The Performance of Nanosilicate from Rice Husk Ash as Green Corrosion Inhibitor for Carbon Steel in 0.5M HCl Denni Asra Awizar 1, a ,Norinsan Kamil Othman 1,b* , Abdul Razak Daud 1,c , Azman Jalar 2,d and Rabiahtul Zulkafli 1,e 1 School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Malaysia 2 Institute of Micro Engineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor Malaysia a deny_chemistry@yahoo.com, b insan@ukm.my, c ard@ukm.my, d azmn@ukm.my, e rabiahtulzulkafli@yahoo.com Keywords: Corrosion inhibitor, nano silicate, TEM and rice husk ash Abstract. Nanosilica powder produced from rice husk ash (RHA) via NaOH treatment has particle size in the range of 10-20 nm as revealed by transmission electron microscopy (TEM). The inhibitive action of nanosilicate from RHA on the corrosion of carbon steel SAE 1045 in 0.5M HCl solution was studied using weight loss and potentiodynamic polarization methods. Result shows that the inhibition efficiency was increased with increasing of the inhibitor concentration. Nanosilicate was tremendously effective on carbon steel; exhibiting high inhibition efficiency attained 99% at optimum concentration of 175 ppm. Pitting was not observed on surface of carbon steel when the inhibitor was present. This finding was confirmed from surface morphology by scanning electron microscopy (SEM). Introduction Prevention and protection of corrosion are the vital aspects in controlling and maintaining the preservation of metals and alloys. There are many ways to protect or reduce the degradation of metals and alloy, such as modifying its composition, surface properties and avoiding from the corrosive environment [1]. Due to the high costs and problems associated with corrosion-resistant materials, the use of corrosion inhibitors is a realistic and cost-effective alternative which can be designed-in. Many researchers actively reported on the use of natural plant in developing green and environmental friendly corrosion inhibitors for metals and alloys [2]. Furthermore, the consumption of local natural raw material in developing the corrosion inhibitors gives worth to the country. It is well known that silicate is effective corrosion inhibitor and has been used to protect many nonferrous metals used in potable water system. Silicates are excellent corrosion inhibitor for carbon steel [3], zinc [4], magnesium [5], and aluminum; however the dosages for this purpose are higher than normally used for potable service [6]. Amaraki, (2001) found that on the surface of zinc formed a protective film composed of a small amount of silicate and zinc hydroxide [4, 7]. Natural plants contain vast amount of silica such from RHA, coconut fiber, bamboo, wheat husk, corn straw, and sawdust. Among the various resources, RHA is an excellent source of silica powder [8]. Concerning the availability of silica in RHA, this renewable resource from agro-waste material would be ideal for the plant-based corrosion inhibitor. Nano particles of silica are thermally stable, cheap, and environmentally benign ceramics. Recently, silica nano particle have been considered to be effective for chemical-mechanical protection material [9]. Zandi-zand et al. (2005) incorporated silica nanoparticles into the organic-inorganic hybrid nanocomposite coatings for corrosion protection. Other researchers [10-12] have carried out the commercial nano silica to protect metal interface, nevertheless nano particle of silica from rice husk ash (RHA) for corrosion inhibitor is not well understood. In this study, the nano silica extracts from RHA was used to produce green corrosion inhibitor solution for protecting carbon steel in acid medium. Materials Science Forum Vol. 756 (2013) pp 266-272 © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.756.266 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 202.185.32.2, Universiti Kebangsaan Malaysia, Bangi, Malaysia-13/03/13,03:15:19)