SEM). The variation of chemical compositions led to differences in morphologies and crystallinity of the synthesized zeolites.