Vol.:(0123456789) 1 3 J Mater Sci: Mater Electron DOI 10.1007/s10854-017-7023-2 Arabic gum as green agent for ZnO nanoparticles synthesis: properties, mechanism and antibacterial activity Muneer M. Ba‑Abbad 1,2,4  · Mohd S. Takrif 1,2  · Abdelbaki Benamor 3  · Ebrahim Mahmoudi 1  · Abdul Wahab Mohammad 1,2   Received: 27 January 2017 / Accepted: 25 April 2017 © Springer Science+Business Media New York 2017 coli against which higher activity, explained by smaller size of the ZnO NPs, was obtained. 1 Introduction Recently, zinc oxide nanoparticles (ZnO NPs) have become one of the most important commercial nanomaterials in the world. This importance is due to their multiple applications such as in photodetectors, paints, gas and biosensors, elec- tronics, lasers, transistors, optoelectronics, solar cells, cos- metics, biomedicine, the food industry, anticorrosive coat- ings, antibacterial and antifungal agents and photocatalysts [1]. To apply ZnO NPs to prominent applications needs special fabrication to control the morphology and func- tionalisation of the surface, as well as the optical properties [2]. Two main methods of synthesis of ZnO NPs, physical and chemical, have been reported, and include evaporation, pulse laser deposition, sputtering and pyrolysis, hydrother- mal, co-precipitation, and sol–gel methods [3]. All these methods could assist to control morphology (as shape, size) and properties of ZnO NPs by optimising the infu- ence of parameters such as molar ratio, pH, calcination temperature, solvent, the presence of additives as capping agents, etc. [4]. Many previous studies have used a capping agent or a surfactant as additive to manage the size of ZnO NPs, but these additives are toxic and costly chemicals, and eradicating them from the surface of the synthesised nanoparticles would prove to be an arduous task. Therefore, large-scale production of nanoparticles would undoubt- edly result in serious contamination of the environment [5]. Diferent additives used as capping agents, such as polyethylene glycol (PEG), polyvinyl alcohol (PVA), eth- ylene diamine, triethanolamine, tetraethyl ammonium bro- mide, glycine, gelatin and octadecyltrimethoxysilane have Abstract The size and morphology of ZnO nanoparticles (ZnO NPs) were controlled in the presence of the natural and green agent, Arabic gum. Lower amounts of Arabic gum showed a greater efect on the size and morphology as well as on the properties of ZnO NPs prepared by a sol– gel method. The hexagonal wurtzite crystal structure was found for all samples ZnO NPs with no other phase for impurities. The size of the spherically shaped ZnO NPs decreased with an increase in the amount of Arabic gum, up to an optimal 1.50 wt%. The smaller size of ZnO NPs of 16 nm was obtained with the optimal amount of Arabic gum, compared to 32 nm produced without Arabic gum. These results were attributed to the ready reaction between Arabic gum molecules and zinc ions within the nucleation and growth processes of ZnO NPs. The optical proper- ties of ZnO NPs, with a band gap of 3.4 eV and enhanced intensity of blue emission, were the result of the smaller size of ZnO at the optimal amount of Arabic gum. Accord- ing to the experimental results, a mechanism to elucidate the formation of ZnO NPs was proposed and explained. The antibacterial activity was tested against Escherichia * Muneer M. Ba-Abbad muneer711@gmail.com 1 Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia 2 Research Centre for Sustainable Process Technology, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia 3 Gas Processing Centre, Qatar University, P.O. Box 2713, Doha, Qatar 4 Department of Chemical Engineering, Faculty of Engineering and Petroleum, Hadhramout University of Science & Technology, Mukalla, Hadhramout, Yemen