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Nowadays, zinc oxide (ZnO) has attracted attention in research and development because of its remarkable antibacterial properties. Chitosan/ZnO nanoparticles were successfully synthesized via microwave heating. The objectives of this work were to investigate the effect of stabilizer, power heating and time heating on size of chitosan/ZnO nanoparticles and to determine antibacterial activity against pathogenic bacteria, where chitosan was used as a stabilizing agent. Chitosan/ZnO nanoparticles were analyzed by Fourier Transform Infra Red (FTIR), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Zetasizer instrument. The power heating and time heating were varied from 400 to 800 Watt and 4 to 8 minutes, respectively. The presence of chitosan has role on preventing the nanoparticles from agglomeration by producing a milky solution of chitosan/ZnO nanoparticles without any suspensions. The increase of power and time heating improved the size of nanoparticles. The peak in FTIR spectrum at around 427 cm -1 was confirmed the existence of the ZnO phase. XRD patterns showed that the chitosan/ZnO nanoparticles materials were pure phase with average crystalline size is 130 nm. FESEM revealed that chitosan/ZnO nanoparticles were uniformly distributed with the mean value of size is 70 nm and spherical shaped. Further impact of power and time heating on the size of the chitosan/ZnO nanoparticles can be shown by a nanoparticles size distribution with the average of 30 to 90 nm. The results showed that chitosan/ZnO nanoparticles have displayed an antibacterial inhibition zone against Gram-positive S. aureus and Gram-negative E. coli which 16.0 and 13.3 mm, respectively. Chitosan/ZnO nanoparticles were synthesized in this work presented have potential application to prevent bacterial infections.

The conventional heating methods of nanoparticle synthesis regularly depend on the energy inputs from outer heat sources that resulted high energy intake and low reaction competences. In this paper ZnO nanoparticles stabilized with gum arabic are synthesized using precipitating method assisted by simple and cost effective microwave heating technique. The objective of this work is to investigate the effect of microwave irradiation time towards ZnO nanoparticles morphology and size. The effect of microwave irradiation time has been investigated at 2, 4, 6, and 10 minutes. Dynamic Light Scattering (DLS) was employed to measure the size of ZnO nanoparticles. Ultraviolet–Visible spectroscopy (UV-vis), Fourier-Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) were used for the characterization of the ZnO nanoparticles. UV-vis absorption spectrum was found in the range of 350 nm indicating the absorption peak of ZnO nanoparticles. FTIR spectra showed peaks range from 424 to 475 cm–1 which indicating standard of Zn–O stretching. The presence of (100), (002), and (101) planes were apparent in the XRD result, indicating the crystalline phase of ZnO nanoparticles. The increase in the microwave irradiation time affected the processes of nucleation and crystal growth promoted larger ZnO nanoparticles size. Microwave irradiation time at 2 minutes was selected as the best microwave irradiation time for smallest ZnO nanoparticles averaging about 168 nm sizes based on DLS analysis. Copyright © 2019 BCREC Group. All rights reservedReceived: 1st October 2018; Revised: 22nd November 2018; Accepted: 12nd December 2018; Available online: 25th January 2019; Published regularly: April 2019How to Cite: Pauzi, N., Zain, N.M., Yusof, N.A.A. (2019). Microwave-assisted Synthesis of ZnO Nanoparticles Stabilized with Gum Arabic: Effect of Microwave Irradiation Time on ZnO Nanoparticles Size and Morphology. Bulletin of Chemical Reaction Engineering & Catalysis, 14 (1): 182-188 (doi:10.9767/bcrec.14.1.3320.182-188)Permalink/DOI: https://doi.org/10.9767/bcrec.14.1.3320.182-188

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The tropical white peppercorns are common commodity crops which have been traditionally used for the treatment of many free radical-related diseases. These medicinal properties are due to the presence of natural antioxidants. This study investigated the combination of microwave extraction parameters for the recovery of natural antioxidants from the white pepper matrix. Microwave-assisted technique was used for the extraction of bioactive oleoresin from white pepper. Taguchi experimental design was employed to investigate the combination of independent extraction parameters for optimal recovery of natural antioxidants. The feed backpropagation artificial neural network model was thereafter applied to optimally predict the result for the different combination of operating parameters. This was achieved by evaluating different algorithms, transfer functions, and neurons. The result obtained from the orthogonal parametric study gave an optimal antioxidant activity of 91.02% at irradiation time of 120 min, microwave power level of 350 W, particle size of 0.300 mm, and liquid-to-solid ratio of 6 mL/g. The gradient descent (GD) algorithm, tansigmoid transfer function, and 4-x-3 topology were used to model the experimental data. A better prediction was then obtained with an overall coefficient (R) and mean square error (MSE) of 0.9595 and 1.4381, respectively. In this study, the feedforward backpropagation neural network was successfully applied to optimally evaluate the complex relationship between the input extraction parameters and the response.

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